Tutorial: Creating and Accessing WCF COBOL Services

Overview and Demonstration Applications

The tutorial is based on the BookWrapper demonstrations supplied with this COBOL development system. The BookWrapper is an intermediary program which maps .NET data types onto COBOL data types. It then calls the existing COBOL program, book.cbl, to perform the business logic.

In this tutorial you expose the functionality of the BookWrapper program as a WCF service and use a console application as a client to communicate with it.

A more sophisticated version of the demonstration shown here is supplied in the Visual COBOL samples. To check the code, start Samples Browser and open the WCF Book Service and Client demonstration in the Windows Communication Foundation category.

Prerequisites

As a prerequisite step for this tutorial, you need to build the BookWrapper and LegacyBook projects that are part of the WinBook sample. To do this:

1. Click Start > All Programs > Micro Focus Visual COBOL > Samples to start the Samples Browser.
   Note: To start the Samples Browser on Windows 8, Windows 10, or Windows Server 2012, go to the Start screen and click the Samples tile.
2. Click Windows Forms in the left pane and then Win Book.
3. Click Open sample in Visual Studio.
4. In Solution Explorer, right-click WinBook solution and choose Build Solution.

   The build creates two binaries, BookWrapper.dll and LegacyBook.dll, in the bin\Debug subfolder of the WinBook solution.

Outline

In order to create and configure a WCF service and then use a client to access it, you need to:

1. Create the WCF service.
2. Define a service contract.
3. Implement the service.
4. Host and test the service.
5. Create and configure a COBOL client application.
6. Run the client and access the service.

Create a WCF Service Project

To start you need to create a solution to hold your WCF service and the client application:

1. Start Visual COBOL with administrative rights. This is to prevent issues for users without administrator privileges for the namespace the WCF service uses.
2. Click File > New > Project.
3. Expand Installed > Templates > COBOL and click Managed in the Installed Templates pane.
4. Ensure .NET Framework 4.5 is selected.
5. Select WCF Service Library.
6. Specify a name such as WCFBook.
7. Specify a location for your project and click OK.

Add the BookWrapper and the LegacyBook Demonstrations to the Solution

You need to add the program that includes the functionality to expose as a service to your solution. To do this:

1. In Solution Explorer, right-click your solution and select Add > Existing Project.
2. Navigate to the Forms\BookWrapper subfolder in the Visual COBOL samples.
3. Select BookWrapper.cblproj and click Open.
4. In a similar way, add the LegacyBook demonstration which is installed in the Forms\LegacyBook subfolder in the samples to your solution.

Add the BookWrapper and the LegacyBook projects as references in the WCFBook Project

To enable your service to access the functionality in the BookWrapper and the LegacyBook projects, you must add them as project references to the WCFBook project:

1. In Solution Explorer, right-click the References folder in your WCFBook project.
2. Select Add Reference.
3. Expand Solution in the left-hand pane and click Projects.
4. Check the the BookWrapper and the LegacyBook projects and click OK.

Define the WCF Service Contract and Create the Service

1. Rename the COBOL files in the WCFBook project as follows:
   • Service1.cbl to BookService.cbl
   • IService1.cbl to IBook.cbl
2. Paste the code below in the IBook.cbl file, overwriting the existing content. This defines the service and data contracts.
   • The methods that are marked with the System.ServiceModel.OperationContract() attribute define the operations from the BookWrapper program that are exposed through the service endpoints.
   • The WCFBookWrapper.Book class that is marked with the DataContract attribute exposes the data from the BookWrapper program.

          interface-id WCFBook.IBook
                        attribute System.ServiceModel.ServiceContract().
            
          method-id GetData public
              attribute System.ServiceModel.OperationContract().
          procedure division using by value the-value as binary-long
                             returning return-value as string.
          end method.
   
          method-id GetDataUsingDataContract public
              attribute System.ServiceModel.OperationContract().
          procedure division using by value stockNumber as string
                             returning return-value as type WCFBookWrapper.Book.
          
          end method.
          
          method-id Read public attribute System.ServiceModel.OperationContract().
          procedure division using by value stockNumber as string returning theBook as type WCFBookWrapper.Book.
          end method.      
   
          end interface.
   
          class-id WCFBookWrapper.Book attribute DataContract().
          
