Calling ClearPath Call Out Services from AB Suite Using Application Integration Services
With the ClearPath® Application Integration Services (AIS) product, you can take advantage of APIs that enable applications running in one operating environment to access resources, such as files or other applications, in a different operating environment.
For example, using AIS, a Microsoft® Windows® application can access COMS transactions or read ClearPath MCP files. Or, AIS can enable a ClearPath MCP application to call out to an external web service residing in the Windows environment.
No matter how you use AIS, you’ll be able to reduce the amount of code your developers have to design, write, and test.
This focus on simplicity is particularly apparent in the product’s ClearPath Call Out Services feature. With the help of this feature, your programmers can extend existing ClearPath applications with newer capabilities – without having to move the applications to another platform.
Your programmers can do this through a familiar programming paradigm that maps a web service or .NET DLL call into something that looks like a procedure call. So as far as the ClearPath program is concerned, it’s making a routine call into an external library. Behind the scenes, meanwhile, the infrastructure we provide calls into a .NET DLL that can switch between a ClearPath friendly format and whatever is required by other applications and responses from a web service.
As shown below, the ClearPath Call Out Services workflow begins when you submit a transaction to the AB Suite application. The transaction processing function then calls the MCP proxy library, which in turn calls out to Windows. The call is processed in the Windows environment – in this case by a .Net DLL – and the result is returned to the AB Suite application.
When calling out from your AB Suite application to the MCP Library that will in turn call out to a web service or DLL, keep the following steps in mind:
1. Define the library as a class with “IsExternal” set to “true.” In the example below, the “AIS_Library” class is created in the Library folder
2. In the Property Pages of the “AIS_Library” class, enter the data in the “Library Name,” “ByFunction,” “Library Usercode,” and “Library Pack” (assuming it’s different from the Application Default pack) fields as shown below.
3. Define all method signatures exported from the AIS/METHOD/LIB that will be invoked by the
AB Suite application under the above Class. In this example there are three methods defined in the “AIS_Library” class: “AddInteger,” “AddReals,” and “SubtractNumbers,” so we add the signatures of these methods under the external “AIS_Library” class.
4. Run the AIS “LibGen” utility in Windows to generate the files required by the MCP environment – the MCP proxy library source and associated files – based on the web service or DLL that will be invoked from the AB Suite application.
5. After compiling the MCP proxy library source on the MCP host, the ClearPath Call Out Services feature is ready for use in AB Suite. Additionally, once you’ve completed steps one through three as described above, you’re free to write the necessary LDL+ logic to invoke the methods. For example, using the definitions noted above, the LDL+ logic to invoke the “AddInteger” method would be: “AIS_Library.AddIntegers(IntResult, Integer1, Integer2),” where “IntResult,” “Integer1,” and “Integer2” are the number variables/attributes declared in your application Model.