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The Messaging Architecture is a powerful and extensible multi-protocol messaging framework introduced in EPOC Release 5. It offers opportunities to build highly-featured message client applications, and to create plug-in modules to support individual messaging protocols. The set of components that make up such a plug-in module is called a Message Type Module (MTM). All interaction with lower-level communication protocols, such as TCP/IP, is performed by the MTMs.
The ER5 message client application, Email, and the MTMs supplied by ER5POP3 and SMTP Internet mail, SMS, and faxuse the Messaging Architecture. They are, however, designed to be separate components, and the Messaging Architecture can be installed and used without them.
This topic describes the key principles and components of the Messaging Architecture. It assumes a knowledge of the client/server, asynchronous processing, and active objects features of the EPOC architecture.
The full messaging architecture is of some complexity. Developers who need only to add message sending capabilities to their application are recommended first to experiment with the Send As interface, which provides this ability.
The Messaging Architecture supersedes the MSGI interface of EPOC Release 3, which is no longer supported.
The design of the Messaging Architecture results from the following principles:
- Dynamic extensibility: The Messaging Architecture allows message client applications to discover at run-time which MTMs are available, and to be notified if new MTMs are installed. Each MTM offers interfaces that allow message client applications to find its capabilities, and to obtain how the MTMs facilities should be offered to the user through the UI, so that appropriate commands can be dynamically added to menus.
- Multiple simultaneous message client applications: The Messaging Architecture can support multiple message client applications having simultaneous access to message data. Examples of such potential message client applications are ER5s Email application, PC mail synchronisation utilities, and messaging-aware applications sending documents as messages.
- Generic message description and operations: The Messaging Architecture allows message client applications to perform common operations, such as copying, moving, and sorting messages, without knowing the particular message type. There is a generic message description structure to allow message properties to be obtained. These features help message client applications to be designed without foreknowledge of the message protocols that may later be used.
- Memory-efficiency: Message client applications need only load particular MTM components when these are required as a result of user actions. The Messaging Architectures server operates in a similar way, dynamically loading and unloading components to handle particular message types.
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