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Messaging Architecture
The weblicon Messages module provides a unified view to the user’s messages including send and receive of Email and sending of SMS messages. It is tightly integrated with the weblicon Address Book and provides full functionality for the HTML, WML, Java, VoiceXML and J2ME servers.
IMAP Server
Instead of implementing a proprietary message store, the Weblicon Messages module relies on an IMAP server for managing hierarchical folder structures and storing messages as well as attachments. Using an IMAP server for message storage has several advantages:
- Interoperability with other 3rd party web services which require access to messages. Using standard IMAP interfaces, other server-side applications such as a unified messaging system can have full access to the user’s messages without negotiating a proprietary protocol.
- Compatibility with existing IMAP / POP3 clients such as Netscape Communicator or Microsoft Outlook. In addition to the weblicon Messages module, users are able to access their messages using native desktop mail clients installed on their PCs.
- Instead of moving data from an internal POP3 server to an RDBMS system, all messages are kept in a single, central storage server. This reduces network traffic and load from the RDBMS server.
- Using an IMAP server for storage of folders and messages removes the requirement of building and handling relational database structures for message storage.
- The weblicon PIM is compatible with existing mail infrastructure and can take over existing IMAP-based mailboxes.
JavaMail API
For accessing the IMAP server, the standard JavaMail API is used. The JavaMail architecture has been developed by JavaSoft and is part of the standard Java 2 API. It is available as a separate package and can be used from JDK 1.1.X applications. Using the JavaMail API offers the following architectural advantages:
- Well defined, abstract, object-oriented API for accessing messages via POP3, SMTP and IMAP. A single API can be used to access internal mailboxes via IMAP and external mailboxes via POP3. The JavaMail API hides the complexity of the underlying protocols by offering an object-oriented API to folders and messages.
- Plug-In architecture can be extended to support additional transport protocols. Additional transport protocol modules (such as SMNP) might be licensed from 3rd parties.
- The source code of the JavaMail API is available for licensing by JavaSoft. This removes dependency on 3rd party libraries and licensing costs associated.
JavaMail EOF Adaptor
Weblicon has developed a custom EOF adaptor using the JavaMail API for accessing the messages and folder structure of an IMAP server. The weblicon JavaMail EOF adaptor provides a standard EOF view to the IMAP folder and messages structure and handles standard behavior of an EOF adaptor such as object creation, deletion and relations by translating to the appropriate JavaMail commands.
Business Logic
The business logic of the Messages module uses standard EOF methods for reading and writing messages and for manipulating folder structures. EOF forwards requests to the JavaMail EOF adaptor which uses the JavaMail API for manipulating structures in the IMAP server.
For sending and receiving messages, other parts of the business logic makes direct use of the JavaMail API.
The business logic for manipulating messages and folders is shared by the HTML, WML and Java servers.
External POP3 Mailboxes
External POP3 Mailboxes are accessed using the JavaMail API. When retrieving mail from external mailboxes, the messages are stored into the IMAP server maintaining a unified storage architecture for all messages.
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