On Mon, Oct 22, 2012 at 8:32 AM, Helmut Dobretzberger
<h.dobretzber...@gmx.at> wrote:
> Hey,
>
> I want to build my new web-application with the racket-webserver, so I have
> worked through the continue-tutorial.
> Now i want to improve the simple blog from the tutorial to learn more
> web-server tecniques which leads to some questions:
>
> - I've tried to change that application to use templates. (It' would be nice
> to include that in the tutorial!)
> The relevant part of template with all posts look like this:
>
> @in[p posts]{
> <div class="post">
> <a href="@????">@(post-title p)
> <p>@(post-body p)</p>
> <div>@(number->string (length (post-comments p))) comment(s)</div>
> </a>
> </div>
> }
> </div>
>
> What ist he best way to fill the @???? - because that is a specific url for
> every post generated by embed/url in the racket-application so it can't be
> accessed with selectors like the other parts.
Templates have all of Racket and the scope of the including location
available to them. You can just do
@embed/url[view-post-handler]
and it will work
>
> - As an alternative, I was thinking about using a url like this
> "?id=@(post-id p)" but then i read in the docs that it is not recommended to
> use extract-binding/single. But how can i create "permanent-urls" for
> linking from other sites etc when i should not use get-parameters?
I'd recommend using web-server/dispatch for that purpose.
> - As a consequence, I've tried the web-server/dispatch with the
> small-example in the docs. (It would also be nice if this topic is treated
> in the continue-tutorial)
> The example runs successful when starting from drracket:
>
> (require web-server/dispatch
> web-server/servlet-env)
>
> (define-values (blog-dispatch blog-url)
> (dispatch-rules
> [("") list-posts]
> [("posts" (string-arg)) review-post]))
>
> (define (list-posts req)
> (response/xexpr
> `(body "list-posts")))
>
> (define (review-post req p)
> (response/xexpr
> `(body ,(string-append "review-posts " p))))
>
> (serve/servlet blog-dispatch
> #:servlet-path "/"
> #:servlet-regexp #rx"" ;But is this "the right way"?
> #:launch-browser? #t)
>
>
> But - how do I run that on the plt-web-server? I have removed the
> serve/servlet and added
>
>
> (define interface-version 'v1)
> (define timeout +inf.0)
> (define start blog-dispatch)
> (provide interface-version timeout start)
>
>
> but that leads to the follwing error:
>
>
> servlet-error-responder: contract violation
> expected: exn?, given: #<exn:dispatcher>
> in: the 2nd argument of
> (-> url? exn? response?)
> contract from:
> <collects>/web-server/configuration/responders.rkt
> blaming:
> <collects>/web-server/web-config-unit.rkt
> at: <collects>/web-server/configuration/responders.rkt:126.2
>
>
> What do I have to do to run this code on the server?
Dynamically required servlets (that use 'plt-web-server') can't
customize the server itself. The use of web-server/dispatch requires
the server to be customized. (In particular, 'plt-web-server' uses a
cgi-bin-like URL structure to associate URLs with servlets and the
whole point of web-server/dispatch is to not do that.)
You probably shouldn't use the 'plt-web-server' cmdline program for
serious sites.
Jay
--
Jay McCarthy <j...@cs.byu.edu>
Assistant Professor / Brigham Young University
http://faculty.cs.byu.edu/~jay
"The glory of God is Intelligence" - D&C 93
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