145 lines
8.6 KiB
HTML
145 lines
8.6 KiB
HTML
<?xml version="1.0" encoding="UTF-8"?>
|
|
<!DOCTYPE html
|
|
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
|
<html lang="en-us" xml:lang="en-us">
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
|
<meta name="security" content="public" />
|
|
<meta name="Robots" content="index,follow" />
|
|
<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
|
|
<meta name="DC.Type" content="reference" />
|
|
<meta name="DC.Title" content="INVITE (Invite) keyword for display files" />
|
|
<meta name="abstract" content="Use this file- or record-level keyword to invite the device for a later read operation." />
|
|
<meta name="description" content="Use this file- or record-level keyword to invite the device for a later read operation." />
|
|
<meta name="DC.subject" content="INVITE (Invite) keyword" />
|
|
<meta name="keywords" content="INVITE (Invite) keyword" />
|
|
<meta name="DC.Relation" scheme="URI" content="rzakcmstkeyent.htm" />
|
|
<meta name="copyright" content="(C) Copyright IBM Corporation 2001, 2006" />
|
|
<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2001, 2006" />
|
|
<meta name="DC.Format" content="XHTML" />
|
|
<meta name="DC.Identifier" content="rzakcmstdfinv" />
|
|
<meta name="DC.Language" content="en-us" />
|
|
<!-- All rights reserved. Licensed Materials Property of IBM -->
|
|
<!-- US Government Users Restricted Rights -->
|
|
<!-- Use, duplication or disclosure restricted by -->
|
|
<!-- GSA ADP Schedule Contract with IBM Corp. -->
|
|
<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
|
|
<link rel="stylesheet" type="text/css" href="./ic.css" />
|
|
<title>INVITE (Invite) keyword for display files</title>
|
|
</head>
|
|
<body id="rzakcmstdfinv"><a name="rzakcmstdfinv"><!-- --></a>
|
|
<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
|
|
<h1 class="topictitle1">INVITE (Invite) keyword for display files</h1>
|
|
<div><p>Use this file- or record-level keyword to invite the device for
|
|
a later read operation.</p>
|
|
<div class="section"><p>To send an invite to a specific device, your program sends an
|
|
output operation to the device with the INVITE keyword in effect. If the record
|
|
format used has output-capable fields, the data is sent to the device before
|
|
the device is invited.</p>
|
|
<p>This keyword has no parameters.</p>
|
|
<p>INVITE
|
|
must be used if the display file can have multiple acquired devices and your
|
|
program does read from invited devices operations. This is because a read
|
|
from invited devices to a multiple device display file only returns a record
|
|
from one of the devices that was invited. If you want all the acquired devices
|
|
to be able to return data, an output operation with INVITE in effect must
|
|
be sent to each device before the read from invited devices. Even if there
|
|
is only one device acquired on the multiple device file, the device must be
|
|
invited via INVITE before a read from invited devices.</p>
|
|
<p>INVITE also gives
|
|
you the ability to create a subset of acquired devices that are eligible to
|
|
respond on a read from invited devices. For example, if ten devices are currently
|
|
acquired to the file but only three devices were invited, the next read from
|
|
invited devices operation returns a record from one of the three invited devices.
|
|
This is true even if the other devices have data available.</p>
|
|
<p>INVITE provides
|
|
some performance improvement. Normally a read request is issued to a device
|
|
when your program sends an input operation. However, INVITE allows you to
|
|
request the read when you issue the output operation. After the output operation
|
|
is complete, your program can do other processing while the device is issuing
|
|
data and the <span class="keyword">i5/OS™</span> operating
|
|
system is processing the received data. This can be a significant improvement
|
|
if the device is remote.</p>
|
|
<p>For specific instructions on when an invite
|
|
operation is necessary and how to specify a read from invited devices operation
|
|
in your program, see the appropriate high-level language manual.</p>
|
|
<p>INVITE
|
|
cannot be specified at both the file and record level and cannot be specified
|
|
with the subfile keyword (SFL).</p>
|
|
<p>Option indicators are valid for this
|
|
keyword.</p>
|
|
</div>
|
|
<div class="section"><h4 class="sectiontitle">Special considerations when using the INVITE keyword</h4><div class="p">The
|
|
following list shows special considerations when you use the INVITE keyword:
|
|
<ul><li id="rzakcmstdfinv__sp1"><a name="rzakcmstdfinv__sp1"><!-- --></a>An input operation sent to a specific device does not require
|
|
an invite operation. Input operations with a specified record format name
|
|
or device are directed to one device. If that device has an invite outstanding
|
|
at the time of the input operation, the invite operation is deleted after
|
|
the input operation is completed.</li>
|
|
<li>Once an invite operation has been sent to a device,
|
|
the only valid operations (in addition to a read operation from invited devices)
|
|
are as follows: <ul><li>An input operation to a specific device.</li>
|
|
<li>An output operation with data that tries to cancel the invite operation.
