ContentsService Bus Java Programmer’s GuideIntroductionThe E-speak Service FrameworkProgramming ModelThe ServiceBus packageBasic ConceptsA Simple Example: EchoConversationsEcho Example RevisitedConversation Executors : State ManagementIntrospection LibraryNegotiation LibrarySubmitting Offers to a MatchMakerStructure of lookupStructure of revoke-offerEcho example revisitedRunning the MatchMakerServiceAn End to End ExampleAbout The Example ApplicationDiagram: XML Document Being Delivered To An ApplicationDiagram: Application Sends An XML DocumentInstalling & Running The Example ApplicationInstalling Under Apache & TomcatService Framework GuideDeveloper Release 3.01June 2000COPYRIGHT NOTICE© 2000 HEWLETT-PACKARD COMPANYTo anyone who acknowledges that this document is provided "AS IS" WITH NO EXPRESS OR IMPLIED WARRANTY: permission to copy, modify, and distribute this document for any purpose is hereby granted without fee, provided that the above copyright notice and this notice appear in all copies, and that the name of Hewlett-Packard Company not be used in advertising or publicity pertaining to distribution of this document without specific, written prior permission. Hewlett-Packard Company makes no representations about the suitability of this document for any purpose.Developer Release 3.01 June 2000iContentsChapter 1 Service Bus Java Programmer’s Guide . . . . . . . . 1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Programming Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Negotiation Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Chapter 2 An End to End Example. . . . . . . . . . . . . . . . . . .41About The Example Application . . . . . . . . . . . . . . . . . . . . . 41Installing & Running The Example Application . . . . . . . . 46iiDeveloper Release 3.01 June 2000Developer Release 3.01, June 20001Chapter 1Service Bus Java Programmer’s GuideThis chapter describes the E-speak Service Bus package for Java programmers. The e-speak service bus package (net.espeak.servicebus) is a Java implementa-tion of the E-speak Service Framework Specification (SFS). This document contains the following sections:• Section 1 : Introduction: Describes the E-speak Service Framework Specifica-tion (SFS).• Section 2 : Programming Model: Describes the interfaces provided by the net.espeak.servicebus package and how it allows development of SFS-compli-ant services in Java.• Section 3: Matchmaker Service: Describes how a service-provider can advertise its service-offerings at a matchmaker and how service-consumers can look up service-offerings.• Section 4: Negotiation Service: Describes how e-services can negotiate with each other.• Section 5: End-to-End Example: Describes an example in which a paper buyer discovers a paper suplier and completes a business transaction over the Service Bus.IntroductionAThe Internet has evolved from a platform for serving documents to a platform on which services, such as book-purchase or bill-payment are offered. Today, these services are largely implemented as standalone “backend” components and do not leverage other services offered over the Internet. Our vision is that the Internet willIntroduction Service Bus Java Programmer’s Guide2 Developer Release 3.01,June 2000develop into an “e-service” platform where software services can directly interact with each other to provide richer functionality than each service can provide by itself. For example, businesses can achieve tighter supply chain integration by allowing their ERP systems to speak to each other.The E-speak Service Framework AUnlike traditional client-server systems, e-service consumers are not directly under the service-provider’s administrative control. Hence, service-providers cannot assume that service-consumers will use a common programming language, runtime platform, or that they can be trusted to behave well. In fact, the service-provider may not even know its consumer’s identity until it is used. The E-speak framework allows services written in different languages and running on different platforms to interact with each other. It does this by using a document-exchange model of inter-action where each message is an XML document. E-services are programmed to receive XML documents and to respond with XML documents and can be written without any dependence on a specific communication protocol. The communica-tion protocol is configured at deployment-time; hence it is not a development-time decision.The E-speak service framework uses the following terminology :• Service : A service is an end-point that is connected to the service-bus and indi-cates a single entity from a trust perspective. Each service has a unqiue identifier (URI) that distinguishes it from other services and is addresible at a (proto-col-dependent) specific URL. • Conversation: Each service can support multiple conversations. A conversation is a logical group of document exchanges. These interactions may have been grouped together because they form a logical chain of interactions or because they all need the same trust assumptions. Conversations are analogous to inter-faces in the object-oriented paradigm. • Interaction: Each interaction represents a document that is sent across from one service to another and any responses that may be sent back. An interaction is similar to the notion of a method call in traditional object-oriented languages.The E-speak service framework consists of two sets of specifications:Developer Release 3.01, June 2000 3Service Bus Java Programmer’s Guide Programming Model• Basic specifications : These are the basic set of specifications that are required for services to interact with each other.• The E-speak Message Schema specifies the low-level tags used to encode routing and contextual information in documents that are exchanged between services. • The E-speak Service Definition Schema specifies how the interface of a service can be represented in terms of the types of conversations it can participate in.• Conversation Specifications: These are a set of standard conversations that are widely-used and hence provided along with the base set of specifications.• Matchmaking Conversation : Service-providers enter into this conversation with a Matchmaker service to advertise their service-offerings, while service-consumers enter into this conversation with a
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