subject:"servlet\-mapping"

servlet-mapping

2002-01-31 Thread Dan Ascheman






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Re: Servlet Mapping Recursion Problem

2001-05-11 Thread Bill Winspur


Thanks Joni,

very elegant. I've started down that route (ie. having externally visible
urls that are different to the internally visible urls), but hadn't thought
of driving the whole thing off a configuration file.  Neat. The application
provider could package it with the app, leaving the front servlet truly
generic. Also, the *.html servlet-mapping hides *.gif resource mapping, etc.
from the servlet.. And reason number four to like this approach is: "it
should work on any webserver".

After my previous post I discovered that recursion doesn't just happen if
the '/' is mapped to your front servlet (it seems obvious now).  If you map
'myUrl' to your front servlet, and then forward to 'myUrl', you also get
recursion and a crash.

Its been a good day,

Bill.


- Original Message -
From: "Joni Suominen" <[EMAIL PROTECTED]>
To: "Orion-Interest" <[EMAIL PROTECTED]>
Sent: Friday, May 11, 2001 11:48 AM
Subject: Re: Servlet Mapping Recursion Problem


> Hi Bill!
> I am using a front servlet pattern with Orion. I use Struts but I
> suppose this approach should work in any framework.
>
> 1. The front servlet mapping in web.xml:
>   
> action
> *.html
>   
>
> So all the requests ending to .html are processed by the front-end
> servlet.
>
> 2. All the valid URL's are mapped in an xml config file. The front
> servlet initializes its state by reading this file in a startup. An
> entry in this file looks like:
> type="org.shiftctrl.general.interaction.EmptyAction">
> 
>   
>
> This means that the request http://myserver.com/faq.html is first
> processed by front servlet. The servlet searches its configured mapping
> and forwards the request. In this case it would forward the request to
> faq.jsp.
>
> I haven't had problems with this setup and I really like it for
> following reasons:
> 1. It is easy pipeline actions. Just configure the mapping so that its
> forward part points to another mapping.
> 2. You can hide the technology being used. Clients only see URLs which
> are always ending .html (so .jsps are not exposed outside, their
> function is only to provide the view part in MVC pattern)
> 3. It is possible to dynamically change the URL mapping by calling
> appropriate methods in front servlet.
>
> --
> Joni
> [EMAIL PROTECTED]
>
> > Bill Winspur wrote:
> >
> > In my web.xml I set up the servlet mapping, for a (front) servlet to
> > handle all requests for the web app, to '/'. This works to the extent
> > that all requests are passed to the servlet. BUT... if I do a forward
> > to another resource from the servlet, the servlet's doGet() method is
> > invoked recursively with no response generated until the jvm runs out
> > of memory. The same thing happens with a url-pattern of '/*'. If the
> > servlet itself generates html output, that works.  If I map my servlet
> > to a specific resource, like /index.html, forwarding works fine, but
> > the servlet cant handle all requests and 'http://myhost/myapp' returns
> > 'no directory browsing'.
> >
> > The url-pattern '/' seems like a valid directory specification (as per
> > the servlet 2.2 spec, 'Servlet Mapping Techniques') and a front
> > component, handling all requests is fundamental in the j2EE blueprints
> > (http://java.sun.com/j2ee/blueprints/index.html, section 10.6), so my
> > approach seems architecturally reasonable.
> >
> > I've looked thru the archives and found two reports of the same
> > problem. A proposed workaround from Magnus seems to recommend
> > explicitly mapping every request your app generates (which would make
> > the web.xml coding difficult to maintain in a large app) pendng the
> > delivery of 'filters', perhaps in Servlet 2.3. I dont really
> > understand what Magnus is suggesting:
> >
> > PS: If you're bound to 2.2 or lower then you will not be able to use
> > Filters, in that case you'd have to apply a more complex solution with
> > duplicate resource roots and so on.
> >
> > It looks like 'no front servlets on Orion' to me, but I hope I'm
> > wrong.
> >
> > I was not able to find any references to the problem on bugzilla, but
> > I'm not very adept with its query interface.
> >
> > My hunch is that Orion's request dispatcher is invoked in two contexts
> > (from a client, and from a forward) and does not distinguish between
> > them when it comes to selecting a resource to respond to the client.
> > If the dispatcher ignored ma

Re: Servlet Mapping Recursion Problem

2001-05-11 Thread Joni Suominen


Hi Bill!
I am using a front servlet pattern with Orion. I use Struts but I
suppose this approach should work in any framework.

