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HTTP API & Py Milan Čermák Pyvo Praha, 20. 2. 2013 Wednesday, February 20, 13

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What makes a good API? Wednesday, February 20, 13

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Wednesday, February 20, 13

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Consistency Wednesday, February 20, 13

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Consistency Predictability Wednesday, February 20, 13

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Consistency Predictability Adherence to standards Wednesday, February 20, 13

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Consistency Predictability Adherence to standards Great documentation Wednesday, February 20, 13

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Why HTTP? Wednesday, February 20, 13

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"While HTTP isn’t always the best answer, it’s a damn fine first guess." Coda Hale Wednesday, February 20, 13

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Benefits of HTTP Wednesday, February 20, 13

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Benefits of HTTP The most widespread application protocol Wednesday, February 20, 13

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Benefits of HTTP The most widespread application protocol Statelessness Wednesday, February 20, 13

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Benefits of HTTP The most widespread application protocol Statelessness Optional caching Wednesday, February 20, 13

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Benefits of HTTP The most widespread application protocol Statelessness Optional caching Promotes layered infrastructure Wednesday, February 20, 13

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Benefits of HTTP The most widespread application protocol Statelessness Optional caching Promotes layered infrastructure etc. Wednesday, February 20, 13

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Limitations of HTTP Wednesday, February 20, 13

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Limitations of HTTP Authorization Wednesday, February 20, 13

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Limitations of HTTP Authorization Statelessness Wednesday, February 20, 13

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Limitations of HTTP Authorization Statelessness Verbosity Wednesday, February 20, 13

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Limitations of HTTP Authorization Statelessness Verbosity Crippled parallelism Wednesday, February 20, 13

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"REST" if protocol.startswith("http") else "you're doing it wrong" Wednesday, February 20, 13

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Set of architectural constraints Wednesday, February 20, 13

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Set of architectural constraints Client-server Wednesday, February 20, 13

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Set of architectural constraints Client-server Stateless Wednesday, February 20, 13

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Set of architectural constraints Client-server Stateless Cacheable Wednesday, February 20, 13

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Set of architectural constraints Client-server Stateless Cacheable Layered Wednesday, February 20, 13

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Set of architectural constraints Client-server Stateless Cacheable Layered Uniform interface * Wednesday, February 20, 13

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How can Python help? Wednesday, February 20, 13

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OOP Wednesday, February 20, 13

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OOP URI ~ Class handler mapping Wednesday, February 20, 13

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import handlers urls = [(r"/user", handlers.users.NewUser), (r"/user/(\d+)", handlers.users.User)] class User(handler.base.BaseHandler): def delete(self, user_id): pass def get(self, user_id): pass def post(self, user_id): pass Wednesday, February 20, 13

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class UserValidatorMixin(object): def check_user_data(self, user_dict): pass class User(handler.base.BaseHandler, UserValidatorMixin): def post(self, user_id): new_user = self.get_argument(“user”) if not self.check_user_data(new_user): return self.http_error(400, “Invalid data”) Wednesday, February 20, 13

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Middleware Wednesday, February 20, 13

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Wednesday, February 20, 13

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Extending JSONEncoder Wednesday, February 20, 13

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import json class AppJSONEncoder(json.JSONEncoder): def default(self, obj): if isinstance(obj, User): return {"name": obj.name, "height": obj.height, "cash": obj.get_bank_account_balance()} return json.JSONEncoder.default(self, obj) user = User("1337") json.dumps(user, cls=AppJSONEncoder) Wednesday, February 20, 13

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What about mobile? Wednesday, February 20, 13

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Compression of HTTP bodies GET /user/1337 HTTP/1.1 Host: api.napyvo.io Accept-Encoding: gzip, identity Wednesday, February 20, 13

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Compression of HTTP bodies HTTP/1.1 200 OK Content-Encoding: gzip Content-Type: application/json; charset=utf-8 Wednesday, February 20, 13

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Compression of HTTP bodies POST /user HTTP/1.1 Host: api.napyvo.io Content-Encoding: gzip Content-Type: application/json [gzipped representation of a user] Wednesday, February 20, 13

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Caching Cache-Control: max-age=3600 Expires: Thu, 31 Jan 2013 22:00:00 GMT <- Last-Modified: Thu, 31 Jan 2013 18:30:00 GMT -> If-Modified-Since: Wed, 30 Jan 2013 13:37:00 GMT ETag: foo If-None-Match: foo Wednesday, February 20, 13

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Partial resources Wednesday, February 20, 13

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GET /car/9 {"car": { "color": "red", "passengers": [ {"href": "/user/1337", "rel": "self"}] } } Wednesday, February 20, 13

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GET /car/9?zoom=passengers {"car": { "color": "red", "passengers": [ {"href": "/user/1337", "rel": "self", "name": "Milan", "drink": "beer", "skills": ["python", "http"], }] } } Wednesday, February 20, 13

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The promise of Hypermedia Wednesday, February 20, 13

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Hypermedia as the engine of application state Wednesday, February 20, 13

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Q & A Wednesday, February 20, 13