Differences between the embedded global cache and an external WebSphere eXtreme Scale grid

The embedded cache is optimized for use in IBM® Integration Bus. When the default configuration that is provided by the embedded cache does not meet your needs, use an external WebSphere® eXtreme Scale grid. With an external grid, you can also make the data in the cache available to both integration flows and other applications outside of IBM Integration Bus.

You can use the embedded global cache or an external WebSphere eXtreme Scale grid (or both) in your IBM Integration Bus solution.

The embedded global cache is a WebSphere eXtreme Scale grid, which consists of WebSphere eXtreme Scale catalog and container servers that are hosted in integration servers. This grid is designed and optimized for use within (and between) integration nodes. You can configure the topology of this grid by specifying the number of catalogs and containers, and where they are hosted. But you cannot modify the underlying WebSphere eXtreme Scale configuration of the grid. The embedded cache is supplied as part of IBM Integration Bus and no further installation is needed to use the cache. By contrast, the external grid is not provided with IBM Integration Bus and must be obtained and installed separately. However, with an external grid, you have complete control over the WebSphere eXtreme Scale configuration.

The catalog and container servers for the embedded grid are hosted in integration server processes. Therefore, the catalog and container servers share their Java™ virtual machines (JVMs) with all other components that are running in the integration server. These components include IBM Integration Bus components, user-defined Java code, and data. As a result, the cache servers do not have control over their containing JVMs, and cannot modify or restart the JVMs. The maximum JVM heap size is determined by the relevant integration server property. Also, the lifecycle of each cache server is tied to the lifecycle of the integration server in which it is hosted.

With an external grid, you must create, administer, and manage the WebSphere eXtreme Scale server components outside of IBM Integration Bus. Therefore, you can separate the availability and management of your cache from IBM Integration Bus.

For more information about connecting to external WebSphere eXtreme Scale grids, see WebSphere eXtreme Scale grids.

Common reasons for choosing an external grid over the embedded cache

Choose an external grid if you have any of the following requirements:
  • You need to configure the grid for specific capabilities that are not supported by the embedded global cache.
  • You have an architectural preference for the cached data not to be placed in the integration servers themselves.
  • You want to separate the availability of the cache from the availability of the integration servers.
  • You need an enterprise cache, with multiple applications (other than IBM Integration Bus) that are accessing the data.
  • You have (or want) sophisticated, or custom, tools to manage the cache.
  • The cache needs to span multiple data centers for disaster recovery.

Comparison of function

The following table shows the requirements that are supported in the embedded global cache or an external grid:
Requirement Embedded global cache External WXS grid
A cache is available to IBM Integration Bus with minimal configuration
Cache components are hosted inside integration server processes
Simple MbGlobalMap access exists to the cache
Same cached data can be accessed by multiple integration nodes
Connections are managed by IBM Integration Bus
Resource statistics and activity log provided for cache interactions
Manage your cache components outside of IBM Integration Bus processes
Configure the number of partitions and the number and type of replicas
Configure multiple zones
Define your own backing maps, both fixed and templates
Configure your preferred locking strategy, eviction strategy, and copy mode
Use plug-ins (for example, eviction or loading)
Access other configuration options by using WebSphere eXtreme Scale objectgrid.xml and deployment.xml files
Configure the grid name, zones, quorum, and heartbeat settings on the components
Enterprise grid capability, which can be used by multiple applications
Administer and monitor your grid outside of IBM Integration Bus
Multi-master replication to synchronize grids in different data centers