Network Working Group T. Berners-Lee, MIT/LCS Request for Comments: 1945 R. Fielding, UC Irvine Category: Informational H. Frystyk, MIT/LCS May 1996
HTTP has been in use by the World-Wide Web global information initiative since 1990. This specification reflects common usage of the protocol referred to as "HTTP/1.0".
1. Introduction 1.1 Purpose 1.2 Terminology 1.3 Overall Operation 1.4 HTTP and MIME 2. Notational Conventions and Generic Grammar 2.1 Augmented BNF 2.2 Basic Rules 3. Protocol Parameters 3.1 HTTP Version 3.2 Uniform Resource Identifiers 3.2.1 General Syntax 3.2.2 http URL 3.3 Date/Time Formats 3.4 Character Sets 3.5 Content Codings 3.6 Media Types 3.6.1 Canonicalization and Text Defaults 3.6.2 Multipart Types 3.7 Product Tokens 4. HTTP Message 4.1 Message Types 4.2 Message Headers 4.3 General Header Fields 5. Request 5.1 Request-Line 5.1.1 Method 5.1.2 Request-URI 5.2 Request Header Fields 6. Response 6.1 Status-Line 6.1.1 Status Code and Reason Phrase 6.2 Response Header Fields 7. Entity 7.1 Entity Header Fields 7.2 Entity Body 7.2.1 Type 7.2.2 Length 8. Method Definitions 8.1 GET 8.2 HEAD 8.3 POST 9. Status Code Definitions 9.1 Informational 1xx 9.2 Successful 2xx 200 OK 201 Created 202 Accepted 204 No Content 9.3 Redirection 3xx 300 Multiple Choices 301 Moved Permanently 302 Moved Temporarily 304 Not Modified 9.4 Client Error 4xx 400 Bad Request 401 Unauthorized 403 Forbidden 404 Not Found 9.5 Server Error 5xx 500 Internal Server Error 501 Not Implemented 502 Bad Gateway 503 Service Unavailable 10. Header Field Definitions 10.1 Allow 10.2 Authorization 10.3 Content-Encoding 10.4 Content-Length 10.5 Content-Type 10.6 Date 10.7 Expires 10.8 From 10.9 If-Modified-Since 10.10 Last-Modified 10.11 Location 10.12 Pragma 10.13 Referer 10.14 Server 10.15 User-Agent 10.16 WWW-Authenticate 11. Access Authentication 11.1 Basic Authentication Scheme 12. Security Considerations 12.1 Authentication of Clients 12.2 Safe Methods 12.3 Abuse of Server Log Information 12.4 Transfer of Sensitive Information 12.5 Attacks Based On File and Path Names 13. Acknowledgments 14. References 15. Authors' Addresses Appendix A. Internet Media Type message/http Appendix B. Tolerant Applications Appendix C. Relationship to MIME C.1 Conversion to Canonical Form C.2 Conversion of Date Formats C.3 Introduction of Content-Encoding C.4 No Content-Transfer-Encoding C.5 HTTP Header Fields in Multipart Body-Parts Appendix D. Additional Features D.1 Additional Request Methods D.1.1 PUT D.1.2 DELETE D.1.3 LINK D.1.4 UNLINK D.2 Additional Header Field Definitions D.2.1 Accept D.2.2 Accept-Charset D.2.3 Accept-Encoding D.2.4 Accept-Language D.2.5 Content-Language D.2.6 Link D.2.7 MIME-Version D.2.8 Retry-After D.2.9 Title D.2.10 URI
Practical information systems require more functionality than simple retrieval, including search, front-end update, and annotation. HTTP allows an open-ended set of methods to be used to indicate the purpose of a request. It builds on the discipline of reference provided by the Uniform Resource Identifier (URI) [2], as a location (URL) [4] or name (URN) [16], for indicating the resource on which a method is to be applied. Messages are passed in a format similar to that used by Internet Mail [7] and the Multipurpose Internet Mail Extensions (MIME) [5].
HTTP is also used as a generic protocol for communication between user agents and proxies/gateways to other Internet protocols, such as SMTP [12], NNTP [11], FTP [14], Gopher [1], and WAIS [8], allowing basic hypermedia access to resources available from diverse applications and simplifying the implementation of user agents.
Most HTTP communication is initiated by a user agent and consists of a request to be applied to a resource on some origin server. In the simplest case, this may be accomplished via a single connection (v) between the user agent (UA) and the origin server (O).
request chain ------------------------> UA -------------------v------------------- O <----------------------- response chainA more complicated situation occurs when one or more intermediaries are present in the request/response chain. There are three common forms of intermediary: proxy, gateway, and tunnel. A proxy is a forwarding agent, receiving requests for a URI in its absolute form, rewriting all or parts of the message, and forwarding the reformatted request toward the server identified by the URI. A gateway is a receiving agent, acting as a layer above some other server(s) and, if necessary, translating the requests to the underlying server's protocol. A tunnel acts as a relay point between two connections without changing the messages; tunnels are used when the communication needs to pass through an intermediary (such as a firewall) even when the intermediary cannot understand the contents of the messages.
request chain --------------------------------------> UA -----v----- A -----v----- B -----v----- C -----v----- O <------------------------------------- response chainThe figure above shows three intermediaries (A, B, and C) between the user agent and origin server. A request or response message that travels the whole chain must pass through four separate connections. This distinction is important because some HTTP communication options may apply only to the connection with the nearest, non-tunnel neighbor, only to the end-points of the chain, or to all connections along the chain. Although the diagram is linear, each participant may be engaged in multiple, simultaneous communications. For example, B may be receiving requests from many clients other than A, and/or forwarding requests to servers other than C, at the same time that it is handling A's request.
Any party to the communication which is not acting as a tunnel may employ an internal cache for handling requests. The effect of a cache is that the request/response chain is shortened if one of the participants along the chain has a cached response applicable to that request. The following illustrates the resulting chain if B has a cached copy of an earlier response from O (via C) for a request which has not been cached by UA or A.
request chain ----------> UA -----v----- A -----v----- B - - - - - - C - - - - - - O <--------- response chainNot all responses are cachable, and some requests may contain modifiers which place special requirements on cache behavior. Some HTTP/1.0 applications use heuristics to describe what is or is not a "cachable" response, but these rules are not standardized.
On the Internet, HTTP communication generally takes place over TCP/IP connections. The default port is TCP 80 [15], but other ports can be used. This does not preclude HTTP from being implemented on top of any other protocol on the Internet, or on other networks. HTTP only presumes a reliable transport; any protocol that provides such guarantees can be used, and the mapping of the HTTP/1.0 request and response structures onto the transport data units of the protocol in question is outside the scope of this specification.
Except for experimental applications, current practice requires that the connection be established by the client prior to each request and closed by the server after sending the response. Both clients and servers should be aware that either party may close the connection prematurely, due to user action, automated time-out, or program failure, and should handle such closing in a predictable fashion. In any case, the closing of the connection by either or both parties always terminates the current request, regardless of its status.
name = definition
"<"
and ">"
) and is
separated from its definition by the equal character "="
. Whitespace is only significant in
that indentation of continuation lines is used to indicate a rule definition that spans more
than one line. Certain basic rules are in uppercase, such as SP
, LWS
, HT
, CRLF
, DIGIT
,
ALPHA
, etc. Angle brackets are used within definitions whenever their presence will
facilitate discerning the use of rule names.
"literal"
rule1 | rule2
"I"
) are alternatives, e.g., "yes | no"
will accept yes
or no
.
(rule1 rule2)
"(elem (foo | bar) elem)"
allows the token sequences "elem foo elem"
and "elem bar elem"
.
*rule
"*"
preceding an element indicates repetition. The full form is
"<n>*<m>element"
indicating at least <n>
and at most <m>
occurrences of element
. Default
values are 0
and infinity so that "*(element)"
allows any number, including zero; "1*element"
requires at least one; and "1*2element"
allows one or two.
[rule]
"[foo bar]"
is equivalent to "*1(foo bar)"
.
rule
"<n>(element)"
is equivalent to "<n>*<n>(element)"
; that is, exactly <n>
occurrences of (element)
. Thus 2DIGIT
is a 2-digit number, and 3ALPHA
is a string of three
alphabetic characters.
#rule
"#"
is defined, similar to "*"
, for defining lists of elements. The full form is
"<n>#<m>element"
indicating at least <n>
and at most <m>
elements, each separated by one
or more commas (","
) and optional linear whitespace (LWS). This makes the usual form of
lists very easy; a rule such as "( *LWS element *( *LWS "," *LWS element ))
" can be shown as
"1#element"
. Wherever this construct is used, null elements are allowed, but do not
contribute to the count of elements present. That is, "(element), , (element)"
is permitted, but
counts as only two elements. Therefore, where at least one element is required, at least one
non-null element must be present. Default values are 0
and infinity so that "#(element)"
allows any number, including zero; "1#element"
requires at least one; and "1#2element"
allows one or two.
; comment
implied *LWS
LWS
) can be included between any two adjacent words (token
or
quoted-string
), and between adjacent tokens and delimiters (tspecials
), without changing the
interpretation of a field. At least one delimiter (tspecials
) must exist between any two
tokens, since they would otherwise be interpreted as a single token. However, applications
should attempt to follow "common form" when generating HTTP constructs, since there
exist some implementations that fail to accept anything beyond the common forms.
OCTET = <any 8-bit sequence of data> CHAR = <any US-ASCII character (octets 0 - 127)> UPALPHA = <any US-ASCII uppercase letter "A".."Z"> LOALPHA = <any US-ASCII lowercase letter "a".."z"> ALPHA = UPALPHA | LOALPHA DIGIT = <any US-ASCII digit "0".."9"> CTL = <any US-ASCII control character (octets 0 - 31) and DEL (127)> CR = <US-ASCII CR, carriage return (13)> LF = <US-ASCII LF, linefeed (10)> SP = <US-ASCII SP, space (32)> HT = <US-ASCII HT, horizontal-tab (9)> <"> = <US-ASCII double-quote mark (34)>HTTP/1.0 defines the octet sequence
CR LF
as the end-of-line marker for all protocol elements
except the Entity-Body
(see Appendix B for tolerant applications). The end-of-line marker
within an Entity-Body
is defined by its associated media type, as described in Section 3.6.
CRLF = CR LFHTTP/1.0 headers may be folded onto multiple lines if each continuation line begins with a space or horizontal tab. All linear whitespace, including folding, has the same semantics as
SP
.