          working-storage section.
          01 BookTitle string property as "Title" attribute DataMember().
   	   01 BookType string property as "Type" attribute DataMember().
   	   01 BookAuthor string property as "Author" attribute DataMember().
          01 BookStockno string property as "StockNumber" attribute DataMember().
          01 BookRetail decimal property as "RetailPrice" attribute DataMember().
          01 BookOnhand binary-long property as "NumberOnHand" attribute DataMember().
          01 BookSold binary-long property as "NumberSold" attribute DataMember().
          01 StockValue float-short property as "StockValue" attribute DataMember().
          
          method-id New.
          working-storage section.
          01 newBook type WCFBookWrapper.Book.
          procedure division using by value stdbook as type BookWrapper.Book.
              set BookTitle to stdbook::Title
              set BookType to stdbook::Type
              set BookAuthor to stdbook::Author
              set BookStockno to stdbook::StockNumber
              set BookRetail to stdbook::RetailPrice
              set BookOnhand to stdbook::NumberOnHand
              set BookSold to stdbook::NumberSold
              set StockValue to stdbook::StockValue
              goback.
          end method.
          
          end class.

3. Paste the code below into the BookService.cbl file. This is the actual WCF service.

          class-id WCFBook.Service1 
                    implements type WCFBook.IBook. 
                     
          working-storage section. 
    
          method-id GetData public. 
          procedure division using by value the-value as binary-long 
                             returning return-value as string. 
              set return-value to string::Format("You entered {0}" the-value) 
              goback. 
          end method. 
    
          method-id GetDataUsingDataContract public. 
          working-storage section. 
          01 book type BookWrapper.Book. 
          01 bookException type BookWrapper.BookException. 
          procedure division using by value stockNumber as string returning theBook as type WCFBookWrapper.Book.                
    
              try                          
                  set book to type BookWrapper.Book::Read(stockNumber) 
                  set theBook to new WCFBookWrapper.Book(book) 
              catch bookException 
                  raise new System.ServiceModel.FaultException(bookException::Message) 
              end-try 
              goback. 
          end method. 
           
          method-id Read public. 
          working-storage section. 
          01 book type BookWrapper.Book. 
          01 bookException type BookWrapper.BookException. 
          procedure division using by value stockNumber as string returning theBook as type WCFBookWrapper.Book.
    
              try 
                  set book to type BookWrapper.Book::Read(stockNumber) 
                  set theBook to new WCFBookWrapper.Book(book) 
              catch bookException 
                  raise new System.ServiceModel.FaultException(bookException::Message) 
              end-try 
              goback. 
          end method.       
    
          end class. 

Provide Access to the Legacy Code

Additionally, you need to configure your WCF service to call the BookWrapper code as follows:

1. Right-click the App.config file in your WCF service project and select Open.
2. Add the code below immediately after the opening <configuration> tag:

   
     <configSections>
       <!--The following code declares a section group for application configuration -->
       <sectionGroup name="MicroFocus.COBOL.Application">
         <section name="Switches" type="System.Configuration.NameValueSectionHandler" />
         <section name="Environment" type="System.Configuration.NameValueSectionHandler" />
       </sectionGroup>
       <!--The following code declares a section group for run-time configuration -->
       <sectionGroup name="MicroFocus.COBOL.Runtime">
         <section name="Tunables" type="System.Configuration.NameValueSectionHandler" />
         <section name="Switches" type="System.Configuration.NameValueSectionHandler" />
       </sectionGroup>
     </configSections>
     <MicroFocus.COBOL.Application>
       <Switches />
       <Environment>
         <add key="dd_bookfile" value="%Public%\Documents\Micro Focus\Product Name\Samples\BookData\bookfile.dat" />
       </Environment>
     </MicroFocus.COBOL.Application>
    

3. Save and close the App.config file.
4. Build the WCFBook project.

Configure the service endpoints

You need to configure the service endpoint details as follows:

1. Right-click the App.config file in your WCF service project select Edit WCF Configuration.
2. In the Microsoft Service Configuration Editor, expand WCFBook.Service1.
3. Click Host.
   Note: The default base address of the service is localhost - Visual Studio hosts the service on your machine.
4. Expand Endpoints and click on the first item in the group.

   This displays the general details of the endpoint - the address of the service, its binding and the service contract you want to expose - all known as the ABC of the endpoint. You need to configure the endpoint to use the IBook contract you defined earlier.

5. On the General tab, click on the row for Contract.
6. Navigate to the \bin\Debug subfolder in the WCFBook project directory.
7. Double-click the WCFBook.dll file.
8. Select the WCFBook.IBook contract and click Open.
9. Click the second item under Endpoints.

