Invalid Argument Error

Question

I am getting above error on load of the JNLP file. When I access the URL for the JNLP, the JNLP file downloads (I can see the content using Ethereal) and WebStart does launch. So, I assume MIME type is OK and the download servlet is working, at least enough to serve up the JNLP.
What makes this more curious is that it is a working configuration in Jetty. I can take the exact same application - drop it in Jetty, it works; drop the SAME file in Tomcat 4.1.27, it doesn't work.
Anyone seen this?
WS 1.2
J2SDK 1.4.1_01 on both ends.
Tomcat 4.1.27
The error and log information is as follows.
Error dialog/General Tab:
An error occurred while launching/running the application.
Category: Invalid Argument error
Could not load file/URL specified: C:\Documents and Settings\mjf860\Local Settings\Temporary Internet Files\Content.IE5\2DQR21KT\cwms[1].jnlp
The JNLP file does in fact NOT exist (the directory does, no JNLP files are in in it), despite the fact that I saw it go over the network to my box.
The JNLPServetLog stuff:
JnlpDownloadServlet(3): Request: /cwms/app/cwms.jnlp
JnlpDownloadServlet(3): User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; H010818)
JnlpDownloadServlet(4): DownloadRequest[path=/app/cwms.jnlp isPlatformRequest=false]
JnlpDownloadServlet(4): Basic Protocol lookup
JnlpDownloadServlet(4): JnlpResource: JnlpResource[WAR Path: /app/cwms.jnlp lastModified=Tue Sep 09 17:14:51 EDT 2003]]
JnlpDownloadServlet(3): Resource returned: /app/cwms.jnlp
JnlpDownloadServlet(4): lastModified: 1063142091684 Tue Sep 09 17:14:51 EDT 2003
TIA,
Mike

Answer 1

I just found out by searching tomcat list that in your
dynamic jnlp file you can set the cache-control to
public using
response.setHeader("Cache-Control", "public")
This will allow Internet Explorer to cache the jnlp
file and you won't get the exception.
This way you can keep your jnlp file under a security
constraint.I wasn't sure what was meant by "dynamic JNLP" or how to follow the above procedure, so I created a servlet (a JSP, actually) to implement the above workaround. It will serve JNLP files from a password-protected directory in a way that works for the Tomcat-to-Internet Explorer combination. It's posted below in case it can help anyone else.
There are still a few things to watch out for: (1) the protection (the <auth-method> tag in your web.xml file) for the JNLP file must be BASIC--FORM will not work. (2) you will have to enter the password twice--once for the browse and again for Web Start.
The servlet itself is enclosed below. If you have questions about it, please post them to this forum.
Bob Pollack
Gestalt, LLC
<%@ page import="java.io.*" %>
<%
// This is a fetch program to retrieve a JNLP file from a
// password-protected directory. Java Webstart has problems
// doing this directly, so this program must be used instead.
// That is, instead of a link that points to "xxx.jnlp", make
// a link that points to "fetchJNLP.jsp?name=xxx.jnlp".
// Even with this program, the only kind of authentication
// that Webstart understands is basic authentication.
// You cannot use form-based authentication and Webstart together.
String jnlpName = request.getParameter ("name");
String myPath = request.getServletPath ();
String myURL = request.getRequestURL ().toString ();
String dirPath = null;
String dirURL = null;
String jnlpPath = null;
String jnlpRealPath = null;
boolean abort = false;
// Screen the name parameter to make sure that hackers
// cannot use this program to fetch any old thing
// The current criteria are that the name must be a JNLP file
// in this directory
if (jnlpName == null)
abort = true;
else if (! jnlpName.endsWith (".jnlp"))
abort = true;
else if (jnlpName.indexOf ("/") >= 0)
abort = true;
if (abort)
response.sendError (response.SC_FORBIDDEN);
return;
int pos = myPath.lastIndexOf ("/");
if (pos < 0)
pos = myPath.length ();
dirPath = myPath.substring (0, pos);
pos = myURL.lastIndexOf ("/");
if (pos < 0)
pos = myURL.length ();
dirURL = myURL.substring (0, pos);
if (jnlpName.startsWith ("/"))
jnlpPath = jnlpName;
else
jnlpPath = dirPath + "/" + jnlpName;
out.clear ();
response.setContentType ("application/x-java-jnlp-file");
// The following line is the reason this servlet exists.
// If a JNLP file is in a protected directory, Tomcat will
// send it out with a Cache-Control header of "no-cache",
// which keeps the client end of JNLP from working.
// See Java Developer Forum,
// "Java Web Start & JNLP: Invalid Argument Error",
// at http://forum.java.sun.com/spider.jsp?f=38&t=442995
// for a rambling discussion of this issue.
response.setHeader ("Cache-Control", "public");
jnlpRealPath = application.getRealPath (jnlpPath);
File jnlpFile = new File (jnlpRealPath);
FileReader fr = new FileReader (jnlpFile);
BufferedReader br = new BufferedReader (fr);
while (true)
String line = br.readLine ();
if (line == null)
break;
// As long as we're doing this anyway, we'll add a service
// that substitutes the full URL for this directory into
// the codebase of the outgoing JNLP file. This will make it
// possible for the files to be moved from machine to machine
// without changes.
// For example, instead of saying
// codebase="http://myhost:8080/home/protected"
// the JNLP file can say
// codebase="$BASE"
String base = "$BASE";
pos = line.indexOf (base);
if (pos < 0)
out.println (line);
else
out.print (line.substring (0, pos));
out.print (dirURL);
out.print (line.substring (pos + base.length ()));
out.println ();
out.flush ();
out.close ();
%>