1. The front servlet mapping in web.xml:
  
action
*.html
  

So all the requests ending to .html are processed by the front-end
servlet.

2. All the valid URL's are mapped in an xml config file. The front
servlet initializes its state by reading this file in a startup. An
entry in this file looks like:
  

  

This means that the request http://myserver.com/faq.html is first
processed by front servlet. The servlet searches its configured mapping
and forwards the request. In this case it would forward the request to
faq.jsp.

I haven't had problems with this setup and I really like it for
following reasons:
1. It is easy pipeline actions. Just configure the mapping so that its
forward part points to another mapping.
2. You can hide the technology being used. Clients only see URLs which
are always ending .html (so .jsps are not exposed outside, their
function is only to provide the view part in MVC pattern)
3. It is possible to dynamically change the URL mapping by calling
appropriate methods in front servlet.

--
Joni
[EMAIL PROTECTED]

> Bill Winspur wrote:
> 
> In my web.xml I set up the servlet mapping, for a (front) servlet to
> handle all requests for the web app, to '/'. This works to the extent
> that all requests are passed to the servlet. BUT... if I do a forward
> to another resource from the servlet, the servlet's doGet() method is
> invoked recursively with no response generated until the jvm runs out
> of memory. The same thing happens with a url-pattern of '/*'. If the
> servlet itself generates html output, that works.  If I map my servlet
> to a specific resource, like /index.html, forwarding works fine, but
> the servlet cant handle all requests and 'http://myhost/myapp' returns
> 'no directory browsing'.
> 
> The url-pattern '/' seems like a valid directory specification (as per
> the servlet 2.2 spec, 'Servlet Mapping Techniques') and a front
> component, handling all requests is fundamental in the j2EE blueprints
> (http://java.sun.com/j2ee/blueprints/index.html, section 10.6), so my
> approach seems architecturally reasonable.
> 
> I've looked thru the archives and found two reports of the same
> problem. A proposed workaround from Magnus seems to recommend
> explicitly mapping every request your app generates (which would make
> the web.xml coding difficult to maintain in a large app) pendng the
> delivery of 'filters', perhaps in Servlet 2.3. I dont really
> understand what Magnus is suggesting:
> 
> PS: If you're bound to 2.2 or lower then you will not be able to use
> Filters, in that case you'd have to apply a more complex solution with
> duplicate resource roots and so on.
> 
> It looks like 'no front servlets on Orion' to me, but I hope I'm
> wrong.
> 
> I was not able to find any references to the problem on bugzilla, but
> I'm not very adept with its query interface.
> 
> My hunch is that Orion's request dispatcher is invoked in two contexts
> (from a client, and from a forward) and does not distinguish between
> them when it comes to selecting a resource to respond to the client.
> If the dispatcher ignored mapping in the forward context and just
> accepted the specified resource, the recursion problem would vanish
> and the front servlet would trap ALL client requests as per the
> blueprint architecture. Just a hunch, things are probably not that
> simple.
> 
> Does anyone know if this is a problem with other webservers ? My
> experience with Apache was all static pages.
> 
> My environment is NT4(sp6), Orion 1.4.8, IE 5.00, JDK 1.2.2.
> 
> Also, if somebody is actually using the front servlet pattern and
> univeral mapping on Orion, and could let me know how to set it up
> and/or get around the recursion I'd be a happy camper.
> 
> TIA,
> 
> Bill.

RE: Servlet Mapping Recursion Problem

2001-05-11 Thread elephantwalker

Bill,
yeh...we need the apache url re-writting stuff in a
servlet. That's an issue with orion. I think the opensymphony people are writing
something.
There
is a simple workaround. Have a forward.jsp as your welcome page for the default
app. In the forward.jsp, use this code:
<% String servletPath =
request.getRequestURI().substring(0,
request.getRequestURI().indexOf(request.getServletPath()));
response.sendRedirect(servletPath+"/somepath/to/index or home or whatever.html")
;
%>
the
somepath can be /main/home.html, for example.
in
your web.xml, map your "controller-rewriter servlet" to the
/main/*
so
instead of your pages asking for resouces at /myfavoritegif.gif, they would
just be /main/myfavoritegif.gif.
This
is ugly, and quick and dirty, but it works. You can even read in an xml file
when you rewriter servlet starts up so that all of your path mapping, rewritting
works like apache.
Regards,
The
elephantwalker

