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Re: REST implementation

 

Hi Mike

I hope you understand that I'm not rejecting your proposal at all :-) just
throwing balls in the air and alternative suggestions so we can reach the
best solution. Tonight I am gonna review your branch in more detail and
give you some feedback.

Earlier you mentioned that all you really need to describe the restful
service is a list of objects. I don't entirely agree with this unless that
list also contains object info ie. attribute names and types.

/ Jakob

2012/10/23 Mykhailo Stadnyk <mikhus@xxxxxxxxx>

> Initially I was supposed to implement in some kind of way, but just using
> the class-level decorator. But! It is too strict and not as flexible as
> could be.
> I told already taht I imagine that exposing RESTful methods might be a bit
> more flexible.  Let's imagine that I already have some SOAP service which
> is easily could map to REST by exposing the methods (assuming that SOAP
> service is "almost RESTful", but all I need is to expose to HTTP GET not a
> single method but several). You can look at, for example, JAX-WS - the REST
> implementation is something like in my proposal. You put TOO strict
> constraints for the REST service, mine is more flexible. I propose to
> developer to decide what does he want to do with his service (he might want
> to have 2 POST, 5 GET, 1 PUT and no DELETE HTTP methods exposed for
> concrete service object). This mapping could be easily done by matching the
> arguments passed through an HTTP, so the rule is a following:
>  1. If you have several methods exposed to the same type of HTTP request,
> which method to call is determined by matching the bypassed HTTP params and
> the service method arguments
>  2. REST is not RPC, so you can not tell which method to call by name, but
> we can call different methods relying on their signatures
>
> 1,2 - the same but with different words.
>
> Regards,
> Mike
>
> 2012/10/23 Jakob Simon-Gaarde <jakobsg@xxxxxxxxx>
>
>> Let's try to define the end-user result, and then discuss the
>> implementation afterwards.
>>
>> In the following I have defined a very simple type as a case we can
>> collaborate through.
>>
>> Maybe we have an object called Client that needs to be RESTful. I think
>> the nicest thing to do would be to SubClass LadonType (ie.
>> RESTfulLadonType) which has some virtual methods:
>>
>> class Client(RESTfulLadonType):
>>
>>   uid = PORTABLE_STRING
>>   name = PORTABLE_STRING
>>   account = PORTABLE_STRING
>>   credit = bool
>>
>>   def get(self,id):
>>     pass
>>
>>   def put(self,id):
>>     pass
>>
>>   def delete(self,id):
>>     pass
>>
>> Ladon sees right away that some og the objects used in the Service class
>> are RESTful and adds restful to the list of protocols.
>> Your turn!
>>
>> / Jakob
>>
>>
>>
>> 2012/10/23 Jakob Simon-Gaarde <jakobsg@xxxxxxxxx>
>>
>>> I knew this already :-) And that's not nessesarilly a bad thing,
>>> depending on what you are developing. I just think we need to think through
>>> how to implement it in Ladon. Since you have enjoyed using Ladon until now,
>>> you probably already know that I am a hugh fan of end-user simplicity.
>>>
>>> And since REST is strictly object-oriented, I really think we should be
>>> looking at decorating the LadonType instead of methods. I haven't thought
>>> it all the way through yet, but I'm almost sure that would be the place to
>>> do it.
>>>
>>>
>>> / Jakob
>>>
>>>
>>> 2012/10/23 Mykhailo Stadnyk <mikhus@xxxxxxxxx>
>>>
>>>> Exacly! REST is a constraint to objects by design! You've caught it.
>>>> But it's good principal for data-oriented services with no overhead by any
>>>> top-level protocol. It's a principal of building RESTful services. And will
>>>> be good if Ladon will support it
>>>>
