So far we have been processing events using callbacks, and from various sources such as HTTP or TCP servers. Callbacks allow us to reason about events one at a time.
Processing an incoming data buffer from a TCP connection, from a file or from a HTTP request is not very different: you need to declare a callback handler that reacts to each event and allows custom processing.
That being said, most events need to be processed as series rather than as isolated events. Processing the body of a HTTP request is a good example, as several buffers of different sizes need to be assembled to reconstitute the full body payload.
Vert.x offers a unified abstraction of streams. A read stream is a source of events that can be read, while a write stream is a destination for events to be sent. As an example, a HTTP request is a read stream, while a HTTP response is a write stream.
Streams in Vert.x span a wide range of sources and sinks, including those from table 4.1.
| Stream resource | Read support | Write support |
| TCP sockets |
Yes |
yes |
| UDP datagrams |
Yes |
Yes |
| HTTP requests and responses |
Yes |
Yes |
| WebSockets |
Yes |
Yes |
| Files |
Yes |
Yes |
| SQL results |
Yes |
No |
| Kafka events |
Yes |
Yes |
| Periodic timers |
Yes |
No |
| (â¦) |
(â¦) |
(â¦) |
Read and write stream are defined through the ReadStream and WriteStream interfaces of the io.vertx.core.streams package. You will mostly deal with APIs that implement these 2 interfaces rather than implement them yourself, although you may have to do so if you want to connect to some third-party asynchronous events API.
These interfaces can be seen each as having 2 parts:
| Method | Description |
|
|
Handle a new read value of type |
|
|
Handle a read exception. |
|
|
Called when the stream has ended, either because all data has been read, or because an exception was raised. |
Table 4.2 gives the essential methods of read streams. They define callbacks for being notified of 3 types of events: some data is read, an exception arises, and the stream has ended.
| Method | Description |
|
|
Write some data of type |
|
|
Handle a write exception. |
|
|
Ends the stream. |
|
|
Write some data of type |
Similarly, the essential methods of write streams outlined in table 4.3 allow to write data, end a stream, and be notified when an exception arises.
We had already manipulated streams in the previous chapters without knowing it, for example with TCP and HTTP servers.
The java.io APIs form a classic stream I/O abstraction for reading and writing data from various sources in Java, albeit using blocking APIs. It is interesting to compare the JDK streams against the Vert.x non-blocking stream APIs.
Suppose that we want to read the content of a file, and output its content to the standard console output.
public static void main(String[] args) { File file = new File("build.gradle"); byte[] buffer = new byte[1024]; try (FileInputStream in = new FileInputStream(file)) { #1 int count = in.read(buffer); while (count != -1) { System.out.println(new String(buffer, 0, count)); count = in.read(buffer); } } catch (IOException e) { e.printStackTrace(); } finally { System.out.println("\n--- DONE"); #2 } }
Listing 4.1 shows a classical example of using JDK I/O streams to read a file then output its content to the console while taking care of possible errors. We read data to a buffer, then immediately write the buffer content to the standard console before recycling the buffer for the next read.
public static void main(String[] args) { Vertx vertx = Vertx.vertx(); OpenOptions opts = new OpenOptions().setRead(true); #1 vertx.fileSystem().open("build.gradle", opts, ar -> { #2 if (ar.succeeded()) { AsyncFile file = ar.result(); #3 file.handler(System.out::println) #4 .exceptionHandler(Throwable::printStackTrace) #5 .endHandler(done -> { #6 System.out.println("\n--- DONE"); vertx.close(); }); } else { ar.cause().printStackTrace(); } }); }
Listing 4.2 shows the implementation of the very same code as in listing 4.1, but using the Vert.x asynchronous file APIs. The approach is declarative here, as we define handlers for the different types of events when reading the stream. We are being pushed data while in listing 4.1 we are pulling data from the stream.
It may seem like a cosmetic difference at first sight that in one example data is being pulled, while in the other data is being pushed. The difference is major, and certainly one that needs to be understood for mastering asynchronous streams, be it with Vert.x or with other solutions.
This brings us to investigating the notion of back-pressure.
Back-pressure definition
Back-pressure is a mechanism for a consumer of events to signal an events producer that it is emitting events at a faster rate than the consumer can handle them.
In reactive systems back-pressure is useful to pause or slow-down a producer so that consumers avoids accumulating unprocessed events in unbounded memory buffers, possibly exhausting resources.
To understand back-pressure and why it matters with asynchronous streams, let us take the example of a HTTP server used for downloading Linux distribution images, and consider the implementation without any back-pressure management strategy in place.
Linux distribution images are often distributed as .iso files and can easily weigh several gigabytes. The implementation of such a server would consists in:
Figure 4.1 provides an illustration of how this would work with Vert.x, although this directly generalizes to any non-blocking I/O API. Data buffers are read from the file stream, then passed to a handler. The handler is not likely to do anything else but directly writing each buffer back to the HTTP response stream. Each buffer is eventually written to the underlying TCP buffer, either directly or as smaller chunks. Since the TCP buffer may be full (either because of the network or because the client is busy) it is necessary to maintain a buffer of pending buffers to be written (the write queue in figure 4.1). Remember: a write operation is non-blocking, so buffering is needed.
This sounds like a very simple processing pipeline, so… what could possibly go wrong?
Reading from a filesystem is generally fast and low-latency, and given several read requests an operating system is likely to cache some pages into RAM memory. By contrast writing to the network is much slower, and bandwidth depends on the weakest network link. Delays also occur.
As reads here are much faster than writes, a write buffer as in figure 4.1 may quickly grow very large. Suppose that we have several thousand concurrent connections to download ISO images, then we may have lots of buffers accumulated in write buffer queues. We may actually have several gigabytes worth of ISO images in a JVM process memory, waiting to be written over the network!
The more buffers there are in write queues, the more the process consumes memory. The risk here is clearly that of exhaustion, either because the process eats all available physical memory, or because it runs in a memory-capped environment such as a container.
Because of how asynchronous and non-blocking I/Os work, the read and the write streams operate at different paces, requiring buffering, and thus exposing the risk of consuming too much memory and even crashing.
As you can guess one solution lies in back-pressure signaling, so that the read stream adapts to the throughput of the write stream. Back to the previous example when the HTTP response write queue grows too big, then it should be able to notify the file read stream that it goes too fast. In practice pausing the source stream is a good way to manage back-pressure, as it gives a chance to write the items in the write buffer while not accumulating new ones.
Blocking I/O APIs have an implicit form of back-pressure by blocking execution threads until I/O operations complete. Write operations block when buffers are full, which prevents blocked threads from pulling more data until write operations have completed.
| Method | Description |
|
|
Puts the stream in pause, preventing further data to be sent to the handler. |
|
|
Starts reading data again and sending it to the handler. |
|
|
Demand a number |
Table 3.4 gives the back-pressure management methods of ReadStream. By default a read stream reads data as fast as it can, unless it is being paused. A processor can pause then resume a read stream to control the data flow.
When a read stream has been paused, it is possible to ask a certain numbers of elements to be fetched, which is a form of asynchronous pulling. This means that a processor can ask elements using fetch, at its own pace. We will see concrete examples of that in the last section of this chapter.
In any case, calling resume() causes the stream to start pushing data as fast as it can again.
| Method | Description |
|
|
Defines what the maximum write buffer queue size should be like before being considered as full. This is a size in terms of queued Vert.x buffers to be written, not a size in terms of actual bytes as the queued buffers may be of different sizes. |
|
|
Indicates when the write buffer queue size is full. |
|
|
Defines a callback when the write buffer queue has been drained, typically when it is back to half of its maximum size. |
Table 4.5 shows the corresponding back-pressure management methods for WriteStream. The write buffer queue has a maximum size after which it is considered to be full. Write queues have default sizes that you will rarely want to tweak, but you can do so if you want to. Note that writes can still be made and data will just accumulate in the queue. A writer is supposed to check when the queue is full, but there is no enforcement on writes.
When the writer knows that the write queue is full, it can be notified through a drain handler when data can be written again. In general this happens when half the write queue has been drained.
Now that we have seen what back-pressure operations are provided in both ReadStream and WriteStream, here is the recipe for controlling the flow back to our example of providing ISO images via HTTP:
lj jr ja fylf:
Note that this back-pressure management strategy is not always what you need. Indeed:
ReadStream
yvak, zun dkp bonv rv ieedcd tnwbeee pgriopnd crgz xt eufbirfgn nvxk lj rj pmc csaeu oyermm ehosuianxt.The strategy to adopt for dealing with back-pressure depends on the functional requirements of the code you are writing. In general you will prefer flow control like Vert.x streams offer, but when you can’t, you need to adopt another strategy.
Let us now assemble all that we’ve seen into an application.
We are going to illustrate Vert.x streams and back-pressure management through the example of a music streaming jukebox (see figure 4.2).
The idea is that the jukebox has a few MP3 files stored locally, and clients can connect over HTTP to listen to the stream. Individual files may also be downloaded over HTTP. In turn, controlling when to play, pause, and schedule a song to be played happens over a simple, text-based TCP protocol. All connected players shall be listening to the same audio at the same time, modulo minor delays due to the buffering put in place in the players.
This example allows us to see how to deal with custom flow pacing, different back-pressure management strategies, and also how to parse streams.
The application that we are going to build can be run from the examples using a Gradle task, as shown in the console output of listing 4.3.
You will need to copy some of your MP3 files to a folder named tracks/ if you want the jukebox to have music to play.
$ ./gradlew run -PmainClass=chapter4.jukebox.Main #1 > Task :run [vert.x-eventloop-thread-0] chapter4.jukebox.Jukebox - Start #2 [vert.x-eventloop-thread-1] chapter4.jukebox.NetControl - Start
There are 2 verticles being deployed:
Jukebox
ripsoevd rvp jmcn umsic msgitnear lgoci gcn HCXZ erevrs efrntciea ltv imsuc elrsayp kr oecncnt, ngzNetControl
rpdeisvo c krro-sdeba CBL ocloprot ktl teleomyr itcolnnogrl rvy kejoxub atlppcnoaii.To listen to music, one can connect a player such as VLC (see figure 4.3) or even open a web browser directly at localhost:8080/.
On the other hand, the player can be controlled using plain text commands using a tool like netcat with commands to list all files, schedule a track to be played and pause / restart the stream. Listing 4.4 shows an interactive session using netcat.
netcat
$ netcat localhost 3000 #1 /list #2 Daniela-La-Luz-Did-you-Ever-(Original-Mix).mp3 The-Revenge-Let-Love-Take-The-Blame-(Original-Mix).mp3 intro.mp3 SQL-Surrender-(Original-Mix).mp3 /schedule SQL-Surrender-(Original-Mix).mp3 #3 /pause #4 /play #5 /schedule Daniela-La-Luz-Did-you-Ever-(Original-Mix).mp3 #6 ^C #7
netcat may be available as nc on your Unix environment. I am not aware of a friendly and equivalent tool for Windows outside of a WSL environment.
Finally, we want to be able to download any MP3 for which we know the file name over HTTP, as in:
curl -o out.mp3 http://localhost:8080/download/intro.mp3
Let us now dissect the various parts of the implementation.
Since there will be many code snippets referring to the HTTP server processing, it is good to look at figure 4.4 to understand how the next pieces of code will fit together.
There are 2 types of incoming HTTP requests: either a client wants to directly download a file by name, or it want to join the audio stream. The processing strategies are then very different.
In the case of downloading a file, the goal is to perform a direct copy between the file read stream and the HTTP response write stream. This will be done with back-pressure management for avoiding excessive buffering.
Streaming is a bit more involving, as we need to keep track of all streamers HTTP response write streams. Then, a timer periodically reads data from the current MP3 file, and then the data is duplicated and written for each streamer.
Let us now see how these parts are implemented.
Listing 4.5 shows that the state of the Jukebox verticle class is defined by a play status, and a playlist.
private enum State {PLAYING, PAUSED} private State currentMode = State.PAUSED; private final Queue<String> playlist = new ArrayDeque<>();
An enumerated type State defines 2 states, while a Queue holds all scheduled tracks to be played next. Again, the Vert.x threading model ensures single-threaded access so there is no need for concurrent collections and critical sections.
The start method of the Jukebox verticle (listing 4.6) needs to configure a few event-bus handlers that correspond to the command / actions that can be used from the TCP text protocol. Another verticle NetControl that we will dissect later deals with the inners of the TCP server, and sends messages to the event bus.
@Override public void start() { EventBus eventBus = vertx.eventBus(); eventBus.consumer("jukebox.list", this::list); eventBus.consumer("jukebox.schedule", this::schedule); eventBus.consumer("jukebox.play", this::play); eventBus.consumer("jukebox.pause", this::pause); // (...more later!) }
Note that by abstracting the commands part over the event-bus, we could easily plug new ways to command the jukebox, from mobile applications, web applications and more.
Listing 4.7 provides the play / pause and schedule handlers. These methods directly manipulate the play and playlist state.
private void play(Message<?> request) { currentMode = State.PLAYING; } private void pause(Message<?> request) { currentMode = State.PAUSED; } private void schedule(Message<JsonObject> request) { String file = request.body().getString("file"); if (playlist.isEmpty() && currentMode == State.PAUSED) { #1 currentMode = State.PLAYING; } playlist.offer(file); }
Listing available files is a bit more involving as listing 4.8 shows.
private void list(Message<?> request) { vertx.fileSystem().readDir("tracks", ".*mp3$", ar -> { #1 if (ar.succeeded()) { List<String> files = ar.result() .stream() .map(File::new) .map(File::getName) .collect(Collectors.toList()); JsonObject json = new JsonObject().put("files", new JsonArray(files)); request.reply(json); #2 } else { logger.error("readDir failed", ar.cause()); request.fail(500, ar.cause().getMessage()); #3 } }); }
There are 2 types of incoming HTTP clients: either they want the audio stream or they want to download a file.
Starting the HTTP server is done in the start method of the verticle (see listing 4.9).
@Override public void start() { EventBus eventBus = vertx.eventBus(); eventBus.consumer("jukebox.list", this::list); eventBus.consumer("jukebox.schedule", this::schedule); eventBus.consumer("jukebox.play", this::play); eventBus.consumer("jukebox.pause", this::pause); vertx.createHttpServer() .requestHandler(this::httpHandler) .listen(8080); // (...more later!) #1 }
The request handler used by the Vert.x HTTP server is given in listing 4.10, and forwards to utility methods openAudioStream and download to proceeed.
private void httpHandler(HttpServerRequest request) { if ("/".equals(request.path())) { openAudioStream(request); return; } if (request.path().startsWith("/download/")) { String sanitizedPath = request.path().substring(10).replaceAll("/", ""); #1 download(sanitizedPath, request); return; } request.response().setStatusCode(404).end(); #2 }
The implementation of method openAudioStream is given in listing 4.11. It prepares the stream to be in chunking mode, sets the proper content-type, and sets the response object aside for later.
private final Set<HttpServerResponse> streamers = new HashSet<>(); #1 private void openAudioStream(HttpServerRequest request) { HttpServerResponse response = request.response() .putHeader("Content-Type", "audio/mpeg") .setChunked(true); #2 streamers.add(response); response.endHandler(v -> { streamers.remove(response); #3 logger.info("A streamer left"); }); }
Downloading a file is a perfect example of back-pressure management to coordinate a source stream (the file) and a sink stream (the HTTP response).
Listing 4.12 gives how we look for the file, and when it exists, we forward the final download duty to the downloadFile method.
private void download(String path, HttpServerRequest request) { String file = "tracks/" + path; if (!vertx.fileSystem().existsBlocking(file)) { #1 request.response().setStatusCode(404).end(); return; } OpenOptions opts = new OpenOptions().setRead(true); vertx.fileSystem().open(file, opts, ar -> { if (ar.succeeded()) { downloadFile(ar.result(), request); } else { logger.error("Read failed", ar.cause()); request.response().setStatusCode(500).end(); } }); }
The implementation of method downloadFile
is given in listing 4.13.
private void downloadFile(AsyncFile file, HttpServerRequest request) { HttpServerResponse response = request.response(); response.setStatusCode(200) .putHeader("Content-Type", "audio/mpeg") .setChunked(true); file.handler(buffer -> { response.write(buffer); if (response.writeQueueFull()) { #1 file.pause(); #2 response.drainHandler(v -> file.resume()); #3 } }); file.endHandler(v -> response.end()); }
Back-pressure is being taken care of while copying data between the 2 streams. In fact, this is so common to do when the strategy is to pause the source and not lose any data that the same code can be rewritten as in listing 4.14.
HttpServerResponse response = request.response(); response.setStatusCode(200) .putHeader("Content-Type", "audio/mpeg") .setChunked(true); file.pipeTo(response); #1
A pipe deals with back-pressure for copying between a pausable ReadStream and a WriteStream. It also manages the end of the source stream and errors on both streams. The code of listing 4.14 does exactly what is in listing 4.13, but without the boilerplate. There are other variants of pipeTo to specify custom handlers.
MP3 files have a header containing meta-data such as the artist name, genre, bit rate, etc. Then several frames containing compressed audio data follow, which decoders can then turn into pulse-code modulation data that can eventually be turned into sound.
MP3 decoders are very resilient to errors, so if they start decoding right in the middle of a file they will still manage to figure out what is the bit rate, and they will align with the next frame to start decoding audio. You can even concatenate multiple MP3 files and send them to a player, audio will be decoded as long as all files are using the same bit rate and stereo mode.
This is interesting for us in designing a music streaming jukebox: given our files have been encoded the same way, we can simply push each file of a playlist one after the other and decoders will handle the audio just fine.
Now feeding MP3 data to many connected players is not as simple as it seems. The main issue is that of ensuring that all current and future players are listening the same music at roughly the same time. All players have different local buffering strategies to ensure smooth playback even when the network suffers delays, but if the server simply pushes files as fast as it can then for sure not all clients will be synchronized. Worse: when a new player connects it may receive nothing to play at all while the current players have several minutes of music to play in their buffers. Hence to provide a sensible playback experience, we need to control the pace at which files are being read, and for that we are going to use a timer.
This is illustrated in figure 4.5 where we show what happens without and with rate control on the streams.
In both cases, suppose that Player A joined the stream at the beginning, while Player B joined, say, 10 seconds later. Without read rate control we find ourselves back to a similar case as that of downloading a MP3 file. We may of course have back-pressure in place to ensure efficient resource usage while copying MP3 data chunks to the connected clients, yet the streaming experience will be very bad.
Since we are basically streaming data as fast as we can, Player A finds its internal buffers filled with pretty much all the current file data. While it may be playing at position 0 minute 15 seconds, it has already received data up above the 3 minutes mark. In turn when Player B joins it starts receiving MP3 data chunks much farther from the file, hence it starts playing at position 3 minutes and 30 seconds. If we extend our reasoning to multiple files, then a new player can join and receive no data at all, while the previously connected players may have multiple songs to play in their internal buffers.
By contrast if we control the read rate of the MP3 file and hence the rate at which MP3 chunks are being copied and written to the connected players, then we ensure that they are all more-or-less at the same position. Rate control here is all about ensuring that all players receive data fast enough so that they can play without interruption, yet they do not buffer too much data.
Let us now first look at the complete Jukebox verticle start method in listing 4.15, as it shows that much needed timer.
@Override public void start() { EventBus eventBus = vertx.eventBus(); eventBus.consumer("jukebox.list", this::list); eventBus.consumer("jukebox.schedule", this::schedule); eventBus.consumer("jukebox.play", this::play); eventBus.consumer("jukebox.pause", this::pause); vertx.createHttpServer() .requestHandler(this::httpHandler) .listen(8080); vertx.setPeriodic(100, this::streamAudioChunk); #1 }
Beyond connecting the event-bus handlers and starting a HTTP server, the start method also defines a timer so that data is being streamed every 100 milliseconds. We can now look at the implementation of the streamAudioChunk method, given in listing 4.16.
private AsyncFile currentFile; private long positionInFile; private void streamAudioChunk(long id) { if (currentMode == State.PAUSED) { return; } if (currentFile == null && playlist.isEmpty()) { currentMode = State.PAUSED; return; } if (currentFile == null) { openNextFile(); } currentFile.read(Buffer.buffer(4096), 0, positionInFile, 4096, ar -> { #1 if (ar.succeeded()) { processReadBuffer(ar.result()); #2 } else { logger.error("Read failed", ar.cause()); closeCurrentFile(); } }); }
Why do we read data every 100 milliseconds? And why read buffers of 4096 bytes?
These values have been empirically found to work great for 320 kbps constant bit rate MP3 files on my laptop. They ensured no drops in tests while preventing players to buffer too much data, and thus ending several seconds apart in the audio stream.
Feel-free to tinker with these values as you run the samples.
The code of streamAudioChunk reads blocks of at most 4096 bytes. Since the method is always going to be called 10 times per second, it also needs to check if anything is being played at all. Method processReadBuffer streams data, as given in listing 4.17.
private void processReadBuffer(Buffer buffer) { positionInFile += buffer.length(); if (buffer.length() == 0) { #1 closeCurrentFile(); return; } for (HttpServerResponse streamer : streamers) { if (!streamer.writeQueueFull()) { #2 streamer.write(buffer.copy()); #3 } } }
For every HTTP response stream to a player, the method copies the read data. Note that we have another case of back-pressure management here: when the write queue of a client is full, then we simply discard data. On the player end this will result in a audio drops, but since the queue is full on the server it means that the player is going to have delays or drops anyway. Discarding data is fine as MP3 decoders know how to recover, and it ensures that playback will remain closely on time with the other players.
Vert.x buffers cannot be reused once they have been written, as they are placed in a write queue. Re-using buffers will always result in bugs, so don’t look for un-necessary optimizations here.
Finally, the helper methods in listing 4.18 allow opening and closing files.
private void openNextFile() { OpenOptions opts = new OpenOptions().setRead(true); currentFile = vertx.fileSystem() .openBlocking("tracks/" + playlist.poll(), opts); #1 positionInFile = 0; } private void closeCurrentFile() { positionInFile = 0; currentFile.close(); currentFile = null; }
So far our dissection of the jukebox example focused on the Jukebox verticle to download and stream MP3 data.
Now is the time to dissect the NetControl verticle that exposes a TCP server on port 3000 for receiving text commands to control what the jukebox plays. Extracting data from asynchronous data streams is a common requirement, and as we will show Vert.x provides effective tools to do that.
The commands in our text protocol are of the following form:
/action [argument]
With the actions being:
/list
: jrcf gkr isfel bleaaliva etl plkyacab,/play
: enresu gkr trsmae yslap,/pause
: supae xrg measrt,/schedule file
: ndpaep file
rs our xyn vl vur ilylaspt.Each text line can have exactly 1 command, hence the protocol is said to be newline-separated.
We need a parser for this, as buffers arrive in chunks that rarely correspond to 1 line each. For example a first read buffer could have:
ettes.mp3 /play /pa
and the next one:
use /schedule right-here-righ
followed by:
t-now.mp3
What we actually want is reasoning about lines, hence the solution is to concatenate buffers as they arrive, and look for new lines in them to split buffers. Instead of manually assembling intermediary buffers, Vert.x offers a handy parsing helper with the RecordParser class. The parser ingests buffers and emits new buffers with parsed data, either by looking for delimiters, or by working with chunks of fixed size.
In our case we just need to look for newline delimiters in the stream. Listing 4.19 shows how to use RecordParser in the NetControl verticle.
@Override public void start() { vertx.createNetServer() .connectHandler(this::handleClient) .listen(3000); } private void handleClient(NetSocket socket) { RecordParser.newDelimited("\n", socket) #1 .handler(buffer -> handleBuffer(socket, buffer)) #2 .endHandler(v -> logger.info("Connection ended")); }
The parser is both a read and a write stream as it works as an adapter between 2 streams. It ingests intermediate buffers coming from the TCP socket, and emits parsed data as new buffers. This is fairly transparent and simplifies the rest of the verticle implementation.
In listing 4.20 each buffer is known to be a line, so we can go directly to processing commands.
private void handleBuffer(NetSocket socket, Buffer buffer) { String command = buffer.toString(); #1 switch (command) { case "/list": listCommand(socket); break; case "/play": vertx.eventBus().send("jukebox.play", ""); break; case "/pause": vertx.eventBus().send("jukebox.pause", ""); break; default: if (command.startsWith("/schedule ")) { schedule(command); } else { socket.write("Unknown command\n"); } } }
The simple commands are in the case clauses, and the other commands in separate methods given in listing 4.21.
private void schedule(String command) { String track = command.substring(10); #1 JsonObject json = new JsonObject().put("file", track); vertx.eventBus().send("jukebox.schedule", json); } private void listCommand(NetSocket socket) { vertx.eventBus().request("jukebox.list", "", reply -> { if (reply.succeeded()) { JsonObject data = (JsonObject) reply.result().body(); data.getJsonArray("files") .stream().forEach(name -> socket.write(name + "\n")); #2 } else { logger.error("/list error", reply.cause()); } }); }
Streams can be more complex that just lines of text, and RecordParser can also greatly simplify our work.
Let us take the example of a key / value database storage, where each key and value is a string. In such a database we could have entries such as 1 → {foo} and 2 → {bar, baz} with 1 and 2 being keys.
There are countless ways to define a serialization scheme for this type of data structure, so imagine that we must use the stream format of table 5.6.
| Data | Description |
| Magic header |
A sequence of bytes |
| Version |
An integer with the database stream format version. |
| Name |
Name of the database as a string ending with a newline character. |
| Key length |
Integer with the number of characters for the next key. |
| Key name |
A sequence of characters for the key name. |
| Value length |
Integer with the number of characters for the next value. |
| Value |
A sequence of characters for the value. |
| (â¦) |
Remaining |
The format mixes binary and text records as the stream starts with a magic number, a version number, a name and then a sequence of key and value entries. While the format in itself is questionable on some points, it is a good example to illustrate more complex parsing.
First of all, let us have a program that writes a database to a file with 2 key / value entries. Listing 4.22 shows how to use the Vert.x filesystem APIs to open a file, append data to a buffer, then write it.
AsyncFile file = vertx.fileSystem().openBlocking("sample.db", new OpenOptions().setWrite(true).setCreate(true)); Buffer buffer = Buffer.buffer(); buffer.appendBytes(new byte[] { 1, 2, 3, 4}); #1 buffer.appendInt(2); #2 buffer.appendString("Sample database\n"); #3 String key = "abc"; #4 String value = "123456-abcdef"; buffer .appendInt(key.length()) .appendString(key) .appendInt(value.length()) .appendString(value); key = "foo@bar"; #5 value = "Foo Bar Baz"; buffer .appendInt(key.length()) .appendString(key) .appendInt(value.length()) .appendString(value); file.write(buffer).close();
Note that in this example as we had little data we used a single buffer that we prepared wholly before writing it to the file, but we could equally use a buffer for the header, and new buffers for each key / value entry.
Writing is easy, but how about reading back?
The interesting property of RecordParser is that its parsing mode can be switched on-the-fly. We can start parsing buffers of fixed size 5, then switch to parsing based on tab characters, then chunks of 12 bytes, etc.
The parsing logic is easier expressed by splitting into methods where each method corresponds to a parsing state. There is a method for parsing the database name, a method for parsing a value entry, etc.
Listing 4.23 opens the file that we previously wrote, and puts the RecordParser object into fixed mode as we are looking for a sequence of 4 bytes that represent the magic header. The handler that we install is called when a magic number is read.
AsyncFile file = vertx.fileSystem().openBlocking("sample.db", new OpenOptions().setRead(true)); RecordParser parser = RecordParser.newFixed(4, file); #1 parser.handler(header -> readMagicNumber(header, parser));
Listing 4.24 provides the implementation of further methods.
private static void readMagicNumber(Buffer header, RecordParser parser) { logger.info("Magic number: {}:{}:{}:{}", header.getByte(0), header.getByte(1), header.getByte(2), header.getByte(3)); parser.handler(version -> readVersion(version, parser)); } private static void readVersion(Buffer header, RecordParser parser) { logger.info("Version: {}", header.getInt(0)); parser.delimitedMode("\n"); #1 parser.handler(name -> readName(name, parser)); } private static void readName(Buffer name, RecordParser parser) { logger.info("Name: {}", name.toString()); parser.fixedSizeMode(4); parser.handler(keyLength -> readKey(keyLength, parser)); }
The readMagicNumber method extracts the 4 bytes of the magic number from a buffer. We know that the buffer is exactly of 4 bytes since the parser was in fixed sized mode.
Now since the next entry is the database version and it is an integer, we don’t have to change the parser mode since an integer is 4 bytes. Once the version has been read, the readVersion method switches to delimited mode to extract the database name.
We then enter looking for a key length, so we need a fixed sized mode in readName.
Listing 4.25 follows by reading the key name, the value length, the proper value, and then finishEntry sets back the parser looking for an integer and delegating to readKey.
private static void readKey(Buffer keyLength, RecordParser parser) { parser.fixedSizeMode(keyLength.getInt(0)); parser.handler(key -> readValue(key.toString(), parser)); } private static void readValue(String key, RecordParser parser) { parser.fixedSizeMode(4); parser.handler(valueLength -> finishEntry(key, valueLength, parser)); } private static void finishEntry(String key, Buffer valueLength, RecordParser parser) { parser.fixedSizeMode(valueLength.getInt(0)); parser.handler(value -> { logger.info("Key: {} / Value: {}", key, value); parser.fixedSizeMode(4); parser.handler(keyLength -> readKey(keyLength, parser)); }); }
Listing 4.26 shows a sample output when reading the database file with the parsing methods of listings 4.23, 4.24 and 4.25.
DatabaseReader - Magic number: 1:2:3:4 DatabaseReader - Version: 2 DatabaseReader - Name: Sample database DatabaseReader - Key: abc / Value: 123456-abcdef DatabaseReader - Key: foo@bar / Value: Foo Bar Baz
These on-the-fly parser mode and handler changes form a very simple yet effective way to parse complex streams.
You may wonder how the parsing mode can be changed on-the-fly while some further data is already available to the parser from the read stream.
Remember that we are on an event-loop, so parser handlers are processing parser records one at a time. When we switch from, say, a delimiter mode to a fixed size mode, then the next record is emitted by processing the remaining stream data based on a number of bytes rather than looking for some string. The same reasoning applies when switching from a fixed sized mode to a delimiter mode.
Before we wrap up this chapter, let us go back to a detail of the ReadStream interface that we deliberately left aside.
Introduced in Vert.x 3.6, the fetch mode that we mentioned earlier in this chapter allows a stream consumer to request an amount of data items, rather than the stream pushing data items to the consumer. This works by pausing the stream, then asking varying number of items to be fetched later on as data is needed.
We could rewrite the jukebox file streaming code with the fetch mode, but we would still need a timer to dictate the pace. In this case manually reading a buffer of 4096 bytes or requesting 4096 to be fetched is not much different.
Instead, let us go back to the database reading example. The read stream was pushing events in listings 4.23, 4.24 and 4.25.
Switching to fetch mode and pulling data does not require many changes. Listing 4.27 shows the stream initialization code.
RecordParser parser = RecordParser.newFixed(4, file); parser.pause(); #1 parser.fetch(1); #2 parser.handler(header -> readMagicNumber(header, parser));
Remember that the RecordParser decorates the file stream. It is paused, then the fetch method asks for 1 element. Since the parser emits buffers of parsed data, asking 1 element in this example means asking for a buffer of 4 bytes (the magic number).
Eventually, the parser handler will be called to process the requested buffer, and nothing else will happen until another call to the fetch method.
Listing 4.28 shows 2 of the parsing handler methods and their adaptation to the fetch mode.
private static void readMagicNumber(Buffer header, RecordParser parser) { logger.info("Magic number: {}:{}:{}:{}", header.getByte(0), header.getByte(1), header.getByte(2), header.getByte(3)); parser.handler(version -> readVersion(version, parser)); parser.fetch(1); #1 } // (...) private static void finishEntry(String key, Buffer valueLength, RecordParser parser) { parser.fixedSizeMode(valueLength.getInt(0)); parser.handler(value -> { logger.info("Key: {} / Value: {}", key, value); parser.fixedSizeMode(4); parser.handler(keyLength -> readKey(keyLength, parser)); parser.fetch(1); }); parser.fetch(1); }
The only difference is again that we need to request elements by calling fetch.
You will not likely need to play with fetch mode while writing Vert.x applications, but if you ever need to manually control a read stream, then it is a useful tool to have.
The next chapter focuses on other models than callbacks for asynchronous programming with Vert.x.