-Original Message-From:
[EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Bill
WinspurSent: Thursday, May 10, 2001 8:51 AMTo:
Orion-InterestSubject: Servlet Mapping Recursion
Problem

In my web.xml I set up the servlet mapping, for a (front) servlet to handle
all requests for the web app, to '/'. This works to the extent that all
requests are passed to the servlet. BUT... if I do a forward to another
resource from the servlet, the servlet's doGet() method is invoked recursively
with no response generated until the jvm runs out of memory. The same thing
happens with a url-pattern of '/*'. If
the servlet itself generates html output, that works. If I map my servlet to a specific resource, like
/index.html, forwarding works fine, but the servlet cant handle all requests and 'http://myhost/myapp' returns
'no directory browsing'.
The url-pattern '/' seems like a valid
directory specification (as per the servlet 2.2 spec, 'Servlet Mapping
Techniques') and a front component, handling all requests is fundamental in
the j2EE blueprints (http://java.sun.com/j2ee/blueprints/index.html, section
10.6), so my approach seems architecturally reasonable.

I've looked thru the archives and found two reports of the same problem. A
proposed workaround from Magnus seems to recommend explicitly mapping every
request your app generates (which would make the web.xml coding difficult to
maintain in a large app) pendng the delivery of 'filters', perhaps in Servlet
2.3. I dont really understand what Magnus is suggesting:
PS: If you're bound to 2.2 or lower then you will not be able to use
Filters, in that case you'd have to apply a more complex solution with
duplicate resource roots and so on.
It looks like 'no front servlets on Orion' to me, but I hope I'm wrong.
I was not able to find any references to the problem on bugzilla, but I'm
not very adept with its query interface.
My hunch is that Orion's request dispatcher is invoked in two contexts
(from a client, and from a forward) and does not distinguish between them
when it comes to selecting a resource to respond to the client.
If the dispatcher ignored mapping in the forward context and just
accepted the specified resource, the recursion problem would vanish and the
front servlet would trap ALL client requests as per the blueprint
architecture. Just a hunch, things are probably not that simple.
Does anyone know if this is a problem with other webservers ? My experience
with Apache was all static pages.
My environment is NT4(sp6), Orion 1.4.8, IE 5.00, JDK 1.2.2.
Also, if somebody is actually using the front servlet pattern and univeral
mapping on Orion, and could let me know how to set it up and/or get around the
recursion I'd be a happy camper.
TIA,
Bill.

Servlet Mapping Recursion Problem

2001-05-11 Thread Bill Winspur

The url-pattern '/' seems like a valid
directory specification (as per the servlet 2.2 spec, 'Servlet Mapping
Techniques') and a front component, handling all requests is fundamental in the
j2EE blueprints (http://java.sun.com/j2ee/blueprints/index.html, section 10.6),
so my approach seems architecturally reasonable.

I've looked thru the archives and found two reports of the same problem. A
proposed workaround from Magnus seems to recommend explicitly mapping every
request your app generates (which would make the web.xml coding difficult to
maintain in a large app) pendng the delivery of 'filters', perhaps in Servlet
2.3. I dont really understand what Magnus is suggesting:
PS: If you're bound to 2.2 or lower then you will not be able to use
Filters, in that case you'd have to apply a more complex solution with duplicate
resource roots and so on.
It looks like 'no front servlets on Orion' to me, but I hope I'm wrong.
I was not able to find any references to the problem on bugzilla, but I'm not
very adept with its query interface.
My hunch is that Orion's request dispatcher is invoked in two contexts (from
a client, and from a forward) and does not distinguish between them when it
comes to selecting a resource to respond to the client. If the
dispatcher ignored mapping in the forward context and just accepted the
specified resource, the recursion problem would vanish and the front servlet
would trap ALL client requests as per the blueprint architecture. Just a hunch,
things are probably not that simple.
Does anyone know if this is a problem with other webservers ? My experience
with Apache was all static pages.
My environment is NT4(sp6), Orion 1.4.8, IE 5.00, JDK 1.2.2.
Also, if somebody is actually using the front servlet pattern and univeral
mapping on Orion, and could let me know how to set it up and/or get around the
recursion I'd be a happy camper.
TIA,
Bill.

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