This concept enables us to develop processes quickly by defining the order in which services will be invoked. This way, applications and information systems become more flexible and can better adapt to the changes in business processes. Business processes are usually of dynamic nature. Companies have to improve and modify, act in an agile manner, optimize, and adapt processes to improve the responsiveness of the whole company.
Every change and improvement in a business process has to reflect in applications that provide support for them. Although this requirement may not sound very difficult to fulfill, the real-world situation shows us a different picture.
Changing and modifying applications is often a difficult job, which requires time. Therefore applications cannot react instantly to changes in business processes—rather, they require some time to implement, test, and deploy the modifications. Making information systems more flexible and adaptable to changes, and better aligned with business processes is the major promise of SOA. The first requirement is fulfilled by the latest distributed architecture—Web services.
The second requirement is fulfilled by the ESB enterprise service bus , which provides support for centralized, declarative, and well-coordinated management of services and their communications. The third requirement, composition of services into processes, is fulfilled by BPEL, the commonly accepted specialized language for business process definition and execution.
A business process, as seen by BPEL, is a collection of coordinated service invocations and related activities that produce a result, either within a single organization or across several. For example, a business process for planning business travels will invoke several services. In an oversimplified scenario, the business process will require us to specify the employee name, destination, dates, and other travel details.
Then the process will invoke a Web service to check the employee status. Based on the employee status, it will select the appropriate travel class. Then it will invoke Web services of several airline companies such as American Airlines, Delta Airlines, etc.
For the clients, the BPEL process will expose its functionality in the same way as any other Web service. From the client perspective, it will look exactly like any other Web service. This is important and useful, as it allows us to compose services into simple processes, simple processes into more complex processes, and so on. A BPEL process consists of steps. A pick activity with two branches: one onMessage for the in-stock response and instructions on what to do if an in-stock message is received.
A second onMessage for the out-of-stock response and instructions on what to do if an out-of-stock message is received. The Service BPEL Process needs a receive activity to accept the message from the client, and a switch activity with two branches, one with an invoke activity sending the in-stock message if the item is available, and a second branch with an invoke activity sending the out-of-stock message if the item is not available.
In this chapter, we will understand the concept of one request, a mandatory response, and an optional response.
Here, the request is to order a product online. If the product is delayed, the service sends a message letting the customer know. In any case, the service always sends a notification when the item ships. The Client BPEL Service needs a scope activity containing the invoke activity to send the request, and a receive activity to accept the mandatory reply. For the optional message, the onMessage handler of the scope activity is set along with the instructions on what to do if the optional message is received for example, notify you that the product has been delayed.
If the mandatory reply is received first, the BPEL Process continues without waiting for the optional reply. The Service BPEL Process needs a scope activity containing the receive activity and an invoke activity to send the mandatory shipping message, and the scope's onAlarm handler to send the optional delayed message if a timer expires for example, send the delayed message if the item is not shipped in 24 hours.
For example, the client sends a request to purchase a vacation package, and the service sends an immediate reply confirming the purchase, then continues to book the hotel, the flight, the rental car, and so on.
The Client BPEL Process needs an invoke activity for each request and a receive activity for each reply for asynchronous transactions, or just an invoke activity for each synchronous transaction.
The Service BPEL Process needs a receive activity for each request from the client, and an invoke activity for each response. Once the responses are finished, the Service BPEL Process as the service can continue with its processing, using the information gathered in the transaction to perform the necessary tasks without any further input from the client.
This A-to-B-to-C-to-A transaction pattern can handle many transactions at the same time. Therefore, a mechanism is required for keeping track of which message goes where. We have discussed in one of the previous chapters that Synchronous Web Service is one, which provides an immediate response to an invocation.
In the screenshot shown below, we have created a Synchronous BPEL Process which has a receive activity to accept the request from the user. The reply activity simultaneously sends the response back. As discussed before Asynchronous Web Service is one which sends a request to other web service and waits for the response.
In the screenshot shown below, we have created the Asynchronous BPEL Process which has a receive activity to accept the request from the user. The assign activity further assigns values to the different elements in the request. Next, the invoke activity invokes the HelloWorld Application which sends the response simultaneously and that is captured in receive activity.
Further, we have the callback activity which finally generates output and sends response asynchronously. If you double-click the receiveInput or callbackClient , you will see each of them has only one variable. A flow activity typically contains many sequence activities, and each sequence is performed in parallel. A flow activity can also contain other activities. For example, two asynchronous callbacks execute in parallel, so that one callback does not have to wait for the other to complete first.
Each response is stored in a different global variable. In the flow activity, the BPEL code determines the number of parallel branches. However, often the number of branches required is different depending on the available information. The flowN activity creates multiple flows equal to the value of N, which is defined at the run time based on the data available and logic within the process.
There is an Index variable increment each time a new branch is created, until the index variable reaches the value of N. The flowN activity performs activities on an arbitrary number of data elements. As the number of elements changes, the BPEL process adjusts accordingly. The branches created by flowN perform the same activities, but use different data. Each branch uses the index variable to look up input variables.
