Jigsaw Frequently Answered Questions
What is Jigsaw ?
Using Jigsaw
Technical stuff
Using Servlets
You think your question about Jigsaw is worth entering this list,
you have a better formulation for some of the answers ? Mail to jigsaw@w3.org
!
What's the purpose of Jigsaw ?
Jigsaw is the new W3C reference server. Its main purpose is to demonstrate
new protocol features as they are defined (such as HTTP/1.1
or PICS), and to provide the basis for experimentations
in the field of server software (such as the provided MUX prototypical
implementation).
Where can I get Jigsaw ?
You can download Jigsaw distribution file in various formats, and
using either ftp or http:
-
Windows zip files (1.5Mo)
-
UNIX gzip tar file (700Ko)
Why is Jigsaw written in Java ?
Java has a number of advantages
that fit well with our purposes. It provides portable threads and garbage
collection, allows for a very dynamic server architecture. It's ability
to move code around may be use in future development to experiment with
the mobile code concept.
Jigsaw is written in Java, it must be really
slow...
No so true ! Check out the performance
evaluation of Jigsaw, which indicates that it performs at least
as well as the CERN server.
The admin server reply "Method GET not implemented.",
how can I use it?
The administration server does not use plain HTTP but a variant of it.
The only tool available for now is an application called JigAdmin.
What is this indexing thing all about
?
To a normal HTTP web-admin, Jigsaw's configuration process might
look really strange...Jigsaw's
design emphasis two different processing stage in serving documents:
-
Indexing stage
-
When documents enter the Web
-
Serving stage
-
When documents are served to clients
In short the rationale for separating these two stages is to make the serving
stage as efficient as possible, by having the indexing stage
prepare as much as possible the work. A document enter the WEB space
the first time Jigsaw serves it; this happen behind the scene most
of the time, and consist in creating a resource for the document
to be served by querying a resource factory. The current resource
factory can be configured to create various kind of resources based either
on the file name extensions, or (in case of a directory) based on its name.
However, once a resource is created, it no longer reflects the settings
of the resource factory (see the indexers);
in some sense the information gets compiled so that at serving time,
processing overhead is reduced as much as possible.
How do I tie a resource to a directory not
under my server root?
Contributed by Sirilyan <sirilyan@io.com>
CERN server implemented this through the Pass directive, which let you
map a server path to an absolute path on your file system. Jigsaw uses
the org.w3c.jigsaw.resources.PassDirectory resource.
COOKBOOK METHOD: Create a new resource with Add resources in
JigAdmin at the location you want the
new server path to exist. Assign whatever name you desire to the new resource,
and assign org.w3c.jigsaw.resources.PassDirectory
for the class. Edit this new resource to change the pass-target attribute
to the absolute path to the directory you want to serve.
You may want to change the name attribute of the 'index' file in that
directory to Overview.html. name and filename are two separate attributes
in Jigsaw; this is also a poor man's (or a Win95/NT user's) symlink.
Serving directories outside your server root may be a security risk.
How do I setup CGI scripts ?
They are two ways to setup CGI scripts. The manual way requires that you
describe each script to the server. Let's say your script's path relative
to the server root is WWW/cgi-bin/myscript. You will first have
to create an appropriate org.w3c.tools.resources.FileResource
with a org.w3c.jigsaw.frames.CgiFrame
instance to wrap your script. See this tutorials
to know how to create a resource in Jigsaw.
Then edit the newly created resource, and setup it's command line (the
command line the server will use to run your script). Each line of the
text field should represent one argument, the first one being the script
full path.
You can also register files of a given extension as scripts, by using
a specialized indexer. When required,
you can even specify the interpreter to be run to execute the script (for
example, under Windows 95, or NT).
How can I extend Jigsaw ?
Jigsaw can be extended in a number of ways. Here are just three
possible things you can play with, from the simplest to the complex ones:
-
Writing new resource classes and new frame classes: you may want to read
the tutorial on this subject
before getting any further. You can think of this as being a n efficient
replacement for CGI scripts, although this is a much more powerful environment
to extend the server.
-
Writing new filter classes: if you want to experiment with specific authentication
needs, or if you require special logging formats. A tutorial
on writing new filters is also available.
-
Hacking Jigsaw. Right now you can just override any of the Jigsaw
classes to replace its implementation. In the future, most of the interesting
things that you can do this way will be turned into specific interfaces
(as is already the case for logging right now).
Why does Jigsaw implement its own persistence
mechanism
Jigsaw implements its own persistence mechanism while RMI already
provides a way to serialize objects, why is it so, will it change ? What
Jigsaw implements in the w3c.tools.store package is more
then persistence. It provides both a way of serializing objects and
a way of describing what and how the object will be dumped. The available
meta-description of objects (that you can obtain through the getAttributes
method of resources), is a central part of Jigsaw architecture,
since it offers the ability to create generic resource editors. This is
not likely to disappear.
