9 p.m.
On 10/17/2011 05:35 PM, Adam Young wrote:
On 10/17/2011 08:10 PM, Jack Magne wrote:
> On 10/17/2011 01:18 PM, Ade Lee wrote:
>> Hi all,
>>
>> I tried to put this on the dogtag wiki, but it did not seem to work.
>> Will chat with Matt.
>>
>> In the meantime, here is a copy for you guys to look at and comment on.
>> It has most everything except the installation servlets and token
>> operations (for which I need to think about the object model). If you
>> look at the mapped servlets, you'll get a sense of what operations are
>> covered in each URL mapping.
>>
>> This is a first cut -- hopefully a good starting point for discussion.
>> So please comment away!
>>
>> Ade
>>
>>
>>
>>
>>
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>>
> Thanks Ade. Just a few questions after having a look.
>
> 1. I noticed we have the following key related resources:
>
>
> PUT /pki/key "Add a key"
>
> POST /pki/key "Modify a key"
>
> In my quick readings, it appeared that the POST method was favored
> for creating brand new resources where PUT was used to modify
> existing ones?
I think you have it backwards. PUT is the normal way for creating
things. The POST operation is very generic and no specific meaning can
be attached to it. In general, use POST when only a subset of a
resource needs to be modified and it cannot be accessed as its own
resource; or when the equivalent of a method call must be exposed.
http://developer.mindtouch.com/REST/REST_for_the_Rest_of_Us says this
about POST:
" usually either create a new one, or replace the existing one with
this copy, where as POST is kinds of a catch all. "
We could possibly use PUT for both add and modify if we wanted.
My bad. I guess I chose to read a conflicting article on this subject:
http://www.ibm.com/developerworks/webservices/library/ws-restful/
where it says the following:
* To create a resource on the server, use POST.
* To retrieve a resource, use GET.
* To change the state of a resource or to update it, use PUT.
* To remove or delete a resource, use DELETE.
Perhaps I was further thrown off about the discussions I've seen about
the idempotence property of PUT, whereby if you replay the same request
more than once, you get the same result as the first time. Where in
POST, if you repeat the exercise multiple times, you will get a list of
new resources. Perhaps you could speak a little to that subject.
I think I see now why he would chose PUT to create a key, because PUT
replaces the entire resource, and POST can be used to replace part of a
resource. If we were to modify a key or a request for a key, I'm
guessing we would not replace the entity entirely.
I tend to favor making objects immutable, and to replacing whole
objects when possible. However, I know that is not always possible,
especially when working with a pre-existing API. So I'd say lets try
to stick to PUT semantics where possible, but deliberately use POST
when we are making finer grain API calls.
>
> I also noticed that you have two GET versions of "pki/key". Is that
> kind of duplication encouraged? Or is that really just the same api
> entity with different input payloads?
>
> 2. You suggested I take a look at some of the TKS TokenServlet stuff.
> I noticed that we have a simple short list of servlets that appear to
> return very short lived resources. Examples being, session keys ,
> encrypted data , and a block of randomly generated data.
>
> I would imagine it would be a POST op like something as follows:
>
> POST /pki/tks/sessionKey , which would return a link to the key
> itself? But does it make sense to have a "resource" for something so
> short lived, or does this concept even belong in such a design?
In general, REST works best if the service is stateless. Session
based information should be minimized if possible.
Perhaps REST is not the way to
go in the token space due to the nature
of the beast.
>
> 3. I was just curious about the Java back-end for this design. Will
> we be using the JAX-RS stuff that provides annotations in the java
> code in order to hook all of this up?
I am not a fan of annotations. Under other circumstances, I might be
prone to say "well, that is the way of the world" and go with JAX-RS,
but since we don not yet have a set of Entity objects that would drive
the JAX-RS, I am more prone to look at other alternatives. THere are
good libraries for serializing to JSON or XML that should be
sufficient for our needs, and that will keep us from having to make
our API conform to JAX-RS. So my inclination is to say no to JAX-RS
to start.
>
> thanks,
> jack
Thanks for the clarifications!
Ade's document has founds its way into the wiki world:
http://pki.fedoraproject.org/wiki/Dogtag_Future_Directions
I might have made some Wiki errors in translation. If this
contradicts Ade's spreadsheet, assume the spreadsheet is Canonical.
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