public interface Message
Message
interface is the root interface of all Jakarta Messaging messages. It defines the message header and the
acknowledge
method used for all messages.
Most message-oriented middleware (MOM) products treat messages as lightweight entities that consist of a header and a body. The header contains fields used for message routing and identification; the body contains the application data being sent.
Within this general form, the definition of a message varies significantly across products. It would be quite difficult for the Jakarta Messaging API to support all of these message models.
With this in mind, the Jakarta Messaging message model has the following goals:
Jakarta Messaging messages are composed of the following parts:
The Jakarta Messaging API defines five types of message body:
StreamMessage
object's message body contains a stream of primitive values in the Java
programming language ("Java primitives"). It is filled and read sequentially.
MapMessage
object's message body contains a set of name-value pairs, where names are
String
objects, and values are Java primitives. The entries can be accessed sequentially or randomly by name.
The order of the entries is undefined.
TextMessage
object's message body contains a java.lang.String
object. This message type
can be used to transport plain-text messages, and XML messages.
ObjectMessage
object's message body contains a Serializable
Java object.
BytesMessage
object's message body contains a stream of uninterpreted bytes. This message type
is for literally encoding a body to match an existing message format. In many cases, it is possible to use one of the
other body types, which are easier to use. Although the Jakarta Messaging API allows the use of message properties with byte
messages, they are typically not used, since the inclusion of properties may affect the format.
The JMSCorrelationID
header field is used for linking one message with another. It typically links a reply
message with its requesting message.
JMSCorrelationID
can hold a provider-specific message ID, an application-specific String
object, or a
provider-native byte[]
value.
A Message
object contains a built-in facility for supporting application-defined property values. In effect,
this provides a mechanism for adding application-specific header fields to a message.
Properties allow an application, via message selectors, to have a Jakarta Messaging provider select, or filter, messages on its behalf using application-specific criteria.
Property names must obey the rules for a message selector identifier. Property names must not be null, and must not
be empty strings. If a property name is set and it is either null or an empty string, an
IllegalArgumentException
must be thrown.
Property values can be boolean
, byte
, short
, int
, long
, float
,
double
, and String
.
Property values are set prior to sending a message. When a client receives a message, its properties are in read-only
mode. If a client attempts to set properties at this point, a MessageNotWriteableException
is thrown. If
clearProperties
is called, the properties can now be both read from and written to. Note that header fields
are distinct from properties. Header fields are never in read-only mode.
A property value may duplicate a value in a message's body, or it may not. Although Jakarta Messaging does not define a policy for what should or should not be made a property, application developers should note that Jakarta Messaging providers will likely handle data in a message's body more efficiently than data in a message's properties. For best performance, applications should use message properties only when they need to customize a message's header. The primary reason for doing this is to support customized message selection.
Message properties support the following conversion table. The marked cases must be supported. The unmarked cases
must throw a JMSException
. The String
-to-primitive conversions may throw a runtime exception if the
primitive's valueOf
method does not accept the String
as a valid representation of the primitive.
A value written as the row type can be read as the column type.
| | boolean byte short int long float double String |---------------------------------------------------------- |boolean | X X |byte | X X X X X |short | X X X X |int | X X X |long | X X |float | X X X |double | X X |String | X X X X X X X X |----------------------------------------------------------
In addition to the type-specific set/get methods for properties, Jakarta Messaging provides the setObjectProperty
and
getObjectProperty
methods. These support the same set of property types using the objectified primitive
values. Their purpose is to allow the decision of property type to made at execution time rather than at compile
time. They support the same property value conversions.
The setObjectProperty
method accepts values of class Boolean
, Byte
, Short
,
Integer
, Long
, Float
, Double
, and String
. An attempt to use any other class
must throw a JMSException
.
The getObjectProperty
method only returns values of class Boolean
, Byte
, Short
,
Integer
, Long
, Float
, Double
, and String
.
The order of property values is not defined. To iterate through a message's property values, use
getPropertyNames
to retrieve a property name enumeration and then use the various property get methods to
retrieve their values.
A message's properties are deleted by the clearProperties
method. This leaves the message with an empty set
of properties.
Getting a property value for a name which has not been set returns a null value. Only the getStringProperty
and getObjectProperty
methods can return a null value. Attempting to read a null value as a primitive type
must be treated as calling the primitive's corresponding valueOf(String)
conversion method with a null value.
The Jakarta Messaging API reserves the JMSX
property name prefix for Jakarta Messaging defined properties. The full set of these
properties is defined in the Jakarta Messaging specification. The specification also defines whether support for
each property is mandatory or optional. New Jakarta Messaging defined properties may be added in later versions of the Jakarta Messaging API. The
String[] ConnectionMetaData.getJMSXPropertyNames
method returns the names of the JMSX properties supported by
a connection.
JMSX properties may be referenced in message selectors whether or not they are supported by a connection. If they are not present in a message, they are treated like any other absent property. The effect of setting a message selector on a property which is set by the provider on receive is undefined.
JMSX properties defined in the specification as "set by provider on send" are available to both the producer and the consumers of the message. JMSX properties defined in the specification as "set by provider on receive" are available only to the consumers.
JMSXGroupID
and JMSXGroupSeq
are standard properties that clients should use if they want to group
messages. All providers must support them. Unless specifically noted, the values and semantics of the JMSX properties
are undefined.
The Jakarta Messaging API reserves the JMS_vendor_name
property name prefix for provider-specific properties.
Each provider defines its own value for vendor_name
. This is the mechanism a Jakarta Messaging provider uses to
make its special per-message services available to a Jakarta Messaging client.
The purpose of provider-specific properties is to provide special features needed to integrate Jakarta Messaging clients with provider-native clients in a single Jakarta Messaging application. They should not be used for messaging between Jakarta Messaging clients.
The Jakarta Messaging API provides a set of message interfaces that define the Jakarta Messaging message model. It does not provide implementations of these interfaces.
Each Jakarta Messaging provider supplies a set of message factories with its Session
object for creating instances of
messages. This allows a provider to use message implementations tailored to its specific needs.
A provider must be prepared to accept message implementations that are not its own. They may not be handled as efficiently as its own implementation; however, they must be handled.
Note the following exception case when a provider is handling a foreign message implementation. If the foreign
message implementation contains a JMSReplyTo
header field that is set to a foreign destination
implementation, the provider is not required to handle or preserve the value of this header field.
A Jakarta Messaging message selector allows a client to specify, by header field references and property references, the messages
it is interested in. Only messages whose header and property values match the selector are delivered. What it means
for a message not to be delivered depends on the MessageConsumer
being used (see
QueueReceiver
and TopicSubscriber
).
Message selectors cannot reference message body values.
A message selector matches a message if the selector evaluates to true when the message's header field values and property values are substituted for their corresponding identifiers in the selector.

If the value of a message selector is an empty string, the value is treated as a null and indicates that there is no
message selector for the message consumer.
