1. A program development system for developing client and server programs, for a client computer and a server computer, respectively, wherein the client-program is configured to issue method invoking instructions for the server program, the program development system comprising: a program development computer programmed to provide support for legacy protocol method invocation, the program development computer programmed to include a converter having instructions to cause the program development computer to construct a server program and a client program wherein the instruction to construct the server program comprises instructions to cause the program development computer to: read a source program; recognize in the source program annotations that provide a mapping between method names for methods invoked using messages in a legacy protocol and a native protocol; create a mapping data structure using the annotations that provide a mapping between method invoking instructions in the legacy protocol and method invoking instructions in the native protocol; append the mapping data structure to an executable server program produced by a compiler and the converter; include in the executable server program a legacy-protocol-message-to-native-protocol-message transformation mechanism; create a client-program-interface for a client; wherein the instructions to create a client-program comprises instructions to cause the program development computer to: compile a client-program source program against the client-program-interface by including in the compiled client-program instructions; include instructions to transmit a select-a-server-program instance message in the client-program; and include a legacy-protocol method invocation in the client-program; wherein the server computer comprises a mechanism to receive a select-a-server-program-instance message and to save an instance identifier in response thereto; wherein the instructions to create a server-program further includes instructions to cause the program development computer to: include in the server-program a mechanism to save an instance identifier in response to receiving a select-server-program-instance message; wherein the legacy-protocol-message-to-native-protocol-message transformation mechanism comprises instructions to cause the server program to build a native protocol method invocation message using the saved instance identifier and the mapping between method invoking instructions in the legacy protocol and method invoking instructions in the native protocol.