>>>> 2012/10/23 Jakob Simon-Gaarde <jakobsg@xxxxxxxxx>
>>>>
>>>>>  But, I think I know what you mean. It's the fact that it utilizes all
>>>>> HTTP methods that makes you say that REST is in the HTTP protocol. I just
>>>>> don't nessesarily find that this is very revolutionary. It's more of a
>>>>> constraint, cause you are limited to objects by design.
>>>>>
>>>>> / Jakob
>>>>>
>>>>>
>>>>> 2012/10/23 Mykhailo Stadnyk <mikhus@xxxxxxxxx>
>>>>>
>>>>>> For REST HTTP is not underlying level but the protocol itself. In
>>>>>> terms of REST design of service is known, so all you need is just to
>>>>>> describe a list of objects. And then for each object there is 4 operations
>>>>>> you are able to perform Create (HTTP PUT), Read (HTTP GET), Update (HTTP
>>>>>> POST) and Delete (HTTP DELETE). That's why in terms of REST you do not need
>>>>>> the description. You have only URLs each representing the object you can do
>>>>>> direct HTTP requests and you have no overhead of having some top-level
>>>>>> protocol, etc. That's why I said that REST is HTTP, because there is
>>>>>> nothing on top of HTTP in REST. And there is nothing to describe, only the
>>>>>> object URLs.
>>>>>>
>>>>>> It means that RESTful service architecture is not as flexible as
>>>>>> SOAP, so if you, as developer decided to create RESTful service it means
>>>>>> that you already chosen the service architecture. It also means that not
>>>>>> every SOAP service can be RESTful, but RESTful service could be delivered
>>>>>> with SOAP.
>>>>>> So you, as developer MUST decide first if you are building a RESTful
>>>>>> service, if so - go ahead, make it and Ladon give you benefit to deliver
>>>>>> your RESTful service throug varius different supported protocols.
>>>>>>
>>>>>> Again. You CAN deliver RESTful service throug
>>>>>> SOAP/XML-RPC/JSON-WSP/etc. But you CAN NOT deliver abstract
>>>>>> SOAP/XML-RPC/JSON-WSP service through REST if it wasn't designed as RESTful
>>>>>>
>>>>>> In my implementation I've tried to make everything with maximum
>>>>>> flexibility, so each RESTFul service could have more than 4 CRUD methods,
>>>>>> for each HTTP request method you can have as many service methods as you
>>>>>> need if the service methods have different signatures (arguments)
>>>>>>
>>>>>> like
>>>>>>
>>>>>> class Service:
>>>>>>     @restfulize(method="GET")
>>>>>>     def get_one_record( r_id):
>>>>>>          pass
>>>>>>     @restfulize(method="GET")
>>>>>>     def get_last_record( r_time):
>>>>>>          pass
>>>>>>     @restfulize(method="GET")
>>>>>>     def get_all_records():
>>>>>>          pass
>>>>>>     @restfulize(method="GET")
>>>>>>     def get_filtered_records( filters):
>>>>>>          pass
>>>>>>
>>>>>> As you see in this example 4 service methods are bind to HTTP GET
>>>>>> method. Depending of parameters bypassed through HTTP I try to determine
>>>>>> which method to call, but from terms of protocol you always do
>>>>>>
>>>>>> GET
>>>>>> /Service/rest?filters['name']=*bla&filters['another_key']=somevalue HTTP/1.1
>>>>>> Host: yourservice.com
>>>>>> ...
>>>>>>
>>>>>> The same for other HTTP methods. You can have 2 different methods for
>>>>>> POST, for example for User service example you may have split User data
>>>>>> update and user password update, etc..
>>>>>>
>>>>>> Or maybe your service may not provide some methods. Like you create
>>>>>> the public read-only service, so you don't provide PUT/POST/DELETE
>>>>>>
>>>>>> P.S. REST does not provide the way do bypass which service method to
>>>>>> call by name. REST is not RPC. You have only the Resource, it's URL and 4
>>>>>> operations. It is REST.
>>>>>>
>>>>>> Best regards,
>>>>>> Mike
>>>>>>
>>>>>>
>>>>>> 2012/10/23 Jakob Simon-Gaarde <jakobsg@xxxxxxxxx>
>>>>>>
>>>>>>> Everything in Ladon is HTTP :-)
>>>>>>>
>>>>>>> But HTTP is just the underlying protocol, and under that is a
