[TriLUG] XML and DOM

[Joseph Tate]

Mike M wrote:

>1) Configuration.  I've got a draconian mess that needs to be hidden from the 
>normal user.  I want to make a configurator that queries the user and outputs 
>an XML file.  The XML configuration file is then accessed by the application 
>during startup and operation.
>
What's the use case?  Is the user going to use a web browser?  Some GTK+ 
type app?  Something that runs on Windoze?  A handheld?  When we started 
working on our app more than two years ago, libxml hadn't been ported to 
Windows CE, so we couldn't use it there, but since then it has.  It 
would be my library of choice.  There are wrappers in just about every 
language you can think of, whether you use tcl or perl, C++ or PHP.  In 
the open source world that's the de facto XML library for both SAX and DOM.

>2) Interpretation.  I need to create an interpreter between a complex 
>protocol (where much of the complexity is unneeded) to a simple protocol.  
>The complex side is established and institutionalized.  The simple side is 
>being designed from scratch and is TCP/IP sockets-based.  Both sides 
>structure information formally.  I am thinking that the simple side message 
>format should be implemented in XML. The application receives a simple side 
>message and converts it to a complex side message, and vice-versa.
>  
>
If you are designing both the simple protocol and the clients that 
listen to the protocol you might look into SOAP.
Just choose your platform.  Check out Apache's Axis, PHP's Pear::SOAP, 
Perl's SOAP package from CPAN, or any other implementation you like. 
 You'd get that mostly for free with SOAP.  It usually runs over HTTP, 
though there are asynchronous implementations as well.  Then you can say 
your product is web services enabled.  If you care about that kind of 
thing.

>Is XML a good technology for what I describe above?  More detail available 
>upon request.
>
Sounds fair.  XML is nice and extensible.  The tricky thing is 
generating the WSDL the DTD or the SCHEMA to describe your document. 
 There are advantages to each, but as of yet I haven't found good "Free" 
tools to do what I've needed.  Of course sometimes researching that is 
more work sometimes than simply breaking out your favorite text editor 
for very simple designs.

Joseph