I am a Tufts University graduate with a Computer Science & Mathematics degree, currently employed as a Software Engineer with Raytheon Technologies.
Wrote a number of server-side applications that power bot users (or "bots") on the Discord chat application. These bots use discord.py, discord.js, and discordrb, Python/Javascript/Ruby libraries that act as wrappers for Discord's API. These bots are hosted on an AWS EC2 instance and store user information in a PostgreSQL database. The main two are the following:
• Celebi: An administrative/game bot written for an alternate reality game in a partnered Discord server of over 200,000 members. It hosts multiple minigames able to scale to support many players at once.
• Gary: A general-purpose bot built for a private server. Contains a large variety of features pulling from various APIs such as Urban Dictionary, Spotify, and Last.FM.
Web app designed to get incoming Tufts students acquainted with the Tufts campus. Includes a scavenger hunt game that uses the Google Maps API and has the user find specific locations around campus. Also includes a "JumboTour" module that allows the user to explore different locations, and a Quiz module that allows users to quiz themselves on locations.
Reads in a text file containing a program (written in UMASM, an assembly language specific to the Universal Machine), then executes that program. Made to emulate the behavior of a computer using eight registers, a segmented, word-oriented memory system, a 32-bit program counter, and an I/O device capable of inputting and outputting unsigned, 8-bit characters.
Reads in a PPM image then compresses it. This is done by converting the pixels' color values from RGB to component video, using a discrete cosine transform, then packing the resultant values into a binary keyword. The program then decompresses the image by unpacking the binary keyword and following the inverse procedure.
Awarded by management for exceptional work within the program.
Awarded by management for excellent collaboration and accountability.
GPA: 3.26
GPA: 3.8
In my free time, you can usually find me listening to, playing, or as of more recently, making music. I have experience with a large variety of instruments, though these days I mainly stick with guitar, bass guitar, ukulele, and piano. My music taste also varies quite a bit, though notable genres include Punk Rock, Lo-Fi Hip Hop, and Math Rock.
When I'm not playing or listening to music, I enjoy spending my time going for runs, hiking, or playing video games and browsing Reddit, among other websites. I often spend my working on my Discord bots as well, adding new features and tweaking old ones to keep up with new technologies I learn.


