Pilgrim's OSF DCE-based Services Architecture

Within a heterogeneous distributed computing environment, it is necessary to integrate services, such as printing and mail, that are scattered throughout the environment and which perform single logical tasks. This paper discusses a general purpose architecture which provides a framework for designing complex multi-user systems capable of interfacing with these services. The merits of this generalized approach are reflected in the following two case studies of applications being developed by the University of Massachusetts’ Project Pilgrim: PIMS (Pilgrim Interface to Mail Systems) and PIPS (Pilgrim Interface to Print Systems). These designs incorporate the principles of this architecture and utilize OSF DCE. PIPS permits the uniform access of a heterogeneous system’s printing facilities and provides support for printing complex multi-document jobs. This interface is platform independent, supports flexible mappings between logical and physical printers and permits all printing resources to be visible throughout the cell. ISO DPA is used for specifying print job attributes and non-DCE systems are also supported. PIMS similarly allows distributed mail clients to work directly with a set of uniform, system independent primitives. This interface remains consistent regardless of the mail environment/system-architecture native to the client or that used to store a given user’s mailbox and folders. These primitives allow multiple mailboxes to appear as a single unified (coherent) postbox. This enables operations to be performed on individual messages or folders residing on several different machines regardless of underlying mail protocol, the user’s present host, hardware or operating system. PIMS supports variable format messages (multimedia) including executable code, alternate display/audio forms, and message indirection. Various levels of mail access are supported on clients ranging from laptop PCs to supercomputers.