The global cache is embedded in IBM® App Connect Enterprise. You can also connect to
an external WebSphere® eXtreme
Scale grid.
The embedded cache can be used by message
flows running in any integration server, and you can set properties
explicitly for each integration server. The examples in this section
show integration servers that are managed by an integration node;
however, the global cache can also be used by independent integration
servers, which are not managed by an integration node.
The following
diagram shows the embedded global cache in an integration node that
contains six integration servers. Four integration servers host components
for the global cache, but message flows in all six integration servers
can use the cache.
The following diagram shows how
IBM App Connect Enterprise can connect to both an embedded
cache and an external
WebSphere eXtreme
Scale grid.
A policy is used to connect to the external grid.
The following components are involved in the global cache:
- Catalog servers
- The catalog server is a component that is embedded in an integration
server, and it controls the placement of data and monitors the health
of containers. You must have at least one catalog server in your global
cache.
To avoid losing cache data when a catalog server is lost,
you can specify more than one catalog server. If the cache is shared
by two integration servers, each of which hosts a catalog server,
if one catalog server fails, the remaining catalog server can still
be accessed. Having more than one catalog server can affect startup
time until the cache is available.
When you are using multiple
catalog servers, you can improve performance by taking the following
steps:
- Provide other integration servers that host container servers
only, rather than having only integration servers that host both catalog
and container servers.
- Start and stop integration servers in sequence, rather than using
the mqsistart or mqsistop commands to start
or stop all integration servers at once. For example, start the integration
servers that host catalog servers before you start the integration
servers that host only container servers.
- Container servers
- A container server is a component that is embedded in the integration
server that holds a subset of the cache data. Between them, all container
servers in the global cache host all of the cache data at least once.
If more than one container exists, the default cache policy ensures
that all data is replicated at least once. In this way, the global
cache can cope with the loss of container servers without losing data.
You can host more than one container server in a multi-instance
integration node. If the active instance of the multi-instance integration
node fails, the global cache switches to the container server in the
standby instance.
- Catalog domain name
- When you are using a global cache that spans multiple integration
nodes, ensure that all WebSphere eXtreme
Scale servers
that are clustered in one embedded grid use the same domain name.
Only servers with the same domain name can participate in the same
grid. WebSphere eXtreme
Scale clients use the domain
name to identify and distinguish between embedded grids.
Servers
in different domains cannot collaborate in the same grid.
- Grids
- WebSphere eXtreme
Scale provides a scalable,
in-memory data grid. The data grid dynamically caches, partitions,
replicates, and manages data across multiple servers. The catalog
servers and container servers for the IBM App Connect Enterprise global cache collaborate to
act as a WebSphere eXtreme
Scale grid. For more
information about grids, see WebSphere Extreme
Scale product documentation online.
- Maps
- Data is stored in maps. A map is a data structure that maps keys
to values. One map is the default map, but the global cache can have
several maps.
The cache uses WebSphere eXtreme
Scale dynamic
maps. Any map name is allowed, apart from names that begin with SYSTEM.BROKER,
which is reserved for use by the integration node. The default map
is named SYSTEM.BROKER.DEFAULTMAP; you can use or clear this map.
- ObjectGrid® file
- An ObjectGrid XML
file is used to configure the WebSphere eXtreme
Scale client.
You can use this file to override WebSphere eXtreme
Scale properties.
For more information about configuring clients, see WebSphere Extreme
Scale product documentation online.
You can configure WebSphere eXtreme
Scale options
by using the WXSServer policy. For more information, see Connecting to a WebSphere eXtreme Scale grid.
You can use resource statistics
and activity trace to monitor the status of the global cache and
external grid, and to diagnose problems. You can also administer
the embedded global cache by using the mqsicacheadmin command.