SSCollectionViewItem Class Reference
| Inherits from | UIView |
| Declared in | SSCollectionViewItem.h |
Tasks
Other Methods
-
imageView
Returns the image view of the collection view item. (read-only)
property -
textLabel
Returns the label used for the main textual content of the table cell. (read-only)
property -
detailTextLabel
Returns the secondary label of the collection view item. (read-only)
property -
backgroundView
The view used as the background of the item.
property -
selectedBackgroundView
The view used as the background of the item when it is selected.
property -
reuseIdentifier
A string used to identify an item that is reusable. (read-only)
property -
selected
A Boolean value that indicates whether the cell is selected.
property -
highlighted
A Boolean value that indicates whether the item is highlighted.
property -
– initWithStyle:reuseIdentifier:
Initializes a collection view item with a style and a reuse identifier and returns it to the caller.
-
– prepareForReuse
Prepares a reusable item for reuse by the table view’s delegate.
-
– setSelected:animated:
Sets the selected state of the item, optionally animating the transition between states.
-
– setHighlighted:animated:
Sets the highlighted state of the item, optionally animating the transition between states.
Extension Methods
-
indexPath
property -
collectionView
property
Properties
backgroundView
The view used as the background of the item.
@property (nonatomic, strong) UIView *backgroundView
Discussion
The view used as the background of the item.
The default is nil
. SSCollectionViewItem
adds the background view as a subview behind all other views and uses its
current frame location.
Declared In
SSCollectionViewItem.h
detailTextLabel
Returns the secondary label of the collection view item. (read-only)
@property (nonatomic, strong) SSLabel *detailTextLabel
Discussion
Returns the secondary label of the collection view item. (read-only)
Holds the secondary label of the item. SSCollectionViewItem
adds an appropriate label when you create the cell in a
given item style.
Declared In
SSCollectionViewItem.h
highlighted
A Boolean value that indicates whether the item is highlighted.
@property (nonatomic, getter=isHighlighted) BOOL highlighted
Discussion
A Boolean value that indicates whether the item is highlighted.
The highlighting affects the appearance of labels, image, and background. When the the highlighted state of an item is
set to YES
, labels are drawn in their highlighted text color. The default value is NO
. If you set the highlighted
state to YES
through this property, the transition to the new state appearance is not animated. For animated
highlighted-state transitions, see the setHighlighted:animated:
method.
Note that for highlighting to work properly, you must fetch the items’s labels using the textLabel and
detailTextLabel
properties and set each label’s highlightedTextColor
property; for images, get the item’s image
using the imageView
property and set the UIImageView
object’s highlightedImage
property.
See Also
Declared In
SSCollectionViewItem.h
imageView
Returns the image view of the collection view item. (read-only)
@property (nonatomic, strong) UIImageView *imageView
Discussion
Returns the image view of the collection view item. (read-only)
Returns the image view (UIImageView
object) of the collection view item, which initially has no image set.
SSCollectionViewItem
creates the image view object when you create the item.
Declared In
SSCollectionViewItem.h
reuseIdentifier
A string used to identify an item that is reusable. (read-only)
@property (nonatomic, readonly, copy) NSString *reuseIdentifier
Discussion
A string used to identify an item that is reusable. (read-only)
The reuse identifier is associated with a SSCollectionViewItem
object that the collection view’s delegate creates
with the intent to reuse it as the basis (for performance reasons) for multiple items of a collection view. It is
assigned to the item object in initWithFrame:reuseIdentifier:
and cannot be changed thereafter. A SSCollectionView
object maintains a queue (or list) of the currently reusable items, each with its own reuse identifier, and makes them
available to the delegate in the dequeueReusableCellWithIdentifier:
method.
Declared In
SSCollectionViewItem.h
selected
A Boolean value that indicates whether the cell is selected.
@property (nonatomic, getter=isSelected) BOOL selected
Discussion
A Boolean value that indicates whether the cell is selected.
The selection affects the appearance of labels, image, and background. The default value is NO
.
See Also
Declared In
SSCollectionViewItem.h
selectedBackgroundView
The view used as the background of the item when it is selected.
@property (nonatomic, strong) UIView *selectedBackgroundView
Discussion
The view used as the background of the item when it is selected.
The default is nil
. SSCollectionViewItem
adds the value of this property as a subview only when the cell is
selected. It adds the selected background view as a subview directly above the background view (backgroundView
) if it
is not nil
, or behind all other views. Calling setSelected:animated:
causes the selectedBackground
view to
animate in and out with an alpha fade.
Declared In
SSCollectionViewItem.h
textLabel
Returns the label used for the main textual content of the table cell. (read-only)
@property (nonatomic, strong) SSLabel *textLabel
Discussion
Returns the label used for the main textual content of the table cell. (read-only)
Holds the main label of the item. SSCollectionViewItem
adds an appropriate label when you create the cell in a given
item style.
Declared In
SSCollectionViewItem.h
Instance Methods
initWithStyle:reuseIdentifier:
Initializes a collection view item with a style and a reuse identifier and returns it to the caller.
- (id)initWithStyle:(SSCollectionViewItemStyle)style reuseIdentifier:(NSString *)aReuseIdentifier
Parameters
- style
A constant indicating a item style.
- aReuseIdentifier
A string used to identify the item object if it is to be reused for drawing multiple items of a collection view. Pass
nil
if the cell object is not to be reused. You should use the same reuse identifier for all cells of the same form.
Return Value
An initialized SSCollectionViewItem
object or nil if the object could not be created.
Discussion
Initializes a collection view item with a style and a reuse identifier and returns it to the caller.
Declared In
SSCollectionViewItem.h
prepareForReuse
Prepares a reusable item for reuse by the table view’s delegate.
- (void)prepareForReuse
Discussion
Prepares a reusable item for reuse by the table view’s delegate.
Declared In
SSCollectionViewItem.h
setHighlighted:animated:
Sets the highlighted state of the item, optionally animating the transition between states.
- (void)setHighlighted:(BOOL)highlighted animated:(BOOL)animated
Parameters
- highlighted
YES
to set the item as highlighted,NO
to set it as unhighlighted. The default isNO
.
- animated
YES
to animate the transition between highlighted states,NO
to make the transition immediate.
Discussion
Sets the highlighted state of the item, optionally animating the transition between states.
Highlights or unhighlights the item, animating the transition between regular and highlighted state if animated is
YES
. Highlighting affects the appearance of the items’s labels, image, and background.
Note that for highlighting to work properly, you must fetch the item’s label (or labels) using the textLabel
(and detailTextLabel
) properties and set the label’s highlightedTextColor
property; for images, get the items’s
image using the imageView
property and set the UIImageView
object’s highlightedImage
property.
A custom table item may override this method to make any transitory appearance changes.
Declared In
SSCollectionViewItem.h
setSelected:animated:
Sets the selected state of the item, optionally animating the transition between states.
- (void)setSelected:(BOOL)selected animated:(BOOL)animated
Parameters
- animated
YES
to animate the transition between selected states,NO
to make the transition immediate.
Discussion
Sets the selected state of the item, optionally animating the transition between states.
The selection affects the appearance of labels, image, and background. When the the selected state of a cell to YES
,
it draws the background for selected items with its title in its highlightedTextColor
.
Declared In
SSCollectionViewItem.h


