Problem with Servlet Context

[Reema Patel]

Hello All,
I'm using Apache Tomcat/5.0.28. I'm facing a problem while mapping for resources.

I have to precede the app name also,for example, I have to give the full app path before the resource,, as shown in the code fragment here:
<FORM METHOD=POST ACTION="/<my_app_name>/results.jsp">

But, I think this is not requited as this should be picked up automatically.
Pls help.

- Reema

[Ben Souther]

If you start your relative link with a slash "/" then the browser will look in the root of the site (ignoring your contextPath).
If there is no preceeding slash the browser will look in (what it perceives to be) the current directory.

The most solid way to build your relative urls, in my opinion is to read the contextPath from the request object.

<FORM METHOD=POST ACTION="${pageContext.request.contextPath}/results.jsp">

or, if you aren't using JSP 2.0

<FORM METHOD=POST ACTION="<%=request.getContextPath()%>/results.jsp">

[Bear Bibeault]

Originally posted by Reema Patel:
But, I think this is not requited as this should be picked up automatically.

Picked up automatically from where?

Without it, the server would have no way of knowing which web application to deliver the request to.

[Reema Patel]

But, wat about the 1001 books that give URL like the one I have submitted....eg. /results.jsp...I'm yet to see anybody prefexing the app name...

[Ben Souther]

HTML books or Servlet/JSP books?

It all makes sense once you see what's going on.
Here's the structure for a typical URL:
http://domain:port/contextPath/directory/resource

A real example might be:
http://localhost:8080/myApp/images/myImage.png


In this example, there are 3 ways you can send the url for myImage.png to the browser:

An absolute URL: http://localhost:8080/myApp/images/myImage.pngIn this case, you're giving the browser everything it needs to find your image.

A relative URL: images/myImage.png

In this case, you're telling the browser to add the current path to the beginning of this relative URL.

A URL that is relative to the root of the website:

/myApp/images/myImage.png
In this case, you're telling the browser to add the current domain:port combination to the beginning of the absolute url.


Browsers don't know anyting about the concept of a Java webapp.
They don't know that a J2EE app server can house multiple apps and that it uses the first directory entry as the name (contextPath) for the webapp.
They only know to add the current domain:port to the beginning of a relative URL if that relative URL starts with a slash.

You have to add the contextPath to the beginning of your URLs.

[Bear Bibeault]

To add to what Ben said

Originally posted by Reema Patel:
But, wat about the 1001 books that give URL like the one I have submitted....eg. /results.jsp...I'm yet to see anybody prefexing the app name...

Most books, in a mis-guided attempt to keep things simple, assume that you will be replacing Tomcat's root web app with your own.

The root web has a context path of "/".

[Reema Patel]

Thanks Bear!
This means that if I don't explicitly give my app name, it by default looks inside the ROOT web app, and since there's no such resource with a matching name, I get a page not found 404 error.

Correct me if I'm wrong...thanks again!

[Ben Souther]

You've got it.