The video output jack of the VCR sends out video signals according to a predefined video specification. The video service provided by the VCR is represented in Figure 1.2.
The TV was designed for this video specification. Once you hook up the VCR to the TV on the video connection, all the TV has to do is start receiving video signals from the VCR. Any brand of VCR that adheres to the specification will be compatible with the TV.
By separating interface specifications from implementation, and guaranteeing that the specifications will not be altered, we have started to form the basis of the Component Model.
Can we apply this model to software? Lets get back to our simulation program.