123 lines
9.7 KiB
HTML
123 lines
9.7 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="Server jobs" />
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<meta name="abstract" content="Server jobs are jobs that run continuously in the background on the iSeries system." />
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<meta name="description" content="Server jobs are jobs that run continuously in the background on the iSeries system." />
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<meta name="DC.Relation" scheme="URI" content="rzaksjobtypeoverview.htm" />
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<meta name="DC.Relation" scheme="URI" content="rzaksaboutautostartjob.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2004-2006" />
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<meta name="DC.Identifier" content="rzaksserverjobs" />
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Server jobs</title>
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</head>
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<body id="rzaksserverjobs"><a name="rzaksserverjobs"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Server jobs</h1>
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<div><p>Server jobs are jobs that run continuously in the background on
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the iSeries™ system.</p>
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<div class="p">Work can come from network functions, operating system functions, on behalf
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of a user, another system within the network, or from general system services,
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such as the clustering server jobs. Server jobs typically run in one of three
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basic subsystems that are shipped with the system - QSYSWRK, QSERVER, or QUSRWRK.
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Server jobs are most commonly associated with such functions as HTTP, Lotus
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Notes<sup>®</sup> , and TCP/IP. The iSeries system has three basic models for server
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jobs:<dl><dt class="dlterm">Threaded Job Model</dt>
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<dd>In the threaded job model the server job is a job with multiple threads.
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One thread acts as the distributor of work to the other threads. For example,
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when the server receives a client request, the initial thread reads the request
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and passes it to another thread to fulfill the request. With this model, the
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amount of jobs on the system is greatly reduced because work is handled in
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different threads rather than requiring multiple jobs. A few examples of server
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jobs that use the threaded job model are Domino<sup>®</sup>, HTTP server, and WebSphere<sup>®</sup>.</dd>
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</dl>
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<dl><dt class="dlterm">Prestart Job Model</dt>
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<dd>In the prestart job model there is typically a primary job that acts as
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a listener for requests that come into the system. This job is typically called
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the daemon job. The daemon job handles the initial request and then passes
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the request to the appropriate prestart server job. With this job model, using
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prestart jobs can reduce the number of jobs that are required because after
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a request has been fulfilled the prestart server job waits for the next request.
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The server job is reused. Also, from a performance perspective, the prestart
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job is already running and waiting to process the request. Some examples of
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server jobs that use the prestart job model are SQL server, host servers,
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and Simple Mail Transfer Protocol (SMTP).<div class="note"><span class="notetitle">Note:</span> For jobs that run user code,
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typically the job is not reused (like most server jobs). This is because the
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user code may have changed anything in the job (such as the remote command
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server). </div>
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</dd>
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</dl>
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<dl><dt class="dlterm">Multiple Listening Job Model </dt>
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<dd>In the multiple listening job model, several server jobs are started.
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When a request comes in, the job that receives the request handles the job
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request, while the next available server job waits for the next request to
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come in. Once the server job completes the request, it closes the connection
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and ends. A new server job starts and the cycle continues.<p>With this model,
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you do not need to be concerned with prestart job entries. However, sometimes
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configuring subsystems unique to your environment is not possible because
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this model runs in the default subsystem. One exception is File Transfer Protocol
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(FTP). With file transfer protocol you can configure the subsystem in which
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the file transfer protocol server runs. There is no ability to have some FTP
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work to run in one subsystem and the rest of the work to run in a different
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subsystem. Also, from a performance perspective, the cost of job initiation
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and job termination cannot be avoided because once a job is run it is ended
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and another job starts. However, because jobs end when the connection is complete
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and the next job is started, the new job will generally be up and running
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when the next request is received, so the job initiation and termination cost
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should not affect the time it takes to connect to the server. </p>
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<p>Some
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examples of server jobs that use the multiple listening job model are FTP
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and line printer daemon (LPD).</p>
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<p>For more detailed information about the
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job names of the server jobs that run on the system, see the server job table.
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This table shows you the subsystem and the job name so that you can find the
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active job and its job logs. The table also shows the job description each
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server job uses. By default most server jobs do not generate a job log when
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the job ends (the LOG parameter is set to 4 0 *NOLIST), which means that the
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job log is not created. If you want a job log to be generated with all the
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messages sent to the job log, the LOG parameter needs to specify 4 0 *SECLVL.</p>
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</dd>
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</dl>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzaksjobtypeoverview.htm" title="The iSeries server processes several different types of jobs.">Job types</a></div>
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</div>
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<div class="relconcepts"><strong>Related concepts</strong><br />
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<div><a href="rzaksaboutautostartjob.htm" title="An autostart job is a batch job doing repetitive work, one-time initialization work that is associated with a particular subsystem, initializes functions for an application, or provides centralized service functions for other jobs in the same subsystem. An autostart job in the controlling subsystem can be used to start other subsystems (as does the IBM-supplied controlling subsystem). The autostart jobs associated with a subsystem are automatically started each time the subsystem is started.">Autostart jobs</a></div>
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<div><a href="rzaksbatchjob.htm" title="A batch job is a predefined group of processing actions submitted to the system to be performed with little or no interaction between the user and the system. Jobs that do not require user interaction to run can be processed as batch jobs. A batch job typically is a low priority job and can require a special system environment in which to run.">Batch jobs</a></div>
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<div><a href="rzaksaboutcommunicationjobs.htm" title="A communications job is a batch job that is started by a program start request from a remote system. Job processing involves a communication request and appropriate specifications.">Communication jobs</a></div>
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<div><a href="rzaksinteractivejob.htm" title="An interactive job is a job that starts when a user signs on to a display station and ends when the user signs off. For the job to run, the subsystem searches for the job description, which can be specified in the workstation entry or the user profile.">Interactive jobs</a></div>
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<div><a href="rzaksprestarttype.htm" title="A prestart job is a batch job that starts running before a work request is received. The prestart jobs are started before any other types of jobs in a subsystem. Prestart jobs are different from other jobs because they use prestart job entries (part of the subsystem description) to determine which program, class, and storage pool to use when they are started.">Prestart jobs</a></div>
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<div><a href="rzaksreaderandwriterjob.htm" title="A reader job is a spooled input job, and a writer job is a spooled output job.">Reader and writer jobs</a></div>
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<div><a href="rzakssystemjobs.htm" title="System jobs are created by the operating system to control system resources and perform system functions. System jobs run when the iSeries server starts or when an independent disk pool is varied on. These jobs perform a variety of tasks from starting the operating system, to starting and ending subsystems, to scheduling jobs.">System jobs</a></div>
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</div>
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<div class="relinfo"><strong>Related information</strong><br />
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<div><a href="../rzaku/rzakuservertable.htm">Server job table</a></div>
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</div>
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</div>
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</body>
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</html>
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