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Message client applications


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Introduction

Message client applications use the Messaging Architecture and installed MTMs to access messaging functionality. Such applications can be of various types, including:


Basic set-up

A message client application typically performs the following steps in a set-up function, such as the ConstructL function of the application UI class:


User interface

A message client application can then discover the immediate children of the root entry. To display entries to the user in a typical message/folder view format, the application can query the MTM type of each entry, and load icon resources from the appropriate User Interface MTMs.

After an initial message view display, it is up to the message client application to handle user input events and access User Interface MTMs if required. For example, if the user selects an entry and then chooses an Edit command, the application should:

This is the most simple presentation of the steps involved for this single command. Applications with rich user interfaces will define handler functions for many such commands. They will also declare classes to generalise handling of issues such as:


Observers and notification

The Messaging Architecture declares a pair of mixin interfaces, which define session observers and entry observers.

A class that is defined as a session observer is notified of events such as shutdown warnings, new message arrival, and registration of new MTMs. A significant class belonging to a message client application, such as the application UI class, implements the interface to handle such events by updating the display or taking other appropriate action. The client’s Message Server session object can call back the interface whenever it completes a request to the Message Server.

Session observers are important in supporting run-time extensibility of the messaging architecture, as message client applications can be informed of new MTMs being registered. As the registry classes are session observers, they also can update their lists of the available MTM components, allowing new components to be loaded.

Entry observers are notified when an individual entry changes, or when access to a message store has been successfully gained.

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