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Unix Tools For Data Science
Data: N/A
Techniques: Unix commands, vi, sftp, screen, grep, git
Date: Oct, 2017
ETL Pipelines With Apache Airflow
Data:
OpenWeatherMap API
Techniques: ETL, Apache Airflow, PostgreSQL
Date: Aug, 2017
Recommender Systems
Data:
Amazon Product Data
Techniques: Collaborative fitlering
Date: April, 2017
Intro To Relational Databases
Data: Created in post
Techniques: SQLite, PostgreSQL, SQLAlchemy
Date: April, 2017
Forecasting Crime Rates In New York City
Data:
NYC Open Data
Techniques: Time series, ARIMA, StatsModels, exploratory analysis
Date: Mar, 2017
Interactive Visualizations With Bokeh
Data:
Chicago Data Portal
Techniques: Bokeh, data visualization, GeoPandas
Date: Mar, 2017
Analyzing Wikimedia's Click-Through Rates
Data:
Wikimedia
Techniques: Pandas, analytics, click-through rate analysis
Date: Feb, 2017


At this point you're probably wondering how to add conditional logic. Outputting values to the page is interesting, but how do we do so conditionally? That is after all what makes dynamic web pages, well dynamic.
To add the tag library, we specify it's xml namespace and the class name. This can be done at any level of the HTML document before you attempt to use the tag, but it's simplest to add it to your  tag.