LWS = [CRLF] 1*( SP | HT )However, folding of header lines is not expected by some applications, and should not be generated by HTTP/1.0 applications.
The TEXT
rule is only used for descriptive field contents and values that are not intended to be
interpreted by the message parser. Words of *TEXT
may contain octets from character sets other
than US-ASCII.
TEXT = <any OCTET except CTLs, but including LWS>Recipients of header field
TEXT
containing octets outside the US-ASCII character set may
assume that they represent ISO-8859-1 characters.
Hexadecimal numeric characters are used in several protocol elements.
HEX = "A" | "B" | "C" | "D" | "E" | "F" | "a" | "b" | "c" | "d" | "e" | "f" | DIGITMany HTTP/1.0 header field values consist of words separated by
LWS
or special characters.
These special characters must be in a quoted string to be used within a parameter value.
word = token | quoted-string
token = 1*<any CHAR except CTLs or tspecials>
tspecials = "(" | ")" | "<" | ">" | "@" | "," | ";" | ":" | "\" | <"> | "/" | "[" | "]" | "?" | "=" | "{" | "}" | SP | HTComments may be included in some HTTP header fields by surrounding the comment text with parentheses. Comments are only allowed in fields containing "
comment
" as part of their field
value definition. In all other fields, parentheses are considered part of the field value.
comment = "(" *( ctext | comment ) ")" ctext = <any TEXT excluding "(" and ")">A string of text is parsed as a single word if it is quoted using double-quote marks.
quoted-string = ( <"> *(qdtext) <"> )
qdtext = <any CHAR except <"> and CTLs, but including LWS>Single-character quoting using the backslash ("\") character is not permitted in HTTP/1.0.
The version of an HTTP message is indicated by an HTTP-Version
field in the first line of the
message. If the protocol version is not specified, the recipient must assume that the message is
in the simple HTTP/0.9 format.
HTTP-Version = "HTTP" "/" 1*DIGIT "." 1*DIGITNote that the major and minor numbers should be treated as separate integers and that each may be incremented higher than a single digit. Thus, HTTP/2.4 is a lower version than HTTP/2.13, which in turn is lower than HTTP/12.3. Leading zeros should be ignored by recipients and never generated by senders.
This document defines both the 0.9 and 1.0 versions of the HTTP protocol. Applications
sending Full-Request
or Full-Response
messages, as defined by this specification, must include
an HTTP-Version
of "HTTP/1.0
".
HTTP/1.0 servers must:
Request-Line
for HTTP/0.9 and HTTP/1.0 requests;
Status-Line
for HTTP/1.0 responses;
URI = ( absoluteURI | relativeURI ) [ "#" fragment ]
absoluteURI = scheme ":" *( uchar | reserved )
relativeURI = net_path | abs_path | rel_path
net_path = "//" net_loc [ abs_path ] abs_path = "/" rel_path rel_path = [ path ] [ ";" params ] [ "?" query ]
path = fsegment *( "/" segment ) fsegment = 1*pchar segment = *pchar
params = param *( ";" param ) param = *( pchar | "/" )
scheme = 1*( ALPHA | DIGIT | "+" | "-" | "." ) net_loc = *( pchar | ";" | "?" ) query = *( uchar | reserved ) fragment = *( uchar | reserved )
pchar = uchar | ":" | "@" | "&" | "=" | "+" uchar = unreserved | escape unreserved = ALPHA | DIGIT | safe | extra | national
escape = "%" HEX HEX reserved = ";" | "/" | "?" | ":" | "@" | "&" | "=" | "+" extra = "!" | "*" | "'" | "(" | ")" | "," safe = "$" | "-" | "_" | "." unsafe = CTL | SP | <"> | "#" | "%" | "<" | ">" national = <any OCTET excluding ALPHA, DIGIT, reserved, extra, safe, and unsafe>For definitive information on URL syntax and semantics, see RFC 1738 [4] and RFC 1808 [9]. The BNF above includes
national
characters not allowed in valid URLs as specified by
RFC 1738, since HTTP servers are not restricted in the set of unreserved
characters allowed to
represent the rel_path
part of addresses, and HTTP proxies may receive requests for URIs not
defined by RFC 1738.
http_URL = "http:" "//" host [ ":" port ] [ abs_path ]
host = <A legal Internet host domain name or IP address (in dotted-decimal form), as defined by Section 2.1 of RFC 1123>
port = *DIGITIf the
port
is empty or not given, port 80 is assumed. The semantics are that the identified
resource is located at the server listening for TCP connections on that port
of that host
, and the
Request-URI
for the resource is abs_path
. If the abs_path
is not present in the URL, it must be
given as "/" when used as a Request-URI
(Section 5.1.2).
Note: Although the HTTP protocol is independent of the transport layer protocol, the http URL only identifies resources by their TCP location, and thus non-TCP resources must be identified by some other URI scheme.The canonical form for "http" URLs is obtained by converting any
UPALPHA
characters in host
to their LOALPHA
equivalent (hostnames are case-insensitive), eliding the [ ":" port ]
if the port
is 80, and replacing an empty abs_path
with "/".
Sun, 06 Nov 1994 08:49:37 GMT ; RFC 822, updated by RFC 1123 Sunday, 06-Nov-94 08:49:37 GMT ; RFC 850, obsoleted by RFC 1036 Sun Nov 6 08:49:37 1994 ; ANSI C's asctime() formatThe first format is preferred as an Internet standard and represents a fixed-length subset of that defined by RFC 1123 [6] (an update to RFC 822 [7]). The second format is in common use, but is based on the obsolete RFC 850 [10] date format and lacks a four-digit year. HTTP/1.0 clients and servers that parse the date value should accept all three formats, though they must never generate the third (asctime) format.
Note: Recipients of date values are encouraged to be robust in accepting date values that may have been generated by non-HTTP applications, as is sometimes the case when retrieving or posting messages via proxies/gateways to SMTP or NNTP.All HTTP/1.0 date/time stamps must be represented in Universal Time (UT), also known as Greenwich Mean Time (GMT), without exception. This is indicated in the first two formats by the inclusion of "GMT" as the three-letter abbreviation for time zone, and should be assumed when reading the asctime format.
HTTP-date = rfc1123-date | rfc850-date | asctime-date
rfc1123-date = wkday "," SP date1 SP time SP "GMT" rfc850-date = weekday "," SP date2 SP time SP "GMT" asctime-date = wkday SP date3 SP time SP 4DIGIT
date1 = 2DIGIT SP month SP 4DIGIT ; day month year (e.g., 02 Jun 1982) date2 = 2DIGIT "-" month "-" 2DIGIT ; day-month-year (e.g., 02-Jun-82) date3 = month SP ( 2DIGIT | ( SP 1DIGIT )) ; month day (e.g., Jun 2)
time = 2DIGIT ":" 2DIGIT ":" 2DIGIT ; 00:00:00 - 23:59:59
wkday = "Mon" | "Tue" | "Wed" | "Thu" | "Fri" | "Sat" | "Sun"
weekday = "Monday" | "Tuesday" | "Wednesday" | "Thursday" | "Friday" | "Saturday" | "Sunday"
month = "Jan" | "Feb" | "Mar" | "Apr" | "May" | "Jun" | "Jul" | "Aug" | "Sep" | "Oct" | "Nov" | "Dec"
Note: HTTP requirements for the date/time stamp format apply only to their usage within the protocol stream. Clients and servers are not required to use these formats for user presentation, request logging, etc.
The term "character set" is used in this document to refer to a method used with one or more tables to convert a sequence of octets into a sequence of characters. Note that unconditional conversion in the other direction is not required, in that not all characters may be available in a given character set and a character set may provide more than one sequence of octets to represent a particular character. This definition is intended to allow various kinds of character encodings, from simple single-table mappings such as US-ASCII to complex table switching methods such as those that use ISO 2022's techniques. However, the definition associated with a MIME character set name must fully specify the mapping to be performed from octets to characters. In particular, use of external profiling information to determine the exact mapping is not permitted.
Note: This use of the term "character set" is more commonly referred to as a "character encoding." However, since HTTP and MIME share the same registry, it is important that the terminology also be shared.HTTP character sets are identified by case-insensitive tokens. The complete set of tokens are defined by the IANA Character Set registry [15]. However, because that registry does not define a single, consistent token for each character set, we define here the preferred names for those character sets most likely to be used with HTTP entities. These character sets include those registered by RFC 1521 [5] -- the US-ASCII [17] and ISO-8859 [18] character sets -- and other names specifically recommended for use within MIME charset parameters.
charset = "US-ASCII" | "ISO-8859-1" | "ISO-8859-2" | "ISO-8859-3" | "ISO-8859-4" | "ISO-8859-5" | "ISO-8859-6" | "ISO-8859-7" | "ISO-8859-8" | "ISO-8859-9" | "ISO-2022-JP" | "ISO-2022-JP-2" | "ISO-2022-KR" | "UNICODE-1-1" | "UNICODE-1-1-UTF-7" | "UNICODE-1-1-UTF-8" | tokenAlthough HTTP allows an arbitrary token to be used as a charset value, any token that has a predefined value within the IANA Character Set registry [15] must represent the character set defined by that registry. Applications should limit their use of character sets to those defined by the IANA registry.
The character set of an entity body should be labelled as the lowest common denominator of the character codes used within that body, with the exception that no label is preferred over the labels US-ASCII or ISO-8859-1.
content-coding = "x-gzip" | "x-compress" | token
Note: For future compatibility, HTTP/1.0 applications should consider "gzip" and "compress" to be equivalent to "x-gzip" and "x-compress", respectively.All
content-coding
values are case-insensitive. HTTP/1.0 uses content-coding
values in the
Content-Encoding
(Section 10.3) header field. Although the value describes the content-coding,
what is more important is that it indicates what decoding mechanism will be required to remove
the encoding. Note that a single program may be capable of decoding multiple content-coding
formats. Two values are defined by this specification:
x-gzip
x-compress
Note: Use of program names for the identification of encoding formats is not desirable and should be discouraged for future encodings. Their use here is representative of historical practice, not good design.
Content-Type
header field (Section 10.5) in order
to provide open and extensible data typing.
media-type = type "/" subtype *( ";" parameter ) type = token subtype = tokenParameters may follow the type/subtype in the form of attribute/value pairs.
parameter = attribute "=" value attribute = token value = token | quoted-stringThe type, subtype, and parameter attribute names are case-insensitive. Parameter values may or may not be case-sensitive, depending on the semantics of the parameter name.