|
|
If the cancel operation is successful, the data is written. If INVITE was
|
|
in effect on the output operation, the device is invited again. If the cancel
|
|
is not successful (because the data has already been received by the system),
|
|
the output operation fails. Your program must perform an input operation to
|
|
process the data. The input operation erases the invite for that device.</li>
|
|
</ul>
|
|
</li>
|
|
<li>On a read operation from invited devices operation to a display file,
|
|
only data from devices with an outstanding invite operation are considered.
|
|
The input operation waits for data from any of the invited devices. (See the
|
|
WAITRCD parameter on the Create Display File (CRTDSPF) and Change Display
|
|
File (CHGDSPF) commands.) If none of the invited devices responds before the
|
|
wait time ends, a notify message is sent and no data is returned. All invited
|
|
devices remain invited.</li>
|
|
<li>If more than one device acquired to the display file has an invite outstanding,
|
|
a read from invited devices operation returns the next available record from
|
|
one of the invited devices. If records are received from more than one device
|
|
before this input operation, the other records are kept for subsequent input
|
|
operations.</li>
|
|
<li>When a read operation from invited devices operation to a display file
|
|
returns a record to your program from an invited device, the invite operation
|
|
for that device is deleted. Other devices that have an invite outstanding
|
|
remain invited. The device that sent the record your program read must be
|
|
invited again if you want to receive data from this device on a later read
|
|
from invited devices operation.</li>
|
|
<li>If no device was invited or if a device was invited but the job was canceled
|
|
with the controlled option, a read operation from invited devices
|
|
operation to a display file results in a notify message and no data is returned
|
|
to your program. All invited devices remain invited.</li>
|
|
<li>If you want to invite a device but have no data to send it, issue an output
|
|
operation using a record format containing no output-capable fields with INVITE
|
|
in effect.</li>
|
|
<li>After the first record is received from an invited display device, the
|
|
device should not be re-invited until all the record formats on the display
|
|
with input-capable fields are read by your program. Your program can read
|
|
those other record formats if you specify the record format name and the device
|
|
name on the read operation.</li>
|
|
<li>If your display file has the delayed write option (DFRWRT(*YES) parameter
|
|
on the (Create Display File (CRTDSPF) and Change Display File (CHGDSPF) commands),
|
|
an output operation with the INVITE keyword in effect causes the delayed output
|
|
to appear on the display before the device is invited.</li>
|
|
</ul>
|
|
</div>
|
|
</div>
|
|
<div class="example"><h4 class="sectiontitle">Example</h4><p>The following example shows how to specify
|
|
the INVITE keyword.</p>
|
|
<pre>|...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
|
|
00010A 01 INVITE
|
|
00020A R RCD1
|
|
00030A FLD1 10 2 2
|
|
00030A FLD2 5 2 24
|
|
A</pre>
|
|
<p>INVITE is in effect only when option indicator 01 is
|
|
set on.</p>
|
|
</div>
|
|
</div>
|
|
<div>
|
|
<div class="familylinks">
|
|
<div class="parentlink"><strong>Parent topic:</strong> <a href="rzakcmstkeyent.htm" title="You type the keyword entries that define display files in positions 45 through 80 (functions).">DDS keyword entries for display files (positions 45 through 80)</a></div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html> |