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From Michal Fojtik <>
Subject Re: [PATCH] Report what operations are available from api and from the client.
Date Wed, 26 Jan 2011 08:25:57 GMT

On Jan 25, 2011, at 9:01 PM, David Lutterkort wrote:

> On Fri, 2011-01-21 at 13:29 -0500, wrote:
>> From: Tobias Crawley <>
>> Changes to the server:
>> This provides capability reporting to the /api and the client. The /api xml format

>> now looks like:
>>  <link href='http://localhost:3001/api/instances' rel='instances'> 
>>    <feature name='hardware_profiles'></feature> 
>>    <feature name='user_name'></feature> 
>>    <feature name='authentication_key'></feature> 
>>    <operation method='post' name='reboot' scope='member'> 
>>    </operation> 
>>    <operation method='get' name='show' scope='member'> 
>>      <param feature='authentication_key' /> 
>>    </operation> 
>>    <operation method='post' name='start' scope='member'> 
>>    </operation> 
>>    <operation method='delete' name='destroy' scope='member'> 
>>    </operation> 
>>    <operation method='post' name='stop' scope='member'> 
>>    </operation> 
>>    <operation method='post' name='create' scope='collection'> 
>>      <param feature='hardware_profiles' /> 
>>      <param feature='user_name' /> 
>>      <param feature='authentication_key' /> 
>>    </operation> 
>>    <operation method='get' name='index' scope='collection'> 
>>    </operation> 
>>  </link> 
> After thinking about this some more, it seems to me we are describing
> too much standard RESTishness here; especially when you look at the
> description of collections like realms.
> I do see the need to express better what operations are supported for a
> certain collection; in particular, more details about how features
> modify specific operations.
> OTOH, the bits of the api XML that document standard REST operations
> look too much like an ad-hoc variant of WADL/WSDL. So I am going to hold
> off on committing this patch.
> I'd be curious to see what others think of this issue, and what needs
> they have in this area.

I personally like to use HTTP protocol instead of additional XML. 

I recently found this:

"The OPTIONS method represents a request for information about the communication options available
on the request/response chain identified by the Request-URI. This method allows the client
to determine the options and/or requirements associated with a resource, or the *capabilities*
of a server, without implying a resource action or initiating a resource retrieval." 


So maybe we could re-think idea of capabilities and use this HTTP method to get all supported
on top of collection/member. 

Something like:

OPTIONS /api/instances

  <operation method='post' name='create'> 

OPTIONS /api/instances/i-123456

  <operation method='post' name='reboot'>

What do you think ?

  -- Michal

Michal Fojtik
Software Engineer, Deltacloud API project

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