Web Development with Java

a
href=”http://server.com/path/page.html”>
Some Page Somewhere on the web
a
>
2. If the resource is on the same server, but is not descended from the current 
directory, then include the full path from the document root, starting with 
a 
/
.
<
a
href=”/path/from/root/page.html”>
Some Page on the Current Server
a
>
3. If the resource is in the same directory as the HTML page that references it, 
then only include the fi le name, not the server or the directory.
<
a
href=”page.html”>
Some Page
a
>
4. If the resource is in a subdirectory of the directory where the HTML page that 
references it is located, then include the name of the subdirectory and the fi le 
name.
<
a
href=”subdir/of/current/dir/page.html”>
Some Page in Some Subdir
a
>

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12
Web Development with Java
There are three types of references.
1. Absolute
2. Relative from document root
3. Relative from current directory
There are just a few rules to determine the kind of reference.
1. If the URL begins with a protocol (like http://, ftp://, or telnet://), then it is an 
absolute reference to that location.
2. If the URL begins with a /, then it is a relative reference from the document 
root of the current server.
3. In all other cases, the URL is a relative reference from the current directory.
1.3 HTML 
Forms
If you have ever logged into a web site, then you have used an HTML form to 
supply your username and password. A form will have places where a user can 
enter data. These are known as 
form elements
and can be for one line of text, 
several lines of text, drop down lists and buttons. The form in Figure 1.6, which is 
from Florida International University, uses several form elements for lines of text 
and a button for submitting the data to the server.
1.3.1 Form 
Elements
The form and the form elements are defi ned using HTML tags. The opening form 
tag is 

and the closing tag is 

. Plain text, other HTML tags and 
form element tags can be placed between the opening and closing form tags. There 
are many form elements, but only two of them will be introduced now. Table 1.3 
Figure 1.6
An entry form from FIU.
Table 1.3
Two essential form element types.
Type Example
text 

The 
value
attribute is the text that appears within the element when the page is loaded.
submit 

The 
value
attribute is the text that appears on the button in the browser.

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Browser – Server Communication 
13
defi nes the two essential form elements: 
text
and 
submit
. Additional form elements 
are covered in Chapter Six.
Each of these has the same tag name (
input
) and attributes (
type
, 
name
, 
value
).
1. The HTML tag name is 
input
.
2. There are many different form elements that use the 
input
tag. The 
type
attri-
bute identifi es which form element to display.
3. There could be several form elements in a form. The 
name
attribute should be 
a unique identifi er for the element.
4. The 
value
attribute stores the data that is in the element. The value that is hard 
coded in the element is the value that is displayed in the browser when the 
HTML page is loaded.
5. The 
name
and 
value
attributes are used to send data to the server. When the 
form is submitted, the data for this element will be sent as 
name
=
value
. 
The value that will be sent will be the current data that is displayed in 
the element.
Listing 1.2 is an example of a simple web page that has a form in it.
<