LDAP Proxy 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. Connections Asynchronous 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.

Connections Pooling As shown in the Proxy example, the Connections.newFixedConnectionPool() returns a connection pool of the maximum size you specify. [jcp:org.forgerock.opendj.examples.Proxy:--- JCite pools ---] 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. The Proxy gets an authenticated connection, which is a connection where the OpenDJ LDAP SDK passes a bind request immediately when getting the connection. The Proxy then uses proxied authorization to handle the identity from the client requesting the operation. As a rule, either handle binds separately and use proxied authorization as in the Proxy example, or else 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. When you close() a connection from the pool, the OpenDJ LDAP SDK does not perform an unbind(). This is why you must be careful about how you manage authentication on connections from a pool.

Connections Load balancing 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. The following excerpt shows how to set up round robin load balancing across directory servers. [jcp:org.forgerock.opendj.examples.Proxy:--- JCite load balancer ---] With multiple pools of directory servers, for example in a deployment across multiple data centers, also use fail over load balancing. Fail over load balancing directs all requests to the first (preferred) pool of servers until problems are encountered with the connections to that pool. Then it fails over to the next pool in the list. Therefore in each data center you can set up round robin load balancing, and then set up fail over load balancing across data centers. // localFactory: ConnectionFactory to servers in the local data center // remoteFactory: ConnectionFactory for servers in a remote data center // localFactory and remoteFactory use round robin load balancing "internally". final List<ConnectionFactory> factories = Arrays.asList(localFactory, remoteFactory); final FailoverLoadBalancingAlgorithm algorithm = new FailoverLoadBalancingAlgorithm(factories); final ConnectionFactory factory = Connections.newLoadBalancer(algorithm); The algorithms also include constructors that let you adjust timeouts and so forth.

Connections Listening for You create an LDAPListener to handle incoming client connections. The LDAPListener takes a connection handler that deals with the connections, in this case connections back to the directory servers handling client requests. [jcp:org.forgerock.opendj.examples.Proxy:--- JCite listener ---] The connection handler is a ServerConnectionFactory to handle requests coming from clients. The factory takes a request handler implementation that deals with all supported incoming client requests. The Proxy example uses a ProxyBackend to handle requests. The ProxyBackend sends the requests on to the backend directory servers and routes the results returned back to client applications. [jcp:org.forgerock.opendj.examples.Proxy:--- JCite backend ---] For details about the ProxyBackend implementation, see ProxyBackend.java.

Attributes Rewriting Suppose you have a client application that expects a different attribute name, such as fullname for a standard attribute like cn (common name), and that expects a distinguished name (DN) suffix different from what is stored in the directory. If you cannot change the application, one possible alternative is a proxy layer that does DN and attribute rewriting.Some servers, such as OpenDJ directory server, can do attribute rewriting without a proxy layer. See your directory server's documentation for details. # A search accessing the directory server $ ldapsearch -b dc=example,dc=com -p 1389 "(cn=Babs Jensen)" cn dn: uid=bjensen,ou=People,dc=example,dc=com cn: Barbara Jensen cn: Babs Jensen # The same search search accessing a proxy that rewrites requests and responses $ ldapsearch -b o=example -p 8389 "(fullname=Babs Jensen)" fullname dn: uid=bjensen,ou=People,o=example fullname: Barbara Jensen fullname: Babs Jensen The OpenDJ LDAP SDK RewriterProxy example builds on the Proxy example, rewriting requests and search result entries. When you read the example, look for the rewrite() methods. In the above output, the rewriter proxy listens on port 8389, connecting to a directory server listening on 1389. The directory server contains data from Example.ldif.