<h1>
JavaServer Pages (tm) Web Development Kit</h1>
<h1>
Frequently Asked Questions</h1>
Thisdo
cument lists some frequently asked questions about the JavaServer(TM)
Web Development Kit (JSWDK). Separatedo
cuments are available on the component
technologies (Servlets and JSP) at java.sun.com:
<ul>
<li>
<b><a href="http://java.sun.com/products/jsp/faq.html">JSP FAQ</a></b></li>
<li>
<b><a href="http://java.sun.com/products/servlet">Information on Servlets</a></b></li>
</ul>
<b>What environment variablesdo
I need to set to use the JSWDK?</b>
<p>You need a correct version of the JDK in the CLASSPATH variable. (For
Unix, JDK 1.1.x or 1.2. For Windows, JDK 1.2.)
<p>If you are using JDK 1.2, you also need todo
<i>one</i> of the following:
<ul>
<li>
Set JAVA_HOME to the JDK directory.</li>
<li>
Put tools.jar in the CLASSPATH variable.</li>
</ul>
All other necessary classes and jar files are managed by the startserver
script or batch file.
<p><b>Where are the classes for JSPs and Servlets?</b>
<br>&nbsp;The files are as follows:
<ul>
<li>
webserver.jar -- class files for the Servlet Engine</li>
<li>
lib/jspengine.jar -- class files for the JSP Engine</li>
<li>
lib/servlet.jar -- public APIs for Servlets</li>
<li>
lib/xml.jar -- classes for parsing XMLdo
cuments</li>
</ul>
<b>Can I combine these classes with other webservers?</b>
<p>The JSP engine uses only the public portion of the Java Servlet 2.1
API. In theory, it could run on other Servlet engines that support the
Servlet 2.1 API. Sun has not tested this release on any Servlet engine
other than the one in the JSWDK.
<p><b>Wheredo
I put my JSP sources and beans?</b>
<p>If you are testing JSP pages without creating a separate web application,
you can use the default "Example" application. If you are creating a new
web application, refer to the question on installing a new web application
in this FAQ.
<p>To use the default "Example" application:
<ol>
<li>
Put all of your JSP source files in /examples/jsp, either directly or in
their own subdirectory.</li>
<li>
Put all of your Beans (class files) under /examples/WEB-INF/jsp/beans.
The startserver script automatically adds these classes to CLASSPATH at
runtime.</li>
<li>
If your server is already running, stop and restart it.</li>
<li>
Invoke your JSP pages using http://locahost:8080/examples/jsp/yours.jsp</li>
</ol>
<b>What is a web application?</b>
<p>A web application is a collection of resources that is mapped to a specific
Uniform Resource Identifier (URI) prefix. These resources may include JSP
pages, Servlets, HTML files, and images.
<p>For example, all of the resources related to baseball can be assembled
into a "baseball" directory. All requests starting with "/baseball" could
then
be mapped to this application.
<p><b>Howdo
I install a new web application?</b>
<ol>
<li>
Create a directory for the web application. In the following examples,
we will call this WEBAPP. The directory could have the same structure as
the Examples directory, with subdirectories for jsp, servlets, WEB-INF,
and images, if appropriate. One way todo
this is to copy the Examples
directory and then
edit the files as necessary.</li>
<li>
Add a new application to the JSWDK by editing the file webserver.xml in
the root JSWDK directory.</li>
<p><br>For example, to create a baseball application, you would make the
following additions to the file (at the appropriate location):
<pre>&nbsp;&nbsp;&nbsp;
&lt;WebApplication id="baseball0" mapping="/baseball"do
cBase="baseball="/></pre>
Read the webserver.xml file for more details on the syntax and options.
