Sample: .NET COBOL Dialog System Application

The .NET COBOL Customer sample ManagedCustomer.sln is broadly the original Customer sample that was supplied with Dialog System. The key difference with this sample is that it is compiled to .NET COBOL code and run under .NET. The existing Dialog System run-time calls remain but are automatically converted to Platform Invoke calls into the native code. In other words, the user interface and screensets are all still running as native code. The following diagram illustrates this.

This sample is using the Platform Invoke technique, which enables .NET COBOL code to call unmanaged functions implemented in dynamic link libraries (.dlls). Platform invoke is similar to an API call.

The sample has just one project, a .NET COBOL code project, comprising:

Properties - Notice that the project is compiled to .NET COBOL code. See Project > ManagedCustomer Properties > Application tab, which shows the application is .NET because it targets the .NET Framework (4, in our case).
References - Notice that one of the references is to the Dialog System run-time system, dsgrun.dll, which is compiled as native COBOL. This enables the .NET COBOL to call into dsgrun, using CALL statements. These CALL statements generate a Platform Invoke call if the CALL matches an entry in the native .dll.
Customer.cbl - original source code, plus some additional code to call the native Dialog System run-time system correctly.
Customer.cpb - original copybook generated from the Dialog System data block. This is unchanged.
Customer.gs - original screenset, which is unchanged.
Cust.ism - the original data file, which is unchanged.

Customer.cbl

Customer.cbl contains the original code for the business logic and for interaction with the Dialog System screenset.

The only change to Customer.cbl is to ensure that the .NET COBOL code calls the native Dialog System run-time system correctly. The code must supply all the parameters that Dialog System might need (or at least signify that we are not passing all the parameters). The original Customer sample uses only two parameters, so the code here needs to add a third parameter as 'omitted'.

  Call-Dialog-System SECTION.
      CALL dialog-system USING ds-control-block,
                               customer-data-block
                               omitted