Messaging Application Programming Interface
From Wikipedia, the free encyclopedia
Messaging Application Programming Interface (MAPI) is a messaging architecture and a Component Object Model based API for Microsoft Windows. MAPI allows client programs to become (e-mail) messaging-enabled, -aware, or -based by calling MAPI subsystem routines that interface with certain messaging servers. MAPI is closely related to MAPI/RPC, the proprietary protocol that Microsoft Outlook uses to communicate with Microsoft Exchange.
Simple MAPI is a subset of 12 functions which enable developers to add basic messaging functionality. Extended MAPI allows complete control over the messaging system on the client computer, creation and management of messages, management of the client mailbox, service providers, and so forth. Simple MAPI ships with Microsoft Windows as part of Outlook Express/Windows Mail while the full Extended MAPI ships with Office Outlook and Exchange.
As well as the Extended MAPI client interface, programming calls can be made indirectly through the API client interface Simple MAPI, or through the Common Messaging Calls (CMC) API client interface, or by the object-based CDO Library interface. These three methods are easier to use and designed for less complex messaging-enabled and -aware applications. (Simple MAPI and CMC were removed from Exchange 2003.)
MAPI was originally designed by Microsoft. The company founded its MS Mail team in 1987, but it was not until it acquired Consumers Software Inc in 1991 to obtain Network Courier that it had a messaging product. Reworked, it was sold as MS PC Mail (or Microsoft Mail for PC Networking). The basic API to MS PC Mail was known as MAPI version 0 (or MAPI0). MAPI uses functions loosely based on the X.400 XAPIA standard.
MAPI includes facilities to access message transports, message stores, and directories.
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[edit] Service provider interface
The full Extended MAPI interface is required for interfacing messaging-based services to client applications such as Outlook. For example, several non-Microsoft e-mail server product vendors created "MAPI service providers" to allow their products to be accessed via Outlook. Notable examples included Zimbra, HP OpenMail, IBM Lotus Notes, Zarafa and Bynari.
MAPI0 also had a service provider interface of sorts. Indeed, Microsoft used this to interface MS Mail to an email system based on Xenix, for internal use.
Extended MAPI is the main e-mail data access method used by Outlook, to interface to Microsoft Exchange, via MAPI service providers shipped with Outlook.
[edit] MAPI/RPC protocol details
The MAPI/RPC protocol is proprietary to Microsoft, implemented using Microsoft's MSRPC variant of the DCE/RPC protocol.[1] Microsoft does not publish the details of the protocol to the public. However, it does license the protocol for a fee.
What is known about the protocol comes predominantly from third-parties who have reverse-engineered the protocol. Complicating such efforts, the protocol contents are filtered with an XOR operation against 0xa5 hexadecimal.[2] This helps ensure that the protocol contents are not directly readable as clear text.
"MAPI protocol" is a colloquial name for the MAPI/RPC. At times, Microsoft has also called it "Exchange RPC" and "Outlook-Exchange Transport Protocol".
[edit] See also
[edit] External links
- Messaging API at MSDN Library
- OpenChange project - details of MAPI protocol and tools for exploring MAPI protocol
[edit] References
- ^ Leighton, Luke Kenneth Casson (2001). Samba - The Next Generation: Architecture and Design, Introduction. Retrieved on 2006-03-20.
- ^ Leighton, Luke Kenneth Casson (2000). encryption of MAPI. Retrieved on 2006-03-20.
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