That says that I'll prefix all of my standard tag library tags with the letter 'c'. "urn:nsttl" says it's a local nest tag library that's in the include path, and the class is HTML_Template_Nest_Taglib_Standard.
Tag libraries follow PEAR naming conventions, so it will look for the file "HTML/Template/Nest/Taglib/Standard.php".
Once you've added that namespace declaration to the top of your file you can start using the standard tags.
<c:if test="isAdmin"> Admin Interface </c:if>
<c:if test="isAdmin"> Admin Interface </c:if> <c:elseif test="isPowerUser"> Power Interface </c:elseif>
<c:if test="isAdmin"> Admin Interface </c:if> <c:elseif test="isPowerUser"> Power Interface </c:elseif> <c:else> User Profile </c:else>
Add an indexed array to your view:
$view->addAttribute("groceryList", Array("Bananas", "Milk", "Ground Beef"));
Your array is specified in the <foreach> tag using the items attribute. The value of var will be the local variable that wil contain the individual array element.

Shopping List

 <c:foreach items="groceryList" var="shoppingListItem">
${shoppingListItem}
 </c:foreach>

Add an indexed array to your view:
$view->addAttribute("groceryReceipt", Array("Bananas" => ".75", "Milk" => "3.59", "Ground Beef" => "1.99"));
Your array and local variable for value are specified the same was an indexed array. Associate arrays add a key attribute for pulling out the array's key.

Shopping Receipt

 Item	 Price
 <c:foreach items="groceryReceipt" var="itemPrice" key="itemName">
 ${itemName}	 ${itemPrice}
 </c:foreach>

Shopping Receipt

 Item	 Price
 <c:foreach items="groceryReceipt" var="itemPrice" key="itemName" rowcount="i">
 ${itemName}	 ${itemPrice}
 </c:foreach>

This will alternate between the css class 'rowA' and 'rowB'
<c:for var="i" test="i < 10"> Should print 10 times. </c:for>
Should print 10 times. Should print 10 times. Should print 10 times. Should print 10 times. Should print 10 times. Should print 10 times. Should print 10 times. Should print 10 times. Should print 10 times. Should print 10 times.

 <c:attribute name="class" trim="true"> <c:for var="i" test="i < 10"> class${i} </c:for> </c:attribute>

<c:set var="mylocalvar" value="${bulletClass}"> ${mylocalvar} </c:set>


Up Next
| Group #2 is presenting in
Room 118 at 10:00am!
Schedule
- 9:00am - 9:50am
- Group #1 Presentations
- 10:00am - 10:50am
- Group #2 Presentations
- 11:00am - 11:50am
- Group #3 Presentations
- 12:00pm - 12:50pm
- Group #4 Presentations
- 2:00pm - 2:50pm
- Award Ceremony
To Do List


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Select group.
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UNIVERSITY OF PIPTSBURGH
"FACULTY OF ARTS AND SCIENCES
This dissertation was presented by
Henry L. Pollak.
It was defended on
May 25, 1971
- and approved by. mo Dr. M.D. Fuller
‘Dr. E. Strick:
Dr. B. Hapke | >
_ Dr. M. S. Kanefsky
Dr. R. D. Wyckoff © Chateman : :
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.


Before Change
image_url=image_url,
execution_role=role,
sage_client=sage_client)
eprint("Created new model with arn: %s" % new_model_response["ModelArn"])
if mode == DEPLOYMENT_MODE_ADD:
new_model_weight = 0
production_variants = deployed_production_variants
After Change
image_url=image_url,
execution_role=role,
sage_client=sage_client)
_logger.info("Created new model with arn: %s", new_model_response["ModelArn"])
if mode == DEPLOYMENT_MODE_ADD:
new_model_weight = 0
production_variants = deployed_production_variants
elif mode == DEPLOYMENT_MODE_REPLACE:
new_model_weight = 1
production_variants = []
new_production_variant = {
"VariantName": new_model_name,
"ModelName": new_model_name,
"InitialInstanceCount": instance_count,
"InstanceType": instance_type,
"InitialVariantWeight": new_model_weight
}
production_variants.append(new_production_variant)
// Create the new endpoint configuration and update the endpoint
// to adopt the new configuration
new_config_name = _get_sagemaker_config_name(endpoint_name)
endpoint_config_response = sage_client.create_endpoint_config(
EndpointConfigName=new_config_name,
ProductionVariants=production_variants,
Tags=[
{
"Key": "app_name",
"Value": endpoint_name,
},
],
)
_logger.info("Created new endpoint configuration with arn: %s",
endpoint_config_response["EndpointConfigArn"])
sage_client.update_endpoint(EndpointName=endpoint_name,
EndpointConfigName=new_config_name)
_logger.info("Updated endpoint with new configuration!")
// If applicable, clean up unused models and old configurations
if not archive:
_logger.info("Cleaning up unused resources...")
if mode == DEPLOYMENT_MODE_REPLACE:
s3_client = boto3.client("s3")
for pv in deployed_production_variants:
deployed_model_arn = _delete_sagemaker_model(model_name=pv["ModelName"],
sage_client=sage_client,
s3_client=s3_client)
_logger.info("Deleted model with arn: %s", deployed_model_arn)
sage_client.delete_endpoint_config(
EndpointConfigName=deployed_config_name)
_logger.info("Deleted endpoint configuration with arn: %s", deployed_config_arn)
def _create_sagemaker_model(model_name, model_s3_path, flavor, vpc_config, run_id, image_url,
execution_role, sage_client):


QUIZ BOARD
INSTRUCTIONS
Read all question carefull
Answer all question
Cheek well what you did
What is the other name for JavaScript?
ECMAScript
Vue
I don't know
of the following is the correct syntax to print a page using JavaScript?
window.print();
browser.print();
navigator.print()
Which built-in method returns the calling string value converted to upper case?
toUpper()
toUpperCase()
changeCase(case)
Which built-in method calls a function for each element in the array?
while()
loop()
forEach()
Which of the following function of Array object sorts the elements of an array?
toSource()
sort()
toString()
Good Luck!!!!
submit
Your score is: 0


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|
|
|---|
Object Workspace Window This is the Object Workspace display window.
Arrow Button This will increase the size of the Object Workspace display window.
X Button This will minimize the size of the Object Workspace.
Visgroups Button This will display all Visgroups in the Object Workspace display window.
Anchors Button This will display all Anchors (positionable view references) in the Object Workspace display window.
Objects Button This will display all Objects (Brushes and Models) in the Object Workspace display window.


Mr Key has lately been described, elsewhere, as a “Diogenesian recluse”. There is an element of truth in this. How many readers were aware that the material at Hooting Yard issues forth from inside a barrel, or large tub? Now you know.
NOTE : For those following the link above, further details of The Fatal Duckpond—in the form of a blatant advertisement—will appear here when it is actually available (soon, as far as I'm aware).


--- layout: page sidebar: false fluid: false responsive: false title: API Workshop icon: icon-apiworkshop_v2 weight: 2 navigation: show: false ---


Copyright © 2006-2011 Huiqing Li, Simon Thompson
Version: 0.1
Authors: Huiqing Li, Simon Thompson [web site: http://www.cs.kent.ac.uk/projects/wrangler].
col() = integer()
dir() = string()
filename() = string()
functionarity() = integer()
functionname() = atom()
line() = integer()
modulename() = atom()
pos() = {integer(), integer()}
| calls_to_fun/4 | Report the functions by which the function specified is called. |
| cyclic_dependent_modules/3 | Report the cyclic module dependencies, if there is any, for a given list of directories of Erlang source code. |
| dependencies_of_a_module/2 | Report modules that depend on the module specified, as well as modules on which the module specified in dependent. |
| find_var_instances/3 | Find all the instances of a variable, including both defining and use instances. |
| gen_function_callgraph/3 | Generate the function callgraph for a given Erlang file. |
| gen_module_graph/3 | Generate the module graph for a given list of directories of Erlang source code. |
| improper_inter_module_calls/2 | Report improper module dependencies, if there is any, for a given list of directories of Erlang source code. |
| large_modules/2 | Report all the modules that consist of more than a specified number of lines of code. |
| long_functions/2 | Report all the functions that consist of more than specified number of lines of code. |
| nested_exprs/3 | Find all the functions that contain certain type of expressions that are nested a specified number of levels or more. |
| non_tail_recursive_servers/1 | Report non tail-recursive server functions. |
| not_flush_unknown_messages/1 | Report functions whose receive expression, if there is one, does not flush unknown messages. |
calls_to_fun(FileName::filename(), FunctionName::functionname(), Arity::integer(), SearchPaths::[dir()]) -> {error, string()} | ok
Report the functions by which the function specified is called. A function is reported only if Wrangler is certain that it calls the function specified.
cyclic_dependent_modules(OutputDotFileName::filename(), SearchPaths::[filename() | dir()], WithLabel::boolean()) -> true
Report the cyclic module dependencies, if there is any, for a given list of directories of Erlang source code.
dependencies_of_a_module(ModOrFileName::modulename() | filename(), SearchPaths::[filename() | dir()]) -> ok
Report modules that depend on the module specified, as well as modules on which the module specified in dependent.
find_var_instances(FileName::filename(), X2::{Line::integer(), Col::integer()}, TabWidth::integer()) -> {error, string()} | {ok, [{pos(), pos()}], [pos()]}
Find all the instances of a variable, including both defining and use instances.
gen_function_callgraph(OutputDotFileName::filename(), FileName::filename(), SearchPaths::[filename() | dir()]) -> true
Generate the function callgraph for a given Erlang file.
gen_module_graph(OutputDotFileName::filename(), SearchPaths::[filename() | dir()], WithLabel::boolean()) -> true
Generate the module graph for a given list of directories of Erlang source code.
improper_inter_module_calls(OutputDotFileName::filename(), SearchPaths::[filename() | dir()]) -> true
Report improper module dependencies, if there is any, for a given list of directories of Erlang source code.
large_modules(SearchPaths::[dir()], Lines::integer()) -> {error, string()} | ok
Report all the modules that consist of more than a specified number of lines of code.
long_functions(FileOrDirNames::[filename() | dir()], Lines::integer()) -> {error, string()} | ok
Report all the functions that consist of more than specified number of lines of code.
nested_exprs(FileOrDirNames::[filename() | dir()], NestLevel::integer(), ExprType::'if' | 'case' | 'receive') -> {error, string()} | ok
Find all the functions that contain certain type of expressions that are nested a specified number of levels or more.
non_tail_recursive_servers(FileOrDirNames::[filename() | dir()]) -> ok
Report non tail-recursive server functions.
The Erlang Programming Rules says: All servers must be tail-recursive, otherwise the server will consume memory until the system runs out of it. Don't program like this:
loop() -> receive {msg1, Msg1} -> ..., loop(); stop -> true; Other -> error_logger:log({error, {process_got_other, self(), Other}}), loop() end, io:format("Server going down"). The above is not tail-recusive. This is a correct solution: loop() -> receive {msg1, Msg1} -> ..., loop(); stop -> io:format("Server going down"); Other -> error_logger:log({error, {process_got_other, self(), Other}}), loop() end.
not_flush_unknown_messages(FileOrDirNames::[filename() | dir()]) -> ok
Report functions whose receive expression, if there is one, does not flush unknown messages.
The Erlang Programming Rules says: Every server should have an Other alternative in at least one receive statement. This is to avoid filling up message queues. Example:
main_loop() -> receive {msg1, Msg1} -> ..., main_loop(); {msg2, Msg2} -> ..., main_loop(); Other -> % Flushes the message queue. error_logger:error_msg( "Error: Process ~w got unknown msg ~w~n.", [self(), Other]), main_loop() end.
Generated by EDoc, Jan 18 2011, 11:56:20.


