[Dancer-users] RESTful applications in Dancer

Gabor Szabo szabgab at gmail.com
Mon Dec 20 16:12:15 CET 2010

On Mon, Dec 20, 2010 at 4:34 PM, damien krotkine <dkrotkine at gmail.com> wrote:
> First, I'd suggest that you think about what makes your webapp RESTy ?

Well, I don't have a clue what makes and application RESTy but as I understood
there are not many people who understand that. :)

> It's not because a webapp returns YYML/JSON that it is RESTy. To be REST
> oriented, the bare minimum is to have the logic of your app based on
> resources. 'login' is definitely not a resource. It looks like a verb, like
> "please log me on or off or something". In REST, the verbs are only HTTP
> verbs. URLs are resources, so you should be able to explain them as nouns.
> That said, maybe you already know all that and took 'login' as a strange
> example :)

So maybe it would be

    GET /authorized_cookie

or even

    GET /authorized_token

instead of  /login ?

In any case it would require some kind of credentials.
e.g. username/password  or some way - and I don't know yet how
that works - to get authenticated by OpenID or some OAuth
based service.

I am not sure though if even this is "allowed" in pure REST terms
as I can see from http://en.wikipedia.org/wiki/Representational_State_Transfer
a RESTful application should be stateless?
Does that mean for every request that involves private data I'd need
to supply my credentials?

Anyway, here is an example, which is just the first step in my future

A bookmark storing application. So I'd have operations such as
add, delete, change     ITEM
list items (with some restirctions)
Do these need to map to the HTTP keywords?

e.g. fetching all the perl related bookmarks would be

GET /bookmarks?title='%perl%'

fetching all the details about a single bookmark would be:

GET /bookmark/42

adding a new one would be

POST /bookmark?title='The Perl Web Frameworks'&url=http://perldancer.org/

PUT /bookmark?id=42&comment="Nice framework"

Is that the idea or would using GET in each case ok?

(Personally I am now trying to implement the API of a web services and it
drives me crazy that some requests only work as GET others only as POST
and I don't even understand the errors I get from the other requests)

Is that right that I have /bookmarks (in plural) above and /bookmark
(in singular) in
the other requests?

> If I were you (but I don't know much about your webapp and its goal), I
> would design a pure REST application.
> - routes would be resource names
> - I'd use the Dancer REST plugin to handle serialization
> - /url/to/resource would return json or yaml based on Accept header.
> No Accept header would produce a server error
> - /url/to/resource.json would work, as well as yaml.
> Then, if you need a web frontend, do an other webapp :) or at least, a
> different Dancer::App. But Dancer being lightweight, it may be valid to have
> a completely seperated app.

I think I'll write both a perl client and a Javascript client for it
and the Javascript
client will use some static files from the same Dancer app to provide the
base HTML to build on.

> For authentication, I'd use plack and some auth mechanism.
> REST means it's stateless. Usually we accept that Authentication is the only
> state retains accross a RESTy webapp. If you need a very complicated
> authentication mechanism, you may end up with resources like
> /some/authentication. But these will be nouns, not verbs. But most of the
> time, some plugin/middleware/stuf will provide it for you transparently.
> Hope I made some sense and were not off topic

This answers my previous question about statelessness and authentication.

Yes it was very useful, though I am not sure what did you mean by
and how is plack related to authentication.


> On 20 December 2010 15:22, Gabor Szabo <szabgab at gmail.com> wrote:
>> hi,
>> I have a general web related question and then I wonder which of the
>> answers can be easily implemented in Dancer?
>> I am building an application that probably will be mostly just send
>> out serialized data though I am not 100% sure so I might want to
>> mix in sending out traditional HTML files as well.
>> So I wonder what is the "best practice" to write RES-ish application,
>> one that might also serve HTML?
>> I thought about a few strategies I am going to describe now
>> using a single route as an example:
>> 1)
>> /login    always returns HTML
>> no XML, JSON, YAML interface
>> old school, no buzzwords here :)
>> 2)
>> /login         always returns HTML
>> /login.yml   returns YAML
>> /login.json  returns JSON
>> etc. (some of these might be allowed  some might not)
>> Q: What is the relationship between the HTML and the YAML?
>> Is the data returned as YAML the same as would be passed to
>> the template for generating HTML? How?
>> 3)
>> /login         returns HTML or YAML or JSON depending on the
>> Accept header of the request.
>> In order to fetch the YAML response the request needs to supply:
>> Accept: application/json
>> I am not sure if HTTP allows multiple Accept headers and if yes then how
>> should the application behave?
>> Otherwise the same as 2 above.
>> 4) No HTML responses at all (only some static pages) so
>> 4.2)  the serialization is the same as in 2) based on extension
>> 4.3)  the serialization is the same as in 3) based on Accept header
>> Are any of these good strategies? Are there other good ones?
>> Which one can be implemented in Dancer and how?
>> regards
>>   Gabor

More information about the Dancer-users mailing list