Introduction to Creating and Applying Filters

If the built-in Filter Expressions in the centralized filter Library do not provide the filtering functionality you need to analyze your message traffic, you can create your own custom Filter Expressions. To help you create Filter Expressions, Message Analyzer has a built-in Filter IntelliSense service that provides a statement completion capability that is similar to the Visual Studio Statement Completion Service. The Filter IntelliSense Service provides support for configuring Session Filters for a Data Retrieval Session or a Live Trace Session, and for configuring view Filters in an Analysis Session. For further details about Filter IntelliSense for Filter Expressions, see the Filter IntelliSense Service topic.

Creating a Custom Filter

To create your own custom Filters, you will need to understand the Message Analyzer Filtering Language. As indicated earlier in Assessing the Built-In Filter Expressions, you should first familiarize yourself with various Filter Expressions that exist in the Message Analyzer Filters asset collection, which is accessible from the Library drop-down list on the Filtering toolbar that appears above the main analysis surface for any set of trace results. As you work with these filters and observe how they impact your trace results, you can derive an understanding that will help you when creating your own Filter Expressions that you can use as a view Filter, Session Filter, or Viewpoint Filter, which all use the same centralized filter Library. In the sections listed immediately below, you will learn about the concepts and constructs of the Filtering Language, so you can use this information to create custom Filter Expressions and optionally add them as new assets to the centralized filter Library.

Generating a View Filter Dynamically

The easiest way to create a Filter Expression and apply it to message data displaying in the Analysis Grid viewer is to right-click a Column value and select the Add <columnName> to Filter command, to add the Column value as a Filter Expression. For example, if you right-click a protocol module in the Module column, the protocol name is added to the Filter Expression text box in a Filter panel on the Filtering toolbar as your Filter Expression. This action creates a simple filter that is also referred to as an “atomic” filter, meaning that the Filter Expression contains no logical combinators such as OR, AND, or NOT, and has no left-hand-side expression. Note that dynamic generation of a Filter Expression only creates the filter code; you must then apply the Filter Expression to see the effects, as described in the section that follows.

Selecting and Applying a View Filter

As described in many topics of this Operating Guide, you can select a built-in Filter Expression from the centralized Library to apply to a set of trace results, as appropriate to the type of analysis you are performing. When you are ready to apply a view Filter to your trace results, click the Apply button on the Filtering toolbar to see the effect of the Filter on your message data. If you added a protocol name as your Filter Expression as previously indicated, the Analysis Grid viewer will display messages from the specified protocol only, which includes top-level messages or operations with that protocol name, in addition to any other top-level message that contains that protocol in its origins tree (stack).

Note that this differs from the way Column Filters work in regard to stack messages, where filtering evaluates exposed layers only, as described in Filtering Column Data. The application of a view Filter is extremely useful for rapidly isolating the message data you want to analyze, especially in very large traces with thousands of messages. Also, in using the right-click method for adding a Filter, configuration is fast and return results are guaranteed, given that these Filter Expressions are derived from values that already exist in the set of trace results with which you are working.

You can also use a Filter Expression to restrict your filter results to messages containing specific values. For example, you might specify a Filter Expression such as UDP.Length > 100 to return only those UDP messages that have a message Length (Header + Payload) value that is greater than 100 bytes. Also, if you want to display all messages that are not UDP traffic, you could apply a filter such as !UDP. Moreover, if you want to filter out all UDP and TCP messages, you could apply a filter expression such as !UDP&&!TCP.

Maintaining History of View Filter Application

After you create and apply a custom Filter Expression, it is maintained in a common History drop-down list, where the last filter applied appears first. Like the centralized filter Library, the History drop-down list is accessible from any Data Retrieval Session, Live Trace Session, or Analysis Session, so that you can reapply any custom Filter Expression in the common History drop-down list as a Session Filter or a view Filter.

In the remaining topics of this section, you will learn more about the Filter IntelliSense service in addition to the concepts, semantics, syntax, and other details about the Filtering Language, so you can create robust Filter Expressions that manipulate trace results in unique ways for data analysis purposes. You can also review a set of procedures that provide numerous examples of using Filter Expressions to isolate data for focused analysis, as indicated below in See Also.

See Also

Procedures: Using the Data Filtering Features
Applying and Managing Filters