Building A PHP-Based Mail Client (part 1) - Requiring Immediate Attention (
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Before we get into the
nitty-gritty of syntax and structure, it's important to first put down the
requirements of the software to be designed. This is a sometimes-tedious but
always-necessary precedent to actual implementation of any software project, as
it simultaneously offers a "big picture" view of the entire project and also
provides a reference for the actual code development.
Typically, the
software requirements are obtained after an analysis of the problems faced by
the customer - an intensive, frequently-frustrating process involving large
amounts of caffeine. In this specific case, though, I was able to arrive at the
requirements after a fairly short conversation with the customer, during which
the following problems became clear:
1. Members of the customer's sales
team were frequently on the road chasing down leads. During this period, they
had no way of accessing their internal corporate mail. The customer was looking
for a tool that would allow employees to get to their mail even if they weren't
physically at the workplace.
2. A number of the customer's employees were
part-time or freelance workers, who came to the office only occasionally. Rather
than assign these part-timers a dedicated computer each, the customer wanted to
assign them a single "guest" machine, which could be used by them whenever they
came in to work. A Web-based mail solution would be useful here too, as it would
allow different users to use a single machine to read their mail.
The
customer's evaluation of his problems has led him to conclude that he needed a
simple Web-based mail client, along the lines of Hotmail (
http://www.hotmail.com) or Mail.com (
http://www.mail.com). Consequently, the brief was
simple enough: a mail client which supported the standard feature set of Windows
mail clients like Eudora and Microsoft Outlook, yet was accessible via a Web
browser.
After a little research, I came up with the following list of
software requirements (which was eventually approved by the customer):
1.
The application must be capable of connecting to any POP3-compatible mail server
(IMAP support was not a requirement) and retrieving a list of messages for a
user-specified mailbox on that server. This message list must display important
message headers - the sender, subject and size - together with (optionally) an
attachment icon.
2. The application must be capable of displaying the
contents of any message from the message list.
3. The application must
allow the user to create and send a new email message (to multiple recipients
simultaneously, if required)
4. The application must allow the user to
reply to any message.
5. The application must allow the user to forward
any message, with the option to include all, some or none of the message's
original attachments.
6. The application must allow the user to delete
any message from the server.
7. The application must support mail
attachments, and allow the user to download these to his local workstation, or
upload them for attachment to a new message.
This is a fairly standard
feature set, and you'll find that almost every mail client allows you to perform
these actions. Note that the list above is somewhat abridged - the actual
requirements document was a bit more detailed, and included some additional
items that will not be discussed here - but it still has enough material to give
you a fairly good idea of what I'll be covering in this case
study.
Putting down software requirements is a good starting point for
any project, both from the implementation point of view and for other, related
activities. Once the requirements are written down and approved by the customer,
the developer can begin thinking about how to design and code the application,
the interface designer can begin work on the application's user interface, and
the QA team can begin building test cases to verify the final release of the
code.
