[CONF] Apache Qpid: Restructuring Java Broker and Client Design (page edited)

[confluence]

Page Edited : qpid : Restructuring Java Broker and Client Design Restructuring Java Broker and Client Design has been edited by Rajith Attapattu (Jul 31, 2007). (View changes) Content: Proposed Architecture The following diagram depicts the architecture for the client and broker. The idea is to auto generate and share as much code as possible between the broker and the client. ------------------------------- JMS for Client/ Broker Logic ------------------------------- Qpid Layer( Client/Broker) Invoker – For out going Delegate – For incomming ------------------------------- Communication Layer ------------------------------- The communication layer will be common to both client and broker. The Qpid Layer contains handlers that are both common to client and broker as well as Client and Server specific classes. The 3rd Layer is where the message processing logic will be implemented. For Client there will be a thin wrapper called Qpid API to mask around the Invoker and expose methods by class. The client will use the Delegate to handle incomming events. This can be used to implement JMS on top. Or application logic directly on top of the Qpid API. The Broker will build it's logic around the Invoker and Delegate. Invoker and Delegate Invoker and Delegate are generated classes that contains all the methods in the spec. To call a method you use the Invoker and to handle a method you use the Delegate. Multi Version Support To tackle multi version support the following stratergy is used. Struct interfaces are defined with a union of methods from different versions. And version specific struct factories will produce concrete structs for each version. All these classes are auto generated from the spec. Ex: interface Struct_A Unknown macro: { public getX(String s); // AMQP 0-10 public getX(String s, int i); // AMQP 0-11 public getY(); // AMQP 0-10 public getZ(); // AMQP 0-11 } Struct_A_v0_10 { public getX(String s) Unknown macro: {.... } public getY() } Struct_A_v0_11 { public getX(String s) Unknown macro: {.... } public getX(String s,int i) public getY() Unknown macro: {.... } public getZ() } Client code can still use v0-10 methods with a v0-11 library and compile as the Interface and existing methods have not changed. Changes are handled by adding the new or modified methods. Note this strategy is only envisaged for incremental changes. A major change in spec would need substantial code changes. Qpid Client API Is a thin wrapper around the Invoker plus a few convinence methods. For example lets look at the Session class. Invoker Unknown macro: { // All the spec methods } CommonSession extends Invoker Unknown macro: { // convinience methods for messaging header(Header h); data(byte[] src); endData(); messageTransfer(String destination,Message msg); } ClientSession extends CommonSession implements Session Unknown macro: { // no implementations for 90% of the methods // Acts as a Mask for Session 'class' so only session specific methods are visible to the user. }

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