The order of evaluation of a message selector is from left to right within precedence level. Parentheses can be used to change this order.
Predefined selector literals and operator names are shown here in uppercase; however, they are case insensitive.
A selector can contain:
'literal'
and 'literal''s'
. Like string literals in the Java programming language, these use
the Unicode character encoding.
57
, -957
, and
+62
; numbers in the range of long
are supported. Exact numeric literals use the integer literal
syntax of the Java programming language.
7E3
and
-57.9E2
, or a numeric value with a decimal, such as 7.
, -95.7
, and +6.2
; numbers in
the range of double
are supported. Approximate literals use the floating-point literal syntax of the Java
programming language.
TRUE
and FALSE
.
Character.isJavaLetter
returns true. This includes '_'
and '$'
. A letter or digit is any character for which the method Character.isJavaLetterOrDigit
returns true.
NULL
, TRUE
, and FALSE
.
NOT
, AND
, OR
, BETWEEN
, LIKE
, IN
,
IS
, or ESCAPE
.
NULL
.
myMessage.setStringProperty("NumberOfOrders", "2");The following expression in a message selector would evaluate to false, because a string cannot be used in an arithmetic expression:
"NumberOfOrders > 1"
JMSDeliveryMode
, JMSPriority
,
JMSMessageID
, JMSTimestamp
, JMSCorrelationID
, and JMSType
. JMSMessageID
,
JMSCorrelationID
, and JMSType
values may be null and if so are treated as a NULL
value.
'JMSX'
is a Jakarta Messaging defined property name.
'JMS_'
is a provider-specific property name.
'JMS'
is an application-specific property name.
true
matches; a selector that
evaluates to false
or unknown does not match.
()
for ordering expression evaluation is supported.
NOT
, AND
, OR
=
, >
, >=
, <
, <=
, <>
(not equal)
NULL
, the value of the expression is unknown.
=
and <>
. Two strings are equal if and only if
they contain the same sequence of characters.
+
, -
(unary)
*
, /
(multiplication and division)
+
, -
(addition and subtraction)
arithmetic-expr1 [NOT] BETWEEN arithmetic-expr2
AND arithmetic-expr3
(comparison operator)
"age BETWEEN 15 AND 19"
is equivalent to
"age >= 15 AND age <= 19"
"age NOT BETWEEN 15 AND 19"
is equivalent to
"age < 15 OR age > 19"
identifier [NOT] IN (string-literal1,
string-literal2,...)
(comparison operator where identifier
has a
String
or NULL
value)
"Country IN (' UK', 'US', 'France')"
is true for 'UK'
and
false for 'Peru'
; it is equivalent to the expression
"(Country = ' UK') OR (Country = ' US') OR (Country = ' France')"
"Country NOT IN (' UK', 'US', 'France')"
is false for
'UK'
and true for 'Peru'
; it is equivalent to the expression
"NOT ((Country = ' UK') OR (Country = ' US') OR (Country = ' France'))"
IN
or NOT IN
operation is NULL
, the value of the
operation is unknown.
identifier [NOT] LIKE pattern-value [ESCAPE
escape-character]
(comparison operator, where identifier
has a
String
value; pattern-value
is a string literal where '_'
stands for
any single character; '%'
stands for any sequence of characters, including the empty sequence; and all
other characters stand for themselves. The optional escape-character
is a single-character string
literal whose character is used to escape the special meaning of the '_'
and '%'
in
pattern-value
.)
"phone LIKE '12%3'"
is true for '123'
or '12993'
and false for
'1234'
"word LIKE 'l_se'"
is true for 'lose'
and false for 'loose'
"underscored LIKE '\_%' ESCAPE '\'"
is true for '_foo'
and false
for 'bar'
"phone NOT LIKE '12%3'"
is false for '123'
or '12993'
and
true for '1234'
identifier
of a LIKE
or NOT LIKE
operation is NULL
,
the value of the operation is unknown.
identifier IS NULL
(comparison operator that tests for a null header field value or a missing
property value)
"prop_name IS NULL"
identifier IS NOT NULL
(comparison operator that tests for the existence of a non-null header
field value or a property value)
"prop_name IS NOT NULL"
Jakarta Messaging providers are required to verify the syntactic correctness of a message selector at the time it is presented. A
method that provides a syntactically incorrect selector must result in a JMSException
. Jakarta Messaging providers may also
optionally provide some semantic checking at the time the selector is presented. Not all semantic checking can be
performed at the time a message selector is presented, because property types are not known.
The following message selector selects messages with a message type of car and color of blue and weight greater than 2500 pounds:
"JMSType = 'car' AND color = 'blue' AND weight > 2500"
As noted above, property values may be NULL
. The evaluation of selector expressions containing NULL
values is defined by SQL92 NULL
semantics. A brief description of these semantics is provided here.
SQL treats a NULL
value as unknown. Comparison or arithmetic with an unknown value always yields an unknown
value.
The IS NULL
and IS NOT NULL
operators convert an unknown value into the respective TRUE
and
FALSE
values.
The boolean operators use three-valued logic as defined by the following tables:
The definition of the AND
operator
| AND | T | F | U +------+-------+-------+------- | T | T | F | U | F | F | F | F | U | U | F | U +------+-------+-------+-------
The definition of the OR
operator
| OR | T | F | U +------+-------+-------+-------- | T | T | T | T | F | T | F | U | U | T | U | U +------+-------+-------+-------
The definition of the NOT
operator
| NOT +------+------ | T | F | F | T | U | U +------+-------
When used in a message selector, the JMSDeliveryMode
header field is treated as having the values
'PERSISTENT'
and 'NON_PERSISTENT'
.
Date and time values should use the standard long
millisecond value. When a date or time literal is included
in a message selector, it should be an integer literal for a millisecond value. The standard way to produce
millisecond values is to use java.util.Calendar
.
Although SQL supports fixed decimal comparison and arithmetic, Jakarta Messaging message selectors do not. This is the reason for restricting exact numeric literals to those without a decimal (and the addition of numerics with a decimal as an alternate representation for approximate numeric values).
SQL comments are not supported.
