Digital Agriculture Public Service Platform Web-based Research Service Chain

With the rapid development of Internet technology, in the form of softwaregradually shift from the desktop version, online version of the service. Sharing ofinformation resources, growing demand for the integration of various industries to getattention, using service-oriented architecture (SOA) to build information systems, is apowerful way of sharing information resources, along with the use of SOA to buildinformation systems becomes a trend. Digital Agriculture public service platform isdeveloped by the Shanghai Academy of Agricultural Sciences for the "three rural"public service platform to provide agricultural information technology services.Platform is based on service-oriented architecture (SOA), the use of Web Servicetechnology, dozens of agricultural application system to extract the core functionalityas Web services and released to achieve the integration and sharing of informationresources. Each Web service in the public service platform of digital agricultureregistered a single function can be provided, so to complete a complex task, it isnecessary to combine multiple existing Web services. In this paper, a combination ofWeb services to build applications which require specialized IT staff tediousprogramming, the average user is difficult to complete alone issue, explore theworkflow technology for Web services to build service-chain approach and thedevelopment of the service chain to build tools to visualize the interface met through acombination of simple drag-demand dynamic service application requirements,reduce the difficulty of the application to build and improve the efficiency of systemdevelopment.In recent years, information systems built using SOA architecturegradually become the mainstream trend, at the same time, the emergence of a largenumber of Web services. These Web services are often able to provide a singlefunction, for the completion of a complex task; you need to call a number of existingWeb services. Invoke multiple Web services are currently often usedprogrammatically to achieve, through a combination of visual modeling, dynamicassembling existing multiple Web services to meet real business needs to build a Webservice chains are the key elements of this thesis. In order to achieve the user can dynamically assemble existing services on demand through visualization methods, thepaper by comparing select an existing workflow technology, select the appropriateworkflow engine and its application to build a Web service chain, so you can give fullplay to workflow technology advantage, visualization, dynamic assembly dispersedon the network isolated, heterogeneous Web services. Through workflow technologycan achieve dynamic combination to build Web service chain, greatly simplifying theexisting invocation, forward-looking.First, this paper analyzes the basics of Web services and workflow chain,including four aspects: First, the architecture of Web services and Web services;Second, workflow technology, including workflow concepts and ideas, analyzing thework Web streaming services combined with the advantages of complementary; Third,analyze and compare the three forms of the service chain, established the translucentchain as contents of this article; fourth is to build demand service chain combining theanalysis and comparison of existing on the basis of the workflow engine, the choice ofjBPM workflow engine as a workflow execution engine.Then studied for Web service chain workflow technology, including two aspects:First, the Web service chain process modeling, which includes modeling and processdefinition language. In the analysis of today’s popular modeling method based on thepaper grid modeling activities be expanded so that it can meet the needs of Webservices modeling chain; in process definition language, the study of existing processdefinition made on the basis of their own language defined service descriptionlanguage WSCPML, can conveniently be described on the Web service chain. Second,the expansion of the service chain workflow engine, the paper drawing "SOA" of the"triangle" structure, in the jBPM workflow engine were open its system design andexpansion: Taking into account the decentralized and heterogeneous nature of Webservices, for data model and control model of workflow engine made the appropriatechanges, the design workflow application framework.Finally, build a service chain to build tools to build the tools in the service chainvisual interface, drag and drop way through dynamic combination that can demandthe required Web services become agricultural applications. Use a combination ofdigital service chain modeling tools in agriculture-related public service platformconstructed of discrete Web services leafroller early warning and control decisions,crop suitability evaluation two applications, through practical application to verify thework chain availability, reliability and stability.