Hey everyone,

So I've been working on the transport layer today and wanted to run some thing 
past everyone to make sure we're all on the same page. There's no new major new 
work: just tweeking some existing stuff and moving functionality into new files 
where I thought it would make things clearer.

1. Minor updates `ClientInterface`

I agree with Matt: we need to keep this interface as simple as possible for new 
client classes to implement. There's two discrete pieces of functionality the 
interface should care about: requests and configuration. Here's an outline of 
what I thought might work:

https://gist.github.com/jamiehannaford/01bbf366f5f3da07bbcd

I tried to keep things as simple as possible - can people lend me their 
thoughts on it?

One of the main differences with the current version is that it separates out 
the process of creating a request from sending it. Right now we do it in one 
method, which is disadvantageous for two reasons:

1. It prevents users from modifying the Request object before sending it. Matt 
raised a very good point that you can pass in extra headers, etc. into the 
signature itself - but what I'm talking about is things like event subscribers. 
In the lifecycle of a cURL transaction (a Request being created, prepared, and 
sent; a response being parsed, etc.) different events are emitted. These events 
are incredibly useful and empowering for end-users because they enable people 
to add in their own custom logic to processes which are usually unavailable 
(unless you actually extend the SDK code). By having a "createRequest" method 
that actually returns a Request rather than just sending it, we're allowing 
users to add their own subscribers. Here are a few use-cases: a user might want 
to add a subscriber which logs everything for that 1 request; a user might want 
to use a subscriber to handle exceptions differently for that 1 request; a user 
might want to retry the Request if a particular status code is returned, etc.

2. Most common HTTP frameworks, like Guzzle and ZF2, use these two methods 
("createRequest" and "send"). It makes sense to stick with convention so 
end-users and contributors are not confused.


2. Moving Guzzle stuff to a sub-directory

Right now we're using Guzzle by default, but we also want to support the 
ability for users to inject their own HTTP client in. So to make this clearer, 
I've moved Guzzle-specific files to their own "Guzzle" sub-directory (under the 
OpenStack\Common\Transport\Guzzle namespace). I've also changed the 
"GuzzleClient" classname to "GuzzleAdapter" because it's actually adapting an 
existing client, not serving as one. All it's doing is wrapping Guzzle and 
implementing our standard interface - so I wanted to make that clearer and 
avoid confusion.


3. HTTP exceptions

I also discovered a really cool way to handle exceptions. Right now, we're 
throwing exceptions in the adapter - which adds a lot of exception-specific 
logic to a base class. So instead, I copied all of this existing logic to a new 
"RequestException" class. All the GuzzleClient/GuzzleAdapter needs to do is 
call RequestException::create($request, $response) and all of the logic for 
finding the right class for the right HTTP status code is determined inside 
RequestException like this:

https://gist.github.com/jamiehannaford/0a085d4b1507308b0190

Another thing I wanted to do is make it easier for devs to debug the problem 
once an exception is thrown - so I made the Request and Response objects (for a 
failed request) available in the exception. So instead of printing out a 
generic message, we also allow them the ability to retrieve the offending 
request/response with $e->getRequest() and $e->getResponse()

---

That's about it, basically :)

Does anybody have any questions or concerns with any of this?

Jamie



Jamie Hannaford
Software Developer III - CH     [experience Fanatical Support]

Tel:    +41434303908
Mob:    +41791009767
        [Rackspace]



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