Implementing the Client Side

The animation framework requires implementers to write server side and client side code. On the client side, provided by the Window Server Client-Side API, RAnimDll should be derived from for DLL level functionality, and for each animation an RAnim class should be derived. The client side classes can be thought of as thin layers of code that are used to pass information through to the matching server side classes, where the detailed logic is implemented.

Clients must request an animation DLL to be loaded before the animations provided by it can be used. This is done using the RAnimDll.

RAnim provides functions for implementing client side behavior. Generally, the client side code is concerned with setting up and initializing the server side classes which implement the actual animation graphics. The mechanisms that allow information to be packaged on the client side, passed through the Window Server, and recovered on the server side, are described in Passing Arguments from Client to Server.

Two kinds of command function are provided, RAnim::Command() and RAnim::CommandReply(). The choice of which one to use depends on whether a return value is required and whether the command takes effect immediately or can be cached to the Window Server queue. If leaves are possible in code within or called from a command function, a return code should be tested and errors handled appropriately.

The CommandReply() function forces immediate action. In general by the time these functions return, Window Server requests have been carried out. The background to this behavior is Window Server buffering of the requests it receives. In effect the behavior of these commands is to put a request to the Window Server queue and then flush the queue to ensure immediate action. The Command() function is buffered by the Window Server. Although these functions return immediately, there is no guarantee when the Window Server request will actually be carried out.