There are two basic alternative approaches to developing an e-mail application in the Palm OS environment. These are:
Our goal in this article is to accommodate incorporation of EMSD as a Mail Transport Service provider in both models.
In the separate mail user interface and mail transport service model, the application is split into two parts. One part is responsible for transferring the mail message, while the other part is responsible for processing and displaying the message.
An example of this approach is the standard Palm Mail application. The basic distribution of Palm OS lacks mail transport services such as SMTP[12], POP[8], or IMAP[5]. It normally depends on its desktop synchronization capabilities to accomplish the actual sending and receiving. Messages written by the user are put into a queue; then upon synchronization with the desktop, the desktop counterpart sends the queued messages and also retrieves received messages.
However there are add-on packages, such as Top Gun Postman [6] that provide SMTP and POP/IMAP support within the Palm OS device. This enables users of the standard Mail application to send and receive messages directly from their devices via a wireless modem.
Incorporation of EMSD into packages such as Top Gun Postman can be rapidly accomplished as an add-on or replacement for SMTP/POP/IMAP. Figure 1 shows the components involved as well as the layering of services in this model.
In the integrated mail user interface and mail transport service model, the application is entirely self-contained.
There are numerous examples of this approach, since it offers greater convenience of operation and usage in the Palm OS environment. In particular MsgAgent [9] and DoodleMail [13] are very popular clients.
Figure 2 shows the components involved and the layering of services.
