Application architecture

The application architecture provides the framework for the policy for file use, building on file server and window server features. Policy is implemented by the UI libraries and shell programs.

Since these policies are either fixed, or facilitated by high-level dialogs in the GUI, most application programs do not need to provide any code to implement them. Application writers should, however, be aware of these policies, and deliver their applications in such as way that they are fulfilled.

The key policy is that application program files must be located in directories of the form \system\apps\program\. Initialisation and configuration files should be in the same directory, or where the application is in ROM, in the equivalent directory on a writable drive.

Document files can be located in any desired directory except \system\, and may be given any name: the system will not alter the capitalisation of that name, and will not attempt to add or remove any extension.

The application architecture does not dictate the requirements for all files, or even all file stores. For instance, an e-mail application is not document based. An e-mail subsystem would store its messages in a directory structure using special e-mail policies to implement inbox, outbox and folders. Normally, this folder would be in a \system\ directory.