5.3.6. Class FailoverChainer

This class is based on the StateBasedChainer class and encapsulates a real TCP/IP connection establishment, and is used when a top-level proxy wants to perform chaining. In addition to ConnectChainer this class adds the capability to perform stateful, failover HA functionality across a set of IP addresses.

Note

Use FailoverChainer if you want to connect to the servers in a predefined order: i.e., connect to the first server, and only connect to the second if the first server is unavailable.

If you want to distribute connections between the servers (i.e., direct every new connection to a different server to balance the load) use RoundRobinChainer .

Example 5.13. A DirectedRouter using FailoverChainer

The following service definition uses a DirectedRouter class with two possible destination addresses. These destinations are used in a failover fashion, targeting the second address only if the first one is unaccessible.

Service(name="intra_HTTP_inter", router=DirectedRouter(dest_addr=(SockAddrInet('192.168.55.55', 8080), SockAddrInet('192.168.55.56', 8080)), forge_addr=FALSE, forge_port=Z_PORT_ANY, overrideable=FALSE), chainer=FailoverChainer(protocol=ZD_PROTO_AUTO, timeout_state=60000, timeout_connect=30000), max_instances=0, proxy_class=HttpProxy,)
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