The OpenDJ LDAP SDK example Proxy demonstrates a simple LDAP proxy that forwards requests to one or more remote directory servers. Although the implementation is intended as an example, it does demonstrate use of the asynchronous API, load balancing, and connection pooling. The Proxy example sets up connections pools with load balancing to the directory servers. It passes the connection factories to a ProxyBackend that handles the requests passed back to the directory servers. It also sets up an LDAP listener to receive incoming connections from clients of the Proxy. The ProxyBackend uses separate connection factories, one for bind operations, the other for other operations. It uses the proxied authorization control to ensure operations are performed using the bind identity for the operation. The ProxyBackend's function is to handle each client request, encapsulating the result handlers that allow it to deal with each basic operation. It authenticates to the directory server to check incoming credentials, and adds the proxied authorization control to requests other than binds. The ProxyBackend handles all operations using asynchronous connections and methods.

As shown in the Proxy example, the Connections.newFixedConnectionPool() returns a connection pool of the maximum size you specify. final List<ConnectionFactory> factories = new LinkedList<ConnectionFactory>(); factories.add(Connections.newFixedConnectionPool(new LDAPConnectionFactory( remoteAddress, remotePort), Integer.MAX_VALUE)); Connections are returned to the pool when you close() them. Notice that Connections also provides methods to return ConnectionFactorys with a heart beat check on connections provided by the factory, and connection factories that authenticate connections before returning them. Connections in the pool are intended for reuse. Therefore when you close() a connection from the pool, the OpenDJ LDAP SDK does not perform an unbind(). You must therefore be careful about how you manage authentication on connections from a pool. As a rule, either bind separately and use proxied authorization as in the Proxy example, or make sure that the first operation on a connection retrieved from the pool is a bind that correctly authenticates the user currently served by the connection.

The Connections.newLoadBalancer() method returns a load balancer based on the algorithm you choose. Algorithms include both round robin for equitably sharing load across local directory servers, and also failover usually used for switching automatically from an unresponsive server group to an alternative server group. The algorithms take collections of connection factories, such as those that you set up for connection pooling. final RoundRobinLoadBalancingAlgorithm algorithm = new RoundRobinLoadBalancingAlgorithm(factories); final ConnectionFactory factory = Connections.newLoadBalancer(algorithm); The algorithms also include constructors that let you adjust timeouts and so forth.

TODO