   This is the default endpoint that exposes metadata details about your service through the IMetaData Exchange contract.

10. Click File > Save in the Configuration Editor and close the window.

Start and Test the Service

Visual Studio provides a built-in WCF Service Host application and a WCF Test Client application to help you test your service without your own client application. This is enabled by default on the WCF Options tab in the project properties.

1. In Solution Explorer, right-click the WCFBook project and select Set as StartUp Project.
2. Click Debug > Start Without Debugging.

   Visual Studio hosts your service in the WCF Service Host and loads it in the WCF Test Client application. The test client displays the endpoint for your service and the operations that are exposed.

3. Double-click the GetDataUsingDataContract() operation.

   This displays the operation details and enables you to test the operation with various parameters.

4. In the Request pane, change the value for stockNumber from null to 1111 and press Enter.
5. Click Invoke.

   This displays the details about record 1111 in the BookWrapper application in the Response pane.

6. Test the Read operation with other stock numbers. The valid numbers are 1111, 2222 and 3333.
7. Close the WCF Test Client application.

Create a WCF Client Application

In the real world, you use various client applications to access services through their available endpoints. As part of this tutorial, you will create a simple managed console application that accesses the BookWrapper application through the WCF service contract and reads the records that it contains:

1. In Solution Explorer, right-click the solution and select Add > New Project.
2. Select the managed Console Application template.
3. Specify a name such as WCFClient and click OK.

Add the WCF Service as a Service Reference to the Client

Visual Studio provides an easy way to use a WCF service in a client application. The Add Service Reference functionality adds the service to the client project and generates a proxy for the client to use.

1. Start the WCF Service.
2. Right-click the project for the client and choose Add Service Reference.
3. Click Discover in the Add Service Reference dialog to locate the WCF service.
4. In the Namespace field, rename the namespace for the service to WCFBook.
5. Click OK.

Edit the Client Application

You need to program your WCF client so that it uses the exposed operations of the WCF service reference. In this tutorial, the client uses the Read operation to access the information in the BookWrapper application and displays the record for a specified stock number.

1. Edit Program1.cbl in the project for the client application.
2. Replace the code in the COBOL program with the following:

          program-id. Program1 as "WCFClient.Program1".
   
          data division.
          working-storage section.
          01 stock-no              string.
          01 bookClient            type WCFBook.BookClient.
          01 myBook                type WCFBook.Book.
          
          procedure division.
   
          invoke type System.Console::WriteLine("Enter a stock number and press Enter.")
   
          set stock-no to type System.Console::ReadLine() 
          set bookClient to new WCFBook.BookClient
          set myBook to bookClient::Read(stock-no)
          
          invoke type System.Console::WriteLine(myBook::Title)
          invoke type System.Console::WriteLine(myBook::Type)
          invoke type System.Console::WriteLine(myBook::Author)
          invoke type System.Console::WriteLine(myBook::StockNumber)
          invoke type System.Console::WriteLine(myBook::RetailPrice)
          invoke type System.Console::WriteLine(myBook::NumberOnHand)
          invoke type System.Console::WriteLine(myBook::NumberSold)
          invoke type System.Console::WriteLine(myBook::StockValue)
          
          invoke type System.Console::WriteLine("Press Enter to exit.")
          invoke type System.Console::ReadLine()
          
          
                     goback.
              
          end program Program1.

3. Click File > Save.

Configure the Client Endpoints

You need to configure the client so that it uses the WCF service endpoint and the service contract:

1. Right-click the app.config file in the WCFClient project.
2. Click Edit WCF Configuration.
3. In the Configuration pane, expand Client and then Endpoints.
4. Click WCHttpBinding_IBook.
5. In the Client Endpoint pane and on the General tab, click on the row for the Contract.
6. Navigate to the \bin\Debug subfolder in the directory of the WCFService project.
7. Double-click WCFBook.dll.
8. Select the WCFBook.IBook contract and click Open.
9. In the Microsoft Service Configuration Editor window, click File > Save.
10. Close the configuration editor.

Use the Client to Access the Service

1. Set the WCFClient project as the StartUp project for the entire solution.
2. Click Debug > Start Debugging.

   This hosts the service in the WCF Service Host and starts the client.

3. In the console, enter a valid stock number and press Enter.

   The record for that stock number is displayed.