These services are deployed on the Tomcat server. The project is built using the Ant build system. Each service code resides in its own folder and each folder has the following set of files to build and deploy services on the Tomcat server:

Service Invocation Flow
When it receives a request for gross pay, the payroll service invokes calls to get the total hours and the rate information from the Timesheet service. Then it makes calls to the Insurance service to get health, life, and disability insurance premium information. Finally, it calculates the gross pay and returns it as a response to the calling service.

 

Let's discuss the Timesheet service further. We will not discuss the Insurance service since the implementation of both the services is very similar.

The Timesheet interface (see Listing 1) defines two methods, getHours(int empId) and getRate(int empId). Both methods take empId as a parameter and return hours billed for the current period and the consulting rate of the employee. A simple implementation of the service is described in Listing 2.

Listing 3 describes the configuration file for the Timesheet service needed for the wscompile tool and Listing 4 describes a configuration file read by the wsdeploy tool. The wscompile tool automatically generates the WSDL file when the service is compiled and deployed on the server. A complete listing of the WSDL file can be browsed when you visit the http://localhost:8080/time sheet-jaxrpc/timesheet and click the WSDL link on that page. JAX-RPC takes care of marshalling and unmarshalling the data returned by the service methods.

Listing 5 describes the partial code of the payroll client that uses both Timesheet and Insurance services. As mentioned before, the payroll client can very well be built as a "Payroll" service that invokes Timesheet and Insurance services to compute employee salary.

EAI/BPM Techniques
Let's look at how we can use our business logic layer along with EAI (enterprise application integration) and BPM (business process management). We will look at these options briefly and then apply the concepts to our case study. Business Process Modeling Language (BPML) is the language of choice to implement complex business processes as declarative business logic.

Today's enterprises also consider Web services while implementing BPM and EAI. Enterprises are exploring new avenues to automate business processes and share business data across the enterprise, allowing departments to be more efficient and productive. There is a dire need for a full duplex, bidirectional solution to share business processes seamlessly and exchange data among ERP, CRM, SCM, databases, data warehouses, and other important internal systems within the company. Enterprises have been using EAI technologies that enable unrestricted data sharing throughout networked applications within the company. EAI is the process of creating an integrated infrastructure for linking disparate systems, applications, and data sources across the corporate enterprise. The implementation of EAI technology has been an expensive affair with proprietary interface implementations to interact with various applications in real time. With the nightmare of managing disparate applications, data, data transformations, and proprietary interfaces, corporations are hoping SOAP-based architecture of Web services will be a breather.

The emerging BPM breed of software provides analysis, design, automation, and optimization of business processes. They allow business managers and analysts to change the business process logic without changing the underlying IT programs. Many enterprises have applications where changing business processes involves engineers and programmers. BPM is the foundation of next-generation EAI. BPML is an XML-based business process definition language. The Business Process Management Initiative's (www.bpmi.org) mission is to promote and develop the use of BPM through the establishment of standards for process design, deployment, execution, maintenance, and optimization. BPMI.org develops open specifications, assists IT vendors in marketing their implementations, and supports businesses using BPM technologies. Enterprises are exploring Web services as a viable option for EAI and BPM solutions to leverage their existing software assets. The use of standard XML protocols makes Web services platform, language, and vendor independent, and an ideal candidate for use in EAI and BPM solutions.

Declarative programming techniques are used to capture the business logic of your application as business rules and process models in the transaction logic and process logic layers. Transaction rules can be compiled into reusable components and executed within the Transaction Logic Engine. Process models are executed within the Process Logic Engine.

In this case study, we've implemented business process logic for payroll functionality. A business analyst can easily change the business parameters (integration points) regarding time tracking and insurance data extraction without changing the application programs to implement new business logic. Figure 3 is a re-representation of the case study from a BPML point of view. Instead of integrating with time tracking and insurance Web services, as in the case study, we are now integrating with enterprise products based on EAI or BPM. These products provide integration points that can hook into their applications. Once the data is obtained from these products, it can be utilized in real time by building a BPML layer. Figure 4 is a process diagram for our Payroll layer.

Conclusion
Web services as stand-alone processes in themselves are powerful interfaces to complete B2B transactions. By building a logical layer over multiple Web services, you can leverage application-resident business logic in real time and take Web services technology to another level. Web services can also be built over enterprise products based on EAI and BPM. Business Process Modeling Language (BPML) is an emerging language to build such a logical layer over enterprise applications.

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