I use an open source product called TinyXML
(http://www.gibaradunn.srac.org/tiny/) to parse the configuration file.
It's a pretty simple, non-validating XML parser. I found their example
really easy to follow and wound up accidently building the parser while
playing around over a lunchbreak. The website I'm working on will
eventually need to deliver XML files (translated through XSL) so I'll
eventually switch to Cacoon or something similar.
I preload it into a hashtable of actions in the main servlet's init() method
(because the configuration data is so heavily used). The hashtable of
actions contain action objects which in turn have a hashtable of intents
(containing intent objects). Code readability and ease of maintenance is
why I decided on this method. I don't imagine hashtables to be a terribly
efficient performance wise, but I find it really helps keeps things straight
when coding.
Donald
> Interesting. My only question, due to performance...why not use "int"
value
> returns instead of Strings. Mainly because I am quite sure evaulating an
int
> value is much faster than doing a string comparison. I realize Strings are
> nice, easy to understand, but in terms of performance I would imagine
using
> int values would be much faster for lookup in the DOM.
>
> Incidentally, how are you reading in your XML file, and into what type of
> object? I have heard alot about how some of the free XML parsers turn XML
> files into a DOM object. Is that part of the XML package? Or is it an
object
> you create? I would love to get more info on this process as I want to
> implement this soon.
>
>
>
> >-----Original Message-----
> >From: A mailing list about Java Server Pages specification and reference
> >[mailto:[EMAIL PROTECTED]]On Behalf Of Donald E. Vandenbeld
> >Sent: Tuesday, April 11, 2000 1:48 PM
> >To: [EMAIL PROTECTED]
> >Subject: Re: More on Model 2/little confused
> >
> >
> >I'm doing it something like this:
> >
> >First off, I'm using an xml file to store my configuration. This
> >works best
> >for me but a simpler configuration could easily use a properties file.
> >
> >The first part of the config file defines resource types (by resource I
> >basically mean 'pages' within the site that may be accessed). I define
the
> >following:
> >
> > <resource id="static">
> > <path>/</path>
> > <extension>.html</extension>
> > </resource>
> >
> > <resource id="dynamic">
> > <path>/</path>
> > <extension>.jsp</extension>
> > </resource>
> >
> > <resource id="program">
> > <path>/servlet/</path>
> > </resource>
> >
> >I then create a series of stimulus defintions. These define what action
to
> >take given a certain stimulus. The stimulus is simply a parameter called
> >'action' that gets defined in every form in the site. Here is a simple
> >stimulus definition:
> >
> ><stimulus id="Login">
> > <action type="dynamic">login</action>
> ></stimulus>
> >
> >So, if the current 'action' request parameter is equal to "Login", the
> >controller servlet should redirect to the 'login' page. Because of my
use
> >of resource types, this gets translated into: /login.jsp (this make it
> >really easy to install the site in different directories on different
> >servers). Here is a more complex stimulus definition:
> >
> ><stimulus id="ValidateInitialLogin">
> > <action type="program">AuthenticateServlet</action>
> > <intent>
> > <default>CheckAnnouncement</default>
> > <condition result="user">CheckAnnouncement</condition>
> > <condition result="instructor">CheckInstructorAnnouncement</condition>
> > <condition result="staff">CheckStaffAnnouncement</condition>
> > <condition result="admin">CheckAdminErrors</condition>
> > <condition result="error">Login</condition>
> > </intent>
> ></stimulus>
> >
> >If the current action is 'ValidateInitialLogin', the controller servlet
> >should redirect to the AuthenticateServlet. Where my
> >implementation differs
> >a bit is that I can specify different actions to take depending on the
> >results of the AuthenticateServlet. For instance, if this latter servlet
> >gets an error, it should set the action variable to 'Login'. If the
> >AuthenticateServlet runs and finds that the user belongs to a
> >class of users
> >called 'instructor', the servlet should get the action variable to
> >'CheckInstructorAnnouncement'. The default tag is maybe a little
> >missleading - it is really supposed to indicate the default condition.
> >
> >This system works pretty nicely. These 'action servlets' simply create
> >beans that do all the real work (connecting to databases, performing
> >queries, etc) and then set a (string) result code. A few lines of code
at
> >the end of each of these action servlets redirects to the
> >appropriate jsp or
> >servlet depending on the result code. I'd be interested in hearing about
> >how others implemented this idea (or critiques of the way I did it).
> >
> >Donald
> >
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