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From blorit...@apache.org
Subject cvs commit: jakarta-avalon-excalibur/event/src/xdocs command.xml menu.xml
Date Wed, 25 Sep 2002 20:03:57 GMT
bloritsch    2002/09/25 13:03:57

  Modified:    event/src/xdocs menu.xml
  Added:       event/src/xdocs command.xml
  Add new page to event docs
  Revision  Changes    Path
  1.3       +2 -2      jakarta-avalon-excalibur/event/src/xdocs/menu.xml
  Index: menu.xml
  RCS file: /home/cvs/jakarta-avalon-excalibur/event/src/xdocs/menu.xml,v
  retrieving revision 1.2
  retrieving revision 1.3
  diff -u -r1.2 -r1.3
  --- menu.xml	25 Sep 2002 18:03:47 -0000	1.2
  +++ menu.xml	25 Sep 2002 20:03:56 -0000	1.3
  @@ -12,8 +12,8 @@
       <menu name="Overview">
         <item href="event.html" name="Event"/>
  - <!--     <item href="command.html" name="Command"/>
  -      <item href="mpool.html" name="MPool"/>
  +      <item href="command.html" name="Command"/>
  + <!--     <item href="mpool.html" name="MPool"/>
         <item href="thread.html" name="Thread"/>
         <item href="util.html" name="Util"/>    -->
  1.1                  jakarta-avalon-excalibur/event/src/xdocs/command.xml
  Index: command.xml
  <?xml version="1.0"?>
      <title>Excalibur Event - Command</title>
        <person name="Berin Loritsch" email="bloritsch@apache.org"/>
      <s1 title="Why Command Was Created">
          Command was created as a way to offload management functions
          to a CommandManager which would execute the functions in the
          background.  The benefits of this approach are tremendous
          when you are handling several requests at the same time.  As
          load increases, you don't increase the frequency in which
          certain functions are performed (as in the normal synchronous
          management), and you reduce the time for the critical path
          to execute.  The critical path is the part of your code that
          actually solves your problems as opposed to managing resources.
      <s1 title="When To Use Command">
          A better question might be "when should I not to use Command?".
          The complexity of the thread management and command timing is
          completely hidden from you.  That makes Command as easy to
          use as any event based system like Swing.  That said, if you
          have a really trivial system, or you do not work with heavy
          request loads it is definitely easier to design your system
          the old fashioned way.  If you do expect your application to
          work under heavy load, you will find Command to be indespensible.
      <s1 title="Core Concepts">
          Command is built on top of <link href="event.html">Event</link>.
          That means we use a Command Sink to enqueue Commands for the
          CommandManager to process.  The CommandManager then executes the
          commands as they are pulled off of the queue.  A Command can be
          a repeating command, so CommandManager will automatically requeue
          that command for you.
        <s2 title="Command">
            A Command is an object that performs any function you desire.
            You create it by simply implementing the Command interface.
            There are three types of commands: a generic command that is
            executed immediately in a background thread, a delayed command
            that is executed after a specified period of time, and a
            repeated command that is executed again and again until the
            Command Manager is shut down.
        <s2 title="Command Manager">
            The Command Manager takes care of processing both Commands
            and Signals.  With Signals, it will notify the registered
            Signal listener.  With commands it schedules their execution
            in a background thread.
        <s2 title="Thread Manager">
            A Thread Manager takes care of the threading policy for the
            Command Manager.  It manages the thread pool size, and how
            often the Event Pipeline (the path from a Source to an
            EventHandler) is checked.
        Copyright (c) @year@ The Jakarta Apache Project All rights reserved.
        $Revision: 1.1 $ $Date: 2002/09/25 20:03:56 $

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