LWS
must not
be generated between the type and subtype, nor between an attribute and its value. Upon receipt
of a media type with an unrecognized parameter, a user agent should treat the media type as if
the unrecognized parameter and its value were not present.
Some older HTTP applications do not recognize media type parameters. HTTP/1.0 applications should only use media type parameters when they are necessary to define the content of a message.
Media-type values are registered with the Internet Assigned Number Authority (IANA [15]). The media type registration process is outlined in RFC 1590 [13]. Use of non-registered media types is discouraged.
Entity-Body
transferred
via HTTP must be represented in the appropriate canonical form prior to its transmission. If the
body has been encoded with a Content-Encoding
, the underlying data should be in canonical
form prior to being encoded.
Media subtypes of the "text" type use CRLF
as the text line break when in canonical form.
However, HTTP allows the transport of text media with plain CR
or LF
alone representing a line
break when used consistently within the Entity-Body
. HTTP applications must accept CRLF
, bare
CR
, and bare LF
as being representative of a line break in text media received via HTTP.
In addition, if the text media is represented in a character set that does not use octets 13 and 10
for CR
and LF
respectively, as is the case for some multi-byte character sets, HTTP allows the
use of whatever octet sequences are defined by that character set to represent the equivalent of
CR
and LF
for line breaks. This flexibility regarding line breaks applies only to text media in
the Entity-Body
; a bare CR
or LF
should not be substituted for CRLF
within any of the HTTP
control structures (such as header fields and multipart boundaries).
The "charset" parameter is used with some media types to define the character set (Section 3.4) of the data. When no explicit charset parameter is provided by the sender, media subtypes of the "text" type are defined to have a default charset value of "ISO-8859-1" when received via HTTP. Data in character sets other than "ISO-8859-1" or its subsets must be labelled with an appropriate charset value in order to be consistently interpreted by the recipient.
Note: Many current HTTP servers provide data using charsets other than "ISO-8859-1" without proper labelling. This situation reduces interoperability and is not recommended. To compensate for this, some HTTP user agents provide a configuration option to allow the user to change the default interpretation of the media type character set when no charset parameter is given.
Entity-Body
. The multipart types registered by IANA [15] do not have any
special meaning for HTTP/1.0, though user agents may need to understand each type in order
to correctly interpret the purpose of each body-part. An HTTP user agent should follow the
same or similar behavior as a MIME user agent does upon receipt of a multipart type. HTTP
servers should not assume that all HTTP clients are prepared to handle multipart types.
All multipart types share a common syntax and must include a boundary parameter as part of
the media type value. The message body is itself a protocol element and must therefore use only
CRLF
to represent line breaks between body-parts. Multipart body-parts may contain HTTP
header fields which are significant to the meaning of that part.
product = token ["/" product-version] product-version = tokenExamples:
User-Agent: CERN-LineMode/2.15 libwww/2.17b3 Server: Apache/0.8.4Product tokens should be short and to the point -- use of them for advertizing or other non-essential information is explicitly forbidden. Although any token character may appear in a
product-version
, this token should only be used for a version identifier (i.e., successive versions
of the same product should only differ in the product-version
portion of the product
value).
HTTP-message = Simple-Request ; HTTP/0.9 messages | Simple-Response | Full-Request ; HTTP/1.0 messages | Full-Response
Full-Request
and Full-Response
use the generic message format of RFC 822 [7] for transferring
entities. Both messages may include optional header fields (also known as "headers") and an
entity body. The entity body is separated from the headers by a null line (i.e., a line with nothing
preceding the CRLF
).
Full-Request = Request-Line ; Section 5.1 *( General-Header ; Section 4.3 | Request-Header ; Section 5.2 | Entity-Header ) ; Section 7.1 CRLF [ Entity-Body ] ; Section 7.2
Full-Response = Status-Line ; Section 6.1 *( General-Header ; Section 4.3 | Response-Header ; Section 6.2 | Entity-Header ) ; Section 7.1 CRLF [ Entity-Body ] ; Section 7.2
Simple-Request
and Simple-Response
do not allow the use of any header information and are
limited to a single request method (GET
).
Simple-Request = "GET" SP Request-URI CRLF
Simple-Response = [ Entity-Body ]Use of the
Simple-Request
format is discouraged because it prevents the server from identifying
the media type of the returned entity.
General-Header
(Section 4.3), Request-Header
(Section 5.2),
Response-Header
(Section 6.2), and Entity-Header
(Section 7.1) fields, follow the same generic
format as that given in Section 3.1 of RFC 822 [7]. Each header field consists of a name
followed immediately by a colon (":"
), a single space (SP
) character, and the field value. Field
names are case-insensitive. Header fields can be extended over multiple lines by preceding
each extra line with at least one SP
or HT
, though this is not recommended.
HTTP-header = field-name ":" [ field-value ] CRLF
field-name = token field-value = *( field-content | LWS )
field-content = <the OCTETs making up the field-value and consisting of either *TEXT or combinations of token, tspecials, and quoted-string>The order in which header fields are received is not significant. However, it is "good practice" to send
General-Header
fields first, followed by Request-Header
or Response-Header
fields prior
to the Entity-Header
fields.
Multiple HTTP-header
fields with the same field-name
may be present in a message if and only
if the entire field-value
for that header field is defined as a comma-separated list [i.e., #(values)
].
It must be possible to combine the multiple header fields into one "field-name: field-value" pair,
without changing the semantics of the message, by appending each subsequent field-value to
the first, each separated by a comma.
General-Header = Date ; Section 10.6 | Pragma ; Section 10.12General header field names can be extended reliably only in combination with a change in the protocol version. However, new or experimental header fields may be given the semantics of general header fields if all parties in the communication recognize them to be general header fields. Unrecognized header fields are treated as
Entity-Header
fields.
Request = Simple-Request | Full-Request
Simple-Request = "GET" SP Request-URI CRLF
Full-Request = Request-Line ; Section 5.1 *( General-Header ; Section 4.3 | Request-Header ; Section 5.2 | Entity-Header ) ; Section 7.1 CRLF [ Entity-Body ] ; Section 7.2If an HTTP/1.0 server receives a
Simple-Request
, it must respond with an HTTP/0.9
Simple-Response
. An HTTP/1.0 client capable of receiving a Full-Response
should never
generate a Simple-Request
.
Request-Line
begins with a method token, followed by the Request-URI
and the protocol
version, and ending with CRLF
. The elements are separated by SP
characters.
No CR
or LF
are allowed except in the final CRLF
sequence.
Request-Line = Method SP Request-URI SP HTTP-Version CRLFNote that the difference between a
Simple-Request
and the Request-Line
of a Full-Request
is the
presence of the HTTP-Version
field and the availability of methods other than GET
.
Method
token indicates the method to be performed on the resource identified by the
Request-URI
. The method is case-sensitive.
Method = "GET" ; Section 8.1 | "HEAD" ; Section 8.2 | "POST" ; Section 8.3 | extension-method
extension-method = tokenThe list of methods acceptable by a specific resource can change dynamically; the client is notified through the return code of the response if a method is not allowed on a resource. Servers should return the status code 501 (not implemented) if the method is unrecognized or not implemented.
The methods commonly used by HTTP/1.0 applications are fully defined in Section 8.
Request-URI
is a Uniform Resource Identifier (Section 3.2) and identifies the resource upon
which to apply the request.
Request-URI = absoluteURI | abs_pathThe two options for
Request-URI
are dependent on the nature of the request.
The absoluteURI
form is only allowed when the request is being made to a proxy. The proxy is
requested to forward the request and return the response. If the request is GET
or HEAD
and a
prior response is cached, the proxy may use the cached message if it passes any restrictions in
the Expires
header field. Note that the proxy may forward the request on to another proxy or
directly to the server specified by the absoluteURI
. In order to avoid request loops, a proxy must
be able to recognize all of its server names, including any aliases, local variations, and the
numeric IP address. An example Request-Line
would be:
GET http://www.w3.org/pub/WWW/TheProject.html HTTP/1.0The most common form of
Request-URI
is that used to identify a resource on an origin server
or gateway. In this case, only the absolute path of the URI is transmitted (see Section 3.2.1,
abs_path
). For example, a client wishing to retrieve the resource above directly from the origin
server would create a TCP connection to port 80 of the host "www.w3.org" and send the line:
GET /pub/WWW/TheProject.html HTTP/1.0followed by the remainder of the
Full-Request
. Note that the absolute path cannot be empty; if
none is present in the original URI, it must be given as "/" (the server root).
The Request-URI
is transmitted as an encoded string, where some characters may be escaped
using the "% HEX HEX" encoding defined by RFC 1738 [4]. The origin server must decode
the Request-URI
in order to properly interpret the request.
Request-Header = Authorization ; Section 10.2 | From ; Section 10.8 | If-Modified-Since ; Section 10.9 | Referer ; Section 10.13 | User-Agent ; Section 10.15
Request-Header
field names can be extended reliably only in combination with a change in the
protocol version. However, new or experimental header fields may be given the semantics of
request header fields if all parties in the communication recognize them to be request header
fields. Unrecognized header fields are treated as Entity-Header
fields.
Response = Simple-Response | Full-Response
Simple-Response = [ Entity-Body ]
Full-Response = Status-Line ; Section 6.1 *( General-Header ; Section 4.3 | Response-Header ; Section 6.2 | Entity-Header ) ; Section 7.1 CRLF [ Entity-Body ] ; Section 7.2A
Simple-Response
should only be sent in response to an HTTP/0.9 Simple-Request
or if the
server only supports the more limited HTTP/0.9 protocol. If a client sends an HTTP/1.0
Full-Request
and receives a response that does not begin with a Status-Line
, it should assume that
the response is a Simple-Response
and parse it accordingly. Note that the Simple-Response
consists only of the entity body and is terminated by the server closing the connection.
Full-Response
message is the Status-Line
, consisting of the protocol version
followed by a numeric status code and its associated textual phrase, with each element
separated by SP
characters. No CR
or LF
is allowed except in the final CRLF
sequence.
Status-Line = HTTP-Version SP Status-Code SP Reason-Phrase CRLFSince a status line always begins with the protocol version and status code
"HTTP/" 1*DIGIT "." 1*DIGIT SP 3DIGIT SP(e.g.,
"HTTP/1.0 200 "
), the presence of that expression is sufficient to differentiate a
Full-Response
from a Simple-Response
. Although the Simple-Response
format may allow such
an expression to occur at the beginning of an entity body, and thus cause a misinterpretation of
the message if it was given in response to a Full-Request
, most HTTP/0.9 servers are limited to
responses of type "text/html" and therefore would never generate such a response.