--- layout: example ---
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Implements Affinity Propagation clustering introduced by Frey and
Dueck (2007) <doi:10.1126/science.1136800>. The algorithms are largely
analogous to the 'Matlab' code published by Frey and Dueck.
The package further provides leveraged affinity propagation and an
algorithm for exemplar-based agglomerative clustering that can also be
used to join clusters obtained from affinity propagation. Various
plotting functions are available for analyzing clustering results.
| Version: |
1.4.7 |
| Depends: |
R (≥ 3.0.0) |
| Imports: |
Rcpp (≥ 0.11.1), methods, Matrix, stats, graphics, grDevices |
| LinkingTo: |
Rcpp |
| Suggests: |
Biostrings, kebabs (≥ 1.5.4), knitr |
| Published: |
2018-05-29 |
| Author: |
Ulrich Bodenhofer, Johannes Palme, Chrats Melkonian, Andreas Kothmeier,
Nikola Kostic |
| Maintainer: |
Ulrich Bodenhofer <bodenhofer at bioinf.jku.at> |
| License: |
GPL-2 | GPL-3 [expanded from: GPL (≥ 2)] |
| URL: |
http://www.bioinf.jku.at/software/apcluster/
https://github.com/UBod/apcluster |
| NeedsCompilation: |
yes |
| Citation: |
apcluster citation info |
| Materials: |
README NEWS |
| In views: |
Cluster |
| CRAN checks: |
apcluster results |


Contact Me
If you have any query or any advance to develop this website
please feel free to contact me
Here are my contact informations
First Email<EMAIL_ADDRESS>or<EMAIL_ADDRESS>Second Social Media: QQ: 645265746
Twitter: kanelmis
Thanks for all your support


A long time ago I walked into a granite shop and told them I needed a job. Decades later and I'm still here.
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This Privacy Policy (the "Policy") explains the way of treatment of the information which is provided or collected in the websites on which this Policy is posted. In addition the Policy also explains the information which is provided or collected in the course of using the applications of the Company which exist in the websites or platforms of other company.
Through this Policy, the Company regards personal information of the users as important and inform them of the purpose and method of Company's using the personal information provided by the users and the measures taken by the Company for protection of those personal information.
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It does not collect all information that is relevant to you.


{% load i18n %} {% with table.needs_form_wrapper as needs_form_wrapper %} {% if needs_form_wrapper %}


The old version of FRB/US used the Divisia index for most of its aggregation. It introduced undesirable non-linear dynamics in the stochastic simulations and dependence on the initial conditions with respect to projecting the model forward. The costs of these features motivated us to rely instead on a fixed-weigthed aggregation scheme.
The new version of the model uses fixed, constant shares over time for aggregation. For example, for adjusted final sales (XP), the changes entail the new equations:
log(xp) - xp_aerr = log(xp(-1)) + .5*(ecnian/xpn + ecnian(-1)/xpn(-1))*d(log(ecnia)) + .5*(ehn/xpn + ehn(-1)/xpn(-1)) *d(log(eh)) + .5*(epdn/xpn + epdn(-1)/xpn(-1)) *d(log(epd)) + .5*(epin/xpn + epin(-1)/xpn(-1)) *d(log(epi)) + .5*(epsn/xpn + epsn(-1)/xpn(-1)) *d(log(eps)) + .5*(egfon/xpn + egfon(-1)/xpn(-1)) *d(log(egfo)) + .5*(egfin/xpn + egfin(-1)/xpn(-1)) *d(log(egfi)) + .5*(egson/xpn + egson(-1)/xpn(-1)) *d(log(egso)) + .5*(egsin/xpn + egsin(-1)/xpn(-1)) *d(log(egsi)) + .5*(exn/xpn + exn(-1)/xpn(-1)) *d(log(ex))
log(xp) - xp_aerr = log(xp(-1)) + y_xp(1)*log(ecnia/ecnia(-1)) + y_xp(2)*log(eh/eh(-1)) + (y_xp(3))*log(ebfi/ebfi(-1)) + (y_xp(4))*log(egfe/egfe(-1)) + (y_xp(5))*log(egse/egse(-1)) + y_xp(6)*log(ex/ex(-1))
d(log(pxp)) - pxp_aerr = .5*(ecnian/xpn + ecnian(-1)/xpn(-1))*d(log(pcnia)) + .5*((xpn - ecnian)/xpn + (xpn(-1) - ecnian(-1))/xpn(-1))*d(log(pxnc))
log(pxp) - pxp_aerr = log(pxp(-1)) + y_pxp(1)*log(pcnia/pcnia(-1)) + y_pxp(2)*log(pxnc/pxnc(-1))


NSURL /
NSURLComponents
Written by Mattt Thompson on
There is a simple beauty to—let's call them "one-dimensional data types": numbers or strings formatted to contain multiple values, retrievable through a mathematical operator or parsing routine. Like how the hexadecimal color #EE8262 can have red, green, and blue components extracted by masking and shifting its bits, or how regular expressions can match and capture complex patterns in just a few characters.
Of all the one-dimensional data types out there, URIs reign supreme.
In its most basic form, a URI is comprised of a scheme name and a hierarchical part, with an optional query and fragment:
<scheme name> : <hierarchical part> [ ? <query> ] [ # <fragment> ]
Many protocols, including HTTP, specify a regular structure for information like the username, password, port, and path in the hierarchical part:
| foo | :// | username | : | password | @ | example.com | : | 8042 | /over/there/index | . | dtb | ? | type=animal&name=narwhal | # | nose |
| scheme | username | password | hostname | port | path | extension | query | fragment |
A solid grasp of network programming is rooted in an unshakeable familiarity with URL components. As a software developer, this means having a command over the URI functionality in your programming language's standard library.
If a programming language does not have a URI module in its standard library, run, don't walk, to a real language that does.
In Foundation, URLs are represented by
NSURL
.
NSURL
instances are created using the
class method URLWithString:
NSURL *url = [NSURL URLWithString:@"http://example.com"];
If the passed string is not a valid URL, this method
will return nil
.
NSString
also has some vestigial
functionality for path manipulation, as
described a few weeks back, but that's being
slowly migrated over to NSURL
. While the
extra conversion from NSString
to
NSURL
is not the most convenient step,
it's always worthwhile. If a value is a URL, it
should be stored and passed as an NSURL
;
conflating the two types is reckless and lazy API
design.
As a side note,
@@
would be a nice literal forNSURL
, (e.g.@@"http://example.com"
), don't you think?
NSURL
also has the class method
+URLWithString:relativeToURL:
, which can
be used to construct a URL from a string relative to
a base URL. The behavior of this method can be a
source of confusion, because of how it treats leading
/
's in relative paths.
For reference, here are representative examples of how this method works:
NSURL *baseURL = [NSURL URLWithString:@"http://example.com/v1/"];
[NSURL URLWithString:@"foo" relativeToURL:baseURL];
// http://example.com/v1/foo
[NSURL URLWithString:@"foo?bar=baz" relativeToURL:baseURL];
// http://example.com/v1/foo?bar=baz
[NSURL URLWithString:@"/foo" relativeToURL:baseURL];
// http://example.com/foo
[NSURL URLWithString:@"foo/" relativeToURL:baseURL];
// http://example.com/v1/foo
[NSURL URLWithString:@"/foo/" relativeToURL:baseURL];
// http://example.com/foo/
[NSURL URLWithString:@"http://example2.com/" relativeToURL:baseURL];
// http://example2.com/
URL Components
NSURL
provides accessor methods for each
of the URL components as defined by RFC 2396:
– absoluteString
–
absoluteURL
– baseURL
–
fileSystemRepresentation
–
fragment
– host
–
lastPathComponent
–
parameterString
– password
– path
– pathComponents
–
pathExtension
– port
–
query
– relativePath
–
relativeString
–
resourceSpecifier
– scheme
– standardizedURL
– user
The documentation and examples found in
NSURL
's documentation are a great
way to familiarize yourself with all of the different
components.
Although username & password can be stored in a URL, consider using
NSURLCredential
when representing user credentials, or persisting them to the keychain.
NSURLComponents
Quietly added in iOS 7 and Mac OS X 10.9 Mavericks
was NSURLComponents
, which can best be
described by what it could have been named instead:
NSMutableURL
. Still lacking
documentation, this class remains one of the more
obscure recent additions to Foundation.
NSURLComponents
instances are
constructed much in the same way as
NSURL
, with a provided
NSString
and optional base URL to
resolve against (+componentsWithString:
&
+componentsWithString:resolvingAgainstBaseURL:
).
It can also be alloc init
'd without any
arguments to create an empty storage container,
similar to NSDateComponents
.
The difference here, between NSURL
and
NSURLComponents
, is that component
properties are readwrite
. This provides
a safe and direct way to modify individual components
of a URL:
-
scheme
-
user
-
password
-
host
-
port
-
path
-
query
-
fragment
Attempting to set an invalid scheme string or negative port number will throw an exception.
In addition, NSURLComponents
also has
readwrite
properties for percent-encoded
versions of each component.
-
percentEncodedUser
-
percentEncodedPassword
-
percentEncodedHost
-
percentEncodedPath
-
percentEncodedQuery
-
percentEncodedFragment
Getting these properties retains any percent encoding these components may have. Setting these properties assumes the component string is already correctly percent encoded. Attempting to set an incorrectly percent encoded string will cause an exception. Although ';' is a legal path character, it is recommended that it be percent-encoded for best compatibility with NSURL (
-stringByAddingPercentEncodingWithAllowedCharacters:
will percent-encode any ';' characters if you pass theURLPathAllowedCharacterSet
).
Percent-Encoding
Speaking of percent-encoding...
NSURL
is
toll-free bridged to CFURLRef
. This
lower-level C API effectively mirrors the
functionality of NSURL
, with the
exception of
CFURLCreateStringByAddingPercentEscapes
and
CFURLCreateStringByReplacingPercentEscapesUsingEncoding
:
-
CFURLCreateStringByAddingPercentEscapes
: Creates a copy of a string, replacing certain characters with the equivalent percent escape sequence based on the specified encoding.
CFStringRef CFURLCreateStringByAddingPercentEscapes (
CFAllocatorRef allocator,
CFStringRef originalString,
CFStringRef charactersToLeaveUnescaped,
CFStringRef legalURLCharactersToBeEscaped,
CFStringEncoding encoding
);
-
CFURLCreateStringByReplacingPercentEscapesUsingEncoding
: Creates a new string by replacing any percent escape sequences with their character equivalent.
CFStringRef CFURLCreateStringByReplacingPercentEscapesUsingEncoding (
CFAllocatorRef allocator,
CFStringRef origString,
CFStringRef charsToLeaveEscaped,
CFStringEncoding encoding
);
Bookmark URLs
One final topic worth mentioning are bookmark URLs, which can be used to safely reference files between application launches. Think of them as a persistent file descriptor.
A bookmark is an opaque data structure, enclosed in an
NSData
object, that describes the location of a file. Whereas path- and file reference URLs are potentially fragile between launches of your app, a bookmark can usually be used to re-create a URL to a file even in cases where the file was moved or renamed.
You can read more about bookmark URLs in "Locating Files Using Bookmarks" from Apple's File System Programming Guide
Forget jet packs and flying cars—my idea of an exciting future is one where everything has a URL, is encoded in Markdown, and stored in Git. If your mind isn't blown by the implications of a universal resource locator, then I would invite you to reconsider.
Like hypertext, universal identification is a philosophical concept that both pre-dates and transcends computers. Together, they form the fabric of our information age: a framework for encoding our collective understanding of the universe as a network of individual facts, in a fashion that is hauntingly similar to how the neurons in our brains do much the same.
We are just now crossing the precipice of a Cambrian Explosion in physical computing. In an internet of things, where every object of our lives has a URL and embeds an electronic soul, a digital consciousness will emerge. Not to say, necessarily, that the singularity is near, but we're on the verge of something incredible.
Quite lofty implications for a technology used most often to exchange pictures of cats.


