module TSTPMessage {
	enum MessageType { Request, Reply }
	enum Operation { ECHO, REVERT, TOUPPER, TOLOWER }

	interface RequestHeader {
		MessageType type;          // unsigned char
		Operation operationId;     // unsigned char
		unsigned short dataLength; // two bytes
	}

	interface ReplyHeader {
		MessageType type;          // unsigned char
		unsigned short dataLength; // two bytes
	}	
}

// There are two messages: RequestMessage and ReplyMessage.
//
//     RequestMessage
//
// The RequestMessage contains a RequestHeader and a RequestBody.
// The RequestBody contains as many bytes as specified by dataLength.
// The RequestMessage encodes a string to be processed, together
// with the operation to be performed on that string.
//
//    ReplyMessage
//
// The ReplyMessage contains a ReplyHeader and a ReplyBody.
// The ReplyBody contains as many bytes as specified by dataLength.
// The ReplyMessage encodes the result of applying an operation
// to a string. Both the operation and the string were received
// in the corresponding RequestMessage. The result is also a string
// (no other results yet :( )
//
//    dataLength Coding Convention
//
// The member dataLength that appears in both headers is coded
// using 'Little Endian' notation.