Status-Code
element is a 3-digit integer result code of the attempt to understand and satisfy
the request. The Reason-Phrase
is intended to give a short textual description of the Status-Code
.
The Status-Code
is intended for use by automata and the Reason-Phrase
is intended for the
human user. The client is not required to examine or display the Reason-Phrase
.
The first digit of the Status-Code
defines the class of response. The last two digits do not have
any categorization role. There are 5 values for the first digit:
Reason-Phrase
's, are presented below. The reason phrases listed here are only
recommended -- they may be replaced by local equivalents without affecting the protocol.
These codes are fully defined in Section 9.
Status-Code = "200" ; OK | "201" ; Created | "202" ; Accepted | "204" ; No Content | "301" ; Moved Permanently | "302" ; Moved Temporarily | "304" ; Not Modified | "400" ; Bad Request | "401" ; Unauthorized | "403" ; Forbidden | "404" ; Not Found | "500" ; Internal Server Error | "501" ; Not Implemented | "502" ; Bad Gateway | "503" ; Service Unavailable | extension-code
extension-code = 3DIGIT
Reason-Phrase = *<TEXT, excluding CR, LF>HTTP status codes are extensible, but the above codes are the only ones generally recognized in current practice. HTTP applications are not required to understand the meaning of all registered status codes, though such understanding is obviously desirable. However, applications must understand the class of any status code, as indicated by the first digit, and treat any unrecognized response as being equivalent to the x00 status code of that class, with the exception that an unrecognized response must not be cached. For example, if an unrecognized status code of 431 is received by the client, it can safely assume that there was something wrong with its request and treat the response as if it had received a 400 status code. In such cases, user agents should present to the user the entity returned with the response, since that entity is likely to include human-readable information which will explain the unusual status.
Status-Line
. These header fields give information about the server
and about further access to the resource identified by the Request-URI
.
Response-Header = Location ; Section 10.11 | Server ; Section 10.14 | WWW-Authenticate ; Section 10.16
Response-Header
field names can be extended reliably only in combination with a change in the
protocol version. However, new or experimental header fields may be given the semantics of
response header fields if all parties in the communication recognize them to be response header
fields. Unrecognized header fields are treated as Entity-Header
fields.
Full-Request
and Full-Response
messages may transfer an entity within some requests and
responses. An entity consists of Entity-Header
fields and (usually) an Entity-Body
. In this section,
both sender and recipient refer to either the client or the server, depending on who sends and
who receives the entity.
Entity-Header
fields define optional metainformation about the Entity-Body
or, if no body is
present, about the resource identified by the request.
Entity-Header = Allow ; Section 10.1 | Content-Encoding ; Section 10.3 | Content-Length ; Section 10.4 | Content-Type ; Section 10.5 | Expires ; Section 10.7 | Last-Modified ; Section 10.10 | extension-header
extension-header = HTTP-headerThe
extension-header
mechanism allows additional Entity-Header
fields to be defined without
changing the protocol, but these fields cannot be assumed to be recognizable by the recipient.
Unrecognized header fields should be ignored by the recipient and forwarded by proxies.
Entity-Header
fields.
Entity-Body = *OCTETAn entity body is included with a request message only when the request method calls for one. The presence of an entity body in a request is signaled by the inclusion of a
Content-Length
header field in the request message headers. HTTP/1.0 requests containing an entity body must
include a valid Content-Length
header field.
For response messages, whether or not an entity body is included with a message is dependent
on both the request method and the response code. All responses to the HEAD
request method
must not include a body, even though the presence of entity header fields may lead one to
believe they do. All 1xx (informational), 204 (no content), and 304 (not modified) responses
must not include a body. All other responses must include an entity body or a Content-Length
header field defined with a value of zero (0).
Entity-Body
is included with a message, the data type of that body is determined via
the header fields Content-Type
and Content-Encoding
. These define a two-layer, ordered
encoding model:
entity-body := Content-Encoding( Content-Type( data ) )A
Content-Type
specifies the media type of the underlying data. A Content-Encoding
may be used
to indicate any additional content coding applied to the type, usually for the purpose of data
compression, that is a property of the resource requested. The default for the content encoding
is none (i.e., the identity function).
Any HTTP/1.0 message containing an entity body should include a Content-Type
header field
defining the media type of that body. If and only if the media type is not given by a Content-Type
header, as is the case for Simple-Response
messages, the recipient may attempt to guess the
media type via inspection of its content and/or the name extension(s) of the URL used to
identify the resource. If the media type remains unknown, the recipient should treat it as type
"application/octet-stream
".
Entity-Body
is included with a message, the length of that body may be determined in
one of two ways. If a Content-Length
header field is present, its value in bytes represents the
length of the Entity-Body
. Otherwise, the body length is determined by the closing of the
connection by the server.
Closing the connection cannot be used to indicate the end of a request body, since it leaves no
possibility for the server to send back a response. Therefore, HTTP/1.0 requests containing an
entity body must include a valid Content-Length
header field. If a request contains an entity body
and Content-Length
is not specified, and the server does not recognize or cannot calculate the
length from other fields, then the server should send a 400 (bad request) response.
Note: Some older servers supply an invalid Content-Length when sending a document that contains server-side includes dynamically inserted into the data stream. It must be emphasized that this will not be tolerated by future versions of HTTP. Unless the client knows that it is receiving a response from a compliant server, it should not depend on the Content-Length value being correct.
GET
method means retrieve whatever information (in the form of an entity) is identified by
the Request-URI
. If the Request-URI
refers to a data-producing process, it is the produced data
which shall be returned as the entity in the response and not the source text of the process,
unless that text happens to be the output of the process.
The semantics of the GET
method changes to a "conditional GET
" if the request message
includes an If-Modified-Since
header field. A conditional GET
method requests that the identified
resource be transferred only if it has been modified since the date given by the If-Modified-Since
header, as described in Section 10.9. The conditional GET
method is intended to reduce
network usage by allowing cached entities to be refreshed without requiring multiple requests
or transferring unnecessary data.
HEAD
method is identical to GET
except that the server must not return any Entity-Body
in
the response. The metainformation contained in the HTTP headers in response to a HEAD
request should be identical to the information sent in response to a GET
request. This method
can be used for obtaining metainformation about the resource identified by the Request-URI
without transferring the Entity-Body
itself. This method is often used for testing hypertext links
for validity, accessibility, and recent modification.
There is no "conditional HEAD
" request analogous to the conditional GET
. If an If-Modified-Since
header field is included with a HEAD
request, it should be ignored.
POST
method is used to request that the destination server accept the entity enclosed in the
request as a new subordinate of the resource identified by the Request-URI
in the Request-Line
.
POST
is designed to allow a uniform method to cover the following functions:
POST
method is determined by the server and is usually
dependent on the Request-URI
. The posted entity is subordinate to that URI in the same way
that a file is subordinate to a directory containing it, a news article is subordinate to a
newsgroup to which it is posted, or a record is subordinate to a database.
A successful POST
does not require that the entity be created as a resource on the origin server
or made accessible for future reference. That is, the action performed by the POST
method
might not result in a resource that can be identified by a URI. In this case, either 200 (ok) or
204 (no content) is the appropriate response status, depending on whether or not the response
includes an entity that describes the result.
If a resource has been created on the origin server, the response should be 201 (created) and contain an entity (preferably of type "text/html") which describes the status of the request and refers to the new resource.
A valid Content-Length
is required on all HTTP/1.0 POST
requests. An HTTP/1.0 server should
respond with a 400 (bad request) message if it cannot determine the length of the request
message's content.
Applications must not cache responses to a POST request because the application has no way of knowing that the server would return an equivalent response on some future request.
Status-Code
is described below, including a description of which method
(s) it can follow
and any metainformation required in the response.
Status-Line
and
optional headers, and is terminated by an empty line. HTTP/1.0 does not define any 1xx status
codes and they are not a valid response to a HTTP/1.0 request. However, they may be useful
for experimental applications which are outside the scope of this specification.
GET
HEAD
Entity-Body
;
POST
Status-Code
. If the action cannot be carried
out immediately, the server must include in the response body a description of when the
resource will be available; otherwise, the server should respond with 202 (accepted).
Of the methods defined by this specification, only POST
can create a resource.
The 202 response is intentionally non-committal. Its purpose is to allow a server to accept a request for some other process (perhaps a batch-oriented process that is only run once per day) without requiring that the user agent's connection to the server persist until the process is completed. The entity returned with this response should include an indication of the request's current status and either a pointer to a status monitor or some estimate of when the user can expect the request to be fulfilled.
GET
or
HEAD
. A user agent should never automatically redirect a request more than 5 times, since such
redirections usually indicate an infinite loop.
The requested resource is available at one or more locations. Unless it was a HEAD
request, the
response should include an entity containing a list of resource characteristics and locations
from which the user or user agent can choose the one most appropriate. If the server has a
preferred choice, it should include the URL in a Location
field; user agents may use this field
value for automatic redirection.
Request-URI
to the new reference returned by the server,
where possible.
The new URL must be given by the Location
field in the response. Unless it was a HEAD
request,
the Entity-Body
of the response should contain a short note with a hyperlink to the new URL.
If the 301 status code is received in response to a request using the POST
method, the user agent
must not automatically redirect the request unless it can be confirmed by the user, since this
might change the conditions under which the request was issued.
Note: When automatically redirecting a POST request after receiving a 301 status code, some existing user agents will erroneously change it into a GET request.
Request-URI
for future requests.
The URL must be given by the Location
field in the response. Unless it was a HEAD
request, the
Entity-Body
of the response should contain a short note with a hyperlink to the new URI(s).
If the 302 status code is received in response to a request using the POST
method, the user agent
must not automatically redirect the request unless it can be confirmed by the user, since this
might change the conditions under which the request was issued.
Note: When automatically redirecting a POST request after receiving a 302 status code, some existing user agents will erroneously change it into a GET request.
GET
request and access is allowed, but the document
has not been modified since the date and time specified in the If-Modified-Since
field, the server
must respond with this status code and not send an Entity-Body
to the client. Header fields
contained in the response should only include information which is relevant to cache managers
or which may have changed independently of the entity's Last-Modified
date. Examples of
relevant header fields include: Date
, Server
, and Expires
. A cache should update its cached entity
to reflect any new field values given in the 304 response.
HEAD
request, the server should
include an entity containing an explanation of the error situation, and whether it is a temporary
or permanent condition. These status codes are applicable to any request method.