MessageConsumer.receive()
,
MessageConsumer.receive(long)
,
MessageConsumer.receiveNoWait()
,
MessageListener.onMessage(Message)
,
BytesMessage
,
MapMessage
,
ObjectMessage
,
StreamMessage
,
TextMessage
| Modifier and Type | Field and Description |
|---|---|
static long |
DEFAULT_DELIVERY_DELAY
The message producer's default delivery delay is zero.
|
static int |
DEFAULT_DELIVERY_MODE
The message producer's default delivery mode is
PERSISTENT . |
static int |
DEFAULT_PRIORITY
The message producer's default priority is 4.
|
static long |
DEFAULT_TIME_TO_LIVE
The message producer's default time to live is unlimited; the message never expires.
|
| Modifier and Type | Method and Description |
|---|---|
void |
acknowledge()
Acknowledges all consumed messages of the session of this consumed message.
|
void |
clearBody()
Clears out the message body.
|
void |
clearProperties()
Clears a message's properties.
|
<T> T |
getBody(java.lang.Class<T> c)
Returns the message body as an object of the specified type.
|
boolean |
getBooleanProperty(java.lang.String name)
Returns the value of the
boolean property with the specified name. |
byte |
getByteProperty(java.lang.String name)
Returns the value of the
byte property with the specified name. |
double |
getDoubleProperty(java.lang.String name)
Returns the value of the
double property with the specified name. |
float |
getFloatProperty(java.lang.String name)
Returns the value of the
float property with the specified name. |
int |
getIntProperty(java.lang.String name)
Returns the value of the
int property with the specified name. |
java.lang.String |
getJMSCorrelationID()
Gets the correlation ID for the message.
|
byte[] |
getJMSCorrelationIDAsBytes()
Gets the correlation ID as an array of bytes for the message.
|
int |
getJMSDeliveryMode()
Gets the
DeliveryMode value specified for this message. |
long |
getJMSDeliveryTime()
Gets the message's delivery time value.
|
Destination |
getJMSDestination()
Gets the
Destination object for this message. |
long |
getJMSExpiration()
Gets the message's expiration time.
|
java.lang.String |
getJMSMessageID()
Gets the message ID.
|
int |
getJMSPriority()
Gets the message priority level.
|
boolean |
getJMSRedelivered()
Gets an indication of whether this message is being redelivered.
|
Destination |
getJMSReplyTo()
Gets the
Destination object to which a reply to this message should be sent. |
long |
getJMSTimestamp()
Gets the message timestamp.
|
java.lang.String |
getJMSType()
Gets the message type identifier supplied by the client when the message was sent.
|
long |
getLongProperty(java.lang.String name)
Returns the value of the
long property with the specified name. |
java.lang.Object |
getObjectProperty(java.lang.String name)
Returns the value of the Java object property with the specified name.
|
java.util.Enumeration |
getPropertyNames()
Returns an
Enumeration of all the property names. |
short |
getShortProperty(java.lang.String name)
Returns the value of the
short property with the specified name. |
java.lang.String |
getStringProperty(java.lang.String name)
Returns the value of the
String property with the specified name. |
boolean |
isBodyAssignableTo(java.lang.Class c)
Returns whether the message body is capable of being assigned to the specified type.
|
boolean |
propertyExists(java.lang.String name)
Indicates whether a property value exists.
|
void |
setBooleanProperty(java.lang.String name,
boolean value)
Sets a
boolean property value with the specified name into the message. |
void |
setByteProperty(java.lang.String name,
byte value)
Sets a
byte property value with the specified name into the message. |
void |
setDoubleProperty(java.lang.String name,
double value)
Sets a
double property value with the specified name into the message. |
void |
setFloatProperty(java.lang.String name,
float value)
Sets a
float property value with the specified name into the message. |
void |
setIntProperty(java.lang.String name,
int value)
Sets an
int property value with the specified name into the message. |
void |
setJMSCorrelationID(java.lang.String correlationID)
Sets the correlation ID for the message.
|
void |
setJMSCorrelationIDAsBytes(byte[] correlationID)
Sets the correlation ID as an array of bytes for the message.
|
void |
setJMSDeliveryMode(int deliveryMode)
Sets the
DeliveryMode value for this message. |
void |
setJMSDeliveryTime(long deliveryTime)
Sets the message's delivery time value.
|
void |
setJMSDestination(Destination destination)
Sets the
Destination object for this message. |
void |
setJMSExpiration(long expiration)
Sets the message's expiration value.
|
void |
setJMSMessageID(java.lang.String id)
Sets the message ID.
|
void |
setJMSPriority(int priority)
Sets the priority level for this message.
|
void |
setJMSRedelivered(boolean redelivered)
Specifies whether this message is being redelivered.
|
void |
setJMSReplyTo(Destination replyTo)
Sets the
Destination object to which a reply to this message should be sent. |
void |
setJMSTimestamp(long timestamp)
Sets the message timestamp.
|
void |
setJMSType(java.lang.String type)
Sets the message type.
|
void |
setLongProperty(java.lang.String name,
long value)
Sets a
long property value with the specified name into the message. |
void |
setObjectProperty(java.lang.String name,
java.lang.Object value)
Sets a Java object property value with the specified name into the message.
|
void |
setShortProperty(java.lang.String name,
short value)
Sets a
short property value with the specified name into the message. |
void |
setStringProperty(java.lang.String name,
java.lang.String value)
Sets a
String property value with the specified name into the message. |
static final int DEFAULT_DELIVERY_MODE
PERSISTENT
.DeliveryMode.PERSISTENT
,
Constant Field Valuesstatic final int DEFAULT_PRIORITY
static final long DEFAULT_TIME_TO_LIVE
static final long DEFAULT_DELIVERY_DELAY
java.lang.String getJMSMessageID() throws JMSException
The JMSMessageID
header field contains a value that uniquely identifies each message sent by a provider.
When a message is sent, JMSMessageID
can be ignored. When the send
or publish
method returns,
it contains a provider-assigned value.
A JMSMessageID
is a String
value that should function as a unique key for identifying messages in a
historical repository. The exact scope of uniqueness is provider-defined. It should at least cover all messages for a
specific installation of a provider, where an installation is some connected set of message routers.
All JMSMessageID
values must start with the prefix 'ID:'
. Uniqueness of message ID values across
different providers is not required.
Since message IDs take some effort to create and increase a message's size, some Jakarta Messaging providers may be able to
optimize message overhead if they are given a hint that the message ID is not used by an application. By calling the
MessageProducer.setDisableMessageID
method, a Jakarta Messaging client enables this potential optimization for all messages
sent by that message producer. If the Jakarta Messaging provider accepts this hint, these messages must have the message ID set to
null; if the provider ignores the hint, the message ID must be set to its normal unique value.
JMSException
- if the Jakarta Messaging provider fails to get the message ID due to some internal error.setJMSMessageID(String)
,
MessageProducer.setDisableMessageID(boolean)
void setJMSMessageID(java.lang.String id) throws JMSException
This method is for use by Jakarta Messaging providers only to set this field when a message is sent. This message cannot be used by clients to configure the message ID. This method is public to allow a Jakarta Messaging provider to set this field when sending a message whose implementation is not its own.
id
- the ID of the messageJMSException
- if the Jakarta Messaging provider fails to set the message ID due to some internal error.getJMSMessageID()
long getJMSTimestamp() throws JMSException
The JMSTimestamp
header field contains the time a message was handed off to a provider to be sent. It is not
the time the message was actually transmitted, because the actual send may occur later due to transactions or other
client-side queueing of messages.
When a message is sent, JMSTimestamp
is ignored. When the send
or publish
method returns, it
contains a time value somewhere in the interval between the call and the return. The value is in the format of a
normal millis time value in the Java programming language.
