IBM Integration Bus, Version 10.0.0.17 Operating Systems: AIX, HP-Itanium, Linux, Solaris, Windows, z/OS


Enabling content-based filtering with publish/subscribe

WebSphere® MQ provides the ability to specify a filter when a subscription is made, but this can only refer to items in headers. IBM® Integration Bus can act as a content filtering provider for WebSphere MQ, and so allows extended filters to be specified by subscribers that can refer to elements in the body of publications.

Before you begin

About this task

IBM Integration Bus extends the message selection support provided by WebSphere MQ. IBM Integration Bus does this by allowing ESQL statements rather than SQL92 statements, and filtering based on message content. See Content-based filtering using ESQL for details of the scope and exclusions of supported ESQL.

The main external differences in the current implementation of content-based filtering are:
  • Content based filtering is no longer limited to WebSphere MQ MQRFH2 subscribers. IBM Integration Bus provides content filtering services for the following WebSphere MQ subscribers:
    • MQRFH2
    • MQSUB
    If you are performing content filtering based on the NameValueData field, within an MQRFH2 header, on z/OS, the data can be present either in the first or second MQRFH2 header. For example, the filter:
    Root.MQRFH2.mcd.Msd='XML'
    might not work as you expect on z/OS. Use the following syntax to search all MQRFH2 headers:
    FOR ANY Root.MQRFH2[] AS I (I.mcd.Msd='XML')
  • WebSphere MQ message properties are supported as part of the filter expression.
  • If the publication does not contain an mcd folder, the payload is assumed to be XMLNSC.

Read the following steps to see how to enable content-based filtering on IBM Integration Bus.

Procedure

  1. Set the cbfEnabled property of the ContentBasedFiltering object for the integration server in which you want content-based filtering to run.

    You set the cbfEnabled property from the command line using the mqsichangeproperties command; see Content based filtering component parameter values for more information.

    Note that you must explicitly enable the cbfEnabled property for content based filtering to work; the default setting is for content based filtering to be off.

  2. Restart the integration server for the change to take effect.
    If you enable content based filtering in multiple integration servers on z/OS, content based filtering is active in only one integration server at any time. Subsequent integration servers for which content based filtering is enabled, propagate the following messages to the syslog on start up (for each content based filtering thread) and then every 30 minutes, as they fail to connect to the queue manager:
    BIP2111E MQ04BRK jheg1 15 IBM Integration Bus INTERNAL ERROR: DIAGNOSTIC INFORMATION 
     'Error occurred in Content Based Filtering Thread'. : ImbCbfWorker(909) 
    BIP2624E MQ04BRK jheg1 14 UNABLE TO CONNECT TO QUEUE MANAGER 'MQ04': MQCC=2;
     MQRC=2002; MESSAGE FLOW NODE 'ContentBasedFiltering'. : ImbCbfWorker(214)
    If you stop the integration server that is currently providing content based filtering services, another integration server for which content based filtering is enabled connects to the queue manager and provides content based filtering services.

    Both the evaluationThreads and validationThreads properties default to one if content-based filtering is enabled.

    Evaluation threads are used to validate content filters against a given publication at publication time. A network with a high number of publications might require the evaluationThreads property to be increased (up to a maximum of 32) to handle the workload at publication time.

    Validation threads are used to validate syntax of content filters at subscription time. A publish/subscribe network with a high number of subscribers, especially if dynamic subscribers, might require the validationThreads property to be increased (up to a maximum of 32) to handle the high throughput of subscription requests.

    It is possible to enable this function in multiple integration servers, but you must ensure that any message sets required to parse any published message (and referenced in the mcd folder of that message) are deployed to all the integration servers that have been enabled for content-based filtering.

    Any errors encountered parsing the message within the evaluation thread cause WebSphere MQ to return MQRC_CONTENT_ERROR to the publishing application. The parsing error appears as well in the event log as an IBM Integration Bus exception.

    Example of a subscription <psc> folder processing ESQL and message properties in the filter:
    <psc>
    <Topic>topic</Topic>
       <Filter>
       SUBSTRING(Root.XMLNSC.Name.FirstName FROM 1 FOR 1) = ‘J' and usr.flag = ‘yes'
       </Filter>
    </psc>

bq13460_.htm | Last updated 2019-07-13 08:14:00