Message +Type Module Overview

Message Type Modules (MTMs) are polymorphic DLL plug-ins that implement +the interfaces defined by the Message Server framework to handle various message +types—such as, IMAP4, POP3, SMTP, SMS and MMS.

Purpose

Client applications can access different +types of message and every message type must handled in a specific way. To +support a new message type within the client applications, MTMs to implement +that type must be provided. The following points are specific to each message +type, and so must be implemented in an MTM:

Message structure
User interface requirements
Addressing mechanism
Error handling mechanism
MTM DLL information

A Message Server abstraction that is used to locate and load particular +MTM components.

Description

The MTM architecture is the plug-in +scheme provided by the Messaging Framework to integrate different message +transports to the Message Server. The plug-in scheme consists of four interfaces, +the UI MTM, UI Data MTM, Client MTM and Server MTM.

Client MTM manages the +message type’s data model, providing the UI MTM and client applications with +interfaces to access and to search for messages.
User Interface (UI) +Data MTM provides icons, menu text and a list of capabilities for a message +type.
User Interface (UI) +MTM implements the user interface required for the message type, including +a viewer, editor and dialog settings.
Server MTM provides +message transport over the network and manages a queue of outstanding client +requests, and ensures that more than one message of a given type is sent simultaneously.

Each of the MTM DLLs is a polymorphic DLL that exports an instance +of a system-defined base class. The Message Server and client applications +use these base class interfaces to access MTM functionality in a generic and +extensible way. The MTM in turn implements a specialized version of the class +to provide specific message type functionality.

Client applications +can load and use the UI MTM, UI Data MTM and Client MTM DLLs. The DLLs are +loaded within the client’s process space. The Server MTM DLLs are loaded within +the Message Server process. The Messaging Middleware architecture allows clients +to access the combined functionality of the Message Server and the Server +MTMs through a single server interface. The following figure shows the MTM +architecture.

+ MTM architecture + +

Message Server and MTMs

The following figure shows +the relationship between the Message Server and MTMs. The grey classes are +realisations of the MTM interfaces defined by the Messaging Framework. The +Message Server depends on the Server MTM interface and controls access to +message data and delegates protocol-specific requests to Server side MTMs. +Messaging clients depend on the Client, UI and UI Data MTM interfaces and +the Message Server client API.

+ Relationship between Message Server and MTMs + + +

MTM class summary

Messaging Middleware provides +the following base classes, which defines the component interfaces for MTM +implementations.

The base class for UI +MTMs is CBaseMtmUi.
The base class for UI +Data MTMs is CBaseMtmUiData.
The base class for Client +MTMs is CBaseMtm.
The base class for Server +MTMs is CBaseServerMtm.

Important: MTMs can also provide message type-specific functionality +that is not defined by the base class interfaces. For example, for IMAP4, +perform a full synchronization with a remote service; for POP3, connect to +a remote server and download messages. The APIs for the client interfaces +are extensible through run time type information provided by the QueryCapability API, +and the InvokeAsyncFunction and InvokeSyncFunction APIs.

For +information on how to implement the base classes, see the Implementing +MTMs.

MTM functions

The MTM DLLs provide the following +functions. MTMs implement them according to the requirements for the message +type:

Querying functionality

Allow +the client applications to query the supported functionality for the message +type. For example, the maximum message size or whether attachments are supported.
Message management functionality

Allow +the client applications to manage the messages, for example, to send, reply +and forward messages.
Attachment management +functionality

Allow the client applications to handle attachments. +For example, to add, remove or create an attachment for a particular message.