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...
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