Data collectors enable you to supplement your performance monitoring or transaction analytics data with application data. Application data gives you with the visibility of the application context to performance or business analysis.

For example, you can use application data to identify the users who experienced stalled transactions or determine if slow transactions are associated with users in particular geographic region.

You can also use them to add technical context to performance issues. For example, you may suspect that a cache is performing poorly for a specific set of keys. You can create a data collector on the cache retrieve method and then use transaction snapshots to identify a correlation between the suspect keys and poor business transaction performance

The types of application data you can capture comes in two forms corresponding to the two types of data collectors:
*Method invocation data collectors capture code data such as method arguments, variables, and return values.
*HTTP data collectors capture the URLs, parameter values, headers, and cookies of HTTP messages exchanged in a business transaction.

Configuring a Data Collector

You add a data collector from the Configuration > Instrumentation page. Click the Data Collector tab and click the Add button below the Method Invocation Data Collectors panel or the HTTP Request Data Collectors panel.

The general steps in configuring a data collector are:

1.Identifying the method on which to capture data. To do this, you define the method signature and optionally, filters based on the value of a code point in the method (such as return value or argument).

2.Specifying the actual code point that serves as the source of the data.

3.If the data collector applies to business transactions, choose the applicable business transactions.

Typically, creating a data collector requires knowledge of the code on which you are setting up the collector, whether based on access to the source code for the application or its documentation.