Note: If the client is sending data, server implementations on TCP should be careful to ensure that the client acknowledges receipt of the packet(s) containing the response prior to closing the input connection. If the client continues sending data to the server after the close, the server's controller will send a reset packet to the client, which may erase the client's unacknowledged input buffers before they can be read and interpreted by the HTTP application.
WWW-Authenticate
header field (Section 10.16) containing a challenge
applicable to the requested resource. The
client may repeat the request with a suitable Authorization
header field (Section 10.2). If the
request already included Authorization credentials, then the 401 response indicates that
authorization has been refused for those credentials. If the 401 response contains the same
challenge as the prior response, and the user agent has already attempted authentication at least
once, then the user should be presented the entity that was given in the response, since that
entity may include relevant diagnostic information. HTTP access authentication is explained
in Section 11.
HEAD
and the server wishes
to make public why the request has not been fulfilled, it should describe the reason for the
refusal in the entity body. This status code is commonly used when the server does not wish to
reveal exactly why the request has been refused, or when no other response is applicable.
Request-URI
. No indication is given of whether
the condition is temporary or permanent. If the server does not wish to make this information
available to the client, the status code 403 (forbidden) can be used instead.
HEAD
request, the server should include an entity containing an
explanation of the error situation, and whether it is a temporary or permanent condition. These
response codes are applicable to any request method and there are no required header fields.
Note: The existence of the 503 status code does not imply that a server must use it when becoming overloaded. Some servers may wish to simply refuse the connection.
Allow
entity-header field lists the set of methods supported by the resource identified by the
Request-URI
. The purpose of this field is strictly to inform the recipient of valid methods
associated with the resource. The Allow
header field is not permitted in a request using the POST
method, and thus should be ignored if it is received as part of a POST
entity.
Allow = "Allow" ":" 1#methodExample of use:
Allow: GET, HEADThis field cannot prevent a client from trying other methods. However, the indications given by the
Allow
header field value should be followed. The actual set of allowed methods is defined
by the origin server at the time of each request.
A proxy must not modify the Allow
header field even if it does not understand all the methods
specified, since the user agent may have other means of communicating with the origin server.
The Allow
header field does not indicate what methods are implemented by the server.
Authorization
request-header field with
the request. The Authorization
field value consists of credentials
containing the authentication
information of the user agent for the realm of the resource being requested.
Authorization = "Authorization" ":" credentialsHTTP access authentication is described in Section 11. If a request is authenticated and a
realm
specified, the same credentials
should be valid for all other requests within this realm
.
Responses to requests containing an Authorization
field are not cachable.
Content-Encoding
entity-header field is used as a modifier to the media-type
. When present,
its value indicates what additional content coding has been applied to the resource, and thus
what decoding mechanism must be applied in order to obtain the media-type
referenced by the
Content-Type
header field. The Content-Encoding
is primarily used to allow a document to be
compressed without losing the identity of its underlying media type.
Content-Encoding = "Content-Encoding" ":" content-codingContent codings are defined in Section 3.5. An example of its use is
Content-Encoding: x-gzipThe
Content-Encoding
is a characteristic of the resource identified by the Request-URI
. Typically,
the resource is stored with this encoding and is only decoded before rendering or analogous
usage.
Content-Length
entity-header field indicates the size of the Entity-Body
, in decimal number
of octets, sent to the recipient or, in the case of the HEAD
method, the size of the Entity-Body
that
would have been sent had the request been a GET
.
Content-Length = "Content-Length" ":" 1*DIGITAn example is
Content-Length: 3495Applications should use this field to indicate the size of the
Entity-Body
to be transferred,
regardless of the media type of the entity. A valid Content-Length
field value is required on all
HTTP/1.0 request messages containing an entity body.
Any Content-Length
greater than or equal to zero is a valid value. Section 7.2.2 describes how
to determine the length of a response entity body if a Content-Length
is not given.
Note: The meaning of this field is significantly different from the corresponding definition in MIME, where it is an optional field used within the "message/external-body" content-type. In HTTP, it should be used whenever the entity's length can be determined prior to being transferred.
Content-Type
entity-header field indicates the media type of the Entity-Body
sent to the
recipient or, in the case of the HEAD
method, the media type that would have been sent had the
request been a GET
.
Content-Type = "Content-Type" ":" media-typeMedia types are defined in Section 3.6. An example of the field is
Content-Type: text/htmlFurther discussion of methods for identifying the media type of an entity is provided in Section 7.2.1.
Date
general-header field represents the date and time at which the message was originated,
having the same semantics as orig-date
in RFC 822. The field value is an HTTP-date
, as
described in Section 3.3.
Date = "Date" ":" HTTP-dateAn example is
Date: Tue, 15 Nov 1994 08:12:31 GMTIf a message is received via direct connection with the user agent (in the case of requests) or the origin server (in the case of responses), then the date can be assumed to be the current date at the receiving end. However, since the date--as it is believed by the origin--is important for evaluating cached responses, origin servers should always include a
Date
header. Clients should
only send a Date
header field in messages that include an entity body, as in the case of the POST
request, and even then it is optional. A received message which does not have a Date
header
field should be assigned one by the recipient if the message will be cached by that recipient or
gatewayed via a protocol which requires a Date
.
In theory, the date should represent the moment just before the entity is generated. In practice, the date can be generated at any time during the message origination without affecting its semantic value.
Note: An earlier version of this document incorrectly specified that this field should
contain the creation date of the enclosed Entity-Body
. This has been changed to reflect
actual (and proper) usage.
Expires
entity-header field gives the date/time after which the entity should be considered
stale. This allows information providers to suggest the volatility of the resource, or a date after
which the information may no longer be valid. Applications must not cache this entity beyond
the date given. The presence of an Expires field does not imply that the original resource will
change or cease to exist at, before, or after that time. However, information providers that know
or even suspect that a resource will change by a certain date should include an Expires header
with that date. The format is an absolute date and time as defined by HTTP-date
in Section 3.3.
Expires = "Expires" ":" HTTP-dateAn example of its use is
Expires: Thu, 01 Dec 1994 16:00:00 GMTIf the date given is equal to or earlier than the value of the
Date
header, the recipient must not
cache the enclosed entity. If a resource is dynamic by nature, as is the case with many
data-producing processes, entities from that resource should be given an appropriate Expires
value which reflects that dynamism.
The Expires field cannot be used to force a user agent to refresh its display or reload a resource; its semantics apply only to caching mechanisms, and such mechanisms need only check a resource's expiration status when a new request for that resource is initiated.
User agents often have history mechanisms, such as "Back" buttons and history lists, which can
be used to redisplay an entity retrieved earlier in a session. By default, the Expires
field does not
apply to history mechanisms. If the entity is still in storage, a history mechanism should display
it even if the entity has expired, unless the user has specifically configured the agent to refresh
expired history documents.
Note: Applications are encouraged to be tolerant of bad or misinformed implementations of the Expires header. A value of zero (0) or an invalid date format should be considered equivalent to an "expires immediately." Although these values are not legitimate for HTTP/1.0, a robust implementation is always desirable.
From
request-header field, if given, should contain an Internet e-mail address for the human
user who controls the requesting user agent. The address should be machine-usable, as defined
by mailbox
in RFC 822 [7] (as updated by RFC 1123 [6]):
From = "From" ":" mailboxAn example is:
From<EMAIL_ADDRESS>header field may be used for logging purposes and as a means for identifying the source of invalid or unwanted requests. It should not be used as an insecure form of access protection. The interpretation of this field is that the request is being performed on behalf of the person given, who accepts responsibility for the
method
performed. In particular, robot agents should
include this header so that the person responsible for running the robot can be contacted if
problems occur on the receiving end.
The Internet e-mail address in this field may be separate from the Internet host which issued the request. For example, when a request is passed through a proxy, the original issuer's address should be used.
Note: The client should not send the From
header field without the user's approval, as
it may conflict with the user's privacy interests or their site's security policy. It is
strongly recommended that the user be able to disable, enable, and modify the value
of this field at any time prior to a request.
If-Modified-Since
request-header field is used with the GET
method to make it conditional:
if the requested resource has not been modified since the time specified in this field, a copy of
the resource will not be returned from the server; instead, a 304 (not modified) response will
be returned without any Entity-Body
.
If-Modified-Since = "If-Modified-Since" ":" HTTP-dateAn example of the field is:
If-Modified-Since: Sat, 29 Oct 1994 19:43:31 GMTA conditional
GET
method requests that the identified resource be transferred only if it has been
modified since the date given by the If-Modified-Since
header. The algorithm for determining this
includes the following cases:
If-Modified-Since
date is invalid, the response is exactly the same as for a
normal GET
. A date which is later than the server's current time is invalid.
If-Modified-Since
date, the response is
exactly the same as for a normal GET
.
If-Modified-Since
date, the server
shall return a 304 (not modified) response.
Last-Modified
entity-header field indicates the date and time at which the sender believes
the resource was last modified. The exact semantics of this field are defined in terms of how the
recipient should interpret it: if the recipient has a copy of this resource which is older than the
date given by the Last-Modified
field, that copy should be considered stale.
Last-Modified = "Last-Modified" ":" HTTP-dateAn example of its use is
Last-Modified: Tue, 15 Nov 1994 12:45:26 GMTThe exact meaning of this header field depends on the implementation of the sender and the nature of the original resource. For files, it may be just the file system last-modified time. For entities with dynamically included parts, it may be the most recent of the set of last-modify times for its component parts. For database gateways, it may be the last-update timestamp of the record. For virtual objects, it may be the last time the internal state changed.
An origin server must not send a Last-Modified date which is later than the server's time of message origination. In such cases, where the resource's last modification would indicate some time in the future, the server must replace that date with the message origination date.
Request-URI
. For 3xx responses, the location must indicate the server's preferred URL
for automatic redirection to the resource. Only one absolute URL is allowed.
Location = "Location" ":" absoluteURIAn example is
Location: http://www.w3.org/hypertext/WWW/NewLocation.html
Pragma
general-header field is used to include implementation-specific directives that may
apply to any recipient along the request/response chain. All pragma directives specify optional
behavior from the viewpoint of the protocol; however, some systems may require that behavior
be consistent with the directives.
Pragma = "Pragma" ":" 1#pragma-directive
pragma-directive = "no-cache" | extension-pragma extension-pragma = token [ "=" word ]When the "
no-cache
" directive is present in a request message, an application should forward
the request toward the origin server even if it has a cached copy of what is being requested. This
allows a client to insist upon receiving an authoritative response to its request. It also allows a
client to refresh a cached copy which is known to be corrupted or stale.
