Designing and Building a Wireless e-mail Application

Problem to be Solved

The user wishes to access the Microsoft Outlook (mail, contacts, calendar) family of programs from the internet, either from a web browser or from a cell phone.

Analysis

The Microsoft Outlook family of programs are very feature rich and it is not practical to consider supporting all features of each program when it is being accessed over the internet. This particularly true in the case of cell phones where the real estate available for displaying data is limited, there is no keyboard, and the maximum packet size is limited. However if the program is being accessed from a standard web browser, then more features can be supported. Rather than have two versions of a Data Transport to access one of the MS Outlook programs, it is best to have one Data Transport that can support most of the features, and then use an agent to utilize whatever features are practical for the display device (browser or cell phone) being used. In this way, if a new display device (such as Blackberry) becomes available, then the Data Transport can be re-used and the agent modified or a new agent written to support the new device.

Design

In order to understand the concepts used in this case study, it is recommended that you read the Tutorial pages on the left first.

Referring to the diagram above, the base of any nTegrator application is a collection (yellow). When deployed as a web based application this collection will be used as an entry point to the application. A user will log into the applications by giving the collection name as the login name and the password associated with the collection as the login password. A collection is a very sophisticated component: it can support orchestration of business processes, parallel operation across processors and computers, the provision of the contents of as a SOAP service, and so on. In this case, however, a collection is used in its most simple form as a repository for some Data Transports.

Access to Outlook mail is accomplished by a Data Transport (green) that contains a VBScript that uses COM to interact with the mail system. There are several good books that describe how to access Outlook with VBScript. Most of the "heavy lifting" in terms of actually interacting with Outlook can be accomplished by copying script samples from the book and pasting them into the nTegrator VBScript template.

An Agent (orange) is used to convert the output from the Data Transport into HTML (for web browsers) or WML (for cell phones). In this case, the Agent is a standard nTegrator XSLT agent that is uses a XSLT script to perform the translations. An XSLT script is an XML based text file that is organized into small XML elements. Each element is responsible for preparing a single web page (or cell phone screen) so that the element size is usually quite small and the implementation can be accomplished one screen at a time, features that make for easy debugging, modification, and maintenance.

 A similar design is used for the provision of Contacts and Calendars from Outlook. Note that the Data Transports and Agents can be created separately, and perhaps, by different individuals, making the programming task easy and efficient.

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