Java Tools

To develop servlets, I currently use IBM's VisualAge for Java version 4. When I first starting using it I found the interface daunting (however I find notepad tricky to use!), however now i'm used to it I find it a very good Java development tool.

There are many other Java tools available, however rather than go through them all here I suggest you search the web, ask colleagues, read books/magazines etc (saves me the typing). I will be aiming the series at the use of any tool, however I will probably be adding Visualage specifics, (ie interface usage stuff) in some of the articles.

Should anyone find any good links on Java tools - send them to me and I will put them up on this site. Likewise if you feel I miss any information out which would be key/useful for the readers of this site then feel free to send them to me.

Structure of a Servlet

When you enter a URL into a browser, a few things happen. Your browser firstly sends a request to the specified Web Server and then that server processes the request and sends a response back to the browser. The browser can actually send two types of request, namely 'get' and 'post'.

The 'Get' request is to retrieve information from the server and the 'Post' request is to send data to the server (ie a document etc).

When you develop a servlet for use with Domino, you use the javax.servlet and javax.servlet.http packages from the Sun JSDK (Java Servlet Development Kit). However you only need to be concerned with three methods when developing as everything else is handled for you. These methods are service(), doGet(), and doPost().

Whichever Java tool you are using, you would normally need to 'import' the JSDK into your environment. If you are using VisualAge, this can be done by selecting File/QuickStart from the menu, and then selecting Features/Add Feature from the QuickStart menu. You will then be presented with a list of features available and near the bottom will be a Sun Servlet Development feature - click on it and ok to install.

Ok back to the three methods. The service() method is called each time the server requests a servlet. Usually this method is not used for Web Server (HTTP) servlets - it is more applicable to generic servlets - so we will skip this one. The doPost() method is invoked by all 'post' requests from the browser and the doGet() method is invoked by all 'get' requests from the browser.

The format of these methods are as follows:

public void doGet (HttpServletRequest req, HttpServletResponse res)

public void doPost (HttpServletRequest req, HttpServletResponse res)

In the above, the HttpServletRequest object represents the request made to the web server, and the HttpServletResponse object represents the response that will be sent to the requester.

As an example, should you be logged on via session based authentication to your Domino Server, you can retrieve the current logged on users name using:

req.getRemoteUser()

Ok thats enough background for now, the next article will involve developing your first servlet - the DXTest servlet!

Questions? - steve.castledine@projectdx.org