Pragma directives must be passed through by a proxy or gateway application, regardless of their significance to that application, since the directives may be applicable to all recipients along the request/response chain. It is not possible to specify a pragma for a specific recipient; however, any pragma directive not relevant to a recipient should be ignored by that recipient.
Referer
request-header field allows the client to specify, for the server's benefit, the address
(URI) of the resource from which the Request-URI
was obtained. This allows a server to
generate lists of back-links to resources for interest, logging, optimized caching, etc. It also
allows obsolete or mistyped links to be traced for maintenance. The Referer
field must not be
sent if the Request-URI
was obtained from a source that does not have its own URI, such as input
from the user keyboard.
Referer = "Referer" ":" ( absoluteURI | relativeURI )Example:
Referer: http://www.w3.org/hypertext/DataSources/Overview.htmlIf a partial URI is given, it should be interpreted relative to the
Request-URI
. The URI must not
include a fragment.
Note: Because the source of a link may be private information or may reveal an otherwise private information source, it is strongly recommended that the user be able to select whether or not theReferer
field is sent. For example, a browser client could have a toggle switch for browsing openly/anonymously, which would respectively enable/disable the sending ofReferer
andFrom
information.
Server
response-header field contains information about the software used by the origin
server to handle the request. The field can contain multiple product tokens (Section 3.7) and
comments identifying the server and any significant subproducts. By convention, the product
tokens are listed in order of their significance for identifying the application.
Server = "Server" ":" 1*( product | comment )Example:
Server: CERN/3.0 libwww/2.17If the response is being forwarded through a proxy, the proxy application must not add its data to the product list.
Note: Revealing the specific software version of the server may allow the server machine to become more vulnerable to attacks against software that is known to contain security holes. Server implementors are encouraged to make this field a configurable option.
Note: Some existing servers fail to restrict themselves to the product token syntax within the Server field.
User-Agent
request-header field contains information about the user agent originating the
request. This is for statistical purposes, the tracing of protocol violations, and automated
recognition of user agents for the sake of tailoring responses to avoid particular user agent
limitations. Although it is not required, user agents should include this field with requests. The
field can contain multiple product tokens (Section 3.7) and comments identifying the agent and
any subproducts which form a significant part of the user agent. By convention, the product
tokens are listed in order of their significance for identifying the application.
User-Agent = "User-Agent" ":" 1*( product | comment )Example:
User-Agent: CERN-LineMode/2.15 libwww/2.17b3
Note: Some current proxy applications append their product information to the list in the User-Agent field. This is not recommended, since it makes machine interpretation of these fields ambiguous.
Note: Some existing clients fail to restrict themselves to the product token syntax within the User-Agent field.
WWW-Authenticate
response-header field must be included in 401 (unauthorized) response
messages. The field value consists of at least one challenge
that indicates the authentication
scheme(s) and parameters applicable to the Request-URI
.
WWW-Authenticate = "WWW-Authenticate" ":" 1#challengeThe HTTP access authentication process is described in Section 11. User agents must take special care in parsing the
WWW-Authenticate
field value if it contains more than one challenge,
or if more than one WWW-Authenticate
header field is provided, since the contents of a challenge
may itself contain a comma-separated list of authentication parameters.
auth-scheme = token
auth-param = token "=" quoted-stringThe 401 (unauthorized) response message is used by an origin server to challenge the authorization of a user agent. This response must include a
WWW-Authenticate
header field
containing at least one challenge
applicable to the requested resource.
challenge = auth-scheme 1*SP realm *( "," auth-param )
realm = "realm" "=" realm-value realm-value = quoted-stringThe realm attribute (case-insensitive) is required for all authentication schemes which issue a challenge. The realm value (case-sensitive), in combination with the canonical root URL of the server being accessed, defines the protection space. These realms allow the protected resources on a server to be partitioned into a set of protection spaces, each with its own authentication scheme and/or authorization database. The realm value is a string, generally assigned by the origin server, which may have additional semantics specific to the authentication scheme.
A user agent that wishes to authenticate itself with a server--usually, but not necessarily, after
receiving a 401 response--may do so by including an Authorization
header field with the
request. The Authorization
field value consists of credentials
containing the authentication
information of the user agent for the realm of the resource being requested.
credentials = basic-credentials | ( auth-scheme #auth-param )The domain over which credentials can be automatically applied by a user agent is determined by the protection space. If a prior request has been authorized, the same credentials may be reused for all other requests within that protection space for a period of time determined by the authentication scheme, parameters, and/or user preference. Unless otherwise defined by the authentication scheme, a single protection space cannot extend outside the scope of its server.
If the server does not wish to accept the credentials sent with a request, it should return a 403 (forbidden) response.
The HTTP protocol does not restrict applications to this simple challenge-response mechanism for access authentication. Additional mechanisms may be used, such as encryption at the transport level or via message encapsulation, and with additional header fields specifying authentication information. However, these additional mechanisms are not defined by this specification.
Proxies must be completely transparent regarding user agent authentication. That is, they must
forward the WWW-Authenticate
and Authorization
headers untouched, and must not cache the
response to a request containing Authorization
. HTTP/1.0 does not provide a means for a client
to be authenticated with a proxy.
Request-URI
. There are no optional authentication parameters.
Upon receipt of an unauthorized request for a URI within the protection space, the server should respond with a challenge like the following:
WWW-Authenticate: Basic realm="WallyWorld"where "WallyWorld" is the string assigned by the server to identify the protection space of the
Request-URI
.
To receive authorization, the client sends the user-ID and password, separated by a single colon
(":") character, within a base64 [5] encoded string in the credentials
.
basic-credentials = "Basic" SP basic-cookie
basic-cookie = <base64 [5] encoding of userid-password, except not limited to 76 char/line>
userid-password = [ token ] ":" *TEXTIf the user agent wishes to send the user-ID "Aladdin" and password "open sesame", it would use the following header field:
Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==The basic authentication scheme is a non-secure method of filtering unauthorized access to resources on an HTTP server. It is based on the assumption that the connection between the client and the server can be regarded as a trusted carrier. As this is not generally true on an open network, the basic authentication scheme should be used accordingly. In spite of this, clients should implement the scheme in order to communicate with servers that use it.
Entity-Body
from being transmitted in clear text across the
physical network used as the carrier. HTTP/1.0 does not prevent additional authentication
schemes and encryption mechanisms from being employed to increase security.
In particular, the convention has been established that the GET
and HEAD
methods should never
have the significance of taking an action other than retrieval. These methods should be
considered "safe." This allows user agents to represent other methods, such as POST
, in a
special way, so that the user is made aware of the fact that a possibly unsafe action is being
requested.
Naturally, it is not possible to ensure that the server does not generate side-effects as a result of
performing a GET
request; in fact, some dynamic resources consider that a feature. The
important distinction here is that the user did not request the side-effects, so therefore cannot
be held accountable for them.
Server
, Referer
and From
.
Revealing the specific software version of the server may allow the server machine to become
more vulnerable to attacks against software that is known to contain security holes.
Implementors should make the Server
header field a configurable option.
The Referer
field allows reading patterns to be studied and reverse links drawn. Although it can
be very useful, its power can be abused if user details are not separated from the information
contained in the Referer
. Even when the personal information has been removed, the Referer
field may indicate a private document's URI whose publication would be inappropriate.
The information sent in the From
field might conflict with the user's privacy interests or their
site's security policy, and hence it should not be transmitted without the user being able to
disable, enable, and modify the contents of the field. The user must be able to set the contents
of this field within a user preference or application defaults configuration.
We suggest, though do not require, that a convenient toggle interface be provided for the user
to enable or disable the sending of From
and Referer
information.
Request-URI
if it would otherwise allow access to a resource outside those
intended to be accessible via the HTTP server. Similarly, files intended for reference only
internally to the server (such as access control files, configuration files, and script code) must
be protected from inappropriate retrieval, since they might contain sensitive information.
Experience has shown that minor bugs in such HTTP server implementations have turned into
security risks.
The HTTP protocol has evolved considerably over the past four years. It has benefited from a large and active developer community--the many people who have participated on the www-talk mailing list--and it is that community which has been most responsible for the success of HTTP and of the World-Wide Web in general. Marc Andreessen, Robert Cailliau, Daniel W. Connolly, Bob Denny, Jean-Francois Groff, Phillip M. Hallam-Baker, Håkon W. Lie, Ari Luotonen, Rob McCool, Lou Montulli, Dave Raggett, Tony Sanders, and Marc VanHeyningen deserve special recognition for their efforts in defining aspects of the protocol for early versions of this specification.
Paul Hoffman contributed sections regarding the informational status of this document and Appendices C and D.
This document has benefited greatly from the comments of all those participating in the HTTP-WG. In addition to those already mentioned, the following individuals have contributed to this specification:
Gary Adams Harald Tveit Alvestrand Keith Ball Brian Behlendorf Paul Burchard Maurizio Codogno Mike Cowlishaw Roman Czyborra Michael A. Dolan John Franks Jim Gettys Marc Hedlund Koen Holtman Alex Hopmann Bob Jernigan Shel Kaphan Martijn Koster Dave Kristol Daniel LaLiberte Paul Leach Albert Lunde John C. Mallery Larry Masinter Mitra Jeffrey Mogul Gavin Nicol Bill Perry Jeffrey Perry Owen Rees Luigi Rizzo David Robinson Marc Salomon Rich Salz Jim Seidman Chuck Shotton Eric W. Sink Simon E. Spero Robert S. Thau François Yergeau Mary Ellen Zurko Jean-Philippe Martin-Flatin
Roy T. Fielding
Department of Information and Computer Science
University of California
Irvine, CA 92717-3425, U.S.A.
Fax: +1<PHONE_NUMBER>
EMail<EMAIL_ADDRESS>Henrik Frystyk Nielsen
W3 Consortium
MIT Laboratory for Computer Science
545 Technology Square
Cambridge, MA 02139, U.S.A.
Fax: +1<PHONE_NUMBER>
EMail<EMAIL_ADDRESS>Media Type name: message Media subtype name: http Required parameters: none Optional parameters: version, msgtype version: The HTTP-Version number of the enclosed message (e.g., "1.0"). If not present, the version can be determined from the first line of the body. msgtype: The message type -- "request" or "response". If not present, the type can be determined from the first line of the body. Encoding considerations: only "7bit", "8bit", or "binary" are permitted Security considerations: none
Clients should be tolerant in parsing the Status-Line
and servers tolerant when parsing the
Request-Line
. In particular, they should accept any amount of SP
or HT
characters between
fields, even though only a single SP
is required.
