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Revision 5311

Added by daigle over 14 years ago

Merge 1.9.2 changes back into the trunk

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service-base.html
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  </div>
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  <a name="Overview"></a><div class="header1">Overview</div>
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  <p>Metacat is migrating toward a service based architecture.  Basically,
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  what this means is that any internal service that Metacat provides should be
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  represented in a singleton class that extends the BaseService class.</p>
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  <p>There is a goal to migrate Metacat to a service based architecture.  This
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  provides several advantages: </p>
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  <ul>
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    <li>Cached values can be refreshed via the configuration utility without
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    requiring a restart of Metacat.</li>
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    <li>Services can be gracefully shut down when Metacat is stopped.  For
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    instance, the database service can make sure all db requests have completed
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    before continuing with shutdown.</li>
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    <li>Services can have a common interface to expose MBeans for JMX monitoring
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    (see the <a href="http://java.sun.com/javase/technologies/core/mntr-mgmt/javamanagement/">Java Management Extensions</a> page).</li>
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  </ul>
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  <p>From a
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  <p>There are a few basic questions that can be asked when you are creating a
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  class to decide if it should be a service.</p>
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  <ul>
......
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    performs any appropriate state-specific service updates.</li>
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    <li> refresh() - a package level method that calls refreshable() and doRefresh().  It has
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    package level access because we only want the ServiceService to be able to refresh the
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    service</li>
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    service.</li>
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    <li>stop() - Gracefully shut down the service, releasing any resources.</li>
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  </ul>
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  <a name="ServiceService"></a><div class="header1">Controling Services With ServiceService Class</div>

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