RPC over HTTP Process Example

The following figure illustrates the interactions between the Microsoft® Office Outlook® client, the RPC proxy server, and the back-end servers. This example assumes that the user’s public folder server is the same server as the user’s mailbox server. This example also assumes that you are running Microsoft Exchange Server 2003 Service Pack 1 (SP1) on your Exchange servers.

RPC over HTTP Process example

Step 1

The client computer has determined that it will connect to the Exchange server by using RPC over HTTP. The client computer initiates two HTTP sessions to the Exchange server for each RPC request that it must send. The client computer initiates one HTTP session for RPC requests into the Exchange server and another HTTP session for responses from the Exchange server.

The client computer sends the initial RPC requests to the referral service of DSProxy on the Exchange server prompting for a directory referral. The referral service port is 6002.

Step 2

The RPC proxy server extracts the RPC request from the HTTP session and forwards the RPC request to port 6002 on the Exchange server. The Exchange server responds to the directory referral request with itself as the target. This approach is unique to RPC over HTTP. If the client computer was not using RPC over HTTP, the Exchange server would respond with a global catalog server. However, when the client computer uses RPC over HTTP, the Exchange server recognizes the request from the client computer as RPC over HTTP. The client computer cannot access a global catalog server directly when the client computer uses RPC over HTTP. Therefore, the Exchange server responds to the client computer with itself, the Exchange server, as the server to use for directory lookups.

Step 3

The client computer initiates two HTTP sessions to the proxy service of DSProxy on the Exchange server. The proxy service is on port 6004. The client computer initiates one HTTP session for RPC requests into the server and another HTTP session for RPC requests from the server.

Step 4

The RPC proxy server extracts the RPC request from the HTTP session and forwards the RPC request to port 6004 on the Exchange server.

Step 5

The Exchange server forwards the directory request to a global catalog server. The global catalog server responds to the Exchange server that has the appropriate directory information.

Step 6

The Exchange server sends the directory information that it received from the global catalog server to the client computer.

Step 7

The client computer initiates two HTTP sessions to the Microsoft Exchange Information Store service on the Exchange server. The Microsoft Exchange Information Store service is on port 6001. The client computer initiates one HTTP session for RPC requests into the server and another HTTP session for RPC requests from the server.

Step 8

The RPC proxy server extracts the RPC request from the HTTP session and forwards the RPC request to port 6001 on the Exchange server.

Steps 7 and 8 are repeated as needed for any additional store connections, such as accessing public folder data.