Creating Filters for Use with Broker
If a webMethods messaging trigger subscribes to publishable document types associated with a Broker connection alias, you can specify a single filter that can be used by Broker and/or Integration Server. Use the Filter column in the Condition detail table to specify the filter.
The filter can be saved with the subscription on the Broker and with the webMethods messaging trigger on the Integration Server. This is because some filter syntax that is valid on Integration Server is not valid on Broker. For example, Broker prohibits the use of certain words or characters in field names, such as Java keywords, @, *, and names containing white spaces. The location of the filter and whether Broker and/or Integration Server applies the filter, depends on the filter syntax, which is evaluated at design time.
When you save a webMethods messaging trigger, Integration Server and Broker evaluate the filter in the Filter column.
Integration Server evaluates the filter to make sure it uses the proper syntax. If the syntax is correct,
Integration Server saves the
webMethods messaging trigger in an enabled state. If the syntax is incorrect,
Integration Server saves the
webMethods messaging trigger in a disabled state.
Broker evaluates the filter syntax to determine if the filter syntax is valid on the
Broker. If
Broker determines that the syntax is valid for the
Broker, it saves the filter with the document type subscription. If the
Broker determines that the filter syntax is not valid on the
Broker or if attempting to save the filter on the
Broker would cause an error,
Broker saves the subscription without the filter.
Broker saves as much of a filter as possible with the subscription. For example, suppose that a filter consists of more than one expression, and only one of the expressions contains the syntax that the Broker considers invalid. Broker saves the expressions it considers valid with the subscription on the Broker. (Integration Server saves all the expressions.)
When a filter is saved only on Integration Server and not on Broker, the performance of Integration Server can be affected. When the Broker applies the filter to incoming documents, it discards documents that do not meet filter criteria. Integration Server only receives documents that meet the filter criteria. If the subscription filter resides only on Integration Server, Broker automatically places the document in the subscriber’s queue. Broker routes all the documents to the subscriber, creating greater network traffic between the Broker and the Integration Server and requiring more processing by the Integration Server.