Since timestamps take some effort to create and increase a message's size, some Jakarta Messaging providers may be able to optimize
message overhead if they are given a hint that the timestamp is not used by an application. By calling the
MessageProducer.setDisableMessageTimestamp
method, a Jakarta Messaging client enables this potential optimization for all
messages sent by that message producer. If the Jakarta Messaging provider accepts this hint, these messages must have the timestamp
set to zero; if the provider ignores the hint, the timestamp must be set to its normal value.
JMSException
- if the Jakarta Messaging provider fails to get the timestamp due to some internal error.setJMSTimestamp(long)
,
MessageProducer.setDisableMessageTimestamp(boolean)
void setJMSTimestamp(long timestamp) throws JMSException
This method is for use by Jakarta Messaging providers only to set this field when a message is sent. This message cannot be used by clients to configure the message timestamp. This method is public to allow a Jakarta Messaging provider to set this field when sending a message whose implementation is not its own.
timestamp
- the timestamp for this messageJMSException
- if the Jakarta Messaging provider fails to set the timestamp due to some internal error.getJMSTimestamp()
byte[] getJMSCorrelationIDAsBytes() throws JMSException
The use of a byte[]
value for JMSCorrelationID
is non-portable.
JMSException
- if the Jakarta Messaging provider fails to get the correlation ID due to some internal error.setJMSCorrelationID(String)
,
getJMSCorrelationID()
,
setJMSCorrelationIDAsBytes(byte[])
void setJMSCorrelationIDAsBytes(byte[] correlationID) throws JMSException
The array is copied before the method returns, so future modifications to the array will not alter this message header.
If a provider supports the native concept of correlation ID, a Jakarta Messaging client may need to assign specific
JMSCorrelationID
values to match those expected by native messaging clients. Jakarta Messaging providers without native
correlation ID values are not required to support this method and its corresponding get method; their implementation
may throw a java.lang.UnsupportedOperationException
.
The use of a byte[]
value for JMSCorrelationID
is non-portable.
correlationID
- the correlation ID value as an array of bytesJMSException
- if the Jakarta Messaging provider fails to set the correlation ID due to some internal error.setJMSCorrelationID(String)
,
getJMSCorrelationID()
,
getJMSCorrelationIDAsBytes()
void setJMSCorrelationID(java.lang.String correlationID) throws JMSException
A client can use the JMSCorrelationID
header field to link one message with another. A typical use is to link
a response message with its request message.
JMSCorrelationID
can hold one of the following:
String
byte[]
value
Since each message sent by a Jakarta Messaging provider is assigned a message ID value, it is convenient to link messages via
message ID. All message ID values must start with the 'ID:'
prefix.
In some cases, an application (made up of several clients) needs to use an application-specific value for linking
messages. For instance, an application may use JMSCorrelationID
to hold a value referencing some external
information. Application-specified values must not start with the 'ID:'
prefix; this is reserved for
provider-generated message ID values.
If a provider supports the native concept of correlation ID, a Jakarta Messaging client may need to assign specific
JMSCorrelationID
values to match those expected by clients that do not use the Jakarta Messaging API. A byte[]
value is used for this purpose. Jakarta Messaging providers without native correlation ID values are not required to support
byte[]
values. The use of a byte[]
value for JMSCorrelationID
is non-portable.
correlationID
- the message ID of a message being referred toJMSException
- if the Jakarta Messaging provider fails to set the correlation ID due to some internal error.getJMSCorrelationID()
,
getJMSCorrelationIDAsBytes()
,
setJMSCorrelationIDAsBytes(byte[])
java.lang.String getJMSCorrelationID() throws JMSException
This method is used to return correlation ID values that are either provider-specific message IDs or
application-specific String
values.
String
JMSException
- if the Jakarta Messaging provider fails to get the correlation ID due to some internal error.setJMSCorrelationID(String)
,
getJMSCorrelationIDAsBytes()
,
setJMSCorrelationIDAsBytes(byte[])
Destination getJMSReplyTo() throws JMSException
Destination
object to which a reply to this message should be sent.Destination
to which to send a response to this messageJMSException
- if the Jakarta Messaging provider fails to get the JMSReplyTo
destination due to some internal
error.setJMSReplyTo(Destination)
void setJMSReplyTo(Destination replyTo) throws JMSException
Destination
object to which a reply to this message should be sent.
The JMSReplyTo
header field contains the destination where a reply to the current message should be sent. If
it is null, no reply is expected. The destination may be either a Queue
object or a Topic
object.
Messages sent with a null JMSReplyTo
value may be a notification of some event, or they may just be some data
the sender thinks is of interest.
Messages with a JMSReplyTo
value typically expect a response. A response is optional; it is up to the client
to decide. These messages are called requests. A message sent in response to a request is called a reply.
In some cases a client may wish to match a request it sent earlier with a reply it has just received. The client can
use the JMSCorrelationID
header field for this purpose.
replyTo
- Destination
to which to send a response to this messageJMSException
- if the Jakarta Messaging provider fails to set the JMSReplyTo
destination due to some internal
error.getJMSReplyTo()
Destination getJMSDestination() throws JMSException
Destination
object for this message.
The JMSDestination
header field contains the destination to which the message is being sent.
When a message is sent, this field is ignored. After completion of the send
or publish
method, the
field holds the destination specified by the method.
When a message is received, its JMSDestination
value must be equivalent to the value assigned when it was
sent.
JMSException
- if the Jakarta Messaging provider fails to get the destination due to some internal error.setJMSDestination(Destination)
void setJMSDestination(Destination destination) throws JMSException
Destination
object for this message.
This method is for use by Jakarta Messaging providers only to set this field when a message is sent. This message cannot be used by clients to configure the destination of the message. This method is public to allow a Jakarta Messaging provider to set this field when sending a message whose implementation is not its own.
destination
- the destination for this messageJMSException
- if the Jakarta Messaging provider fails to set the destination due to some internal error.getJMSDestination()
int getJMSDeliveryMode() throws JMSException
DeliveryMode
value specified for this message.JMSException
- if the Jakarta Messaging provider fails to get the delivery mode due to some internal error.setJMSDeliveryMode(int)
,
DeliveryMode
void setJMSDeliveryMode(int deliveryMode) throws JMSException
DeliveryMode
value for this message.
This method is for use by Jakarta Messaging providers only to set this field when a message is sent. This message cannot be used by clients to configure the delivery mode of the message. This method is public to allow a Jakarta Messaging provider to set this field when sending a message whose implementation is not its own.
deliveryMode
- the delivery mode for this messageJMSException
- if the Jakarta Messaging provider fails to set the delivery mode due to some internal error.getJMSDeliveryMode()
,
DeliveryMode
boolean getJMSRedelivered() throws JMSException
If a client receives a message with the JMSRedelivered
field set, it is likely, but not guaranteed, that this
message was delivered earlier but that its receipt was not acknowledged at that time.
