Creating Filters for Use with webMethods Broker

If a webMethods messaging trigger subscribes to publishable document types associated with a webMethods Broker connection alias, you can specify a single filter that can be used by webMethods Broker and/or Integration Server. Use the Filter column in the Condition detail table to specify the filter.

Create the filter using the syntax defined in webMethods Service Development Help.

The filter can be saved with the subscription on the webMethods 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 webMethods Broker. For example, webMethods 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 webMethods 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 webMethods 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.

webMethods Broker evaluates the filter syntax to determine if the filter syntax is valid on the webMethods Broker. If webMethods Broker determines that the syntax is valid for the webMethods Broker, it saves the filter with the document type subscription. If the webMethods Broker determines that the filter syntax is not valid on the webMethods Broker or if attempting to save the filter on the webMethods Broker would cause an error, webMethods Broker saves the subscription without the filter.

webMethods 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 webMethods Broker considers invalid. webMethods Broker saves the expressions it considers valid with the subscription on the webMethods Broker. (Integration Server saves all the expressions.)

When a filter is saved only on Integration Server and not on webMethods Broker, the performance of Integration Server can be affected. When the webMethods 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, webMethods Broker automatically places the document in the subscriber’s queue. webMethods Broker routes all the documents to the subscriber, creating greater network traffic between the webMethods Broker and the Integration Server and requiring more processing by the Integration Server.