3. The Enterprise Application: e-Bookstore3.1. Departments3.2 Activities4. Overview of our System4.2.5.1 Class AccountingBean: Entity BeanA. Operation sequence due to customer interaction with the e-bookstore (Fig. 12)Activity 1:Case a: A customer creates an new accountCase b: A customer with an existing account logs into the e-bookstoreActivity 2: Customer query for books in the storeCase 1: Addition of items in the cartActivity 4: Customer buys one or more books from the e-bookstoreActivity 3: Preparing XML Document for the Accounting DepartmentC. Operations occurring to reflect a purchase transaction for every purchase (Fig. 14)5. Distribution of Work6. Conclusion and Future Work1. Objectives and GoalsThe objective of this project is to explore distributed computing technologies -XML (eXtensible Markup Language) and EJB (Enterprise Java Bean). Thesetechnologies are used to develop an EAI (Enterprise Application Integration) application.We are constructing reusable components in the form of EJBs that can integrate variousapplications representing the different business components in an organization. Thisintegration can be achieved by sharing information in an open data format, which isaccomplished using XML. The main goal of using XML here is to achieve transparency,which is an important aspect in a distributed environment. This will enable the variousbusiness processes of the organization, running on heterogeneous platforms, usingdifferent data formats and databases, to interact with each other in a transparent manner.We are implementing business and data transfer logic as server-side componentsfor an e-commerce application, which is demonstrated using an e-bookstore as anexample. The server-side components are EJBs, which integrate the various business-level processes of the organization. The exchange of data within the enterprise isachieved via XML.2. Discussion2.1. Enterprise Application Integration (EAI)An EAI can be described as making one or more disparate applications act as onesingle application. This is a complex task that can be achieved by unrestricted data1sharing among connected applications or data sources in the enterprise, thus requiring thedata to be replicated and distributed to the right systems at the right time. Design issuesinvolved in developing an EAI are:- Identification of the data sources- Common, open format document storage- An easy standard data retrieval method from the stored document- A configurable software component that provides transparent persistency for thedocument- Integration of the various processes- Identification of application interfaces- A cross platform solution. 2.2. Technologies to realize EAIThe different approaches of accomplishing EAI can be:1. Message Oriented Middleware(MOM) and Remote Procedure calls(RPC)2. Message brokers1. Use of distributed objects through CORBA and COM2. Database-oriented middleware and standards, including ODBC, JDBC andOLE DB3. Enterprise Java Beans(EJB) and eXtensible Markup Language(XML)Limitations of the above approaches:2The primary limitation of MOM and RPC is that they provide point-to-point solutions– i.e. linkage between system A and B. Hence any attempt to link additional systemsbecomes a complex tangle of middleware links. Also, this requires significant alterationsto the source and target systems, embedding the middleware layer into the applicationand data store. Message brokers, though provide a better solution for implementing anEAI, might suffer from the limitation of providing open document storage formats. Also,it does not provide the levels of abstractions as proffered by the EJB technology thatmakes the system more flexible. Using distributed objects through CORBA would beanother feasible approach, however it is unable to hide the middleware details from theapplication developer, which is possible using EJB. Database-oriented middlewareaccomplishes integration only at the data level and not at the process level, within theenterprise. Implementing EAI using EJB and XML combines both the flexibility of XMLwith the cross-platform component-based qualities of Enterprise Java Beans [1,2]. 2.3. Why EJB and XML?In an Enterprise Application Integration framework, the EJBs are deployable andreusable java server components, which are application components running in anapplication server. These components run on any platform and are completely portableacross any vendor’s EJB-compliant application server. The specific business moduleswithin the organization are represented as EJB components, whose methods handle thevarious business processes. These components serve the purpose of process integrationand document management.3Process integration is achieved by having exposed methods in the beans that canbe invoked by other beans and applications within the enterprise. These methods withinthe module provide functionality to obtain data from various phases of the businesstransaction, which is then processed and stored in local environment. Each businessmodule in turn generates data, which is stored as an XML document that can beexchanged seamlessly across the enterprise. Document management viz., storing,locating and distributing information across the various modules can be accomplished byhaving exposed methods for creating and parsing XML documents.When applications communicate with each other there is little chance that theymight share similar data structures. Hence an interim format capable of handling semi-structured data is needed which can be made possible by using XML markup. Marking upa document or data results in the formation of a hierarchical container that is platform-,language- and vendor- independent and separates the content from any environment thatmay process it. As a result there is a greater opportunity to reuse this data outside of theapplication and data sources from which it was derived. Document management is a systematic method for storing, locating and keepingtrack of information that is valuable to a business. The document management system(DMS) creates a document repository to store and distribute the document data in anenterprise. Hence, the DMS can be used for accomplishing EAI at the data
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