106 lines
8.5 KiB
HTML
106 lines
8.5 KiB
HTML
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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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<html lang="en-us" xml:lang="en-us">
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<meta name="copyright" content="(C) Copyright IBM Corporation 2005" />
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<meta name="DC.Title" content="Monitor file status with the open and I/O feedback area" />
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<meta name="abstract" content="The server monitors the status of a file in feedback areas once it has successfully opened the file. As the server performs operations on a file, it updates the feedback areas to reflect the latest status. These feedback areas give you greater control over applications and provide important information when errors occur." />
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<meta name="description" content="The server monitors the status of a file in feedback areas once it has successfully opened the file. As the server performs operations on a file, it updates the feedback areas to reflect the latest status. These feedback areas give you greater control over applications and provide important information when errors occur." />
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<meta name="DC.subject" content="file, shared feedback areas, sharing file, feedback areas, open feedback area, description, feedback area, open, general description, input/output, feedback area, I/O, common, file-dependent" />
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<meta name="keywords" content="file, shared feedback areas, sharing file, feedback areas, open feedback area, description, feedback area, open, general description, input/output, feedback area, I/O, common, file-dependent" />
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<meta name="DC.Relation" scheme="URI" content="rbal3share.htm" />
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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>Monitor file status with the open and I/O feedback area</title>
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</head>
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<body id="rbal3openiofba"><a name="rbal3openiofba"><!-- --></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">Monitor file status with the open and I/O feedback area</h1>
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<div><p>The server monitors the status of a file in feedback areas once
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it has successfully opened the file. As the server performs operations on
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a file, it updates the feedback areas to reflect the latest status. These
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feedback areas give you greater control over applications and provide important
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information when errors occur.</p>
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<p>The feedback areas are established at open time, and there is one feedback
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area for each open file. One exception is for shared files, which share feedback
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areas as well as the data path between the program and the file. For more
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information about shared opens, see <a href="rbal3share.htm#rbal3share">Share files</a>.</p>
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<div class="p">Some high-level languages on the server allow you to access the status
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and other information about the file against which operations are being performed. There are two feedback areas of interest to you: <ul><li>Open feedback area <p>This area contains information of a general nature
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about the file after the server has successfully opened the file. Examples
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include the name and library of the file and the file type. See <a href="rbal3feedb.htm#rbal3feedb">Open feedback area</a> for
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a complete list of the information that you can retrieve from the open feedback
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area. In addition to general information about the file, the open feedback
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area also contains file-specific information after the server has successfully
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opened the file. The applicable fields depend on the file type.</p>
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<p>The
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open feedback area also contains information about each device or communications
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session that is defined for the file.</p>
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</li>
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<li>Input/output feedback area <div class="p">There are two sections of the I/O feedback
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area that are updated on the successful completion of input and output operations: <ul><li>Common area <p>This area contains information about I/O operations that
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were performed on the file. This includes the number of operations and the
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last operation performed. See <a href="rbal3fedbk.htm#rbal3fedbk">I/O feedback area</a> for
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a complete list of the information that you can retrieve from the common I/O
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feedback area.</p>
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</li>
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<li>File-dependent feedback area <p>This area contains file-specific information
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for display, database, printer, and ICF files; for example, the major and
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minor return code and amount of data received from the device. See <a href="rbal3ddiof.htm#rbal3ddiof">I/O feedback area for ICF and display files</a>, <a href="rbal3pddio.htm#rbal3pddio">I/O feedback area for printer files</a>,
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and <a href="rbal3dbiof.htm#rbal3dbiof">I/O feedback area for database files</a> for a complete list of
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the information that you can retrieve from the file-dependent I/O feedback
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area.</p>
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</li>
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</ul>
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</div>
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</li>
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</ul>
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</div>
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<p>The above information areas can be useful to you. For example,
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when an error occurs with a device file, the program can determine predefined
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error handling operations based on the major/minor return code in the file-dependent
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feedback area. If data is being received from a communications device and
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the application on the other end sends an error, the program can determine
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that the next operation should be to wait until the next block of data is
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sent indicating the error. Possibly, the next operation might be to close the
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file and end the conversation with the application on the other side or wait
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for the next request from the application.</p>
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<p>Another way might include detecting the type of file that actually opened
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to determine the type of operations that are allowed. If the file type is
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printer, only output operations are allowed.</p>
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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="rbal3open.htm" title="When you want an application to use a file, you do so by referring to that file by name. The file description for that file will then control how the program and the server will interact.">Open files</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="rbal3share.htm" title="File management on iSeries provides several levels of support for shared files. Files can be shared among many users, many jobs, or many programs within the same job.">Share files</a></div>
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</div>
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<div class="relref"><strong>Related reference</strong><br />
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<div><a href="rbal3feedb.htm" title="The open feedback area is the part of the open data path (ODP) that contains general information about the file after it has been opened. It also contains file-specific information, depending on the file type, plus information about each device or communications session defined for the file. This information is set during open processing and can be updated as other operations are performed.">Open feedback area</a></div>
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<div><a href="rbal3fedbk.htm" title="iSeries uses OS/400 messages and I/O feedback information to communicate the results of I/O operations to the program. The server updates the I/O feedback area for every successful I/O operation unless your program uses blocked record I/O.">I/O feedback area</a></div>
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<div><a href="rbal3ddiof.htm" title="The table in this topic shows the I/O feedback area for ICF and display files.">I/O feedback area for ICF and display files</a></div>
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<div><a href="rbal3pddio.htm" title="The table in this topic shows the I/O feedback area for printer files.">I/O feedback area for printer files</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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