Publish/Subscribe and subscriptions to topics
SAM allows messages to be sent either to queues or, for WebSphere MQ and WPM, to publish/subscribe topics. A topic destination is specified to SAM in the usual way, i.e. in the form 'topic://fred', rather than the form 'queue://AQUEUE' used for point to point operation. To use publish/subscribe it is simply necessary to specify the correct broker name on the SAMConnect "connect" call and the desired topic in the destination argument to the SAMConnect "send" and "receive" calls. The PHP interface is otherwise identical to the point to point model.
By default, SAM creates non-durable subscriptions when using publish/subscribe. This means that if a client application is inactive when messages are published to a topic, then it will not receive them when it subsequently restarted. SAM does also allow durable subscriptions to be made to topics when using WPM or WebSphere MQ publish/subscribe. The purpose of these subscriptions is to allow data to be received by a client application even if that client was not active at the time the data was published.
Durable subscriptions are specified by using the SAMConnect "subscribe" call. This method takes the destination topic as an input parameter and returns a subscription identifier that may be used on subsequent "receive" calls. When the subscription is no longer required the SAMConnection "unsubscribe" method should be used to delete the subscription.
Example #1 Creating a durable subscription to a topic
<?php
$subName = $conn->subscribe('topic://A');
if (!$subName) {
echo "Subscribe failed";
} else {
# Subscribe was OK
// ...
}
?>
Example #2 Subscribing to a topic using a WebSphere Platform Messaging (WPM) server
<?php
$conn = new SAMConnection();
// Note: For pub/sub on WPM, when connecting the name of a messaging engine
// to hold the durable subscription (SAM_WPM_DUR_SUB_HOME) must be specified.
$conn->connect(SAM_WMQ, array(SAM_ENDPOINTS => 'localhost:7278:BootstrapBasicMessaging',
SAM_BUS => 'Bus1',
SAM_TARGETCHAIN => 'InboundBasicMessaging',
SAM_WPM_DUR_SUB_HOME => 'MyMachineNode01.server1-Bus1'));
$subName = $conn->subscribe('topic://A');
if (!$subName) {
echo "Subscribe failed";
} else {
# Subscribe was OK
// ...
}
?>
Example #3 Receiving published data using a durable subscription
<?php
$msg = $conn->receive($subName);
if ($msg) {
echo "Received a message OK";
} else {
echo "The receive failed";
}
?>
Example #4 Deleting a durable subscription to a topic
<?php
if (!$conn->unsubscribe($subName)) {
echo "Unsubscribe failed";
}
?>
English translation
You have asked to visit this site in English. For now, only the interface is translated, but not all the content yet.If you want to help me in translations, your contribution is welcome. All you need to do is register on the site, and send me a message asking me to add you to the group of translators, which will give you the opportunity to translate the pages you want. A link at the bottom of each translated page indicates that you are the translator, and has a link to your profile.
Thank you in advance.
Document created the 30/01/2003, last modified the 26/10/2018
Source of the printed document:https://www.gaudry.be/en/php-rf-sam.pubsub.html
The infobrol is a personal site whose content is my sole responsibility. The text is available under CreativeCommons license (BY-NC-SA). More info on the terms of use and the author.
References
These references and links indicate documents consulted during the writing of this page, or which may provide additional information, but the authors of these sources can not be held responsible for the content of this page.
The author This site is solely responsible for the way in which the various concepts, and the freedoms that are taken with the reference works, are presented here. Remember that you must cross multiple source information to reduce the risk of errors.
