[Opensim-dev] HttpServer overview & RFC

[Justin Clark-Casey]

+1

me too

Frisby, Adam wrote:
> Looks good!
> 
>  
> 
> +1
> 
>  
> 
> Adam
> 
>  
> 
> *From:* opensim-dev-bounces at lists.berlios.de 
> [mailto:opensim-dev-bounces at lists.berlios.de] *On Behalf Of *Dr Scofield
> *Sent:* Wednesday, 28 May 2008 2:07 AM
> *To:* opensim-dev at lists.berlios.de
> *Subject:* [Opensim-dev] HttpServer overview & RFC
> 
>  
> 
> hi all, another request for comments :-)
> 
> i've been chewing on HttpServer and how to use it instead of the .NET 
> HttpListener stuff. here's first a short overview of HttpServer and what 
> it offers (keyword is "short", for more details have a look at 
> opensim-libs/HttpServer), then some thoughts on how we could make use of it.
> 
> HttpServer basically offers the following ways of processing HTTP requests:
> 
> * HttpListener()
> * HttpModule
> * Controllers
> 
> == HttpListener ==
> 
> HttpListener (not the .NET one!) basically works like this:
> 
> HttpListener listener;
> listener = new HttpListener(IPAddress.Any, 80);
> listener.RequestHandler += OnRequest;
> listener.Start(5);
> 
> with OnRequest like this:
> 
> void OnRequest(HttpClientContext client, HttpRequest request)
> {
>     ...
>     client.Respond(...);
> }
> 
> to support HTTPS, all we need to do is load an X509 certificate and pass 
> that in to the HttpListener constructor.
> 
> == HttpModule ==
> 
> HttpModule basically allows us to register an HttpModule derived object 
> with an HttpServer object (which internally uses HttpListener). Each 
> registered module gets invoked to handle an incoming request (similar to 
> the handler idea alan webb brainstormed about a couple of days ago) and 
> can signal back whether it has handled the request.
> 
> == Controller ==
> 
> Controller finally is kind of a pre-canned REST handler making use of 
> the first three parts of an URL (slash is separator) as "addressing"
> 
> http://localhost/user/view/1   
> 
> 
> (example from 
> http://www.codeplex.com/webserver/Wiki/View.aspx?title=Part%20five%20-%20Using%20controllers&referringTitle=Home 
> <http://www.codeplex.com/webserver/Wiki/View.aspx?title=Part%20five%20-%20Using%20controllers&referringTitle=Home>)
> 
> would address the controller module User (or UserController) and invoke 
> the method View() with the value "1".
> 
> 
> == Authentication ==
> 
> Authentication is via Authentication modules as well as via callbacks 
> where required (for example for DigestAuthentication the callback occurs 
> to get the password).
> 
> 
> == making use of HttpServer ==
> 
> what i'd actually like to implement (either as an HttpModule or as an 
> HttpListener handler) is an event--event handler scheme:
> 
>     * incoming HTTP request is pushed as an OSHttpRequest object into an
>       HTTP request queue.
>     * each OSHttpRequest encapsulates
>           o the HTTP request header,
>           o an input stream fed by the remote client,
>           o an output stream feeding the remote client
>           o method to produce OSHttpResponse object (for signaling
>             redirects, setting status codes, etc)
>     * we have a pool of OSHttpRequest pumps that take OSHttpRequest
>       objects and pump them via the registered event handlers to whoever
>       registered an interest (via multicast mechanism that stefan
>       already explained a couple of days ago as well)
>     * event handlers return either
>           o Pass --- didn't act on it
>           o Handled --- acted on it, response return as out parameter
>           o Detach --- acting on it, taking care of it myself, don't do
>             anything
>     * if no event handler acted on the OSHttpRequest, we return an error
>       code
>     * as soon as as we get a Handled or Detached response we stop going
>       through the handlers
>     * if we get a Handled we OSHttpResponse.SendHeaders and close the
>       input and output streams
> 
> any event handler that returns Detached is responsible for sending 
> response header and for dealing with the input and output stream itself 
> --- and could, for example, keep an HTTP connection open, implementing a 
> long poll scheme, for example.
> 
> BaseHttpServer would offer two events to which event handlers could 
> attach: OnHttpRequest and OnHttpsRequest.
> 
> 
> what do you think?
> 
>     cheers,
>     dr scofield/dirk
> 
> 
> -- 
> 
> dr dirk husemann ---- virtual worlds research ---- ibm zurich research lab
> 
> SL: dr scofield ---- drscofield at xyzzyxyzzy.net <mailto:drscofield at xyzzyxyzzy.net> ---- http://xyzzyxyzzy.net/
> 
> RL: hud at zurich.ibm.com <mailto:hud at zurich.ibm.com> - +41 44 724 8573 - http://www.zurich.ibm.com/~hud/ <http://www.zurich.ibm.com/%7Ehud/>
> 
> 
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Justin Clark-Casey
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