The line terminator for HTTP-header
fields is the sequence CRLF
. However, we recommend that
applications, when parsing such headers, recognize a single LF
as a line terminator and ignore
the leading CR
.
At the time of this writing, it is expected that RFC 1521 will be revised. The revisions may include some of the practices found in HTTP/1.0 but not in RFC 1521.
This appendix describes specific areas where HTTP differs from RFC 1521. Proxies and gateways to strict MIME environments should be aware of these differences and provide the appropriate conversions where necessary. Proxies and gateways from MIME environments to HTTP also need to be aware of the differences because some conversions may be required.
RFC 1521 requires that content with a Content-Type of "text" represent line breaks as CRLF and forbids the use of CR or LF outside of line break sequences. HTTP allows CRLF, bare CR, and bare LF to indicate a line break within text content when a message is transmitted over HTTP.
Where it is possible, a proxy or gateway from HTTP to a strict RFC 1521 environment should
translate all line breaks within the text media types described in Section 3.6.1 of this document
to the RFC 1521 canonical form of CRLF
. Note, however, that this may be complicated by the
presence of a Content-Encoding
and by the fact that HTTP allows the use of some character sets
which do not use octets 13 and 10 to represent CR
and LF
, as is the case for some multi-byte
character sets.
Date
header
field present in a message conforms to one of the HTTP/1.0 formats and rewrite the date if
necessary.
Content-Encoding
header
field. Since this acts as a modifier on the media type, proxies and gateways from HTTP to
MIME-compliant protocols must either change the value of the Content-Type
header field or
decode the Entity-Body
before forwarding the message. (Some experimental applications of
Content-Type
for Internet mail have used a media-type parameter of
";conversions=<content-coding>"
to perform an equivalent function as
Content-Encoding. However, this parameter is not part of RFC 1521.)
Proxies and gateways from HTTP to MIME-compliant protocols are responsible for ensuring that the message is in the correct format and encoding for safe transport on that protocol, where "safe transport" is defined by the limitations of the protocol being used. Such a proxy or gateway should label the data with an appropriate Content-Transfer-Encoding if doing so will improve the likelihood of safe transport over the destination protocol.
Request-URI
. If
the Request-URI
refers to an already existing resource, the enclosed entity should be considered
as a modified version of the one residing on the origin server. If the Request-URI
does not point
to an existing resource, and that URI is capable of being defined as a new resource by the
requesting user agent, the origin server can create the resource with that URI.
The fundamental difference between the POST and PUT requests is reflected in the different
meaning of the Request-URI
. The URI in a POST request identifies the resource that will handle
the enclosed entity as data to be processed. That resource may be a data-accepting process, a
gateway to some other protocol, or a separate entity that accepts annotations. In contrast, the
URI in a PUT request identifies the entity enclosed with the request -- the user agent knows
what URI is intended and the server should not apply the request to some other resource.
Request-URI
.
Request-URI
and other existing resources.
Request-URI
.
Request-URI
resource can be identified. There is no guarantee that
the resource can be accessed using the URI(s) specified.


Home
Virginia :: Locate The Law
Constitution
Virginia Constitution
(Virginia General Assembly)
Colonial Charters, Grants and Related Documents: Virginia
(Yale Avalon Project)
includes four documents including the
Constitution of Virginia, 1776
(also known as the Virginia Bill of Rights)
Virginia Bill of Rights, 1776
(National Archives and Records Administration)
Executive
Virginia Administrative Code
Cumulative Table of Sections Adopted, Amended or Repealed
PDF
Virginia Register of Regulations
Vol. 14, no. 20 (June 22, 1998-
Virginia Executive Orders
No. 1 (2010-
Virginia Executive Orders
(Library of Virginia)
Virginia Attorney General Opinions
1996-
Virginia Governor
Virginia Attorney General
Virginia Board of Elections
Virginia Secretary of State
Executive Branch Agencies
Judicial
Virginia Supreme Court Opinions:
Virginia Courts
FindLaw
1995-
Virginia Lawyers Weekly
1998-
Court of Appeals Opinions:
Virginia Courts
FindLaw (published and unpublished)
1995-
Virginia Lawyers Weekly
Virginia Workers' Compensation Commission Opinions
U.S. Court of Appeals, 4th Circuit
(U.S. Courts)
U.S. Court of Appeals, 4th Circuit
(FindLaw)
January 1995-
U.S. District Court, Eastern District of Virginia
U.S. District Court, Western District of Virginia - Opinions
Virginia Judicial Branch
Judicial Branch Agencies
Supreme Court Rules
(Virginia Legislature)
Legislative
Virginia Code
Virginia Bills
Virginia General Assembly
- composed of the
Senate
and
House of Delegates
Publications
(Virginia Division of Legislative Services)
Digest of the Acts of the General Assembly of Virginia
(Virginia Division of Legislative Services)
Issue Briefs
(Virginia Division of Legislative Services)
Reports to the General Assembly
, 1897-
Topical Studies of the General Assembly of Virginia
(Virginia Division of Legislative Services)
Virginia Law: Charters
(Virginia Legislative Information Services)
Virginia Code Commission
Virginia Division of Legislative Services


EBD - Easton Bible DIctionary
Spain
SPAIN
"SPAIN" Paul expresses his intention (
Romans 15:24, 28
) to visit Spain.
There is, however, no evidence that he ever carried it into effect, although some think that he probably did so between his first and second imprisonment. (See TARSHISH.)
"SPAIN" Paul expresses his intention (Romans 15:24, 28) to visit Spain.
There is, however, no evidence that he ever carried it into effect, although some think that he probably did so between his first and second imprisonment. (See TARSHISH.)


National Express passengers 'covered in glass' after window smashed by street light
One man forked out £190 for a taxi to make sure he didn't miss his flight to Mexico
by Gayle McDonaldThis was the scene on a National Express coach this morning after the driver turned down a narrow road and crashed into a street light.
Passengers onboard the bus said glass went "over everyone" after a window smashed in Bridgwater, Somerset, while the driver was attempting a manoeuver.
Fortunately, there were no reports of any injuries.
One passenger, Daniel Schofield from Cornwall, said he had to fork out £190 for a taxi to make sure he got to the airport on time after his journey was delayed.
He had to be at Gatwick Airport this morning to catch a flight to Mexico.
He said the company did transfer passengers to an alternative coach but that they were delayed by more than two hours.
He said: "I got it last night at 10.20pm [from Newquay] and didn’t get to Gatwick till 10.10am. The gate was closing at 10.20am I think.
"I had to pay £190 for taxi from Heathrow to Gatwick but couldn’t get a receipt as was rushing."
Mr Schofield added that he thinks the driver took a wrong turn.
"They went down a lane that was tight and the bus was pushing against the light then the pressure got to much and smashed in with the light actually being inside the bus," he said.
"The glass went over everyone but it smashed into so many pieces."
Refunds for passengers
National Express has said it will refund all passengers who were on the bus.
In a statement, the company said: "We can confirm that the vehicle on the 406 Penzance to London service on Sunday 17 November collided with a street light on St Mary’s Street in Bridgwater whilst the driver was attempting a maneuver at low speed.
"There were no reported injuries to customers who were able to continue their journeys, either by taxi or a replacement vehicle.
"An automatic refund is being made to all passengers on board and we will reimburse any additional costs for their onward travel incurred as a result of the delay."


Plugin Information |
|---|
View ClamAV on the plugin site for more information. |
Overview
This plugin allows you to check the artifacts with ClamAV, which is an open source (GPL) antivirus engine designed for detecting Trojans, viruses, malware and other malicious threats.
The artifacts are sent to ClamAV Host and are scaned. So you have to configure your ClamAV to enable TCP port in clamd.conf as follows.
: # TCP port address. # Default: no TCPSocket 3310 # TCP address. # By default we bind to INADDR_ANY, probably not wise. # Enable the following to provide some degree of protection # from the outside world. # Default: no #TCPAddr <IP_ADDRESS> # Close the connection when the data size limit is exceeded. # The value should match your MTA's limit for a maximum attachment size. # Default: 25M StreamMaxLength 100M :
Be Careful
If you get "Broken Pipe", check "StreammaxLength" parameter.
System configuration
When "Scan arhived artifacts" checkbox is selected, the artifacts of job will be scaned if "Archive the artifacts" option is configured in job configuration page.
Job Configuration
To scan a workspace, you may specify "Files to check" option such as "*/". But it will take a long time.
you may specify "Excludes" such as ".git/*/".
Job page and Virus report page
TODO
- add BuildStep to check files.
History
0.3 (11 May, 2015)
- ensure file is closed. (JENKINS-27954).
- skipping of PASSED in console (pull request 1).
0.2 (16 Oct, 2011)
- validate "includes" option, which should be mandatory if "Scan archived artifacts" option is not checked.
- honor "Scan archived artifacts" option.
- show full path in the virus check list.
0.1.1 (26 Jun, 2011)
- failed to check artifacts due to ArrayIndexexception (JENKINS-10103).
- timeout should be longer.
- added the help file of timeout.
0.1 (26 Jun, 2011)
- First release.
Attachments:
system_configuration.png (image/png)
job_configuration.png (image/png)
job.png (image/png)
virus_report.png (image/png)


pypette (to be read as pipette) is a module which makes building pipelines ridiculously simple, allowing users to control the flow with minimal instructions.
Features¶
Ridiculously simple interface.
Ability to view pipeline structure within the comfort of a terminal.
Run pipeline in exception resilient way if needed.
Create dependencies on pipelines easily.
Generate a easy to view/understand report within the comfort of a terminal.
Setup¶
Using pip¶
pip install pypette
Directly from the repository¶
git clone https://github.com/csurfer/pypette.git
python pypette/setup.py install
Quick Start¶
from pypette import BashJob, Job, Pipe
def wish():
print("Hello World!")
wish_job = Job(wish)
build_job = BashJob(["python", "setup.py", "build"])
test_job = BashJob(["python", "setup.py", "test"])
clean_job = BashJob(["rm", "*.pyc"])
def goodbye(msg):
print("Goodbye {}!".format(msg))
goodbye_job = Job(goodbye, args=("World",))
# Pipeline can be created using add_jobs
p = Pipe("Pipeline")
p.add_jobs([wish_job])
p.add_jobs([build_job, test_job], run_in_parallel=True)
p.add_jobs([clean_job])
p.add_jobs([goodbye_job])
# Or using add_stage
p = Pipe("Pipeline")
p.add_stage(wish_job)
p.add_stage(build_job, test_job)
p.add_stage(clean_job)
p.add_stage(goodbye_job)
# Can check how the pipeline looks like
p.graph()
# Can run the pipeline using
p.run()
# Can check on the success states of different stages of pipeline using
p.report()
Example pipeline¶
An example pipeline and its code are included in examples folder.