Contact Michael Cardella. Midwave is a rapidly growing firm that specializes in building highly available and highly secure information technology systems for medium to large companies and government agencies in seven midwestern states. Midwave is an Oracle Partner. Contact Praveen Ramachandran. Sean has over seven years of experience in mission-critical e-commerce implementations, and 15 years of industry experience in software design.
Sean Carey gave us Chapter 7. Contact Sean Carey. Stany Blanvalet contributed Chapter Contact Stany Blanvalet. Contact The Hoa Nguyen.
Contact Yves Coene. Publication date: July Publisher Packt. Pages ISBN Chapter 1. Extending Enterprise Application Integration. Case Study Background.
Parallel web service invocations Asynchronous web service invocations Loose coupling between services and portability Exposing the whole orchestration with standards-based interfaces Orchestration monitoring. BPEL supports loosely coupled web service orchestration. Business logic even parallel flows!
Implementing the Customer Details Management Module. Orchestrate web services using a BPEL process. Add exception-management capability to the BPEL process. Centralize the logging and notification process. Determine the input and output of the process. Define the target namespace for the WSDL document.
Adhere to WS-I standards whenever possible. Step 2: Orchestrate Web Services. Step 3: Add Exception Management Capability. Case 1. Case 2. Case 6.
Step 4: Secure Business Communication. Outbound Security. Inbound Security. Step 5: Centralize Logging and Error Handling. Receives information to be logged from an external process. Read more Unlock this book with a 7-day free trial.
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Contact Markus Zirn Browse publications by this author. Contact Michael Cardella Browse publications by this author. Look in the tnsnames. As shown in the following screenshot, ensure that you use the exact information from the tnsnames. For example, enter the value for Host Name as the database server hostname.
If you are running the Repository Creation Utility on the database server itself, you may use Host Name as localhost , as shown in the following screenshot:. You can ignore the database support warnings. It will initiate the installation step of Checking Prerequisites with all the green ticks, as shown in the following screenshot.
Click on OK :. The next screen allows you to add a prefix with database schemas. Dependent schemas are selected automatically. If you choose to select other components, these install instructions may not match your experience. Also, you may have to increase processes in XE you will get a message telling you what is required :. MDS : Metadata service. Click on OK on the next window and choose a password for the database schemas, as shown in the following screenshot.
It is recommended to keep the same passwords for all schemas for a development environment:. On the next window it will create tablespaces for the all the schemas created earlier:. Click on Create. This will create all schemas in the database, as shown in the following screenshot. On the next window, click on Close. That completes the creation of database schemas for the SOA Suite:.
As shown in the following figure, the final step is to install the SOA Suite. Extract all the disks from the ZIP archive into one folder and run setup. You will need to pass jreLoc as a parameter to setup.
If you are installing JDK manually in a folder, select the entire file path with no spaces. The installer won't recognize a folder name with spaces. It will launch the install window, as shown in the following screenshot.
On the next window click on Skip Software Updates and then click on Next :. On successful checks, we will get all the status as green, as shown in the following screenshot.
Please make sure that you have already installed WebLogic as a standalone install or as part of the JDeveloper install. On the next window, as shown in the following screenshot, enter the location of Oracle Middleware Home and click on Next :.
On the next window, we will get the installation summary, as shown in the following screenshot. On the next window, you will get the installation progress window that may take a few minutes to finish the install. On completion of the install, click on Next and that will take you to the Installation Complete window, as shown in the following screenshot.
However, you can perform the development with a single admin server as well. A production environment will usually be a clustered environment consisting of multiple managed server and single admin instances.
Execute config. Alternatively, you can select Configure Application Server from the Windows Start menu, as shown in the following screenshot:. As shown in the following screenshot, select the Create a new WebLogic domain radio button and click on Next. As shown in the following screenshot, select the Oracle products and then click on Next.
On the next window, enter the desired domain name, domain location, and application locations, or leave the default values for them and click on Next :. Enter the user password and click on Next , as shown in the following screenshot. Store the password at a safe place, you will need it later:. As shown in the following screenshot, enter the database information. Do not modify the schema user session. Please select and enter the data in the order as shown in the following screenshot:.
Check for the tnsnames. Always use the same information used for RCU. To resolve the preceding error, please ensure that you created schemas with the correct RCU version and are able to connect to the database with the username and password provided in the preceding screen.
Please note that we should not modify the username to the schemas. The username is selected by the utility. Change only the password. For a development environment, always prefix the schema with DEV. Ensure that all the steps described in the RCU install session executed, including steps for changing the number of default Oracle database processes.
Shut down and start the database after the changes. The preceding changes are required only in the case of the database connection error messages. On the next window you will see the configuration summary, as shown in the following screenshot. On the next window, you will see the progress of writing the domain setup files. Now, to start the admin server, go to the domain's bin folder for which you wish to start the administration server using the following command:.
To start WebLogic, execute the startWeblogic. Start JDeveloper from the Start menu with the default role. Enter the Project Name and click on Finish , as shown in the following screenshot:. As shown in the following screenshot, you can name your BPEL process.
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