The Cocoon Scheduler is a recently-added component, which uses the Avalon Cornerstone scheduler. It allows you do to anything at a specific interval or at a certain time every day, week, month, etc, much like the cron daemon. It currently lives in the 2.1-dev scratchpad.

Starting Out

First, you must compile Cocoon with the scratchpad enabled. Make sure that exclude.webapp.scratchpad and exclude.scratchpad are either commented out or set to false.

Second, compile and deploy Cocoon as you would normally.

Third, you must make some changes to your WEB-INF/cocoon.xconf file. Add the following lines to the bottom of the file, inside the closing </cocoon> tag:

<!-- This is the cornerstone scheduler -->
<component role="org.apache.avalon.cornerstone.services.scheduler.TimeScheduler"
           class="org.apache.cocoon.components.scheduler.DefaultTimeScheduler"/>

<!-- This is the cornerstone thread manager -->
<component role="org.apache.avalon.cornerstone.services.threads.ThreadManager"
           class="org.apache.cocoon.components.scheduler.DefaultThreadManager">
  <thread-group>
    <name>default</name>
  </thread-group>
</component>

<!-- This is an extended cocoon scheduler -->
<component role="org.apache.cocoon.components.scheduler.Scheduler"
           class="org.apache.cocoon.components.scheduler.DefaultScheduler">
    <triggers>
        <!-- This is a sample trigger -->
        <trigger name="aggregatorTrigger"
                 target="org.apache.avalon.cornerstone.services.scheduler.Target/aggy">
            <timed type="periodic">
                <period>10000</period> <!-- ms, e.g. 10 seconds -->
            </timed>
        </trigger>
    </triggers>
</component>

<!-- This is a sample target, that is called as configured in the sample above -->

<component role="org.apache.avalon.cornerstone.services.scheduler.Target/aggy"
           class="org.apache.cocoon.components.scheduler.TestTarget"/>

Now, restart your servlet container of choice, and check it's STDOUT. In Tomcat you probably want $TOMCAT_HOME/logs/stdout.log. Once everything has started, you should now notice a message popping up every ten seconds:

Target aggregatorTrigger triggered at Mon Aug 25 01:21:16 CDT 2003
Target aggregatorTrigger triggered at Mon Aug 25 01:21:26 CDT 2003
Target aggregatorTrigger triggered at Mon Aug 25 01:21:36 CDT 2003
Target aggregatorTrigger triggered at Mon Aug 25 01:21:46 CDT 2003
Target aggregatorTrigger triggered at Mon Aug 25 01:21:56 CDT 2003
Target aggregatorTrigger triggered at Mon Aug 25 01:22:06 CDT 2003

Obviously, this is a very basic example, and a more complicated example could involve periodic file downloading, user management, database operations, etc.

There are currently two different types of triggers available. One is a periodic trigger, which is activated every N milliseconds, and the other is a "cron" type trigger where you have a little more flexibility with how triggers are activated.

Periodic Triggers

Configuration Parameters

offset:Initial delay in milliseconds, -1 means fire immediately

period: After initial delay in milliseconds, -1 means fire only once after initial delay

The following trigger will wait 2 seconds before triggering, and then trigger every 10 seconds afterwards:

<trigger name="test"
         target="org.apache.avalon.cornerstone.services.scheduler.Target/test">
  <timed type="periodic">
    <offset>2000</offset> 
    <period>10000</period> <!-- ms, e.g. 10 seconds -->
  </timed>
</trigger>

Cron Triggers

Configuration Parameters

(Untested, someone wanna futz with this to make sure it works?) -- TonyCollen

minute: the minute at which job is scheduled. (0-59)

hour: hour at which job is scheduled. (0-23 or -1 for every hour)

month: the month at which job is scheduled. (0-11 or -1 for every month)

year: the year when job is scheduled (-1 implies every year)

day: either day of week or day of month depending on value of is!DayOfWeek.

is!DayOfWeek: set to true if you want day to represent the day of the week (1-7), otherwise, set to false to represent the day of the month (1-31).

<trigger name="test"
         target="org.apache.avalon.cornerstone.services.scheduler.Target/test">
  <timed type="cron">
    <minute>34</minute>
    <hour>11</hour>
    <month>-1</month>
    <year>-1</year>
    <day>-1</day>
    <isDayOfWeek>true</isDayOfWeek>
  </timed>
</trigger>

Coming Soon: Creating your own trigger target.

Scheduler (last edited 2009-09-20 23:42:18 by localhost)