JMSException
- if the Jakarta Messaging provider fails to get the redelivered state due to some internal error.setJMSRedelivered(boolean)
void setJMSRedelivered(boolean redelivered) throws JMSException
This method is for use by Jakarta Messaging providers only to set this field when a message is delivered. This message cannot be used by clients to configure the redelivered status of the message. This method is public to allow a Jakarta Messaging provider to set this field when sending a message whose implementation is not its own.
redelivered
- an indication of whether this message is being redeliveredJMSException
- if the Jakarta Messaging provider fails to set the redelivered state due to some internal error.getJMSRedelivered()
java.lang.String getJMSType() throws JMSException
JMSException
- if the Jakarta Messaging provider fails to get the message type due to some internal error.setJMSType(String)
void setJMSType(java.lang.String type) throws JMSException
Some Jakarta Messaging providers use a message repository that contains the definitions of messages sent by applications. The
JMSType
header field may reference a message's definition in the provider's repository.
The Jakarta Messaging API does not define a standard message definition repository, nor does it define a naming policy for the definitions it contains.
Some messaging systems require that a message type definition for each application message be created and that each
message specify its type. In order to work with such Jakarta Messaging providers, Jakarta Messaging clients should assign a value to
JMSType
, whether the application makes use of it or not. This ensures that the field is properly set for
those providers that require it.
To ensure portability, Jakarta Messaging clients should use symbolic values for JMSType
that can be configured at
installation time to the values defined in the current provider's message repository. If string literals are used,
they may not be valid type names for some Jakarta Messaging providers.
type
- the message typeJMSException
- if the Jakarta Messaging provider fails to set the message type due to some internal error.getJMSType()
long getJMSExpiration() throws JMSException
When a message is sent, the JMSExpiration
header field is left unassigned. After completion of the
send
or publish
method, it holds the expiration time of the message. This is the the difference,
measured in milliseconds, between the expiration time and midnight, January 1, 1970 UTC.
If the time-to-live is specified as zero, JMSExpiration
is set to zero to indicate that the message does not
expire.
When a message's expiration time is reached, a provider should discard it. The Jakarta Messaging API does not define any form of notification of message expiration.
Clients should not receive messages that have expired; however, the Jakarta Messaging API does not guarantee that this will not happen.
JMSException
- if the Jakarta Messaging provider fails to get the message expiration due to some internal error.setJMSExpiration(long)
void setJMSExpiration(long expiration) throws JMSException
This method is for use by Jakarta Messaging providers only to set this field when a message is sent. This message cannot be used by clients to configure the expiration time of the message. This method is public to allow a Jakarta Messaging provider to set this field when sending a message whose implementation is not its own.
expiration
- the message's expiration timeJMSException
- if the Jakarta Messaging provider fails to set the message expiration due to some internal error.getJMSExpiration()
long getJMSDeliveryTime() throws JMSException
When a message is sent, the JMSDeliveryTime
header field is left unassigned. After completion of the
send
or publish
method, it holds the delivery time of the message. This is the the difference,
measured in milliseconds, between the delivery time and midnight, January 1, 1970 UTC.
A message's delivery time is the earliest time when a Jakarta Messaging provider may deliver the message to a consumer. The provider must not deliver messages before the delivery time has been reached.
JMSException
- if the Jakarta Messaging provider fails to get the delivery time due to some internal error.setJMSDeliveryTime(long)
void setJMSDeliveryTime(long deliveryTime) throws JMSException
This method is for use by Jakarta Messaging providers only to set this field when a message is sent. This message cannot be used by clients to configure the delivery time of the message. This method is public to allow a Jakarta Messaging provider to set this field when sending a message whose implementation is not its own.
deliveryTime
- the message's delivery time valueJMSException
- if the Jakarta Messaging provider fails to set the delivery time due to some internal error.getJMSDeliveryTime()
int getJMSPriority() throws JMSException
The Jakarta Messaging API defines ten levels of priority value, with 0 as the lowest priority and 9 as the highest. In addition, clients should consider priorities 0-4 as gradations of normal priority and priorities 5-9 as gradations of expedited priority.
The Jakarta Messaging API does not require that a provider strictly implement priority ordering of messages; however, it should do its best to deliver expedited messages ahead of normal messages.
JMSException
- if the Jakarta Messaging provider fails to get the message priority due to some internal error.setJMSPriority(int)
void setJMSPriority(int priority) throws JMSException
This method is for use by Jakarta Messaging providers only to set this field when a message is sent. This message cannot be used by clients to configure the priority level of the message. This method is public to allow a Jakarta Messaging provider to set this field when sending a message whose implementation is not its own.
priority
- the priority of this messageJMSException
- if the Jakarta Messaging provider fails to set the message priority due to some internal error.getJMSPriority()
void clearProperties() throws JMSException
The message's header fields and body are not cleared.
JMSException
- if the Jakarta Messaging provider fails to clear the message properties due to some internal error.boolean propertyExists(java.lang.String name) throws JMSException
name
- the name of the property to testJMSException
- if the Jakarta Messaging provider fails to determine if the property exists due to some internal error.boolean getBooleanProperty(java.lang.String name) throws JMSException
boolean
property with the specified name.name
- the name of the boolean
propertyboolean
property value for the specified nameJMSException
- if the Jakarta Messaging provider fails to get the property value due to some internal error.MessageFormatException
- if this type conversion is invalid.byte getByteProperty(java.lang.String name) throws JMSException
byte
property with the specified name.name
- the name of the byte
propertybyte
property value for the specified nameJMSException
- if the Jakarta Messaging provider fails to get the property value due to some internal error.MessageFormatException
- if this type conversion is invalid.short getShortProperty(java.lang.String name) throws JMSException
short
property with the specified name.name
- the name of the short
propertyshort
property value for the specified nameJMSException
- if the Jakarta Messaging provider fails to get the property value due to some internal error.MessageFormatException
- if this type conversion is invalid.int getIntProperty(java.lang.String name) throws JMSException
int
property with the specified name.name
- the name of the int
propertyint
property value for the specified nameJMSException
- if the Jakarta Messaging provider fails to get the property value due to some internal error.MessageFormatException
- if this type conversion is invalid.long getLongProperty(java.lang.String name) throws JMSException
long
property with the specified name.name
- the name of the long
propertylong
property value for the specified nameJMSException
- if the Jakarta Messaging provider fails to get the property value due to some internal error.MessageFormatException
- if this type conversion is invalid.float getFloatProperty(java.lang.String name) throws JMSException
float
property with the specified name.name
- the name of the float
propertyfloat
property value for the specified nameJMSException
- if the Jakarta Messaging provider fails to get the property value due to some internal error.MessageFormatException
- if this type conversion is invalid.double getDoubleProperty(java.lang.String name) throws JMSException
double
property with the specified name.name
- the name of the double
propertydouble
property value for the specified nameJMSException
- if the Jakarta Messaging provider fails to get the property value due to some internal error.MessageFormatException
- if this type conversion is invalid.java.lang.String getStringProperty(java.lang.String name) throws JMSException
String
property with the specified name.name
- the name of the String
propertyString
property value for the specified name; if there is no property by this name, a null value
is returnedJMSException
- if the Jakarta Messaging provider fails to get the property value due to some internal error.MessageFormatException
- if this type conversion is invalid.java.lang.Object getObjectProperty(java.lang.String name) throws JMSException
This method can be used to return, in objectified format, an object that has been stored as a property in the message
with the equivalent setObjectProperty
method call, or its equivalent primitive
settypeProperty
method.
name
- the name of the Java object propertyint
, an Integer
is returned); if there is no property by this name, a null value is
returnedJMSException
- if the Jakarta Messaging provider fails to get the property value due to some internal error.java.util.Enumeration getPropertyNames() throws JMSException
Enumeration
of all the property names.
