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Sample Web Service: EG2

In all the previous examples, we have relied upon ASP.NET to compile the APLScript into a .NET class prior to running it. This sample illustrates how you can make a .NET class yourself.

For this example, the Web Service script, which is supplied in the file samples\asp.net\webservices\eg2.asmx (mapped via an IIS Virtual Directory to the URL http://localhost/dyalog.net/webservices/eg2.asmx)is reduced to a single statement that merely invokes the pre-defined class called APLServices.Example.

The entire file, viewed in Notepad, is shown below.

eg2_1
Figure 1: eg2_1

Given this instruction, ASP.NET will locate the APLServices.Example Web Service by searching the bin sub-directory for assemblies. Therefore, to make this work, we have only to create a .NET assembly in samples\asp.net\aplservices\bin. The assembly should contain a .NET Namespace named APLServices, which in turn defines a class named Example.

The procedure for creating .NET classes and assemblies in Dyalog APL was discussed in Writing .NET Classes in Dyalog APL. Making a WebService class is done in exactly the same way.

Note that the sub-directory samples\asp.net\aplservices\bin already contains copies of the dependent Dyalog DLLs that are required to execute the code.

Start Dyalog as Administrator. This is essential both to allow you to create an assembly.

Starting with a CLEAR WS, create a namespace called APLServices. This will act as the container corresponding to a .NET Namespace in the assembly. 

      )NS APLServices
#.APLServices

Within APLServices, create a class called Example that inherits from System.Web.Services.WebService. This is the Web Service class. 

      )CS APLServices
#.APLServices
      )ED ○Example

:Class Example: WebService                        
:Using System                                     
:Using System.Web.Services,System.Web.Services.dll
    ∇ R←Add arg                                   
      :Access webmethod                           
      :Signature Int32←Add Int32 arg1, Int32 arg2 
      R←+/arg                                     
    ∇                                             
:EndClass

Within APLServices.Example, we have a function called Add that will represent the single method to be exported by this Web Service.

Fix the class, then click File/Save As ... in the Session menubar and save the workspace in samples\asp.net\aplwebservices\bin. 

C:\Program Files\Dyalog\Dyalog APL 15.0 Unicode\Samples\asp.net\webservices\bin\eg2.dws saved Mon Sep 26 15:31:56 2016

Select the Export… item from the Session File menu, and save the assembly as eg2.dll in the same directory, that is, samples\asp.net\webservices\bin.

eg2_2
Figure 2: eg2_2

When you click Save, the Status Window displays the following information to confirm that the assembly has been created correctly.

eg2_3
Figure 3: eg2_3

Testing EG2 from a Browser

If you point your browser at the URL: 

 http://localhost/dyalog.net.15.0.unicode.32/webservices/eg2.asmx

ASP.NET will fabricate a page about it for the browser to display as shown below.

The Add method exposed by APLServices.Example is shown, together with a Form from which you can invoke it.

eg2_4
Figure 4: eg2_4

If you enter the numbers 123 and 456 in the fields provided, then press Invoke, the method will be called and the result displayed as shown below.

eg2_5
Figure 5: eg2_5