Bolivian President Evo Morales Calls for New Election
by Walter Brandimarte and Fabiola Moura1 / 2
(Bloomberg) -- President Evo Morales called for a new presidential vote in Bolivia amid growing unrest and after the Organization of American States said his re-election was marred by irregularities.
“New national elections will allow the Bolivian people to democratically choose new authorities with their vote,” Morales told reporters in La Paz on Sunday morning, calling for violence on the streets to end. “We all have the duty of pacifying Bolivia.”
Irregularities in the Oct. 20 vote mean it’s statistically unlikely that Morales obtained a 10% lead to avoid a runoff, the OAS said in a report published on its website Sunday. Morales didn’t say when the new vote will take place, but pledged to overhaul the electoral authority, which has been much criticized by the opposition and by monitors.
Protests over the contested election have grown and become more violent, with police mutinying in several cities over the weekend and reports of arson and attacks on local authorities. Before the OAS report, Bolivia’s Armed Forces said it supports a peaceful solution to the country and wouldn’t “confront” the population.
Police stopped guarding the presidential palace on Saturday, allowing protesters to congregate outside, the AP reported. Police in Cochabamba, Chuquisaca, Beni, Santa Cruz, Potosi and Oruro also joined protests challenging the results of the election, according to newspaper La Razon.
At least two people have died in demonstrations over the results of the vote in which Morales narrowly secured a fourth presidential term in the first round. Opponents alleged fraud and were pressing for a second round of elections.
(Adds details from Morales speech, violence over the weekend, starting in second paragraph.)
--With assistance from Fabiola Zerpa.
To contact the reporters on this story: Walter Brandimarte in Brasilia at wbrandimarte@bloomberg.net;Fabiola Moura in Sao Paulo at<EMAIL_ADDRESS>To contact the editors responsible for this story: Juan Pablo Spinetto at<EMAIL_ADDRESS>Matthew Bristow
For more articles like this, please visit us at bloomberg.com
©2019 Bloomberg L.P.


# UI5-Comp-Routing
SAPUI5 Component Based Routing Sample
This sample shows how SAPUI5/OpenUI5 Component Based Routing works
Further details in
this blog
.
Complete Component Based Routing Demo
Suppliers Component Standalone
Categories Component Standalone
Products Component Standalone


Devices
Name
{{con.name}}
Status
Online
Command
send
Type
XXX
Enrolled
{{con.enrolled?'Register':'Unregistered'}}
Operation
edit details delete unenroll


#! /usr/bin/env python
"""
Library of UR5-specific functions for MoveIt! and RViz Motion Planning.
Contains:
1) MoveIt! Parameters and Controllers for controlling the arm
a) Go to a specified pose
b) Go to specified join angles
c) Play a saved trajectory from a file
2) RViz Planning Scene controls for adding, attaching, detaching and removing objects from the Planning Scene
"""
import sys
import yaml
import tf
import actionlib
import moveit_commander
import moveit_msgs.msg
import rospkg
import rospy
from std_srvs.srv import Empty
[docs]class Ur5Moveit(object):
"""
Class for the UR5 Arm, containing essential methods for execution.
:var str _planning_group: The name to be assigned to the move_group
:var str _box_name: The name to be stored to the box in the planning scene
:var _computed_plan: The plan generated by the planner that will be executed
:var str _pkg_path: The file path for the package
:var str file_path: Extends from _pkg_path to point towards the folder containing saved trajectories.
"""
_planning_group = "manipulator"
_box_name = ''
_computed_plan = ''
_pkg_path = rospkg.RosPack().get_path('pkg_task5')
file_path = _pkg_path + '/config/saved_trajectories/'
# Constructor
def __init__(self, arg_robot_name):
"""
Constructor containing all essential MoveIt and RViz assets.
"""
# Initialise node
rospy.init_node('node_moveit_%s' % arg_robot_name, anonymous=True)
self.tf_listener = tf.TransformListener()
self._robot_ns = '/' + arg_robot_name
moveit_commander.roscpp_initialize(sys.argv)
self._robot = moveit_commander.RobotCommander(
robot_description=self._robot_ns + "/robot_description",
ns=self._robot_ns)
self._scene = moveit_commander.PlanningSceneInterface(ns=self._robot_ns)
self._group = moveit_commander.MoveGroupCommander(
self._planning_group,
robot_description=self._robot_ns + "/robot_description",
ns=self._robot_ns)
rospy.Publisher(
self._robot_ns + '/move_group/display_planned_path',
moveit_msgs.msg.DisplayTrajectory, queue_size=1)
actionlib.SimpleActionClient(
self._robot_ns + '/execute_trajectory',
moveit_msgs.msg.ExecuteTrajectoryAction).wait_for_server()
self._touch_links = self._robot.get_link_names(
group=self._planning_group)
# Current State of the Robot is needed to add box to planning scene
self._robot.get_current_state()
rospy.loginfo(
'\033[94m' + "Planning Group: {}".format(self._group.get_planning_frame()) + '\033[0m')
rospy.loginfo(
'\033[94m' + "End Effector Link: {}".format(
self._group.get_end_effector_link()) + '\033[0m')
rospy.loginfo(
'\033[94m' + "Group Names: {}".format(self._robot.get_group_names()) + '\033[0m')
rospy.loginfo("Package Path: {}".format(self.file_path))
rospy.loginfo('\033[94m' + " >>> Ur5Moveit init done." + '\033[0m')
[docs] def go_to_pose(self, arg_pose):
"""
Goes to a specified pose and orientation.
:arg arg_pose: The pose and orientation to execute planning towards.
:type arg_pose: Pose object
:return: Confirmation whether the planning and execution was successful or not.
:rtype: bool
"""
# Get current pose values
pose_values = self._group.get_current_pose().pose
rospy.loginfo('\033[94m' + ">>> Current Pose:" + '\033[0m')
rospy.loginfo(pose_values)
# Set final pose target with given pose value
self._group.set_pose_target(arg_pose)
self._group.set_start_state_to_current_state()
rospy.set_param('/move_group/trajectory_execution/allowed_start_tolerance', 0.0)
flag_plan = self._group.go(wait=True) # wait=False for Async Move
pose_values = self._group.get_current_pose().pose
rospy.loginfo('\033[94m' + ">>> Final Pose:" + '\033[0m')
rospy.loginfo(pose_values)
# Get final joints values calculated
list_joint_values = self._group.get_current_joint_values()
rospy.loginfo('\033[94m' + ">>> Final Joint Values:" + '\033[0m')
rospy.loginfo(list_joint_values)
# Verify planning/executing success
if flag_plan:
rospy.loginfo('\033[94m' + ">>> go_to_pose() Success" + '\033[0m')
else:
rospy.logerr(
'\033[94m' + ">>> go_to_pose() Failed. Solution for Pose not Found." + '\033[0m')
return flag_plan
[docs] def hard_go_to_pose(self, arg_pose, arg_max_attempts):
"""
Uses :meth:`go_to_pose`, but repeatedly tries to find a solution.
:arg arg_pose: The pose and orientation to execute planning towards.
:type arg_pose: Pose object
:arg int arg_max_attempts: The maximum number of attempts for the planner.
"""
number_attempts = 0
flag_success = False
while (number_attempts <= arg_max_attempts) and (flag_success is False):
number_attempts += 1
flag_success = self.go_to_pose(arg_pose)
rospy.logwarn("attempts: {}".format(number_attempts))
# # self.clear_octomap()
return True
[docs] def clear_octomap(self):
"""
Clears the octomap of plans
:return: A call to the :meth:clear_octomap_service_proxy` function
"""
clear_octomap_service_proxy = rospy.ServiceProxy(self._robot_ns + "/clear_octomap", Empty)
return clear_octomap_service_proxy()
[docs] def set_joint_angles(self, arg_list_joint_angles):
"""
Goes to specified joint angles.
:arg arg_list_joint_angles: A list of joint angles in radians to plan towards.
:type arg_list_joint_angles: float[]
:return: Confirmation whether the planning and execution was successful or not.
:rtype: bool
"""
list_joint_values = self._group.get_current_joint_values()
rospy.loginfo('\033[94m' + ">>> Current Joint Values:" + '\033[0m')
rospy.loginfo(list_joint_values)
self._group.set_joint_value_target(arg_list_joint_angles)
self._group.set_start_state_to_current_state()
rospy.set_param('/move_group/trajectory_execution/allowed_start_tolerance', 0.0)
flag_plan = self._group.go(wait=True)
list_joint_values = self._group.get_current_joint_values()
rospy.loginfo('\033[94m' + ">>> Final Joint Values:" + '\033[0m')
rospy.loginfo(list_joint_values)
pose_values = self._group.get_current_pose().pose
rospy.loginfo('\033[94m' + ">>> Final Pose:" + '\033[0m')
rospy.loginfo(pose_values)
if flag_plan:
rospy.loginfo(
'\033[94m' + ">>> set_joint_angles() Success" + '\033[0m')
else:
rospy.logerr(
'\033[94m' + ">>> set_joint_angles() Failed." + '\033[0m')
return flag_plan
[docs] def hard_set_joint_angles(self, arg_list_joint_angles, arg_max_attempts):
"""
Uses :meth:`set_joint_angles`, but repeatedly tries to find a solution.
:arg arg_list_joint_angles: List of joint angles to plan towards.
:type arg_list_joint_angles: float[]
:arg int arg_max_attempts: The maximum number of attempts for the planner.
"""
number_attempts = 0
flag_success = False
while (number_attempts <= arg_max_attempts) and (flag_success is False):
number_attempts += 1
flag_success = self.set_joint_angles(arg_list_joint_angles)
rospy.logwarn("attempts: {}".format(number_attempts))
# self.clear_octomap()
[docs] def moveit_play_planned_path_from_file(self, arg_file_path, arg_file_name):
"""
Plays a saved trajectory from a file.
:arg str arg_file_path: The file path of the .yaml file with the saved trajectory.
:arg str arg_file_name: The name of the .yaml file.
:return: Confirmation of the execution.
"""
file_path = arg_file_path + arg_file_name
with open(file_path, 'r') as file_open:
loaded_plan = yaml.load(file_open, Loader=yaml.Loader)
ret = self._group.execute(loaded_plan)
# rospy.logerr(ret)
return ret
[docs] def moveit_hard_play_planned_path_from_file(
self, arg_file_path, arg_file_name, arg_max_attempts):
"""
Uses :meth:`moveit_play_planned_path_from_file` but tries repeatedly for a solution.
:arg str arg_file_path: The file path of the .yaml file with the saved trajectory.
:arg str arg_file_name: The name of the .yaml file.
:arg int arg_max_attempts: The maximum number of attempts for the planner.
"""
number_attempts = 0
flag_success = False
while (number_attempts <= arg_max_attempts) and (flag_success is False):
number_attempts += 1
flag_success = self.moveit_play_planned_path_from_file(arg_file_path, arg_file_name)
rospy.logwarn("attempts: {}".format(number_attempts))
# # self.clear_octomap()
return True
# Adds box to world
[docs] def add_box(self, box_name, box_length, box_pose):
"""
Adds a box to the RViz planning scene.
:arg str box_name: The name to be assigned to the box.
:arg float box_length: The size of the box.
:arg box_pose: The pose and orientation of the box.
:type box_pose: PoseStamped object
"""
self._scene.add_box(box_name,
box_pose,
size=(box_length, box_length, box_length))
[docs] def attach_box(self, box_name):
"""
Attaches the specified object(box) in the planning scene to the robot hand.
:arg str box_name: The name of the box in the RViz Planning Scene te be attached.
"""
self._scene.attach_box(self._group.get_end_effector_link(),
box_name,
touch_links=self._touch_links)
[docs] def detach_box(self, box_name):
"""
Detaches the specified object(box) from the robot hand in the planning scene.
:arg str box_name: The name of the box in the RViz Planning Scene to be detached.
"""
self._scene.remove_attached_object(self._group.get_end_effector_link(),
name=box_name)
[docs] def remove_box(self, box_name):
"""
Removes the specified object(box) from the RViz Planning Scene.
:arg str box_name: The name of the box to be removed.
"""
self._scene.remove_world_object(box_name)
# Destructor
def __del__(self):
moveit_commander.roscpp_shutdown()
rospy.loginfo(
'\033[94m' + "Object of class Ur5Moveit Deleted." + '\033[0m')