User Guide¶
API Reference¶
If you are looking for information on a specific function, class or method, this part of the documentation is for you.
Contributing¶
Bug Reports and Feature Requests¶
Please use issue tracker for reporting bugs or feature requests.
Development¶
Pull requests are most welcome. Kindly follow the steps suggested below:
Checkout the repository.
Make your changes and add/update relavent tests.
Install `poetry` using `pip install poetry`.
Run `poetry install` to create project’s virtual environment.
Run tests using `poetry run tox` (Any python versions which you don’t have checked out will fail this). Fix failing tests and repeat.
Make documentation changes that are relavant.
Install `pre-commit` using `pip install pre-commit` and run `pre-commit run –all-files` to do lint checks.
Generate documentation using `poetry run sphinx-build -b html docs/ docs/_build/html`.
Generate `requirements.txt` for automated testing using `poetry export –dev –without-hashes -f requirements.txt > requirements.txt`.
Commit the changes and raise a pull request.
Buy the developer a cup of coffee!¶
If you found the utility helpful you can buy me a cup of coffee using


Forum: CleanupIssue: FLOATING-POINT-CONDITION-NAMES
References: CLtL, Section 12.10 "Implementation Parameters" (for floats)
CLtL, P.448 "*features*"
IEEE Standard for Binary Floating-Point Arithmetic
Related Issues: FLOAT-UNDERFLOW
ERROR-CHECKING-IN-NUMBERS-CHAPTER
Category: ADDITION
Edit History: V1, 30 Oct 1989, JonL White
V2, 4 Dec 1990, Kent M. Pitman (amendments per X3J13)
Problem Description:
The currently proposed error system contains names for three conditions
related to floating-point operations: floating-point-underflow,
floating-point-overflow, and division-by-zero. Probably a majority
of implementation will be running on machines that support the IEEE
floating point standard; but there is no name for the remaining two out
of the five mandated trapping conditions, namely floating-point-inexact
and floating-point-invalid-operation.
Furthermore, even though the condition names may appear in an image,
it is not clear that such traps are enabled at every point in time.
The IEEE standard specifies that user-level programs ought to have
the capability of selectively enabling or disabling its five traps;
and other implementations may run on a variety of hardware configurations
for which the traps possible vary from host to host. However, there is
no current way for user-code to ask (1) what conditions are in fact
supporting floating-point traps, nor to ask (2) just what traps are
currently active
Note that some very simple implementations might not be able to cause
trapping even for floating-point-underflow; and in other implementations,
the relevant traps may vary on a host-to-host basic, depending on what
particular optional hardware is available on that host. For example,
Sun3 workstations come in three configurations: one with only software
floating-point support, one with a Motorola MC68881 attached co-processor,
and one with both an MC68881 and a Weitek Floating Point "Accelerator";
the increasing hardware complement gives rise to an increasing number of
implementation-specific traps. Even within the IEEE standard, it is
possible for a conforming implementation to make a refinement of the five
suggested traps [the MC68881 partitions one of the traps into three,
giving a total of eight]; so even though one knows that an implementation
is IEEE compatible, it still makes sense to ask what conditions are
supportable as floating-point traps.
Proposal (FLOATING-POINT-CONDITION-NAMES:X3J13-NOV-89)
1. Add FLOATING-POINT-INVALID-OPERATION and FLOATING-POINT-INEXACT
as conditions which are sub-conditions of ARITHMETIC-ERROR.
The intent is that if condition FOO is a currently enabled floating
point trap, then whenever that particular situation arises the
system will arrange to signal the Lisp condition FOO. The means for
enabling and disabling traps is not addressed in this proposal.
Proposal (FLOATING-POINT-CONDITION-NAMES:ADD-MINIMAL-IEEE)
1. Add FLOATING-POINT-INVALID-OPERATION and FLOATING-POINT-INEXACT
as conditions which are sub-conditions of ARITHMETIC-ERROR.
2. Add a global parameter SUPPORTED-FLOATING-POINT-CONDITIONS which
is to contain a list of all the condition names that can, in that
implementation, be enabled as floating-point traps; this is to
be an "implementation revealing" parameter.
3. Add a function of no arguments ENABLED-FLOATING-POINT-TRAPS which
returns a list of condition names for all currently enabled
floating point trapping conditions.
The intent is that if condition FOO is a currently enabled floating
point trap, then whenever that particular situation arises the
system will arrange to signal the Lisp condition FOO. The means for
enabling and disabling traps is not addressed in this proposal.
Rationale:
Many Common Lisp implementations do in fact run on hardware that
supports the IEEE floating-point standard; a minimal requirement
for porting between these implementations is that they all use the
same name for the five IEEE-mandated floating-point conditions.
Since at least some implementations will provide means for selective
enabling and disabling of various floating-point traps, then the
user must be able to query the system to find out what the current
state is, and what states are supportable.
Current Practice:
Lucid Common Lisp supports this much; moreover, it uses SETF on
(ENABLED-FLOATING-POINT-TRAPS) as the primary means to alter the
currently-enabled traps.
Cost to implementors:
Trivial.
Cost to users:
None; this is an upward-compatible addition.
Benefits:
Portability of a greater amount of user code; portability of "skills",
since IEEE support is so common.
Aesthetics:
It is better for all IEEE implementations to use the same names for
these conditions, rather than have them vary from one to another.
It is also probably better for non-IEEE implementations to use the
IEEE condition names where appropriate, just to minimize the
conceptual overload.
Discussion:
If an implementation is to claim full IEEE support, then it ought to
provide some means of enabling and catching these five IEEE-mandated
traps. Then it would be appropriate to put :IEEE-FLOATING-POINT on
the list *FEATURES* (see CLtL, P.448).
Moon and JonL privately discussed some means for enabling and
disabling various floating-point traps, back in June 1989 when the
float-underflow proposal was under discussion; they came to the
conclusion that "getting the design right and efficient" was more
than a few minutes worth of work, and so postponed further work on it.
[The IEEE standard apparently goes by the name of ANSI-IEEE Std 754-1985;
my working copy is Draft 10.0 from 1982. I don't think there are great
variances between them. -- JonL --]


Welcome to the Waba Source Distribution! To compile the C++ code properly, you should stick this folder inside the NCT_Projects:Demos_NCT folder of the NewtonDev distribution. Just make sure that the MPW C++ compiler is compiling with No Debug, and set to the Demos_NCT:Waba package.
This main directory contains the source code for the Waba Virtual Machine. Other stuff is located in three specific subdirectories:
For more documentation, including an intro to the VM, see the online docs at the Waba for Newton Homepage.


Loboeh
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I am a self-taught UX designer. I prefer to work with Figma and Adobe XD. My design aesthetic is clean and function design. Message me if you want to collabotrate or discuss design.
Alberta Canada
www.loboeh.me
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Reply if you need inspiration for your project!


10 years ago, there was no way to find out if any webpages except Mosaic, Internet Explorer, there was no way to search the web and it was a big problem. Companies that entered the search business were big companies like Yahoo, even the big player couldn’t crack code of proper develop search tools for people to use web easily.
All of us may be thinking the next big idea will come from Apple, Microsoft maybe some other big high-tech company but we had to go to one place for the next big invention, which is Stanford University. Two graduate students name Jerry Yang and David filo were left left alone while their professor was on one-year Sabbatical leave. They were goofing around with a technology which will later turn to be a traffic search engine Yahoo.
Yahoo was a great idea, but all great idea don’t make great business because it requires money and as most of us know that Silicon Valley is full of it. One of the successful Venture Capitalist firm is Sequoia Capital, its most famous partner Michael Mortiz decided to pay meet the people that created Yahoo. What he saw in the was upsetting for him as he describe it as “Every mom biggest nightmare”. The Yahoo company was ran by two people with housekeeping in place, everything was mess. Michael was hesitant about Yahoo after that.
In 2007, search company such Yahoo and google generated billions in revenue, making them the envy of entrepreneur everywhere.
On the other hand, no one really used it for business or commerce, some even thought it was evil to do business online. Until, Adverting took over the web, Yahoo had figure out a way to make money but that will cause them discomfort because at first they were worried that this move might push away their customers but later realized that it was the only option to survive.
In 1995, Yahoo started taking banner ads with their fingers crossed, for the first time Yahoo had shown that there was a way to make money over the web. This was a crucial moment because web boom has begun.
In 1996, Yahoo faced a number of challenges as it had grown competitors breathing under their neck, Excited was the most noticed competitor of Yahoo because their technology was more sophisticated and complex in comparison to Yahoo.
At this stage, Internet was exploding Yahoo, Excited, all companies were turning their search page into portal. All companies were drifted from the main idea was to help people search for what they are looking for, in other words, the search company no longer cared about search. This made the world hungry for better way from searching the web.
At this stage, Internet was exploding Yahoo, Excited, all companies were turning their search page into portal. All companies were drifted from the main idea was to help people search for what they are looking for, in other words, the search company no longer cared about search. This made the world hungry for better way from searching the web.
Even though, Google was getting a traffic a lot of companies didn’t really see potential in Google and thought it was another search page. However, Google found its way to two investors first named David R Cheriton and Andy Bechtolsheim, Sergey showed the demo to Andy and David and Andy automatically was sold to the idea and wrote a check to google for $100,000 and at the time Google didn’t even a bank account.
Google also landed on John Doer for investment and told him that this search engine will make 10 billion dollars in revenue which shook John and left him with no choice but to invest in the technology and he invested 12 million. Moreover, Micheal Mortiz also gave google 12 million. Google wanted to take all the information web and make searchable.
Bill gross brought a big breakthrough for Google. He’s runs a startup company name Idealab, and he was the one that crack adverting. He launched a website name “Overture” which Google copied the idea and launched Google Adwords. This resulted in a lawsuit between Google and Bill gross but it was settled and both parties were happy. As a result of the new addition to Google, became the search engine marketing tool.
Internet economy was on rise and Google was its essential player, on August 19, 2004, Google listed its stock with unconventional way of trading/selling on NASDAQ. This IPO was talk on the world at the time. Google model was “Don’t be Evil”. Later Google launched Google Maps, docs, mail, calendar, blogger, Picasa, Youtube. Google was now dominating the world.