RPC messages

There are two types of messages involved in the implementation of an RPC system.

Types of messages

  1. Call Message
  2. Reply Message

Call Message

This message is sent by the client to the server for requesting execution of a particular remote procedure.

The two basic components necessary in a call message are

  1. The arguments necessary for the execution of the procedure.
  2. The identification information of remote procedure to be executed.

In addition to this, a call message normally has following fields

  • A message type field: To distinguish call messages from reply messages.
  • A client identification field: To permit server to check the authentication of client process for executing the concerned procedure.
  • A message identification field: To consists of sequence numbers to identify duplicates.

RPC call message format

Reply Message

If the RPC server receives a call message from client,it could be faced with one of the following conditions.

  • The specified remote procedure is executed successfully.
  • An exception condition occurs while executing the specified remote procedure.
  • The server finds that the call message is not intelligible to it.
  • The server detects by scanning the clients identifier field that the client is not authorized to use the service.
  • The server finds that the remote program, version or procedure number is not available with it.

A Successful Reply Message Format

A Unsuccessful Reply Message Format

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