Creating the application server

You create an application server very much as you create most database applications. The major difference is that the application server includes a dataset provider.
To create an application server, start a new project, save it, and follow these steps:

1.Add a new remote data module to the project. From the main menu, choose File|New. Choose the Multitier page in the new items dialog, and select

Remote Data Module if you are creating a COM Automation server that clients access using DCOM, HTTP, or sockets.
Transactional Data Module if you are creating a remote data module that runs under MTS or COM+. Connections can be formed using DCOM, HTTP, or sockets. However, only DCOM supports the security services.

NB:When you add a remote data module to your project, the Wizard also creates a special COM Automation object that contains a reference to the remote data module and uses it to look for providers. This object is called the implementation object.

2.Place the appropriate dataset components on the data module and set them up to access the database server.

3.Place a TDataSetProvider component on the data module for each dataset. This provider is required for brokering client requests and packaging data.

4.Set the DataSet property for each provider component to the name of the dataset to access. There are additional properties that you can set for the provider.

5.Write application server code to implement events, shared business rules, shared data validation, and shared security. You may want to extend the application server’s interface to provide additional ways that the client application can call the server.

6.Save, compile, and register or install the application server.
When the application server uses DCOM, HTTP, or sockets as a communication protocol, it acts as an Automation server and must be registered like any other ActiveX or COM server.

If you are using a transactional data module, you do not register the application server. Instead, you install it with MTS or COM+.

7.If your server application does not use DCOM, you must install the runtime software that receives client messages, instantiates the remote data module, and marshals interface calls.

For TCP/IP sockets this is a socket dispatcher application, Scktsrvr.exe.
For HTTP connections this is httpsrvr.dll, an ISAPI/NSAPI DLL that must be installed with your Web server.


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