UWOBO: a Stylesheet Processor

Last update: April 1, 2002

Contact: luca.padovani@cs.unibo.it

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UWOBO 1.2.1 released. UWOBO is now released under GPL. The only other significative change with respect to 1.2.0 is the change of the semantic of the method add when the stylesheet is already loaded. In 1.2.0 the request was interpreted as a reload request. It seems more appropriate to simply ignore it (with a Warning, of course!).

UWOBO goes global. UWOBO has been announced on

• The Xalan user mailing list
• Mulberrytech XSL mailing list
• at www.icewalk.com, see the project page
• at www.freshmeat.net, see the project page

UWOBO 1.2.0 released, incorporating many changes (some also not backward compatible):

1. New syntax: methods add, reload and remove can now process multiple entries with just one method invocation. NO BACKWARD COMPATIBILITY RETAINED.
2. Serialization and deserialization: when serialization is enabled, every time a stylesheet is recompiled it is also serialized on disk. When booting, UWOBO automatically reloads every serialized stylesheet.
3. More verbosity: every method gives back to the user and writes in the log much more information than before.
4. Undocumented methods update and updateAll (whose semantic was unclear) definitely removed.

Note that, due to syntax changes, also the panel has changed.

UWOBO 1.1.13 released. Release 1.1.12 was someway incomplete: error responses were still cached. The problem has been fixed. The output of the help method has been updated. The file build.xml has also been improved.

UWOBO 1.1.12 released. Now responses from the servlet are such that browsers don't cache them.

UWOBO 1.1.11 released. This is just a bug fix: while loading a stylesheet, the files required and included using a relative URL were searched using the wrong absolute URL. In particular, the base URL used was not the one of the main stylesheet, but the path of the directory in which UWOBO was installed.

UWOBO 1.1.10 released. A more flexible support for parameters and output properties is added.

UWOBO 1.1.9 released.

Syntax for application changed, see below.

First public release for UWOBO version 1.0.0.

UWOBO is a Java Servlet, thus it should be possible to use it with any "servlet server". Currently, we use it with TOMCAT. The requirements for this servlet are:

• A servlet server, such as TOMCAT
• The most recent version of the Xerces/Xalan processor. You may need to patch the TOMCAT installation so that Xerces is used.
• JDK 1.3, if you are going to compile the source code.

Download the package and uncompress it somewhere, edit the file build.xml and set the property tomcat.dir with the directory where TOMCAT is installed. In the directory uwobo Do

  chmod +x ./antRun
  ./antRun install

(make sure that the JAVA_HOME environment variable is set and that Java is in your PATH). You may have to be root in order to complete the installation.
When the servlet is installed, restart the servlet server and have fun.

• UWOBO-1.2.1 [.tar.gz, .zip]
• UWOBO-1.2.0 [.tar.gz, .zip]
• UWOBO-1.1.13 [.tar.gz, .zip]
• UWOBO-1.1.12 [.tar.gz, .zip]
• UWOBO-1.1.11 [.tar.gz, .zip]
• UWOBO-1.1.10 [.tar.gz, .zip]
• UWOBO-1.1.9 [.tar.gz, .zip]
• UWOBO-1.1.0 [.tar.gz, .zip]
• UWOBO-1.0.0 [.tar.gz, .zip]

The HELM library on-line is rendered on the fly by means of the UWOBO servlet. You can browse the library here. For some examples of invocation of the processor, take a look at the pages of the library.

The processor accepts a number of commands, each possibly followed by a variable number of arguments. A generic URL to contact the processor is the following:

http://hostname/helm/servlet/uwobo/cmd

Where hostname is the host running the processor and cmd is one of the following commands:

• help
  Gives a brief description of the available commands, along with the processor version and compile date and time.
  
  
• add?bind=key,stylesheet[&bind=key,stylesheet]*
  Compiles a stylesheet into the processor. You must specify a key to refer to the added stylesheet in subsequent operations. If serialization is enabled, i.e. if the SERIALIZATION_DIR property is set to a not-empty value, the compiled stylesheet is also serialized on disk. All serialized stylesheets are automatically re-activated during UWOBO start-up when serialization is enabled.
  
  
• remove[?keys=key1_,...,key_n]
  Removes the stylesheets with the given key. If no key is specified, all currently loaded stylesheets will be removed. If serialization is enabled, the serialized stylesheets are also removed from disk.
  
  
• list
  Lists all the stylesheets compiled into the processor along with their keys and some other (useful?) information about the output format.
  
  
• reload[?keys=key_1,...,key_n]
  Reloads the stylesheets with the given key. If no key is given, then all the stylesheets compiled into the processor are reloaded. This command is often useful while developing stylesheets. If serialization is enabled, the serialized form is also updated.
  
  
• apply?xmluri=source&keys=key_1,...,key_n[&param.name=value]*[&param.key.name=value]*[&prop.name=[value]]*
  The most important command, at last. Its parameters have the following meanings:
  
  
  • xmluri: a URI to the source XML document to be processed.
  • keys: the (ordered) sequence of keys representing the stylesheets to be applied.
  • param.name: a global parameter to be passed to all the stylesheets.
  • param.key.name: a parameter local to the stylesheet identified by the key. The parameter is passed only to this stylesheet. This may be useful if one has a parameter with the same name in different stylesheets and wants to pass different values to that parameter in the different cases. Note that if the same stylesheet is applied several times, the same value of the parameter will be passed at each application. This might not be what you want, but is the way the processor is implemented right now.
  • prop.name: a property of the processed output document. You can thus override the value of one or more properties described in the XSLT specification regarding the <xsl:output> element, possible values are method, encoding and so on.
  
  WARNINGS (non backward-compatible syntax changes):
  1. the syntax for stylesheet application changed from version 1.0.0 to version 1.1.0! The old syntax was:
     apply?xmluri=source[&key=name]+[&param.name=value]*
  2. the syntax for stylesheet removal changed from version 1.1.13 to version 1.2.0! The old syntax was:
     remove[?key=name]
  3. the syntax for stylesheet reloading changed from version 1.1.13 to version 1.2.0! The old syntax was:
     reload[?key=name]
  4. undocumented method update (whose semantic was unclear) was definitely removed in version 1.2.0.
  
  
  

We have designed a simple Web page which allows a simple interaction with the processor. Currently, the page is tuned to be used in the context of HELM, but you can download and customize it to your needs. Browse the panel here.