TOO TIRED TO DIE
Reviewed by Harvey Karten, Ph.D. Dream Search Entertainment Director: Wonsuk Chin Writer: Wonsuk Chin Cast:Takeshi Kaneshiro, Mira Sorvino, Jeffrey Wright, Michael Imperioli, Geno Lechner, Ben Gazzara, Sandra Prosper, David Thornton, Aida Turturro, Hye Soo Kim, Drena De Niro
You know those college applications that ask you to write an essay about yourself? What they ought to ask, specifically, is "What would you do if you found out you had just one year to live?" Liberate the candidates' imaginations and see who can come up with something more original than "See the world" or "Donate all my money to your college." In "Too Tired To Die," Korean-born Wonsuk Chin's first production and one which took eight years to get released, the writer-director poses a question even more focused and immediate: "What would you do if you found out you had just twelve hours to live?" Hug a stranger, as one character in the film advises? Have a quick bedroom fling? Take the Concorde to Paris? "Too Tired To Die" deals with one person's choices, not the kind that you or I would probably make, but nonetheless options which should have provided for an engaging set of adventures. Unfortunately, though its script strives for originality above all, it is merely a pastiche of vistas culled from some of the noted directors like Ingmar Bergman, Woody Allen, and John Woo thrown together without cohesiveness, making for a phlegmatic, talky movie with neither humor nor philosophic depth. At best, movie buffs will find satisfaction in identifying the styles of the masters which are duplicated here. About the only real existential gem that emerges from all the banter is that "life is short: seize the day," and one assumes that somehow many of us had heard that before.
"Too Tired to Die" starts off in an absolutely promising way, a homage to the era of silent films as Death, in the form of the glamorous Mira Sorvino (who is appears time and again in an array of Melissa Toth's smashing outfits), approaches an Arab in Old Baghdad, who temporarily escapes her embrace by running for his life.  As a man who allegedly reads Balzac, Jeffrey Wright expresses himself, mostly about the charms of the opposite sex, while feigning the air of a world-weary intellectual. In truth he has not even read page one. Fabrizio (Michael Imperioli) turns up as a aesthetic film-maker, perhaps the raissoneur for the regisseur himself. The reality is that he is merely a ticket- seller at a theater box office. When Kenji (Takeshi Kaneshiro), a rootless, unemployed Japanese sponging off his Tokyo-residing mother, meets Pola (Geno Lechner), an exotic German woman about to travel to Paris, he is entranced, makes a date with her for that very evening. One day after a disappointing post-prandial visit to her apartment he is told by Death that he has just twelve hours to live.
The movie gives Mira Sorvino the opportunity to appear in several guises, in one case picking up some gangsters who oblige her by falling prey to a John-Woo style gunman ("I'll meet you soon, considering your profession," she advises the killer), in another situation as a Japanese geisha, and in yet a different scene as a Yentl-style figure in a man's outfit. As Kenji remains at a loss for what to do with the remaining hours of his life, he winds up at a dinner party through the invitation of a famous artist (Ben Gazzara) whom he criticizes for hanging out with a woman much younger than he (Hye Soo Kim).
The only real insight we get from the time spent with this oddball cast of characters is the Death is not an automaton, despite her need simply to follow orders. She has feelings, particularly regarding the taking of people who are young and, in fact, can resort to tears in the execution of her gig. You've got to wonder what was in Wonsuk Chin's mind when his payoff is so out of tune with the rest of his story. "Too Tired To Die" feels like a talky French film--the Eric Rohmer variety- -itself a tired effort that departs from the screen an unsatisfying death. it succeeds only too well in pointing out the deadly dull flavor of some European arthouse fare and the exhausted flavor of pseudo-hip victuals.
Not Rated. Running time: 97 minutes. (C) Harvey Karten 1998
The review above was posted to the
rec.arts.movies.reviews newsgroup (de.rec.film.kritiken for German reviews).
The Internet Movie Database accepts no responsibility for the contents of the
review and has no editorial control. Unless stated otherwise, the copyright
belongs to the author.
Please direct comments/criticisms of the review to relevant newsgroups.
Broken URLs inthe reviews are the responsibility of the author.
The formatting of the review is likely to differ from the original due
to ASCII to HTML conversion.
Related links: index of all rec.arts.movies.reviews reviews


lib
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com.kirkbushman.araw.models
/
UploadContract
/
assets
assets
val
assets
:
UploadContractAssets


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| fit_to_timeline {lubridate} | R Documentation |
The POSIXlt format allows you to create instants that do not exist in real life due to daylight savings time and other conventions. fit_to_timeline matches POSIXlt date-times to a real times. If an instant does not exist, fit to timeline will replace it with an NA. If an instant does exist, but has been paired with an incorrect timezone/daylight savings time combination, fit_to_timeline returns the instant with the correct combination.
fit_to_timeline(lt, class = "POSIXct", simple = FALSE)
lt |
a POSIXlt date-time object. |
class |
a character string that describes what type of object to return, POSIXlt or POSIXct. Defaults to POSIXct. This is an optimization to avoid needless conversions. |
simple |
if TRUE, lubridate makes no attempt to detect meaningless time-dates or to correct time zones. No NAs are produced and the most meaningful valid dates are returned instead. See examples. |
a POSIXct or POSIXlt object that contains no illusory date-times
## Not run: tricky <- structure(list(sec = c(5, 0, 0, -1), min = c(0L, 5L, 5L, 0L), hour = c(2L, 0L, 2L, 2L), mday = c(4L, 4L, 14L, 4L), mon = c(10L, 10L, 2L, 10L), year = c(112L, 112L, 110L, 112L), wday = c(0L, 0L, 0L, 0L), yday = c(308L, 308L, 72L, 308L), isdst = c(1L, 0L, 0L, 1L)), .Names = c("sec", "min", "hour", "mday", "mon", "year", "wday", "yday", "isdst"), class = c("POSIXlt", "POSIXt"), tzone = c("America/Chicago", "CST", "CDT")) tricky ## [1] "2012-11-04 02:00:00 CDT" Doesn't exist because clocks "fall back" to 1:00 CST ## [2] "2012-11-04 00:05:00 CST" Times are still CDT, not CST at this instant ## [3] "2010-03-14 02:00:00 CDT" DST gap ## [4] "2012-11-04 01:59:59 CDT" Does exist, but has deceptive internal structure fit_to_timeline(tricky) ## Returns: ## [1] "2012-11-04 02:00:00 CST" instant paired with correct tz & DST combination ## [2] "2012-11-04 00:05:00 CDT" instant paired with correct tz & DST combination ## [3] NA - fake time changed to NA (compare to as.POSIXct(tricky)) ## [4] "2012-11-04 01:59:59 CDT" -real instant, left as is fit_to_timeline(tricky, simple = TRUE) ## Returns valid time-dates by extrapolating CDT and CST zones: ## [1] "2012-11-04 01:00:05 CST" "2012-11-04 01:05:00 CDT" ## [3] "2010-03-14 03:05:00 CDT" "2012-11-04 01:59:59 CDT" ## End(Not run)