Before customizing the PMDB, it is essential that you familiarize yourself with the PMDB processes and their roles. The life cycle of data stored in the PMDB involves the following:

• Defining and creating tables. To load data into and retrieve data from the PMDB, you must first logically define database tables in DDML. DDML describes the database structure using XML document syntax. After you have defined all database entities in DDML, you must run the DDML creation script to physically create the entities in the database. Creating DDML Documents details the DDML format and explains how to create the database entities.

• Loading. The PMDB infrastructure allows you to load data into the PMDB using XML. Both the request protocol and the response protocol are written in XML. You can load data from any server on which the Precise Listener is installed. 
  Loading Data details the XML load format and explains how to load data from a server on which a Listener is installed.

• Retrieving. The PMDB infrastructure allows you to retrieve data using XML. Both the request protocol and the response protocol are written in XML. You can retrieve data from any server on which a Listener is installed.
  Retrieving Data details the XML retrieve format and explains how to retrieve data from a on which a Listener is installed.

• Summarizing. The PMDB summary process aggregates data from one level to another. This process runs automatically in the PMDB FocalPoint in the 55th minute of every hour and summarizes all new data received since the last run.
  Managing Data provides a detailed description of the summary process.

• Purging. The purge process removes unneeded data from the PMDB database based on the purge parameters defined in AdminPoint. The process runs every week, checking the purge definition and removing the data as required. Managing Data provides a detailed description of the purge process.

For examples of DDML documents, load documents, and retrieve documents, see Examples. For more information about the product, refer to the User Defined Reports (UDR) tech note.