Note that Jakarta Messaging standard header fields are not considered properties and are not returned in this enumeration.
JMSException
- if the Jakarta Messaging provider fails to get the property names due to some internal error.void setBooleanProperty(java.lang.String name, boolean value) throws JMSException
boolean
property value with the specified name into the message.name
- the name of the boolean
propertyvalue
- the boolean
property value to setJMSException
- if the Jakarta Messaging provider fails to set the property due to some internal error.java.lang.IllegalArgumentException
- if the name is null or if the name is an empty string.MessageNotWriteableException
- if properties are read-onlyvoid setByteProperty(java.lang.String name, byte value) throws JMSException
byte
property value with the specified name into the message.name
- the name of the byte
propertyvalue
- the byte
property value to setJMSException
- if the Jakarta Messaging provider fails to set the property due to some internal error.java.lang.IllegalArgumentException
- if the name is null or if the name is an empty string.MessageNotWriteableException
- if properties are read-onlyvoid setShortProperty(java.lang.String name, short value) throws JMSException
short
property value with the specified name into the message.name
- the name of the short
propertyvalue
- the short
property value to setJMSException
- if the Jakarta Messaging provider fails to set the property due to some internal error.java.lang.IllegalArgumentException
- if the name is null or if the name is an empty string.MessageNotWriteableException
- if properties are read-onlyvoid setIntProperty(java.lang.String name, int value) throws JMSException
int
property value with the specified name into the message.name
- the name of the int
propertyvalue
- the int
property value to setJMSException
- if the Jakarta Messaging provider fails to set the property due to some internal error.java.lang.IllegalArgumentException
- if the name is null or if the name is an empty string.MessageNotWriteableException
- if properties are read-onlyvoid setLongProperty(java.lang.String name, long value) throws JMSException
long
property value with the specified name into the message.name
- the name of the long
propertyvalue
- the long
property value to setJMSException
- if the Jakarta Messaging provider fails to set the property due to some internal error.java.lang.IllegalArgumentException
- if the name is null or if the name is an empty string.MessageNotWriteableException
- if properties are read-onlyvoid setFloatProperty(java.lang.String name, float value) throws JMSException
float
property value with the specified name into the message.name
- the name of the float
propertyvalue
- the float
property value to setJMSException
- if the Jakarta Messaging provider fails to set the property due to some internal error.java.lang.IllegalArgumentException
- if the name is null or if the name is an empty string.MessageNotWriteableException
- if properties are read-onlyvoid setDoubleProperty(java.lang.String name, double value) throws JMSException
double
property value with the specified name into the message.name
- the name of the double
propertyvalue
- the double
property value to setJMSException
- if the Jakarta Messaging provider fails to set the property due to some internal error.java.lang.IllegalArgumentException
- if the name is null or if the name is an empty string.MessageNotWriteableException
- if properties are read-onlyvoid setStringProperty(java.lang.String name, java.lang.String value) throws JMSException
String
property value with the specified name into the message.name
- the name of the String
propertyvalue
- the String
property value to setJMSException
- if the Jakarta Messaging provider fails to set the property due to some internal error.java.lang.IllegalArgumentException
- if the name is null or if the name is an empty string.MessageNotWriteableException
- if properties are read-onlyvoid setObjectProperty(java.lang.String name, java.lang.Object value) throws JMSException
Note that this method works only for the objectified primitive object types (Integer
, Double
,
Long
...) and String
objects.
name
- the name of the Java object propertyvalue
- the Java object property value to setJMSException
- if the Jakarta Messaging provider fails to set the property due to some internal error.java.lang.IllegalArgumentException
- if the name is null or if the name is an empty string.MessageFormatException
- if the object is invalidMessageNotWriteableException
- if properties are read-onlyvoid acknowledge() throws JMSException
All consumed Jakarta Messaging messages support the acknowledge
method for use when a client has specified that its JMS
session's consumed messages are to be explicitly acknowledged. By invoking acknowledge
on a consumed message,
a client acknowledges all messages consumed by the session that the message was delivered to.
Calls to acknowledge
are ignored for both transacted sessions and sessions specified to use implicit
acknowledgement modes.
A client may individually acknowledge each message as it is consumed, or it may choose to acknowledge messages as an application-defined group (which is done by calling acknowledge on the last received message of the group, thereby acknowledging all messages consumed by the session.)
Messages that have been received but not acknowledged may be redelivered.
JMSException
- if the Jakarta Messaging provider fails to acknowledge the messages due to some internal error.IllegalStateException
- if this method is called on a closed session.Session.CLIENT_ACKNOWLEDGE
void clearBody() throws JMSException
If this message body was read-only, calling this method leaves the message body in the same state as an empty body in a newly created message.
JMSException
- if the Jakarta Messaging provider fails to clear the message body due to some internal error.<T> T getBody(java.lang.Class<T> c) throws JMSException
T
- The type of the message bodyc
- The type to which the message body will be assigned. TextMessage
then this parameter must be set to String.class
or another type to
which a String
is assignable. ObjectMessage
then parameter must must be set to java.io.Serializable.class
or
another type to which the body is assignable. MapMessage
then this parameter must be set to java.util.Map.class
(or
java.lang.Object.class
). BytesMessage
then this parameter must be set to byte[].class
(or
java.lang.Object.class
). This method will reset the BytesMessage
before and after use.TextMessage
, ObjectMessage
, MapMessage
or BytesMessage
and the
message has no body, then the above does not apply and this parameter may be set to any type; the returned value will
always be null.Message
(but not one of its subtypes) then this parameter may be set to any type; the
returned value will always be null.MessageFormatException
- StreamMessage
ObjectMessage
and object deserialization fails.
JMSException
- if the Jakarta Messaging provider fails to get the message body due to some internal error.boolean isBodyAssignableTo(java.lang.Class c) throws JMSException
getBody
on the same message with the same type argument would not throw a
MessageFormatException.