>>>>>>> transport protocol etc.
>>>>>>>
>>>>>>> When I am talking about protocol in Ladon I mean service protocols
>>>>>>> like soap, json-wsp and soon json-rpc which are also protocols. I would put
>>>>>>> REST at this level aswell.
>>>>>>>
>>>>>>> I haven't really used REST before, but from what I can see it is
>>>>>>> nothing more than another service protocol which utilizes the HTTP standard
>>>>>>> a bit more, like using PUT,POST,GET,DELETE methods. Also it looks like
>>>>>>> there is not so much constraint on how parameters are passed so they can be
>>>>>>> JSON or XML or query-string.
>>>>>>>
>>>>>>> I don't like that there is no service description format for REST
>>>>>>> services. That is kind of a key feature in Ladon, that all supported
>>>>>>> protocols should be able to describe themselves.
>>>>>>>
>>>>>>>
>>>>>>> / Jakob
>>>>>>>
>>>>>>> 2012/10/22 Mykhailo Stadnyk <mikhus@xxxxxxxxx>
>>>>>>>
>>>>>>>> What do you mean?
>>>>>>>>
>>>>>>>> Actually REST is HTTP in terms of protocol, so what do I need to
>>>>>>>> implement? Maybe you can explain me more detailed your thought.
>>>>>>>>
>>>>>>>> Best regards,
>>>>>>>> Mike
>>>>>>>>
>>>>>>>> 2012/10/22 Jakob Simon-Gaarde <jakobsg@xxxxxxxxx>
>>>>>>>>
>>>>>>>>> My first question about your RESTful implementation is, why are
>>>>>>>>> you not implementing it as a protocol?
>>>>>>>>>
>>>>>>>>> / Jakob
>>>>>>>>>
>>>>>>>>> 2012/10/22 Jakob Simon-Gaarde <jakobsg@xxxxxxxxx>
>>>>>>>>>
>>>>>>>>>> Just a remark about the package name tracepyd. That might be an
>>>>>>>>>> unfortunate package name, cause on that odd platform called Windows
>>>>>>>>>> pyd-files are binary python modules. Just a remark :-)
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> 2012/10/22 Jakob Simon-Gaarde <jakobsg@xxxxxxxxx>
>>>>>>>>>>
>>>>>>>>>>> Hi Mike.
>>>>>>>>>>>
>>>>>>>>>>> Let's talk about tracepyd first, does it solve this bug:
>>>>>>>>>>>
>>>>>>>>>>> https://bugs.launchpad.net/ladon/+bug/877727
>>>>>>>>>>>
>>>>>>>>>>> rpclib has a terribly ugly solution for this, as you can see in
>>>>>>>>>>> the bug, and we want to be better than rpclib :-)
>>>>>>>>>>>
>>>>>>>>>>> / Jakob
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> 2012/10/22 Jakob Simon-Gaarde <jakobsg@xxxxxxxxx>
>>>>>>>>>>>
>>>>>>>>>>>> Hi Mike
>>>>>>>>>>>>
>>>>>>>>>>>> Looking into this now, you will have my reply today :-)
>>>>>>>>>>>>
>>>>>>>>>>>> / Jakob
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> 2012/10/22 Mykhailo Stadnyk <mikhus@xxxxxxxxx>
>>>>>>>>>>>>
>>>>>>>>>>>>> Currently it's an experimental feature which is not ready to
>>>>>>>>>>>>> be integrated. I didn't test it at all (keep working on it).
>>>>>>>>>>>>>
>>>>>>>>>>>>> So here is my personal road-map for this feature:
>>>>>>>>>>>>>   1. Resolve problem with decorators dependencies (something I
>>>>>>>>>>>>> described in previous message)
>>>>>>>>>>>>>   2. Write tests and test the functionality
>>>>>>>>>>>>>   3. I've not checked how does it deal with requests
>>>>>>>>>>>>> containing multipart boundaries and binary data
>>>>>>>>>>>>>   4. Not sure what to do with service description (currently
>>>>>>>>>>>>> I've just removed, but have an idea we can use it to describe service any
>>>>>>>>>>>>> way, even as long as REST does not specify this)
>>>>>>>>>>>>>   5. Write documentation/examples
>>>>>>>>>>>>>
>>>>>>>>>>>>> But I'm stuck on issue #1. I want to know:
>>>>>>>>>>>>>  * do you agree to add dependency in Ladon to tracepyd module
>>>>>>>>>>>>> or not?
>>>>>>>>>>>>>  * If not - do you agree to include tracepyd's implementation
>>>>>>>>>>>>> into Ladon (not as dependency, but to place it somewhere in tools)?
>>>>>>>>>>>>>  * If not - do you agree to modify @ladonize decorator
>>>>>>>>>>>>> functionality to add extra-params for REST (for me its ugly).
