![Problem description
def add(lhs, rhs):
return lhs + rhs
def api_add(request):
return add(request.args['lhs'],
request.args['rhs'])](https://image.slidesharecdn.com/aopinpythonapidesign-120515042329-phpapp02/85/AOP-in-Python-API-design-8-320.jpg)
![Problem description
def add(lhs, rhs):
return lhs + rhs
def api_add(request):
if request.args['token'] == valid:
return add(request.args['lhs'],
request.args['rhs'])
raise Exception('Security error')](https://image.slidesharecdn.com/aopinpythonapidesign-120515042329-phpapp02/85/AOP-in-Python-API-design-9-320.jpg)
![Problem description
def add(lhs, rhs):
return lhs + rhs
def api_add(request):
if request.args['token'] == valid:
database.query().alter usage counter
return add(request.args['lhs'],
request.args['rhs'])
raise Exception('Security error')](https://image.slidesharecdn.com/aopinpythonapidesign-120515042329-phpapp02/85/AOP-in-Python-API-design-10-320.jpg)
![Problem description
def add(lhs, rhs):
return lhs + rhs
def api_add(request):
if request.args['token'] == valid:
database.query().alter usage counter
result = add(request.args['lhs'],
request.args['rhs'])
return '<xml>{0}</xml>'.format(result)
raise Exception('Security error')](https://image.slidesharecdn.com/aopinpythonapidesign-120515042329-phpapp02/85/AOP-in-Python-API-design-11-320.jpg)
![Problem description
def add(lhs, rhs):
return lhs + rhs
def api_add(request):
if request.args['token'] == valid:
database.query().alter usage counter
result = add(request.args['lhs'],
request.args['rhs'])
return '<xml>{0}</xml>'.format(result)
raise Exception('Security error')](https://image.slidesharecdn.com/aopinpythonapidesign-120515042329-phpapp02/85/AOP-in-Python-API-design-12-320.jpg)
![Problem description
def add(lhs, rhs):
return lhs + rhs
def api_add(request):
if request.args['token'] == valid:
database.query().alter usage counter
result = add(request.args['lhs'],
request.args['rhs'])
return '<xml>{0}</xml>'.format(result)
raise Exception('Security error')](https://image.slidesharecdn.com/aopinpythonapidesign-120515042329-phpapp02/85/AOP-in-Python-API-design-13-320.jpg)
![Implementation
● Serialization aspect
○ Around advice
def serialize(function):
def advice(format, *args, **kwargs):
if not format in ['html', 'xml', 'json']:
raise exception
result = function(*args, **kwargs)
make a http response of 'result' in the right format
return advice](https://image.slidesharecdn.com/aopinpythonapidesign-120515042329-phpapp02/85/AOP-in-Python-API-design-34-320.jpg)
![Implementation
mapping = {
'api_function':
(core_function, ['lhs', 'rhs']),
'create_token':
(create_token, ['username', 'password']),
}](https://image.slidesharecdn.com/aopinpythonapidesign-120515042329-phpapp02/85/AOP-in-Python-API-design-36-320.jpg)
![Implementation
def dispatch(function):
def advice(*args, **kwargs):
if API call proxy mapping:
in
core_function, params = mapping[API call]
kwargs.update(extract(params, request))
return function(proxy=core_function,
params=params, *args, **kwargs)
raise exception
return advice](https://image.slidesharecdn.com/aopinpythonapidesign-120515042329-phpapp02/85/AOP-in-Python-API-design-37-320.jpg)
![Implementation
@secure
@serialize
@statistics
@dispatch
def api_call(*args, **kwargs):
proxy_function = kwargs['proxy']
params = kwargs['params']
return proxy_function(extract params from kwargs)](https://image.slidesharecdn.com/aopinpythonapidesign-120515042329-phpapp02/85/AOP-in-Python-API-design-39-320.jpg)
Ad
More Related Content
What's hot (17)
Similar to AOP in Python API design (20)
Ad
Recently uploaded (20)
Ad
AOP in Python API design
- 1. AOP in Python API design Douwe van der Meij Goldmund, Wyldebeast & Wunderliebe
- 2. Outline ● Problem description ● Aspect Oriented Programming ● Implementation
- 3. Case ● BioBench: ○ Application for biogas installations ● Enter measurements ● Normalize data ● Calculate plant performance
- 4. Problem description ● Large code-base ● A lot of calculations ● Django web-interface ● Make calculations available via an API
- 5. Problem description ● Is there a library/framework? ● Are the alternatives? ● What is the actual impact of the feature? ● What aspects to take into account?
- 6. Problem description ● Aspects: ○ Security ○ Statistics / Logging ○ Serialization ○ More?