However, Jigsaw persistence mechanism may be merged in the future
to the RMI interface, just by providing an implementation of the readObject
and writeObject method through its existing mechanism.
How can I use HotJava on top of Jigsaw's HTTP
client API ?
HotJava is Sun's
Java based browser. If you want to experience an HTTP/1.1 compliant browser,
you can run this browser on top of Jigsaw's HTTP/1.1 compliant HTTP
client API. To do so, you need to define the java.protocol.handler.pkgs
property to w3c.www.protocol before launching HotJava. The best
way to do so is to edit the HotJava property files.
Jigsaw's HTTP client API defines a number of other properties,
if you are planing to use this setting, you should read the HttpManager
documentation to get the complete list of available properties. These will
allow you to add caching, authentication, proxying and more to HotJava
!
Running Jigsaw on port 80 under UNIX
As of release 1.0alpha5, Jigsaw can now run on port 80, without
running as the root user. To implement that you need to install
the relevant piece of native code. This C code has been compiled and tested
under Solaris, porting it to a different platform/architecture should be
pretty easy.
Follow the normal installation procedure, and try to run Jigsaw
on a port greater than 1024. Once this work, stop Jigsaw (through
/Admin/Exit), Make sure your LD_LIBRARY_PATH variable includes
the directory containing libUnix.so (this is the Jigsaw/lib
directory under the standard release).
Select the user and group you want Jigsaw to run as. Make sure
that user has read/write access to the entire config directory.
Then, you just need to run Jigsaw through that special command line:
java org.w3c.jigsaw.Main -user user -group group <other-options>
Where user and group should provide (resp.) the user and
the group you want Jigsaw to run as.
Warning: As the underlying UNIX process will change personnality
right after acquiring the socket, the form based restart button
(available from the properties editor) will no longer work, since the process
will no longer be able to allocate a socket on port 80.
Under such a setting, the only way to restart Jigsaw is to kill
it (through /Admin/Exit) and restart it manually.
Chrooting Jigsaw under UNIX
As of release 1.0alpha5, Jigsaw can now - under UNIX - be chroot'ed.
If you try to do so, you are supposed to have some experiences with chroot'ing
programs. We will assume that you already have a correct root to run a
standard HTTP server and that you have read and understood the Running
Jigsaw on port 80 FAQ entry.
You need to install Java in that root (using whatever prefered way you
want). To install Jigsaw, I would recommend using the following
directory structure:
-
/usr/local/jigsaw/classes
-
Should contain Jigsaw's current distribution jigsaw.zip class
file
-
/usr/local/jigsaw/extensions
-
Is used to add extensions to the server while running, and should be included
in your CLASSPATH, before you start Jigsaw.
-
/usr/local/jigsaw/lib
-
Should contain Jigsaw's native code support - ie libUnix.so
-(to make the appropriate UNIX system calls)
Given that (don't forget to symlink the real /usr/local/jigsaw
to the chroot'ed one), you should be able to reuse that script:
#!/bin/sh
# Jigsaw
# $Id: FAQ.html,v 1.14 1998/08/13 11:47:48 benoit Exp $
# Jigsaw launcher
# LD_LIBRARY_PATH will be set to work *only* before chroot, by the java script
# We add here, support for PATH as they appear to be after the chroot
CR_LD_LIBRARY_PATH=/usr/local/jigsaw/lib:/usr/local/java/lib/sparc:/usr/lib:/lib
LD_LIBRARY_PATH=$CR_LD_LIBRARY_PATH:$LD_LIBRARY_PATH
export LD_LIBRARY_PATH
# CLASSPATH needs two hacks: one to include jigsaw.zip before chroot, and
# an other one to include everything after chroot
CLASSPATH=/0/w3c/abaird/sbroot/usr/local/jigsaw/classes/jigsaw.zip:/0/w3c/abaird
/sbroot/usr/local/jigsaw/classes/servlet.zip:/0/w3c/abaird/sbroot/usr/local/jigs
aw/classes/plus.zip:/0/w3c/abaird/sbroot/usr/local/jigsaw/extensions
export CLASSPATH
CR_CLASSPATH=/usr/local/jigsaw/classes/jigsaw.zip:/usr/local/jigsaw/classes/serv
let.zip:/usr/local/jigsaw/classes/plus.zip:/usr/local/jigsaw/extensions
CLASSPATH=$CR_CLASSPATH:$CLASSPATH
export CLASSPATH
# Ready to run jigsaw, now:
cd /0/w3c/abaird/sbroot/jigsaw
exec /usr/local/java/bin/java org.w3c.jigsaw.daemon.ServerHandlerManager $* -group n
obody -user nobody -chroot /0/w3c/abaird/sbroot -root /jigsaw
Jigsaw Team
$Id: FAQ.html,v 1.14 1998/08/13 11:47:48 benoit Exp $