Download Diffusion 5.1 User Guide - Documentation

Replication
Diffusion uses a datagrid to share session and topic information between Diffusion servers and
provide high availability for clients connecting to load-balanced servers.
Figure 7: Information sharing using a datagrid
Diffusion uses Hazelcast™ as its datagrid. Servers reflect session and topic information into the
datagrid.
If a server becomes unavailable, another server can access the session and topic information that
is stored in the datagrid and take over the responsibilities of the first server.
Session replication
You can use session replication to ensure that if a client connection fails over from one server to
another the state of the client session is maintained.
When a connection from a client through the load balancer to a Diffusion server fails, the load
balancer routes the client connection to another Diffusion server. This server has access to the
session and client information that is replicated in the datagrid.
Control clients connect to a specific Diffusion server and not through a load balancer. Session
replication cannot be used for control clients.
Figure 8: Session replication
1. A client connects to a Diffusion server through a load balancer. The load balancer is configured
to route based on the client's session ID and requests from the client go to the same server
until that server becomes unavailable.
2. Information about the client, such as its credentials, session ID, and subscription information, is
stored in the datagrid.
Diffusion | 67