- 7. Problem description def add(lhs, rhs): return lhs + rhs
- 8. Problem description def add(lhs, rhs): return lhs + rhs def api_add(request): return add(request.args['lhs'], request.args['rhs'])
- 9. Problem description def add(lhs, rhs): return lhs + rhs def api_add(request): if request.args['token'] == valid: return add(request.args['lhs'], request.args['rhs']) raise Exception('Security error')
- 10. Problem description def add(lhs, rhs): return lhs + rhs def api_add(request): if request.args['token'] == valid: database.query().alter usage counter return add(request.args['lhs'], request.args['rhs']) raise Exception('Security error')
- 11. Problem description def add(lhs, rhs): return lhs + rhs def api_add(request): if request.args['token'] == valid: database.query().alter usage counter result = add(request.args['lhs'], request.args['rhs']) return '<xml>{0}</xml>'.format(result) raise Exception('Security error')
- 12. Problem description def add(lhs, rhs): return lhs + rhs def api_add(request): if request.args['token'] == valid: database.query().alter usage counter result = add(request.args['lhs'], request.args['rhs']) return '<xml>{0}</xml>'.format(result) raise Exception('Security error')
- 13. Problem description def add(lhs, rhs): return lhs + rhs def api_add(request): if request.args['token'] == valid: database.query().alter usage counter result = add(request.args['lhs'], request.args['rhs']) return '<xml>{0}</xml>'.format(result) raise Exception('Security error')
- 14. Problem description Code base
- 15. Problem description ● Security Code base
- 16. Problem description ● Statistics / Logging Code base
- 17. Problem description ● Serialization Code base
- 18. Problem description ● Dispatcher Code base
- 19. Problem description ● Scattered / tangled code Code base
- 20. Aspect Oriented Programming ● What is AOP? ● Separation of concerns (aspects) ● Avoid scattering / tangling
- 21. Aspect Oriented Programming ● Scattered / tangled code Code base
- 22. Aspect Oriented Programming ● Avoid scattering Code base
- 23. Aspect Oriented Programming ● Avoid tangling Code base
- 24. Aspect Oriented Programming ● How to implement these marvelous concepts? ○ In pure python please!
- 25. Aspect Oriented Programming ● Decorators!
- 26. Aspect Oriented Programming ● Aspect: ○ Pointcuts ○ Join points ○ Advices ■ Before advices ■ After advices ■ Around advices
- 27. Aspect Oriented Programming ● Before advice ○ Must execute the function (no side-effects) def aspect(function): def advice(*args, **kwargs): do something here return function(*args, **kwargs) return advice
- 28. Aspect Oriented Programming ● After advice ○ Must execute the function (no side-effects) def aspect(function): def advice(*args, **kwargs): result = function(*args, **kwargs) do something here return result return advice
- 29. Aspect Oriented Programming ● Around advice ○ Allowed to bypass the function def aspect(function): def advice(*args, **kwargs): do something here result = function(*args, **kwargs) do something here return result return advice
- 30. Implementation ● How to apply it to our case?
- 32. Implementation ● Security aspect ○ Around advice def secure(function): def advice(*args, **kwargs): if valid token in request object: return function(*args, **kwargs) raise Exception('No valid token provided') return advice
- 33. Implementation ● Statistics aspect ○ Before advice def statistics(function): def advice(*args, **kwargs): increase API usage count for the user logged in return function(*args, **kwargs) return advice
- 34. Implementation ● Serialization aspect ○ Around advice def serialize(function): def advice(format, *args, **kwargs): if not format in ['html', 'xml', 'json']: raise exception result = function(*args, **kwargs) make a http response of 'result' in the right format return advice
- 35. Implementation ● Dispatcher aspect ○ Around advice def dispatch(function): def advice(*args, **kwargs): proxy the API call to a call to the core system return advice
- 36. Implementation mapping = { 'api_function': (core_function, ['lhs', 'rhs']), 'create_token': (create_token, ['username', 'password']), }
- 37. Implementation def dispatch(function): def advice(*args, **kwargs): if API call proxy mapping: in core_function, params = mapping[API call] kwargs.update(extract(params, request)) return function(proxy=core_function, params=params, *args, **kwargs) raise exception return advice
- 38. Implementation ● The API itself
- 39. Implementation @secure @serialize @statistics @dispatch def api_call(*args, **kwargs): proxy_function = kwargs['proxy'] params = kwargs['params'] return proxy_function(extract params from kwargs)
- 40. Conclusion ● AOP offers some brilliant concepts in software engineering ● Separate your concerns / aspects ○ Avoid classical scattering and tangling
- 41. Questions? ● Thank you! [email protected] @douwevandermeij