How to write a Server (Delphi)

This article shows how to create your first server using the Remoting SDK (Delphi edition). Having read this article, you will probably want to continue with its companion: How to write a Remoting SDK Client (Delphi).

You may use this article as a tutorial and so all steps you need to take are presented as bullet points. The source code for the completed project is attached to this article - see the link at the bottom.

Selecting the server type

The first step is to select the server type you want to create.

• From the Delphi IDE, click on File -> New -> Other and switch to the Remoting SDK tab.

This is what you will be presented with (may differ, of course, depending on your Delphi and Windows version):

In this example we will create a simple VCL Standalone Executable Server. This is the simplest type of server that you can create and it does not require any web server or additional configuration to run.

• Select VCL Standalone and click OK.

Selecting the project options

The following dialog will allow you to enter basic options such as the name of your project and the project's path.

• Set Project Folder and Project Name as shown below (obviously you can choose other values if you prefer) :

For the purposes of this tutorial, we will keep it simple and accept the defaults for Advanced Project Options.

• Uncheck Also create a matching client application and a project group

Normally, you will want this option checked to create a client application too, but you will need to know how to do these simple steps yourself for creating additional clients. Accordingly, we show this separately in the How to write a Remoting SDK Client (Delphi) article.

• Click OK, which will create the server project.

Activate your server

Your project is now created and the main form is displayed inside the Delphi IDE. On top of the form you will see two components which correspond to the Server Class and Message Class that we selected in the previous dialog.

• Click on the ROServer component and set its Active property to TRUE.

• Hit Ctrl-F9 to compile your project.

The Remoting SDK CodeGen

Immediately after hitting F9, a dialog is presented, thus allowing you to select the facilities already provided by the service.

• Click OK and the compilation will continue.

Once this is done, the project will contain new units (see below) and a small window will be displayed at the bottom of your screen (in Delphi 6), or CodeGen messages will appear in your Message pane (Delphi 7 onwards).

Behind the scenes, the Remoting SDK preprocessor has analyzed the NewLibrary.rodl file (generated when the project was first created). The preprocessor found a definition of a service for which there was no implementation unit and then created it.

You will see that three files have been generated:

• NewLibrary_Invk.pas: contains all the internal 'plumbing'. It is regenerated each time you compile and is used by the server only.
• NewLibrary_Intf.pas: the service interface used by the server and clients. Again, this is auto-regenerated as needed and any changes you make would be lost.

• NewService_Impl.pas: contains the service implementation and is where you place your code. Unlike the other two files, this file does not get regenerated. If you update the service (e.g. via the Tools -> Remoting SDK -> Edit Service Library menu item, as shown later) and then compile, you will get errors related to missing method(s). Simply add their interface declarations to the class and hit Ctrl+Shift+C to add implementation stubs for you to complete.

• Select the NewService_Impl.pas unit and provide the following implementation for the Sum and GetServerTime test methods:

function TNewService.Sum(const A: Integer; const B: Integer): Integer;
begin
  result := A + B;
end;

function TNewService.GetServerTime: DateTime;
begin
  result := Now;
end;

• Hit F9 (or select the Tools -> Remoting SDK -> Launch Server Executable menu item) to launch your server.

Testing the server

Now that your server is running, it's time to check if it's working.

Open Internet Explorer (or any other browser) and type in the following URL: http://localhost:8099/Bin

You will see the following XML document displayed:

This is it! The server is successfully running and ready to be used by Remoting SDK clients. The only code we had to write was for our actual services.

Additional

If you open your project directory, you will see the NewLibrary.rodl file, which you will maintain via the supplied Service Builder tool.

• From inside Delphi, click on Tools -> Remoting SDK -> Service Builder.

The Remoting SDK Service Builder will now be launched and the NewLibrary.rodl file will be open.

This tool is all you need to add methods to your service and modify the NewLibrary.rodl file. The Sum and GetServer time methods are the default methods that are added to each first service of all your RO Server projects.

You are now ready to create a client to access this service, see How to write a Remoting SDK Client (Delphi) article.

Enabling JavaScript Access on the Server

Drop the TROJavaScriptHttpDispatcher component onto the server form or data module, and connect its Server property to your server channel component. Please pay attention to the default values of its properties: DefaultFile=index.html, Folder=.\html and Path=/js/ - we'll see these values later.

If you are using JSONMessage, set its WrapResult, its IncludeTypeName, its SessionIdAsId and its SendExtendedException properties to true.

The server is ready, now to How to write a Remoting SDK Client (JavaScript).