一种多屏时代的通用 web 应用架构

一种多屏时代的通用 web 应用架构
赖勇浩 @ 珠三角技术沙龙
2013-5-19

自我介绍
●
game → webgame → web
●
珠三角技术沙龙组委、发起人之一
●
PyCon China 2011/2012 讲师
– Python 于 webgame 的应用
– 页游开发中的 Python 组件与模式
●
http://laiyonghao.com/

内容概述
●
Web 架构的变迁
●
实践经验分享
●
未来之路

Web 架构的变迁（ 1 ）
browser server
text/html

browser
serverwap browser
app

●
问题：
– 返回什么？

●
def request_wants_json():
●
best = request.accept_mimetypes
●
.best_match(['application/json', 'text/html'])
●
return best == 'application/json' and
●
request.accept_mimetypes[best] >
●
request.accept_mimetypes['text/html']

●
@app.route('/')
●
def show_items():
●
items = get_items_from_database()
●
if request_wants_json():
●
return jsonify(items=[x.to_json() for x in items])
●
return render_template('show_items.html',
items=items)

插播： mimerender
●
mimerender = mimerender.FlaskMimeRender()
●
render_xml = lambda message: '<message>
%s</message>'%message
●
render_json = lambda **args: json.dumps(args)
●
render_html = lambda message: '<html><body>
%s</body></html>'%message
●
render_txt = lambda message: message

●
@app.route('/')
●
@app.route('/<name>')
●
@mimerender(
●
default = 'html',
●
html = render_html,
●
xml = render_xml,
●
json = render_json,
●
txt = render_txt
●
)
●
def greet(name='world'):
●
return {'message':
'Hello, ' + name + '!'}
●
if __name__ ==
"__main__":
●
app.run(port=8080)

●
How to get it
– mimerender is in PyPI, so it's as easy as doing:
– $ pip install mimerender

browser
server
text/html
wap browser
app
text/vnd.wap.wml
application/json

●
如果可以通过短信（ SMS ……）使用业务

browser
adapter
text/html
wap browser
app
text/vnd.wap.wml
application/json
adapter
adapter
server
adapterSMS
application/json

browser
adapter
text/html
wap browser
app
text/vnd.wap.wml
application/json
adapter
adapter
server
adapterSMS
application/json
？

●
业务与展现分享
– server 专注业务实现，只需要提供 http api ，无须理
会数据展现形式；
– adapter 的业务简单，只需要维护会话，并对请求 / 响
应进行转换；
●
易于分工
– 内部可以分小组
– 甚至外包（解决了我团队不熟悉短信中心协议的问题）
●
易于扩展
– 支持更多设备（如自助终端、语音电话）

●
安全：对数据进行签名
– client-id 、 client-key
– sha1
– 让 Date header 必填来确保每次请救不同

实践经验分享
●
Flask-RESTful
– https://github.com/twilio/flask-restful

Flask-RESTful: Argument Parsing
●
parser = reqparse.RequestParser()
●
parser.add_argument('rate', type=int, help='Rate to
charge for this resource')
●
args = parser.parse_args()
●
支持必填项、多值项、重命名
●
可从 post body 、 query
string 、 headers 、 cookies 、 file uploads 中读取

Flask-RESTful: Output Fields
●
resource_fields = {
●
'name': fields.String,
●
'address': fields.String,
●
'date_updated': fields.DateTime,
●
}
●
class Todo(Resource):
●
@marshal_with(resource_fields)
●
def get(self, **kwargs):
●
return db_get_todo() # Some function that queries
the db

Flask-RESTful: Output Fields
●
Renaming Attributes
●
Default Values
●
Custom Fields & Multiple Values
●
Url Field
●
Complex Structures
●
List Field
●
Nested Field

Flask-RESTful: Resource Method
Decorators
●
def authenticate(func):
●
@wraps(func)
●
def wrapper(*args, **kwargs):
●
...
●
class Resource(restful.Resource):
●
method_decorators = [authenticate] # applies to all
inherited resources

测试
●
一般情况下使用 curl 足矣
– $ curl http://localhost:5000/todos/todo3
– {"task": "profit!"}

chtest
●
$ chtest --help
●
usage: chtest [-h] [--config-file CONFIG_FILE] --path
PATH [--method METHOD]
●
[--arg ARG] [--header HEADER] [--ensure-status
ENSURE_STATUS]
●
[--ensure-header ENSURE_HEADER]
●
[--ensure-content ENSURE_CONTENT] [--print-
header PRINT_HEADER]
●
[--print-json-path PRINT_JSON_PATH]

requests
●
chtest is requests powered
●
Requests: HTTP for Humans
– >>> r = requests.get('https://api.github.com/user',
auth=('user', 'pass'))
– >>> r.status_code
– 200
– >>> r.headers['content-type']
– 'application/json; charset=utf8'
– >>> r.text
– u'{"type":"User"...'
– >>> r.json()

未来之路
●
http-based VS tcp-based
●
Behavior-Driven Development

browser
adapter
text/html
wap browser
app
text/vnd.wap.wml
application/json
adapter
adapter
server
adapterSMS
RPC ??

RPC 优劣
●
优势
– 减少连接数
– 更小的数据包
– 乱序返回
– 握手后的数据不需要签名（ SSL/TLS ）
●
劣势
– 不能利用 HTTP 的基础设施
– 需要学习好多新东西

lettuce.it
●
Feature: Manipulate strings
●
In order to have some fun
●
As a programming beginner
●
I want to manipulate strings
●
Scenario: Uppercased strings
●
Given I have the string "lettuce leaves"
●
When I put it in upper case
●
Then I see the string is "LETTUCE LEAVES"

lettuce.it
●
>>> @step('I have the string "(.*)"')
●
... def have_the_string(step, string):
●
... world.string = string
●
>>> @step('I put it in upper case')
●
... def put_it_in_upper(step):
●
... world.string = world.string.upper()
●
>>> @step('I see the string is "(.*)"')
●
... def see_the_string_is(step, expected):
●
... assert world.string == expected,
●
... "Got %s" % world.string

lettuce.it
●
from lettuce import step
●
from nose.tools import assert_equals
●
@step('some step with "(.*)"'):
●
def some_step(step, from):
●
assert_equals(from, 'expectation')

额外赠送： flask-pypi-proxy
您值得拥有。

一种多屏时代的通用 web 应用架构

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