If the message is a StreamMessage
then false is always returned. If the message is a ObjectMessage
and object deserialization fails then false is returned. If the message has no body then any type may be specified
and true is returned.
c
- The specified type TextMessage
then this method will only return true if this parameter is set to
String.class
or another type to which a String
is assignable. ObjectMessage
then this method will only return true if this parameter is set to
java.io.Serializable.class
or another class to which the body is assignable. MapMessage
then this method will only return true if this parameter is set to
java.util.Map.class
(or java.lang.Object.class
). BytesMessage
then this this method will only return true if this parameter is set to
byte[].class
(or java.lang.Object.class
). TextMessage
, ObjectMessage
, MapMessage
or BytesMessage
and the
message has no body, then the above does not apply and this method will return true irrespective of the value of this
parameter.Message
(but not one of its subtypes) then this method will return true irrespective of
the value of this parameter.JMSException
- if the Jakarta Messaging provider fails to return a value due to some internal error.


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Quick Tutorial
1.
- Take a photo of the dog with other stuff in background.
2. Verify the results
- Is the result correct?
- Do you get the same result after taking the same photo twice?
- Please use Apples Testflight Feedback channel :)
Technical info
The current machine learning model has a 70% validation accuracy.


I’m feeling very much like the AI companion in a video game.
All I can do is sit here and do math while my friends are having all the fun.


Example_cities.Rmd
This notebook demonstrates the use of extRatum
package drawing on OpenStreetMap data. extRatum
provides summary statistics of local geospatial features within a given geographic area. It does so by calculating the area covered by a target geospatial feature (i.e. buildings, parks, lakes, etc.). The geospatial features can be of any geospatial data type, including point, polygon or line data.
In this example, we focus on built environment characteristics.
We make use of OpenStreetMap data and calculate point-, polygon- and line-based data features. The reference layer is the Lower Layer Super Output Area (LSOA) boundaries for the city of Liverpool in the United Kingdom.
## Warning: package 'sf' was built under R version 4.0.3
## Linking to GEOS 3.8.0, GDAL 3.0.4, PROJ 6.3.1
##
## Attaching package: 'dplyr'
## The following objects are masked from 'package:stats':
##
## filter, lag
## The following objects are masked from 'package:base':
##
## intersect, setdiff, setequal, union
## Data (c) OpenStreetMap contributors, ODbL 1.0. https://www.openstreetmap.org/copyright
First, we read in the LSOA boundaries for Liverpool. The data downloaded from CDRC website: https://data.cdrc.ac.uk/
# 1. Read in the FUA grids
LSOAs <- st_read("layers/E08000012.shp")
## Reading layer `E08000012' from data source `C:\Users\User\Desktop\extRatum\vignettes\layers\E08000012.shp' using driver `ESRI Shapefile'
## Simple feature collection with 298 features and 1 field
## geometry type: MULTIPOLYGON
## dimension: XY
## bbox: xmin: 333086.1 ymin: 381426.3 xmax: 345636 ymax: 397980.1
## projected CRS: Transverse_Mercator
Because the area of interest is in the UK, we select the British National Grid as a planar coordinate system of reference.
BNG = "epsg:27700"
Here, we illustrate the use of extRatum
with point data.
We create a simple query to download point data representing shops in Liverpool.
q <- getbb("Liverpool") %>%
opq() %>%
add_osm_feature(key = "shop")
shops <- osmdata_sf(q)
And plot them.
#tmap_mode("view") #use this code for creating an interactive map
tmap_mode("plot")
## tmap mode set to plotting
# show the points and grids
tm_shape(LSOAs) +
tm_borders() +
tm_shape(shops$osm_points) +
tm_dots()
Then we calculate the number of points in each polygon using the point_calc()
function. Note that we have to pass a planar coordinate system in all our functions. Here we are using the British National Grid. The output of this function will be a dataframe containing:
Note that we have used the argument total_points = TRUE
which returns the total number of points without differentiating between different shop types.
Shops_total <- point_calc(
point_data = shops$osm_points,
higher_geo_lay = LSOAs,
unique_id_code = 'lsoa11cd',
crs = BNG,
total_points = TRUE
)
# inspect the results
head(Shops_total)
## # A tibble: 6 x 4
## lsoa11cd TotalArea NoPoints Ratio
## <chr> <dbl> <int> <dbl>
## 1 E01006513 555037. 29 0.0000522
## 2 E01006514 262031. 2 0.00000763
## 3 E01006515 366500. 16 0.0000437
## 4 E01006518 235181. 1 0.00000425
## 5 E01006520 259435. 1 0.00000385
## 6 E01006522 473782. 3 0.00000633
In some cases, we want to know the split between different types of points. To that end, we can change the total_points = FALSE
and specify the column name that includes the classification (see class_col
).
Shops_class <- point_calc(
point_data = shops$osm_points,
higher_geo_lay = LSOAs,
unique_id_code = 'lsoa11cd',
class_col = 'shop',
crs = BNG,
total_points = FALSE
)
The output of this function will be a list of three dataframes.
head(Shops_class$PointsLong)
## # A tibble: 6 x 5
## lsoa11cd TotalArea shop NoPoints Ratio
## <chr> <dbl> <chr> <int> <dbl>
## 1 E01006513 555037. bakery 2 0.00000360
## 2 E01006513 555037. beauty 1 0.00000180
## 3 E01006513 555037. bookmaker 2 0.00000360
## 4 E01006513 555037. books 2 0.00000360
## 5 E01006513 555037. clothes 1 0.00000180
## 6 E01006513 555037. convenience 8 0.0000144
head(Shops_class$PointsCountWide)
