Remote data access solution
problem
ADO allows applications to access and modify data sources (sometimes called double systems). For example, if it is to be connected to a data source containing the required data, the connection is a direct connection in a double system.
However, there is also a need to access the data source indirectly through a medium like Microsoft Internet Information Server (IIS). This method is called a three-layer system. IIS uses a client / server system that helps local (or client) applications to efficiently call remote (or server) programs via Internet or intranet. The server program accesss the data source and can selectively handle the obtained data.
For example, your intranet web page contains applications written in Microsoft® Visual Basic® Scripting Edition (VBScript) that connects to IIS. IIS corresponds to the actual data source, retrieves data, and handles data in some way, and then returns the processed information to the application.
In this example, the application has never been directly connected to the data source, which is done by IIS. IIS uses ADO to access data.
Note that the client / server application is not necessarily based on Internet or intranet (ie web), which can be constructed only by the compilation program on the local area. However, typical examples are web-based applications.
Because some visual controls such as mesh, check boxes or lists can be used to return information, the return information must be easily used by visual controls.
The user needs to be a simple and effective application programming interface, which should support the three-layer system, and can be easily returned as information as information on the double system. "Remote Data Service" (RDS) is an interface.
solution
RDS defined programming model (access, and update data source required) Access data by an intermediate medium such as Internet Information Server. The programming model summarizes all the features of RDS.
The programming model is expressed and implemented programming models through the object model, ie "object" set. Objects have "methods" that can operate data, and "attributes" that can represent data properties or control certain object methods.
As an object is "event", the event is used to notify some operations that have occurred, or will happen.
