Choose proper stack to build and distribute your apps. You know about monolith style, but what about horizontal scalability, what about your web and mobile clients? How to build API properly and why it's the most important task? You can use several good solutions, balancing between time, money and quality.

1. API-centric Web Development with Tornado
or The Great Refactoring Story
Roman Zaiev, special for

2. Tornado?
Why not Django / Flask / etc

4. is

5. is prototyping tool

7. djangoproject/
manage.py
project/
__init__.py
urls.py
wsgi.py
settings/
__init__.py
base.py
dev.py
prod.py
blog/
__init__.py
models.py
managers.py
views.py
urls.py
templates/
blog/
base.html
list.html
detail.html
static/
…
tests/
__init__.py
test_models.py
test_managers.py
test_views.py
static/
css/
…
js/
…
templates/
base.html
index.html
requirements/
base.txt
dev.txt
test.txt
prod.txt
Django Project Structure

8. Modern
Django
Admin

9. Django ORM Hell

10. Django NoSQL? No. SQL!

11. RedirectView
TemplateView
DetailView
UpdateView
CreateView
FormView
DeleteView
DateDetailView
ListView
DayArchiveView
ArchiveIndexView
TodayArchiveView
MonthArchiveView
YearArchiveView
WeekArchiveView
BaseUpdateView
BaseCreateView
BaseFormView
SingleObjectTemplateResponseMixin
BaseListView
BaseArchiveIndexView
MultipleObjectTemplateResponseMixin
BaseTodayArchiveView
ModelFormMixin
ProcessFormMixin
TemplateResponseMixin
BaseDeleteView
BaseDateDetailView
BaseDayArchiveView
BaseMonthArchiveView
BaseYearArchiveView
BaseWeekArchiveView
FormMixin
DeletionMixin
BaseDetailView
SingleObjectMixin
MultipleObjectMixin
ContextMixin
DateMixin
BaseDateListView
WeekMixin
| connect the dotsCBV

12. Kill me
WTF?!

13. Django is bad

14. Monolith is bad

15. first step
refactoring

16. auth
landings
basket
checkout
product
second step
API
emails

17. API to rule them all

18. ADD. API Driven Development

19. POST /api/v1/authorize
GET /api/v1/user
GET /api/v1/product
POST /users/ajax_user_auth
GET /products/ajax_current_user
GET /products/ajax_prod_info
API
Business logic
Templates rendering
SEO Urls
Mob
Web
UI
AJAX
UI
API Calls

20. Front
Mob
API
Templates rendering
API Calls
SEO Urls
Web
UI
AJAX
POST /api/v1/authorize
GET /api/v1/user
GET /api/v1/product
UI
API Calls

21. API
Monolith Services

22. A A
A A
A A
A A
A A
A
AA A
A A
A A
A
A
A
A
A A A A
auth
product landings
A A
A A
basket
A
P
T
API

23. Stack Choice
framework? transport? proxy?
PTA

24. A framework
Flask? Yes. But no.

25. Easy Light Fast Async Python 2.7
Django
Flask
Pyramid
Tornado
A framework

26. tornadoweb.org
A framework

27. import tornado.ioloop
import tornado.web
class MainHandler(tornado.web.RequestHandler):
def get(self):
self.write("Hello, world")
application = tornado.web.Application([
(r"/", MainHandler),
])
if __name__ == "__main__":
application.listen(8888)
tornado.ioloop.IOLoop.current().start()
A Tornado | Start

28. A Tornado | Async handler
class GenAsyncHandler(tornado.web.RequestHandler):
@gen.coroutine
def get(self):
http_client = AsyncHTTPClient()
response = yield http_client.fetch("http://async.ua")
do_something_with_response(response)
self.render("template.html")

29. PT
Tornado transport? proxy?

30. transport
ZeroMQ + Protocol Buffers
T

31. ProtobufT
message BannerItem {
required string link = 1;
required string image = 2;
optional string title = 3;
required string alt = 4;
required string selector = 5;
required string last_edited = 6;
required string last_editor = 7;
optional string date_start = 8;
optional string date_end = 9;
optional int32 order = 10;
}
‘nx01/x12x07img.pngx1ax04Frau
"x06Muller*x07.snoopy2tyesterday:x02me'
new_banner = banner_pb2.BannerItem()
new_banner.link = ‘/'
new_banner.image = ‘img.png'
new_banner.title = ‘Frau'
new_banner.alt = ‘Muller'
new_banner.selector = ‘.snoopy'
new_banner.last_edited = ‘yesterday'
new_banner.last_editor = ‘me'
new_banner.SerializeToString()

32. P
Tornado ZeroMQ proxy?

33. proxyP
Nginx

34. Tornado ZeroMQ Nginx

35. auth
product landings
basket
API

36. API
Monolith Services

37. API Front

38. A Tornado | API HTTP
class ProductAPIHandler(BaseAPIHandler):
def get(self):
user_attrs = self.request.arguments
pbf_response = get_product(self, **user_attrs)
response = protobuf_to_dict(
pbf_response,
ignore_list=['body']
)
if pbf_response.success:
product = product_pb2.ProductSample()
product.ParseFromString(pbf_response.body)
response['body'] = protobuf_to_dict(product)
self.write(response)

39. A Tornado | API ZeroMQ
class ProductZMQHandler(BaseZMQHandler):
def get(self):
user_attrs = self.request.arguments
pbf_response = get_product(self, **user_attrs)
return pbf_response

40. A Tornado | API Call
class ProductHandler(BaseHandler):
TEMPLATE = 'pdp.html'
@tornado.web.asynchronous
def get(self, slug):
zmq_stream = get_zmq_client(self)
requests = [{
'url': '/api/v1/product',
'callback': self.gen_product,
'data': {
'url': slug
},
}]
self.pbc_client(
zmq_stream=zmq_stream,
requests=requests,
callback=self.on_fetch,
)
...

41. A Tornado | API Call Processing
class ProductHandler(BaseHandler):
...
def gen_product(self, response):
if not response.success:
raise HTTPError(404)
product_pbc = product_pb2.ProductSample()
product_pbc.ParseFromString(response.body)
product_dict = protobuf_to_dict(product_pbc)
self.context['product'] = product_dict
def on_fetch(self):
self.render(self.TEMPLATE, **self.context)

42. Find your balance

43. Use proper technologies

44. github.com/semirook
ua.linkedin.com/in/semirook
Thank you! And good luck!