## # A tibble: 6 x 92
## lsoa11cd alcohol Baby baby_goods bag bakery beauty bed beverages bicycle
## <chr> <int> <int> <int> <int> <int> <int> <int> <int> <int>
## 1 E010065~ NA NA NA NA 2 1 NA NA NA
## 2 E010065~ NA NA NA NA NA NA NA NA NA
## 3 E010065~ NA NA NA NA NA NA NA NA 1
## 4 E010065~ NA NA NA NA NA NA NA NA NA
## 5 E010065~ NA NA NA NA NA NA NA NA NA
## 6 E010065~ NA NA NA NA NA NA NA NA NA
## # ... with 82 more variables: bookmaker <int>, books <int>, `Business
## # Service` <int>, butcher <int>, cakes <int>, car <int>, car_parts <int>,
## # car_repair <int>, carpet <int>, catalogue <int>, charity <int>,
## # chemist <int>, clothes <int>, coffee <int>, computer <int>,
## # confectionery <int>, convenience <int>, cosmetics <int>, craft <int>,
## # deli <int>, department_store <int>, Discount <int>, doityourself <int>,
## # dry_cleaning <int>, electrical <int>, electronics <int>, erotic <int>,
## # estate_agent <int>, florist <int>, food <int>, frozen_food <int>,
## # funeral_directors <int>, furniture <int>, games <int>, garden_centre <int>,
## # gift <int>, greeting_card <int>, `greetings cards` <int>,
## # hairdresser <int>, hardware <int>, health_food <int>, hifi <int>,
## # houseware <int>, jewelry <int>, kiosk <int>, laundry <int>, leather <int>,
## # mall <int>, mobile_phone <int>, music <int>, musical_instrument <int>,
## # newsagent <int>, optician <int>, outdoor <int>, pawnbroker <int>,
## # perfumery <int>, pet <int>, photo <int>, religion <int>, salon <int>,
## # second_hand <int>, shoes <int>, sports <int>, stationery <int>,
## # storage_rental <int>, supermarket <int>, tailor <int>, tea <int>,
## # ticket <int>, `ticket;convenience` <int>, toys <int>, trade <int>,
## # travel_agency <int>, vacant <int>, variety_store <int>, video_games <int>,
## # Vintage_Boutique <int>, watches <int>, window_blind <int>, wine <int>,
## # yes <int>, `<NA>` <int>
head(Shops_class$PointsRatioWide)
## # A tibble: 6 x 92
## lsoa11cd alcohol Baby baby_goods bag bakery beauty bed beverages
## <chr> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
## 1 E010065~ NA NA NA NA 3.60e-6 1.80e-6 NA NA
## 2 E010065~ NA NA NA NA NA NA NA NA
## 3 E010065~ NA NA NA NA NA NA NA NA
## 4 E010065~ NA NA NA NA NA NA NA NA
## 5 E010065~ NA NA NA NA NA NA NA NA
## 6 E010065~ NA NA NA NA NA NA NA NA
## # ... with 83 more variables: bicycle <dbl>, bookmaker <dbl>, books <dbl>,
## # `Business Service` <dbl>, butcher <dbl>, cakes <dbl>, car <dbl>,
## # car_parts <dbl>, car_repair <dbl>, carpet <dbl>, catalogue <dbl>,
## # charity <dbl>, chemist <dbl>, clothes <dbl>, coffee <dbl>, computer <dbl>,
## # confectionery <dbl>, convenience <dbl>, cosmetics <dbl>, craft <dbl>,
## # deli <dbl>, department_store <dbl>, Discount <dbl>, doityourself <dbl>,
## # dry_cleaning <dbl>, electrical <dbl>, electronics <dbl>, erotic <dbl>,
## # estate_agent <dbl>, florist <dbl>, food <dbl>, frozen_food <dbl>,
## # funeral_directors <dbl>, furniture <dbl>, games <dbl>, garden_centre <dbl>,
## # gift <dbl>, greeting_card <dbl>, `greetings cards` <dbl>,
## # hairdresser <dbl>, hardware <dbl>, health_food <dbl>, hifi <dbl>,
## # houseware <dbl>, jewelry <dbl>, kiosk <dbl>, laundry <dbl>, leather <dbl>,
## # mall <dbl>, mobile_phone <dbl>, music <dbl>, musical_instrument <dbl>,
## # newsagent <dbl>, optician <dbl>, outdoor <dbl>, pawnbroker <dbl>,
## # perfumery <dbl>, pet <dbl>, photo <dbl>, religion <dbl>, salon <dbl>,
## # second_hand <dbl>, shoes <dbl>, sports <dbl>, stationery <dbl>,
## # storage_rental <dbl>, supermarket <dbl>, tailor <dbl>, tea <dbl>,
## # ticket <dbl>, `ticket;convenience` <dbl>, toys <dbl>, trade <dbl>,
## # travel_agency <dbl>, vacant <dbl>, variety_store <dbl>, video_games <dbl>,
## # Vintage_Boutique <dbl>, watches <dbl>, window_blind <dbl>, wine <dbl>,
## # yes <dbl>, `<NA>` <dbl>
Finally we can map the results to show the density of shops in the city of Liverpool at the LSOA level.
Next, we illustrate the use of extRatum
with polygon data.
We create a query to download building footprints for the city of Liverpool using OpenStreetMap data.
q2 <- getbb("Liverpool", limit = 100) %>%
opq() %>%
add_osm_feature(key = "building")
buildings <- osmdata_sf(q2)
We can then subset the buildings that are classified as retail.
retail_buildings <- subset(buildings$osm_polygons, building=="retail")
Then, we run the function that calculates the area in sqm covered by retail buildings in each LSOA using areal_calc()
function.
Liv_retail <- areal_calc(
polygon_layer = retail_buildings,
higher_geo_lay = LSOAs,
unique_id_code = 'lsoa11cd',
crs = BNG
)
The output of this function will be a dataframe containing:
Given that everything is measured in sqm, the ratio represents what is the % of area covered by retail buildings by sqm. In this way, we have a relative measure that can be compared across all LSOAs and is independent of their size.
We can also transform the calculated values in sqkm by dividing the value in sqm by 1,000,000. This can be done as follows.
Liv_retail$AreaCovered_sqkm <- Liv_retail$AreaCovered /1000000
head(Liv_retail)
## # A tibble: 6 x 5
## lsoa11cd TotalArea AreaCovered Ratio AreaCovered_sqkm
## <chr> <dbl> <dbl> <dbl> <dbl>
## 1 E01006519 505501. 946. 0.00187 0.000946
## 2 E01006537 1077345. 5864. 0.00544 0.00586
## 3 E01006563 287328. 1455. 0.00506 0.00145
## 4 E01006570 443140. 7.59 0.0000171 0.00000759
## 5 E01006571 404631. 830. 0.00205 0.000830
## 6 E01006572 135551. 110. 0.000813 0.000110
Finally, we can plot the results, showing the total area covered by retail buildings in each LSOA in Liverpool. Note that OSM data on retail buildings are not complete for the city of Liverpool. Thus, we see too many LSOAs with missing data.
Now, we illustrate the use of extRatum
with line data.
We create a query to download highway lines for the city of Liverpool using OpenStreetMap data.
q3 <- getbb("Liverpool") %>%
opq() %>%
add_osm_feature(key = "highway")
highways <- osmdata_sf(q3)
We can then create subsets of the dataset such as pathways for pedestrian use.
pedestrian <- subset(highways$osm_lines, highway == "pedestrian")
Then we can calculate the total length of pedestrian pathways routes by LSOA using line_calc()
function.
Liv_footways <- line_calc(
line_layer = pedestrian,
higher_geo_lay = LSOAs,
unique_id_code = 'lsoa11cd',
crs = BNG
)
The output of this function will be a dataframe containing:
head(Liv_footways)
## # A tibble: 6 x 4
## lsoa11cd TotalArea TotalLength Ratio
## <chr> <dbl> <dbl> <dbl>
## 1 E01006512 283907. 22.7 0.0000799
## 2 E01006513 555037. 208. 0.000375
## 3 E01006514 262031. 9.73 0.0000371
## 4 E01006515 366500. 38.3 0.000104
## 5 E01006518 235181. 29.5 0.000125
## 6 E01006521 603082. 29.2 0.0000484
Finally, we can plot the results, showing the total length of pedestrian pathways in each LSOA in Liverpool. Note that the majority is around Liverpool city centre where we see darker colours.