Administration guide > Monitor the environment > Monitoring with the statistics API
Statistics modules
WebSphere eXtreme Scale uses an internal statistics model to track and filter data, which is the underlying structure that all data views use to gather snapshots of statistics. Use several methods to retrieve the information from the statistics modules.
Overview
Statistics in WebSphere eXtreme Scale are tracked and contained within StatsModules components. Within the statistics model, several types of statistics modules exist:
For details about the statistics modules, see the Statistics API.
- OGStatsModule
- Provides statistics for an ObjectGrid instance, including transaction response times.
- MapStatsModule
- Provides statistics for a single map, including the number of entries and hit rate.
- QueryStatsModule
- Provides statistics for queries, including plan creation and run times.
- AgentStatsModule
- Provides statistics for DataGrid API agents, including serialization times and run times.
- HashIndexStatsModule
- Provides statistics for HashIndex query and maintenance run times.
- SessionStatsModule
- Provides statistics for the HTTP session manager plug-in.
Statistics in a local environment
The model is organized like an n-ary tree (a tree structure with the same degree for all nodes) comprised of all of the StatsModule types mentioned in the previous list. Because of this organization structure, every node in the tree is represented by the StatsFact interface. The StatsFact interface can represent an individual module or a group of modules for aggregation purposes. For example, if several leaf nodes in the tree represent particular MapStatsModule objects, the parent StatsFact node to these nodes contains aggregated statistics for all of the children modules. After you fetch a StatsFact object, you can then use interface to retrieve the corresponding StatsModule.
Much like a tree map, you use a corresponding path or key to retrieve a specific StatsFact. The path is a String[] value that consists of every node that is along the path to the requested fact. For example, you created an ObjectGrid called ObjectGridA, which contains two Maps: MapA and MapB. The path to the StatsModule for MapA would look like [ObjectGridA, MapA]. The path to the aggregated statistics for both maps would be: [ObjectGridA].
Statistics in a distributed environment
In a distributed environment, the statistics modules are retrieved using a different path. Because a server can contain multiple partitions, the statistics tree needs to track the partition to which each module belongs. As a result, the path to look up a particular StatsFact object is different. Using the previous example, but adding in that the maps exist within partition 1, the path is [1, ObjectGridA, MapA] for retrieving that StatsFact object for MapA.
Parent topic:
Monitor with the statistics API