%TOC%

---++ Introduction

XWeb is a generic template-based transformation demonstration service; it's implemented as a CGI application. 
The current version contains a demo for [[Tiger.WebHome][tiger]] (simple and advanced version) and [[ExpTools][exp-tools]], but other demos can be added without to much effort.

The most recent version runs at http://stratego.insanity.nl/cgi/xweb/demo 
This location will change to catamaran.labs.cs.uu.nl when it has a better StrategoXT environment (catamaran is the actual Stratego server).

---++ Resources

	* [[Tools.XmlTools][xml-tools]] : XML tool package, used for XML parsing and generation 
	* [[StrategoNetworking][stratego-net]] : Package for implementing CGI based services
	* [[ExpTools][exp-tools]] : Expression tool package, an incarnation of XtApplet.
	* [[Tiger.WebHome][tiger]] : Tiger in Stratego, currently a demo for this package been implemented
	* [[TigerContract][tiger-contract]] : Experimental tiger compiler package with contract support

---++ Download and installation

The source of XWeb can be checked out using:
<pre>
  svn checkout %SVNROOT%/StrategoXT/trunk/experimental/xweb
</pre>

There's no distribution of XWeb available. 

---+++ Configuration

Configure the package:
	* =--with-xt= or if the packages are installed at different locations:
		* =--with-aterm=
		* =--with-sdf=
		* =--with-strategoxt=
	* =--with-xml-tools=
	* =--with-stratego-net=
	* =--with-exp-tools=
	* =--with-tiger= 
	* =--with-tiger-contract= 
	* =--with-cgi-bin= if you want XWeb to be installed in the cgi-bin of your HTTP server

Flags =--with-exp-tools=, =--with-exp-tools= and =--with-tiger-contract= are in some way optional. For example, if you don't want to deploy the [[ExpTools][exp-tools]] demo, then don't use its configure flag and remove the associated XHTML template from your webserver. 

---+++ Extending xweb with new demos

The two bigger steps to undertake when extending XWeb with new demos are:

	* Add a =--with-[package]= construct in the configure.ac and make sure the XTC repository of the package is imported in the XWeb repository; see Makefile.am in the topdir of the package
	* Create a xhtml template in data/templates/demo directory and create a list of allowed components in the data/config directory. Example sources can be stored in data/sources/[language], see available sources' Makefile.am's for how it's done. 

---++++ Creating a template 

See data/templates/demo/tiger-simple.xhtml for a small example; all tags in the xhtml namespace are rendered by your browser, 
tags in the xweb namespace are transformed by the xweb cgi application. The application is configured using a set
of properties:

	* srcdir: Directory containing programs subject to program transformation with the demo web (make sure that your HTTP server can read/write in this directory, usually this is www-data or nobody)
	* components: File containing list of allowed components that can used in compositions on the demo web (it's in fact an ATerm containing a list of Strings). In tools/ there's a little program called dir2list that scans the current directory for files without an extension (usually binaries) and creates a component list that can be used for this purpose.
	* extension: The extension of program sources. For tiger, this is .tig
	* check: Component called to check whether saving a source is allowed; usually this is a parser (like parse-tiger). XWeb checks whether the transformation of the source with this component yields an ATerm.

A number of tags in the xweb namespace are transformed by the XWeb CGI application (source can be found in src/demo.strxml); see data/templates/demo directory in the package for some nice examples.

---++ Known Bugs (or features)

	* When source is an ATerm and has been pretty-printed by pp-aterm, it might or will not be able to transform it. Regular ATerm's work fine as source.
	* Adding available components from their selectbox isn't very intuitive.
	* When saving a source; XWeb assumes that sources are programs and checks them using the specified component (usually a parser).
	  ATerm sources can't be saved because this checker will fail, need to fix this.

---++ TODO

	* %GRAY%Allow commandline parameters after component names in the dynamic composition%ENDCOLOR% - done
	* %GRAY%Create anonymous compositions/transformations for educational purposes (guess what composition or component has been invoked)%ENDCOLOR% - done
	* Support multiple inputs; this enables more complex transformation demos like [[Tools.XmlTools][xml-tools]] and Stratego
	* Seperate service (transformations) from user-interface (XML generation)
	* Allow saving of ATerm sources

-- Main.NielsJanssen - 23 Oct 2003