This document covers the following topics:

• Interoperability and EntireX Broker

• Messaging Model and Interoperability

• Communication Models and Interoperability

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Interoperability and EntireX Broker

This section introduces the basic concept of EntireX Broker: achieving highly flexible interoperability of application components in a distributed processing environment. This concept is described from the perspectives of

• a messaging model

• communication models

• application programming interfaces

• EntireX components

in order to give you a comprehensive, high-level view of how EntireX Broker enables flexible interoperability between distributed application components.

Messaging Model and Interoperability

Introduction

In a distributed processing environment that uses EntireX Broker, communication occurs through application components exchanging messages. An application component offering a service registers it with EntireX Broker (see REGISTER); this makes the service available to other application components able to communicate with EntireX Broker. An application component intending to access a service issues its request through EntireX Broker, which then routes the request to the specific application component offering the service.

The following concepts help describe how message exchange is structured in EntireX Broker:

• Synchronicity
  The application initiating the request either waits for the result to return, whereby it suspends all processing (synchronous); or it does not wait for the result to return, whereby it is freed to do other processing (asynchronous).

• Conversationality
  The request can either be a single pair of messages comprising request/reply (non-conversational); or it can be a sequence of multiple messages which are all part of the same request (conversational).

Overview Diagram

The following diagram shows the two major concepts of EntireX Broker's messaging model: synchronicity and conversationality. See ACI Syntax of Messaging Model below for a description of the messaging syntax.

ACI Syntax of Messaging Model

The table below describes the messaging terms mentioned in the diagram above from the viewpoint of the application component initiating the request, as expressed in ACI syntax.

The ACI (Advanced Communication Interface) is the lowest level application programming interface that interacts with EntireX Broker. The ACI is common to all of the messaging models and communication models (see Communication Models and Interoperability) of EntireX.

Messaging Term		Client	Server
	Synchronous	SEND (1) WAIT=YES (1)	RECEIVE WAIT=YES
	Asynchronous (2)	SEND WAIT=NO WAIT=YES	RECEIVE WAIT=NO
	Conversational (2)	SEND CONV-ID=NEW	RECEIVE
	Non-conversational (2)	SEND CONV-ID=NONE	RECEIVE

Notes:

1. The synchronous SEND, WAIT=YES command contains an implied RECEIVE command.
2. Persistence available. See Concepts of Persistent Messaging.

Communication Models and Interoperability

The EntireX Broker uses the communication model client-and-server. This model is based on the connection between exactly two partners: client and server. This model covers the requirements of conversational communication and asynchronous processing.