>>>>>>>>>>>>>  * If not - which ideas do you have then? :)
>>>>>>>>>>>>>
>>>>>>>>>>>>> I'd like to suggest to add dependency to tracepyd. Currently I
>>>>>>>>>>>>> have a version locally which works fine, so I can publish this solution to
>>>>>>>>>>>>> my branch to let you see.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Thank you in advance for your time and advice,
>>>>>>>>>>>>> Mike
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> 2012/10/22 Jakob Simon-Gaarde <jakobsg@xxxxxxxxx>
>>>>>>>>>>>>>
>>>>>>>>>>>>>> Interesting :-)
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I'll look at it later - we must make sure that it doesn't
>>>>>>>>>>>>>> break anything.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> 2012/10/22 Mykhailo Stadnyk <mikhus@xxxxxxxxx>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Hi Jacob.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> As I told I'm trying to implement RESTful services support
>>>>>>>>>>>>>>> by Ladon. The basic functionality is implemented - you can check my branch:
>>>>>>>>>>>>>>> lp:~mikhus/ladon/rest<https://code.launchpad.net/~mikhus/ladon/rest> to
>>>>>>>>>>>>>>> see how does it work. Here is an example of RESTful service you may run to
>>>>>>>>>>>>>>> see:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> from ladon.ladonizer import ladonize, restfulize
>>>>>>>>>>>>>>> from ladon.compat import PORTABLE_STRING
>>>>>>>>>>>>>>> from ladon.types.ladontype import LadonType
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> class User(LadonType):
>>>>>>>>>>>>>>>  name = PORTABLE_STRING
>>>>>>>>>>>>>>> email = PORTABLE_STRING
>>>>>>>>>>>>>>> passwd = PORTABLE_STRING
>>>>>>>>>>>>>>>  def __init__():
>>>>>>>>>>>>>>>  self.name = ""
>>>>>>>>>>>>>>>  self.email = ""
>>>>>>>>>>>>>>>  self.passwd = ""
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> class UserService( object) :
>>>>>>>>>>>>>>>  @restfulize(method="PUT")
>>>>>>>>>>>>>>>  @ladonize(str, str, str, rtype=User)
>>>>>>>>>>>>>>> def newUser( self, u_name, u_email, u_passwd) :
>>>>>>>>>>>>>>>  user = User() # where User is LadonType object
>>>>>>>>>>>>>>> user.name   = u_name
>>>>>>>>>>>>>>>  user.email  = u_email
>>>>>>>>>>>>>>> user.passwd = u_passwd
>>>>>>>>>>>>>>> return user
>>>>>>>>>>>>>>>  @restfulize(method="GET")
>>>>>>>>>>>>>>> @ladonize(int, rtype=[User])
>>>>>>>>>>>>>>>  def getUser(self, u_id) :
>>>>>>>>>>>>>>> return User()
>>>>>>>>>>>>>>>  @restfulize(method="GET")
>>>>>>>>>>>>>>> @ladonize(int, rtype=[User])
>>>>>>>>>>>>>>> def getUsers(self) :
>>>>>>>>>>>>>>>  return [User(), User(), User()]
>>>>>>>>>>>>>>>  @restfulize(method="POST")
>>>>>>>>>>>>>>>  @ladonize(int, str, str, str, rtype=User)
>>>>>>>>>>>>>>> def updUser( self, u_id, u_name, u_email, u_passwd):
>>>>>>>>>>>>>>>  user = User()
>>>>>>>>>>>>>>> user.name   = u_name
>>>>>>>>>>>>>>> user.email  = u_email
>>>>>>>>>>>>>>>  user.passwd = u_passwd
>>>>>>>>>>>>>>> return user
>>>>>>>>>>>>>>>  @restfulize(method="DELETE")
>>>>>>>>>>>>>>> @ladonize(int, rtype=bool)
>>>>>>>>>>>>>>> def delUser( self, u_id) :
>>>>>>>>>>>>>>>  return True
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> By the way, there is at least one issue I don't know how to
>>>>>>>>>>>>>>> solve better, so I want your advice.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> As you see I've implemented specific decorator to mark
>>>>>>>>>>>>>>> service methods as RESTful. It's @restfulize decorator. The problem that it
>>>>>>>>>>>>>>> is implemented now as:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> def restfulize( *dargs, **dkwargs):
>>>>>>>>>>>>>>>  def decorator(fn):
>>>>>>>>>>>>>>> * minfo = fn._ladon_method_info*
>>>>>>>>>>>>>>> if 'method' in dkwargs:
>>>>>>>>>>>>>>>  if not minfo.restfulize( **dkwargs):
>>>>>>>>>>>>>>> raise RestfulMethodConfigMismatch( fn.func_name)
