Tutorial 04 09 Add Controller Class

Exposing Endpoints for Traditional Bridge Routines

You're almost there, only two more steps to go, the next of which is to actually expose your Traditional Bridge routines as endpoints of your web service.

There are several ways that you might choose to do this, depending on what your routines do, and how they may or may not relate to existing functionality exposed by existing controllers in your service.

For example, if your service is exposing OData endpoints for Orders, and your Traditional Bridge routines also expose functionality related to Orders, you may choose to expose them via custom endpoint methods on your existing OrdersController class.

But it may be that your Traditional Bridge functions are not related to other controllers in your service. In that case, it probably makes sense to simply add a new custom controller class. That's the approach we'll take here.

Add a Custom Controller Class

1. In Solution Explorer, right-click on the Services.Controllers class and select Add > Class.

2. Name the new class source file TraditionalBridgeController.dbl and click the Add button.

3. Copy and paste the following code into the new class, replacing the default code:

   ;;*****************************************************************************
   ;;
   ;; Title:       TraditionalBridgeController.dbl
   ;;
   ;; Description: WebAPI controller to expose example Traditional Bridge Routines
   ;;
   ;;*****************************************************************************
   
   import Microsoft.AspNetCore.Authorization
   import Microsoft.AspNetCore.Mvc
   import Microsoft.Extensions.Configuration
   import Microsoft.Extensions.Options
   import Newtonsoft.Json
   import System
   import System.Collections.Generic
   import System.Linq
   import System.Text
   import System.Threading.Tasks
   
   import Services.Controllers
   import Services.Models
   
   namespace Services.Controllers
   
       ;{Authorize}
       {Route("TraditionalBridge")}
       public partial class TraditionalBridgeController extends ControllerBase
   
           ;; Services provided via dependency injection
           private _TraditionalBridgeService, @TraditionalBridgeService
   
           public method TraditionalBridgeController
               aTraditionalBridgeService, @TraditionalBridgeService
           proc
               _TraditionalBridgeService = aTraditionalBridgeService
           endmethod
   
   
   
       endclass
   
   endnamespace
   
   

As you can see, the new class inherits from a base class named ControllerBase (actually Microsoft.AspNetCore.Mvc.ControllerBase), which in a nutshell means that it is an MVC Controller (previously referred to as a WebAPI controller).

Again, the dependency injection pattern is being used, this time to get hold of an instance of a class named TraditionalBridgeService. Does that sound familiar? It should, it's the class that you wrote in the previous module of this tutorial, the one that exposes "wrapper" methods for your Traditional Bridge routines. Yes, it's all starting to come together!

Notice also that the class is decorated with an {Authorize} attribute, but it is commented out. You should change this if authentication is enabled in your environment.

4. If your environment uses authentication (or custom authentication) then remove the comment from the {Authorize} attribute.

Notice also that the controller class is also decorated with a {Route("TraditionalBridge")}. This specifies that the endpoints in the controller will be available at the base address of the service, which on this occasion will NOT include the /odata/v1 part, because this controller is an MVC controller, not am OData controller.

5. Save the code

Adding Endpoint Methods

Similar to when you built the TraditionalBridgeService class, the next task is to add an endpoint method for each of the three Traditional Bridge routines being exposed:

Adding the GetEnvironment Endpoint Method

6. Copy and paste the following code into the TraditionalBridgeController class, between the endmethod and endclass statements:

   {Route("GetEnvironment")}
   public async method GetEnvironment, @Task<IActionResult>
   proc
       mreturn ok(await _TraditionalBridgeService.GetEnvironment())
   endmethod
   

As you can see, this endpoint is available at the URL TraditionalBridge/GetEnvironment, and simply makes a call to the appropriate service wrapper method, returning to the client whatever string value comes back, embedded in a 200 OK response. In this case that's really all that is needed, there really are no other valid response codes, and if there is a serious failure of any kind, MVC will trap the exception and return an HTTP 500 Internal Server Error to the client.

7. Save the code

Adding the GetLogicalName Endpoint Method

8. Copy and paste the following code into the TraditionalBridgeController class, between the endmethod and endclass statements:

   {Route("GetLogicalName/{aLogicalName}")}
   public async method GetLogicalName, @Task<IActionResult>
       required in aLogicalName, string
   proc
       mreturn ok(await _TraditionalBridgeService.GetLogicalName(aLogicalName))
   endmethod
   

This endpoint method is very similar. The URL route is different of course, and there is now a parameter. This means that requests to the service must look something like this:

TraditionalBridge/GetLogicalName/DBLDIR

Where DBLDIR is the name of the server-side logical name that we wish to retrieve the value for.

9. Save the code

Adding the AddTwoNumbers Endpoint Method

10. Copy and paste the following code into the TraditionalBridgeController class, between the endmethod and endclass statements:

{Route("AddTwoNumbers/{aNumber1}/{aNumber2}")}
public async method GetAddTwoNumbers, @Task<IActionResult>
    required in aNumber1, decimal
    required in aNumber2, decimal
proc
    mreturn ok(await _TraditionalBridgeService.AddTwoNumbers(aNumber1,aNumber2))
endmethod

And again, this third endpoint method is similar. Again a different URL route, and this time two query string based parameters, meaning that requests need to look something like this:

TraditionalBridge/AddTwoNumbers/1.1/2.2

Where 1.1 and '2.2' are the numbers that we wish to add together.

11. Save the code

Build the Code

Before moving on, make sure the project builds:

12. Right-click on the Services.Controllers project and select Build.

13. Check the Output window and verify that the build was successful.

    1>------ Build started: Project: Services.Controllers, Configuration: Any CPU ------
    ========== Build: 1 succeeded, 0 failed, 2 up-to-date, 0 skipped ==========
    

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Next topic: Configure Traditional Bridge Environment

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