### Writing the Evaluation Routine

The first main topic of the OSF DCE Application Development Guide - Introduction and Style Guide and Developing a Simple RPC Application in this guide explain that when a prospective client attempts to import binding information from a namespace entry that it looks up by name, the NSI import routine checks the binding for compatibility with the client by comparing interface UUIDs and protocol sequences. If the UUIDs match and the protocol sequences are compatible, the NSI operation considers the binding handle contained in the server entry to be compatible and returns it to the client. Internationalized clients need to perform additional compatibility checking on potential server bindings: they need to evaluate the server for character and code set compatibility.

The purpose of the character and code sets compatibility evaluation routine is to determine:

· Whether the character set the server supports is compatible with the client's character set, since incompatible character sets result in unacceptable data loss during character conversion.

· The level of code sets compatibility between client and server, which determines the conversion method that the client and server will use when transferring character data between them.

A conversion method is a process for converting one code set into another. There are four conversion methods:

· Receiver Makes It Right (RMIR) - the recipient of the data is responsible for converting the data from the sender's code set to its own code set. This is the method that the RPC communications protocol uses to convert PCS character data between ASCII and EBCDIC code sets.

· Client Makes It Right (CMIR) - the client converts the input character data to be sent to the server into the server's code set before the data is transmitted over the network, and converts output data received from the server from the server's code set into its local code set.

· Server Makes It Right (SMIR) - the server converts the input character data received from the client into its local code set from the client's code set and converts output data to be sent to the client into the client's code set before the data is transmitted over the network.

· Intermediate - Both client and server convert to a common code set. DCE defines a default intermediate code set to be used when there is no match between the client and server's supported code sets; this code set is the ISO 10646 "universal'' code set. Sites can also specify other code sets to be used as intermediate code sets in preference to ISO 10646; to do this, they run the csrc utility. See the csrc(8dce) reference pages in the OSF DCE Command Reference for a description of csrc utility usage.

A character and code sets compatibility evaluation routine generally employs a conversion model when determining the level of code sets compatibility. A conversion model is an ordering of conversion methods, for example, "CMIR first, then SMIR, then intermediate". Consequently, the actual conversion method used is determined at runtime.

More:

DCE RPC Evaluation Routines

Writing Customized Evaluation Routines

Notes about Tag-Setting

Example Character and Code Sets Evaluation Logic

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