Sun Java System Directory Server Enterprise Edition 6.3 Deployment Planning Guide

Using Referrals For Distribution

A referral is information returned by a server that tells a client application which server to contact to proceed with an operation request. If you do not use Directory Proxy Server to manage distribution logic, you must define the relationships between distributed data in another way. One way to define relationships is using referrals.

Directory Server supports three ways of configuring how and when referrals are returned:

The following figure illustrates how referrals are used to direct clients from the UK to the appropriate server in a global topology. In this scenario, the client application must be able to connect to all the servers in the topology (at the TCP/IP level), to enable it to follow the referral.

Figure 10–14 Using Referrals to Direct Clients to a Specific Server

Figure shows client sending a request to consumer Directory
Server, which refers the client to a different server in the topology.

Using Directory Proxy Server With Referrals

You can use Directory Proxy Server in conjunction with the referral mechanism to achieve the same result. The advantage of using Directory Proxy Server in this regard is that the load and complexity of client applications is reduced. Client applications are only aware of the Directory Proxy Server URL. If the distribution logic is changed, for any reason, this change is transparent to client applications.

The following figure illustrates how the scenario described previously can be simplified with the use of Directory Proxy Server. Client applications always connect to the Proxy Server, which handles the referrals itself.

Figure 10–15 Using Directory Proxy Server With Referrals

Figure shows clients sending requests to Directory Proxy
Server, which handles all referrals.