See the questions below for installing Servlets, JSP pages and Beans.</ol>
<b>Howdo
I install Servlets within my web application?</b>
<p>Use the following procedure, substituting your application directory
for WEBAPP:
<ol>
<li>
Compile the Servlet and determine which web application context you will
add it to.</li>
<li>
Add the Servlet class file to the WEBAPP/WEB-INF/servlets directory.</li>
<li>
Activate the newly installed Servlet by registering (adding) the servlet
in the WEBAPP/WEB_INF/servlets.properties file. See the Examples/WEB-INF/servlets
file for an example.</li>
<li>
Optionally, you can map the Servlet to URI requests relative to the context
in which the Servlet is located by adding an entry in the WEBAPP/WEB-INF/mappings.properties
file. See the Examples/WEB-INF/mappings.properties file for an example.</li>
<li>
Restart the server.</li>
</ol>
Access the Servlet using the following method, where WEBAPP is the web
application URI name, and SERVLET_NAME is the base name of the servlet:
<br>&nbsp;
<br>&nbsp;
<pre>&nbsp;&nbsp;&nbsp;
http://localhost:8080/WEBAPP/servlet/SERVLET-NAME</pre>
If you have associated a URI path mapping to your servlet, you can access
it as follows, where EXTENSION is a file time extension and MAP-PATH is
an associated URI MAP path:
<pre>&nbsp;&nbsp;&nbsp;
http://localhost:8080/WEBAPP/foo.EXTENSION
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
--- or ---&nbsp;&nbsp;
&nbsp;&nbsp;&nbsp;
http://localhost:8080/WEBAPP/MAP-PATH</pre>
<b>Howdo
I install JSP pages and Java Beans in a web application?</b>
<ol>
<li>
Put the JSP source files in any directory under your application directory
(/WEBAPP in the examples above).</li>
<li>
Make sure that the compiled beans are in the CLASSPATH. This can bedo
ne
either by setting the CLASSPATH manually or by editing the startserver
script.</li>
<li>
Edit the file WEBAPP/WEB-INF/mappings.properties and the file WEBAPP/WEB-INF/servlets.properties
to map ".jsp" in the URI to the JSP Servlet which will process the jsp
file. (See the property files in /examples/WEB-INF/ for an example. Your
mapping should be similar.)</li>
<li>
Finally, restart the server.</li>
</ol>
You can invoke your new JSP page using a URI similar to the following:
<pre>&nbsp;&nbsp;&nbsp;
http://localhost:8080/WEBAPP/yourfile.jsp</pre>
<b>How are the URIs mapped at the server?</b>
<p>The web-server matches the begin
ning of the requested URI with the prefixes
of all contexts (web-applications). If no context matches, it uses the
default context instead.
<p><b>Howdo
you pass data from a Servlet to a JSP page?</b>
<p>See the JSP examples included with the JSWDK for samples of passing
data from a Servlet to a JSP page, and from a JSP page to a Servlet.
<p><b>Whatdo
the different init parameters mean?</b>
<dl>
<dt>
keepgenerated:</dt>
<dd>
Indicates whether or not to keep the generated Java file. The options are
true or false. Setting this to true retains the generated files. Setting
it to false deletes these files after compilation.</dd>
<dt>
scratchDir:</dt>
<dd>
This sets the location for the work directory, which will be created for
storing all generated code. This can be set to any directory. The work
directory will be created under thedo
cBase.</dd>
<dt>
largeFile:</dt>
<dd>
True or false. Set this to true for large files. When this value is true,
all static HTML is stored in a separate data file.</dd>
<dt>
sendErrToClient:</dt>
<dd>
True or false. If this parameter is set to true, all compilation/parsing
errors will be sent as part of the response to the client.</dd>
<dt>
ieClassId:</dt>
<dd>
This parameter is used to activate the IE plug-in. The default value is
set for IE 4 and 5. If the classID for IE changes in the future, this parameter
will be helpful.</dd>
</dl>
<b>Whatdo
es a 404 error mean?</b>
<p>It means the server was not able to locate the resource you requested.
This may be due to one of two reasons:
<ul>
<li>
The URL you entered was wrong or had a typo.</li>
<li>
The URL could not be resolved with the current "docBase." If you are running
your own web applications, please read the questions related to installing
your own web application.</li>
</ul>
<b>Whatdo
es a 505 error mean?</b>
<p>A 505 error represents an "internal server error" encountered while
processing your request. To find out more about the error, study the trace
at the server window.
<p>These errors can occur when translating JSP source to a Servlet. Translation-time
errors typically occur because of a syntax error in the JSP file or in
the generated Java file. Use the error message at the server window for
debugging.
<p>Errors can also occur at request time. Again, refer to the server-side
trace for information about the specific problem or exception.
