AIS 4.1 Adds New ClearPath Call Out Services Feature

When you use the ClearPath® Application Integration Services (AIS) tool, you’ll make it incredibly easy for your team to create cross-platform applications that blend proven ClearPath Forward® attributes with the familiarity of the Microsoft® Windows® environment.

This goal – a simple, seamless, cross-platform development environment – remains top of mind as
we work to update and extend the capabilities in AIS. And with the release of AIS 4.1, we’ve added an exciting new feature that brings more freedom and flexibility to the tool: ClearPath call out services.

With this new feature, you’ll be able to call out to web services and easily enhance your existing applications with new capabilities – without having to move them to another platform.

How it Works

The ClearPath call out services feature maps a web service or .NET DLL call into something that looks like a procedure call. So as far as your ClearPath Forward program is concerned, it’s actually making a routine call into an external library.

Meanwhile, the infrastructure behind the scenes calls into a .NET DLL, which can convert between a format that is compatible with the ClearPath Forward environment and one that’s needed for commands to, and responses from, a web service.

At runtime, your application “sees” a proxy generated by a Unisys provided program. The proxy looks and behaves like an ordinary piece of external code – you call it, it returns a result – but the infrastructure results in a function within a .NET DLL being called.

It’s then passed through the parameters the calling program provides, converted into a .NET compliant format, and returns results to the caller that are converted back to a ClearPath Forward compliant format. The call uses an authenticated connection you have the option of encrypting, so the data that’s passed each way is both protected and confidential.

The use of a customized DLL makes calling web services easier by tailoring the web service interface to match the expectations of your ClearPath Forward application. For example, while a web service might return a JSON encoded list of objects, it’s likely that the corresponding ClearPath Forward COBOL structure is a simple array of records with an OCCURS clause.

Here’s a common use case: Imagine your application needs to utilize a feature that’s easily accessible from .NET, such as SOAP-based web services. By providing the .NET DLL as a “bridge,” the ClearPath call out services feature makes it possible to use .NET capabilities right in your ClearPath MCP or OS 2200 environment – with minimal specialized programming knowledge required. As a result, you’ll find it easier to utilize core ClearPath Forward attributes as you take advantage of .NET capabilities and more readily available programming skills.

Generating the Interface

In the ClearPath MCP operating environment, the connection endpoint is an individual application – either a batch application or a COMS TP – from which the user credentials will be inherited. For OS 2200 environments, the connection endpoint is the AIS subsystem, with programs making individual method calls using a connection pool.

The .NET DLL to be called is specified by the program – it’s likely a default provided by the generated proxy – and isn’t expected to change for the life of a connection. Because each MCP endpoint is owned by an application, it can make multiple calls and retain state between them. Idle connections won’t be reused, however, because they aren’t shared by other application instances. Because OS 2200 programs make individual calls through a pool of connections, they may not retain state in called methods. But they won’t bear the overhead of individual connections.

To learn more about the ClearPath call out services feature, please refer to the “Application Integration Services Server Installation and Programming Guide For ClearPath Call Out Services” documentation on the support site. And if you’d like some help putting this feature to use in your organization, please contact your Unisys sales representative today.