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> return fn # returns ladonized method
>>>>>>>>>>>>>>> return decorator
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> The problem is highlighted with bold. Will be good to make
>>>>>>>>>>>>>>> this decorator independent of what @ladonize defined in it's private props.
>>>>>>>>>>>>>>> But, as far as "fn" here is a reference to ladon's "injector" function I
>>>>>>>>>>>>>>> have no way to determine correctly which real method in which class is
>>>>>>>>>>>>>>> decorated. It means that in such case I have no way to extract
>>>>>>>>>>>>>>> LadonMethodInfo associated to "fn" in other way but implemented for the
>>>>>>>>>>>>>>> moment.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> The real problem is when I want to override @ladonize
>>>>>>>>>>>>>>> decorator. In this case @resftulize becomes nonoperational because I loose
>>>>>>>>>>>>>>> reference to "_ladon_method_info" and means that I should take care to
>>>>>>>>>>>>>>> bypass all the existing private properties in 3-d party override
>>>>>>>>>>>>>>> implementation, which is not good at all. So I want to have @restfulize and
>>>>>>>>>>>>>>> @ladonize implemented without hard dependency between them.
>>>>>>>>>>>>>>> Via global_service_collection() it's possible to do but you
>>>>>>>>>>>>>>> need to determine real method function in some way.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> So I see the following ways to fix it:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> 1. Via decorator registry (Here we solved such kind of
>>>>>>>>>>>>>>> problem by creating DecoratorRegistry (I've published it as
>>>>>>>>>>>>>>> http://pypi.python.org/pypi/tracepyd))
>>>>>>>>>>>>>>> 2. By adding REST functionality to @ladonize decorator
>>>>>>>>>>>>>>> itself, to have something like:
>>>>>>>>>>>>>>>     @ladonize(PORTABLE_STRING, rtype=[PORTABLE_STRING], *rest={
>>>>>>>>>>>>>>> "method" : "GET", "produces": "XML" }*)
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Maybe you can point me to some other ideas you know how to
>>>>>>>>>>>>>>> resolve such kind of problem.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Best regards,
>>>>>>>>>>>>>>> Mike
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> --
>>>>>>>>>>>>>> Med venlig hilsen / Best regards
>>>>>>>>>>>>>> Jakob Simon-Gaarde
>>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> --
>>>>>>>>>>>> Med venlig hilsen / Best regards
>>>>>>>>>>>> Jakob Simon-Gaarde
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> --
>>>>>>>>>>> Med venlig hilsen / Best regards
>>>>>>>>>>> Jakob Simon-Gaarde
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> --
>>>>>>>>>> Med venlig hilsen / Best regards
>>>>>>>>>> Jakob Simon-Gaarde
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> Med venlig hilsen / Best regards
>>>>>>>>> Jakob Simon-Gaarde
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Med venlig hilsen / Best regards
>>>>>>> Jakob Simon-Gaarde
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Med venlig hilsen / Best regards
>>>>> Jakob Simon-Gaarde
>>>>>
>>>>> --
>>>>> Mailing list: https://launchpad.net/~ladon-dev-team
>>>>> Post to     : ladon-dev-team@xxxxxxxxxxxxxxxxxxx
>>>>> Unsubscribe : https://launchpad.net/~ladon-dev-team
>>>>> More help   : https://help.launchpad.net/ListHelp
>>>>>
>>>>>
>>>>
>>>
>>>
>>> --
>>> Med venlig hilsen / Best regards
>>> Jakob Simon-Gaarde
>>>
>>
>>
>>
>> --
>> Med venlig hilsen / Best regards
>> Jakob Simon-Gaarde
>>
>> --
>> Mailing list: https://launchpad.net/~ladon-dev-team
>> Post to     : ladon-dev-team@xxxxxxxxxxxxxxxxxxx
>> Unsubscribe : https://launchpad.net/~ladon-dev-team
>> More help   : https://help.launchpad.net/ListHelp
>>
>>
>


-- 
Med venlig hilsen / Best regards
Jakob Simon-Gaarde

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