Administration guide > Plan the WebSphere eXtreme Scale environment


Catalog service

The catalog service hosts logic that should be idle during a steady state and has little influence on scalability. The catalog service is built to service hundreds of containers becoming available simultaneously and runs services to manage the containers.

The catalog responsibilities consist of the following services:

Location service Provides locality for clients that are looking for containers hosting applications and for containers that are looking to register hosted applications with the placement service. The location service runs in all of the grid members.
Placement service Allocates shards to their host container. Runs as a One of N elected service in the cluster. Because the One of N policy is used, there is always exactly one instance of the placement service running. If that instance should stop, another process takes over. All states of the catalog service are replicated across all servers hosting the catalog service for redundancy.
Core group manager The core group manager...

  • manages peer grouping for health monitoring
  • organizes containers into small groups of servers
  • federates groups of servers

When a container first contacts the catalog service, the container waits to be assigned to either a new or an existing group of several JVM. Each group of JVMs monitors the availability of each of its members through heartbeating. One of the group members relays availability information to the catalog service to allow for reacting to failures by reallocation and route forwarding.

Administration The four stages of administering the WXS environment are planning, deploying, managing, and monitoring.


Catalog service domain

For availability, configure a catalog service domain. A catalog service domain consists of multiple JVMs, including a master JVM and a number of backup JVMs.


See also


Parent topic:

Plan the WebSphere eXtreme Scale environment


Related concepts

Plan overview
Hardware and software requirements
JEE considerations
Cache topology: In-memory and distributed caching
Container servers, partitions, and shards
Capacity planning


Related tasks

Create catalog service domains in WAS
Start and stop servers in a WAS environment
Ovveride catalog service quorum
Configure quorum
Monitor with the xsAdmin sample utility

Related reference

Directory conventions
Operational checklist