OpenEdge Management and OpenEdge Explorer: Configuration
OpenEdge Management and OpenEdge Explorer: Configuration
OpenEdge Management and OpenEdge Explorer: Configuration
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Configuring fault tolerance <strong>and</strong> load balancing<br />
Configuring fault tolerance <strong>and</strong> load balancing<br />
With the NameServer, you have access to connection-level fault tolerance, server-level fault<br />
tolerance, <strong>and</strong> load balancing.<br />
Connection-level fault tolerance<br />
Multiple NameServers can cooperate to resolve a client connection. If one NameServer<br />
becomes unavailable, another can take its place, thus providing connection-level fault tolerance.<br />
When you configure <strong>and</strong> use NameServers with connection-level fault tolerance, each<br />
requesting client uses the Unified Broker connection provided by the first responding<br />
NameServer <strong>and</strong> ignores the rest.<br />
You can configure two types of connection-level fault tolerance:<br />
• NameServer replication<br />
• NameServer neighbors<br />
NameServer replication<br />
To use NameServer replication, you first configure multiple NameServers on one subnet to<br />
listen on the same UDP port. You then have each Unified Broker instance register with its<br />
controlling NameServer <strong>and</strong> have each client contact its connecting NameServer using the<br />
subnet broadcast address <strong>and</strong> the same UDP port number. Thus, Unified Broker registrations<br />
are automatically replicated in each NameServer, <strong>and</strong> client connection requests are h<strong>and</strong>led by<br />
each NameServer. The first replicated NameServer to respond to a client request provides the<br />
Unified Broker connection.<br />
NameServer neighbors<br />
To use NameServer neighbors, you configure multiple NameServers on one or more subnets.<br />
For each such NameServer, you specify the instance name of each of the other NameServers<br />
that you want to act as a NameServer neighbor. When a client makes a connection request to a<br />
specific NameServer, if this NameServer determines that it cannot satisfy the request (usually<br />
because it does not recognize the specified application service), it passes the request to all of its<br />
NameServer neighbors. The first NameServer neighbor to respond to a client request provides<br />
the Unified Broker connection.<br />
You can configure <strong>and</strong> use NameServer replication <strong>and</strong> NameServer neighbors together to<br />
provide the maximum in connection-level fault tolerance.<br />
Server-level fault tolerance<br />
If you have the load-balancing option installed, you can configure multiple Unified Broker<br />
instances of a given type to support the same application service <strong>and</strong> share the same controlling<br />
NameServer. In this configuration, the controlling NameServer distributes client connection<br />
requests r<strong>and</strong>omly across Unified Broker instances. If one Unified Broker instance becomes<br />
unavailable to h<strong>and</strong>le client requests, another is available to take its place, thus providing<br />
server-level fault tolerance.<br />
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