Hi,
If I may add a snippet from the first para of the specs (1.1)
<snippet>
Servlets interact with web clients via a request response paradigm
implemented by the servlet container. This request-response model is based
on the behavior of the Hypertext Transfer Protocol (HTTP).
</snippet>
This explains why it might be difficult to implement other protocol because
servlet architecture is HTTP centric.
Regds,
Gokul
----- Original Message -----
From: "Nic Ferrier" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, January 31, 2001 3:15 AM
Subject: Re: [SERVLET-INTEREST] other protocol than http
> >>> Julien Gilli <[EMAIL PROTECTED]> 30-Jan-01 8:43:05 PM >>>
>
> >Ths is very interesting and, to me, would be one
> >of the most original part of the Servlet technology.
> >However, i haven't seen any of these possibilities
> >in the real world. So my questions are : Have you
> >seen it ? Are there plans to do it (beta server,
> >beginning of support somewhere) ? Is it at least
> >possible ?
>
> If you look on the archives you'll see that there has been quite a
> lot of discussion on this (but you have to go back to the very early
> days).
>
> Answers to your questions:
>
> Yes it's possible.
>
> Apache James is a servlet implementation of SMTP so that servlets can
> do mail filtering.
>
> No there aren't plans to do it (from any major vendor AFAIK).
>
>
> >This could lead to extends the functionalities of a
> >FTP server for example. Thanks for your help in
> >advance.
>
> After many of us early adopters had tried building other protocol
> implementations of servlet engines we discovered that servlets weren't
> that usefull at doing session based protocols.
>
> Since most other protocols are session based this is why not many
> have been tried. Apache's SMTP implementation is the exception.
>
>
> There are 2 ways to implement another protocol:
>
> 1. provide a protocolServletRequest and protocolServletResponse
> which are used to call a single protocolServlet.service() method. The
> method code must establish what the command to process is and what to
> do.
>
> There must also be a state carrying element to the request/response
> since most commands in most protocols have state, eg: the RCPT command
> in SMTP must be issued after the FROM: command; the CD command in FTP
> changes the directory, etc....
>
> It's quite complicated to write methods like this... if you've ever
> tried to have a single servlet handle state across multiple
> invocations you'll know what I mean.
>
>
> 2. provide a protocolServlet with command methods
> the command methods get called with a light weight request/response.
>
> This is slightly better but for complex protocols you end up having
> to implement an awfull lot of methods.
>
> Also the request/response end up not being that lightweight.
>
> You're also still stuck with the state question.
>
> eg an FTP servlet:
>
> public class MyFTPServ
> extends FTPServlet
> {
> public void cd(FTPServletRequest req,FTPServletResponse resp)
> {
> req.setCurrentDirectory(req.getCDArgument());
> }
> }
>
> Extrapolate from that.
>
>
> Lastly why would you want a servlet engine dealing with another
> protocol? HTTP is pretty much the standard for information retrieval
> now... sure specialist needs require other protocols but those
> specialist needs don't need scripting.
>
> For example, the only reason to use FTP these days is for large file
> transfers (because it's more efficient). But when are you going to
> need to generate a large file transfer on the fly?
>
>
> Nic
>
>
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