When collecting volumes of data, handling the information sometimes becomes a problem. Applications often fire off events to be logged and analyzed later, such as HTTP requests logged by a web server. Often you summarize the data, then archive or delete the detailed events. In some applications the detailed events are not even pertinent; it is only the summary that is required. Logging huge volumes of data to files or to an SQL database just to summarize it carries an unnecessary performance and administrative overhead. You can handle situations of this sort using a data collection summarizer (atg.service.datacollection.GenericSummarizer).

A summarizer is a data listener that listens for data items and summarizes them in memory. The summarizer summarizes and groups beans by one or more properties. Summarized data can then be logged to flat files or SQL tables. At intervals, the summarizer flushes summarized data to its dataListeners (typically, a file logger or an SQL logger).