Writing Filter Expressions
Updated: September 14, 2016
This section provides you with practical knowledge that you can utilize to create your own Filter Expressions with the Message Analyzer Filtering Language. This language is a derivative of the full OPN language that developers use to write OPN protocol descriptions that Message Analyzer utilizes to parse the messages of such protocols. As a result, there are various elements, constructs, and syntax that both languages share. Any Filter Expressions that you create can be saved in the centralized filter Library. Thereafter, you can use them as a Session Filter when configuring a new session, or as a View Filter when analyzing trace results in an Analysis Session.
To aid your understanding of the Filtering Language, you are advised to work with some of the predefined Filter Expressions in the centralized filter Library in parallel with the studies that you do here. The goal is accelerate the learning process through observation and assessment of working example results. You can even work with any existing Filter Expression by creating a copy, modifying the copy, and saving it as a new Filter Expression in your central user Library without affecting the original filter configuration. This enables you to start with a known working filter configuration and perform some experimental modifications to see the effects of your changes when applied to a set of trace results.
Although you can specify a Filter Expression as a Session Filter when configuring a Data Retrieval Session or a Live Trace Session, the topics in this section focus on applying View Filters in an Analysis Session with the default Analysis Grid viewer, because this environment provides the most robust environment for demonstrating filtering functionality.
What You Will Learn
In this section, you will learn about the Filtering Language and how to create some simple Filter Expressions, in addition to others that are more complex. The material begins with an introductory overview to help you get started with custom Filter Expressions and includes a few simple examples followed by a description of the Filter IntelliSense Service. The discussions then move into understanding the basics about the Filtering Language, which includes the use of logical operators, arithmetic operators, and literals; how to traverse the message hierarchy; and applying other filtering considerations. A walkthrough of filter features, special functions, and other capabilities concludes this section. In addition, examples are provided that combine different language features, including various applications of Filter Expression syntax, semantics, statements, truncation, traversers, aliases, and so on. This content is covered in the topics below:
Getting Started with Creating and Applying Filters
Understanding the Filtering Language Basics
Using the Filtering Language