Class QueueTemplate

java.lang.Object
sunlabs.brazil.template.Template
sunlabs.brazil.template.QueueTemplate
All Implemented Interfaces:
TemplateInterface

public class QueueTemplate extends Template
Template class for Managing simple Queues, allowing text communication among sessions. The "name" attribute names the Q. When enqueueing messages, "name" is a white space separated list of queue recipients. When Dequeueing Messages, "name" is the recipient Queue.

The following tags are recognized.

  • <enqueue name="recipients ..." data=var1 var2 ... varn" [glob="..." delim="." from="sender" nocreate="true|false"] >

  • <dequeue name="name" prepend="props prefix" timelimit="sec"> If "timelimit" has a suffix of "ms", then the time is taken in ms.
  • <queueinfo name="q_name" prepend="props prefix" clear remove=true|false create=true|false>
This format is supported for backward compatibility with the old behavior. (Just in case the compatibility isn't quite right, see QueueTemplateOld).
  • <enqueue name="recipients ..." meta="anything" message="msg" from="sender" [nocreate="true|false"] >
Version:
@(#)QueueTemplate.java 1.5 1.5
Author:
Stephen Uhler
  • Field Details

  • Constructor Details

    • QueueTemplate

      public QueueTemplate()
  • Method Details

    • tag_enqueue

      public void tag_enqueue(RewriteContext hr)
      Add a text message onto a named queue. Attributes:
      - name: the name of the queue (required). "name" is a delim list of queues to send the data too.
      - from: the sender name
      - data: a set of property names to send as name/value pairs. If Names provided of the form nnn#vvv, then "vvv" is taken as the value to use if it is not already set, otherwise the empty string is used as the value.
      - nocreate: If set, The item will not be Queued if the Q for that recipient does not already exist.
      - force: put to the queue even if its closed
      - delim: The delimiter character for the list of names. (It defaults to " " for backward compatibility with the previous behavior)

      The property "count" contains the number of recipients for which the message was successfully Queued. The property "error.name" will contain an error message if Queueing failed. In both cases, the template prefix will be prepended. It is not considered an error condition for a message not to be delivered to a non existent Queue if "nocreate" is set.

      The experimental attribute "glob" may be used instead of "name", in which case name is taken as the list of "delim" separated tokens named by the first wildcard substring of the matching glob pattern.

    • enqueue

      public static boolean enqueue(String to, String from, String message, String meta, boolean noCreate, boolean force)
      Deprecated.
      Allow a message to be enqueued from java code. Use the enqueue(String to, String from, Dictionary data, boolean noCreate, boolean force) method instead.
      Parameters:
      to - : The queue name
      from - : The sender of the data
      message - : The message to enqueue
      meta - : The meta data, if any
      noCreate - : If true, don't create a Q if it doesn't already exist
      force - : Force item onto Q even if it is closed
      Returns:
      True, if the data was enqueued
    • enqueue

      public static boolean enqueue(String to, String from, Dictionary data, boolean noCreate, boolean force)
      Allow a message to be enqueued from java code.
      Parameters:
      to - : The queue name (only a single q)
      from - : The sender of the data
      data - : a dictionary f name/value pairs
      noCreate - : If true, don't create a Q if it doesn'a already exist
      force - : Force item onto Q even if it is closed
      Returns:
      True, if the data was enqueued
    • destroyQueue

      public static void destroyQueue(String name)
      Remove a Queue, freeing its resources.
    • tag_dequeue

      public void tag_dequeue(RewriteContext hr)
      Remove an item from the queue, and generate the appropriate properties. Attributes:
      name
      The name of the queue to examine
      prepend
      The prefix in the properties table to use to set the results. Defaults to our prefix.
      timelimit
      how long to wait for an item to appear, in sec. Defaults to 30.
      If an item is retrieved, the following request properties are set (preceded by prepend):
      age
      Set how long the message has been q's (in seconds)
      sent
      Set the timestamp (in sec) of when the item was q'd.
      items
      Set the number of Q'd items.
      from
      Set the (unauthenticated) sender.
      error
      Something went wrong. Set an error message.
      In addition, all name/value pairs send as part of the message will be set as well. (In prewvious versions of this template, that consists of "message" and (optionally) "meta".)

      Note: this tag blocks until an item is received in the Queue (or a timelimit expires). As template processing is synchronized based on sessions, care should be taken to avoid blocking other (unrelated) session based requests while waiting on the queue.

    • dequeue

      public static QueueTemplate.QueueItem dequeue(String name, int timelimit)
      Program access to the Q.
      Parameters:
      name - ; The name of the Q. A new Q will be created if it doesn't already exist.
      timelimit - : how long (in ms) to wait before returning
      Returns:
      The Queue item, or Null if no item is available.
    • tag_queueinfo

      public void tag_queueinfo(RewriteContext hr)
      Return info about the Q, and optionally clear or remove it. If the queue doesn't already exist, it is created. Attributes:
      name
      The name of the queue to examine
      prepend
      The prefix in the properties table to use to set the results. Defaults to our prefix.
      clear
      If set, then clear the queue
      remove
      If set, then remove the queue
      closed=[true|false]
      set the closed state of the Q
      create=[true|false]
      Should the Q be created if it doesn't already exist (defaults to true).
      The following request properties are set (preceded by prepend):
      lastIn
      The timestamp (ms) of the last Q insert attempt.
      lastOut
      The timestamp (ms) of the last Q retrieval attempt.
      size
      The number of items in the Q.
      count
      The total number of items inserted into the Q
      created
      The timestamp (in ms) of the Q's creation
      expires
      The Q's expiration period (in ms)
      If the Q doesn't exist (e.g. create=false), then the property "error" is set.
    • getQ

      public static QueueTemplate.Queue getQ(String name, boolean create)
      Return a Q. All calls to the session manager go through here, so we can reap old queues some day.
    • getQ

      public static QueueTemplate.Queue getQ(String name)