最近在做游戏服务分层的时候，一直想把mysql的访问独立成一个单独的服务DBGate，原因如下:

请求收拢到DBGate，可以使DBGate变为无状态的，方便横向扩展

当请求量或者存储量变大时，mysql需要做分库分表，DBGate可以内部直接处理，外界无感知

通过restful限制对数据请求的形式，仅支持简单的get/post/patch/put 进行增删改查，并不支持复杂查询。这个也是和游戏业务的特性有关，如果网站等需要复杂查询的业务，对此并不适合

DBGate使用多进程模式，方便控制与mysql之间的链接数，进行mysql访问量阀值保护

方便在DBGate上进行访问量统计，慢查询统计、权限控制等等一系列逻辑

目前是使用python，以后要使用其他语言进行mysql操作时，只要进行标准的http请求即可，不会出现不兼容的情况

当然坏处也是有的：

首当其冲就是单次请求的响应时间变长，毕竟中间加了一层服务，并且还是http格式

部署上比原来复杂了一些，很多对mysql直接操作的思维需要进行转变，一开始可能会有些不适

不过总的来说，还是利大于弊，所以最终还是决定搭建DBGate

当然，我们不可能去手工挨个写每个库表对应的restful服务，值得庆幸的是django和flask都提供了对应的解决方案，我们一个个介绍.
Flask

参考链接: flask-restless

flask-restless使用方法比较简单，我直接贴一下代码即可:

# -*- coding: utf-8 -*-

import datetime
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_restless import APIManager

app = Flask(__name__)
db = SQLAlchemy(app)
restless = APIManager(app, flask_sqlalchemy_db=db)

class User(db.Model):
"""
user
"""

id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(255), unique=True, nullable=False)
password = db.Column(db.String(255), nullable=False)
create_time = db.Column(db.DateTime, nullable=False, default=datetime.datetime.utcnow)
login_time = db.Column(db.DateTime)

restless.create_api(User, methods=['GET', 'POST', 'DELETE', 'PATCH', 'PUT'], results_per_page=100)

db.create_all()

if __name__ == '__main__':
app.run(port=25000)

# -*- coding: utf-8 -*-

import datetime
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_restless import APIManager


app = Flask(__name__)
db = SQLAlchemy(app)
restless = APIManager(app, flask_sqlalchemy_db=db)


class User(db.Model):
"""
user
"""

id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(255), unique=True, nullable=False)
password = db.Column(db.String(255), nullable=False)
create_time = db.Column(db.DateTime, nullable=False, default=datetime.datetime.utcnow)
login_time = db.Column(db.DateTime)


restless.create_api(User, methods=['GET', 'POST', 'DELETE', 'PATCH', 'PUT'], results_per_page=100)

db.create_all()

if __name__ == '__main__':
app.run(port=25000)

其对应的restful操作如下:

获取用户列表: GET /user
添加用户: POST /user
获取单个用户: GET /user/1
覆盖单个用户: PUT /user/1
修改单个用户: PATCH /user/1

获取用户列表: GET /user
添加用户: POST /user
获取单个用户: GET /user/1
覆盖单个用户: PUT /user/1
修改单个用户: PATCH /user/1

注意:

• 在http请求中，记得加入header: Content-Type: application/json
• flask-restless中，PUT和PATCH一样，都是传入什么字段，只修改什么字段，不会完全覆盖

Django

参考链接: Django REST framework

Django用起来要更复杂一些，也因为django版自带了一个可视化的操作页面，如下:

1. 在settings中添加:

REST_FRAMEWORK = { # Use hyperlinked styles by default. # Only used if the `serializer_class` attribute is not set on a view. 'DEFAULT_MODEL_SERIALIZER_CLASS': 'rest_framework.serializers.HyperlinkedModelSerializer', # Use Django's standard `django.contrib.auth` permissions, # or allow read-only access for unauthenticated users. 'DEFAULT_PERMISSION_CLASSES': [ #'rest_framework.permissions.DjangoModelPermissionsOrAnonReadOnly', 'rest_framework.permissions.IsAdminUser', ]} REST_FRAMEWORK = { # Use hyperlinked styles by default. # Only used if the `serializer_class` attribute is not set on a view. 'DEFAULT_MODEL_SERIALIZER_CLASS': 'rest_framework.serializers.HyperlinkedModelSerializer', # Use Django's standard `django.contrib.auth` permissions, # or allow read-only access for unauthenticated users. 'DEFAULT_PERMISSION_CLASSES': [ #'rest_framework.permissions.DjangoModelPermissionsOrAnonReadOnly', 'rest_framework.permissions.IsAdminUser', ]}

2. 通过startapp建立一个app: demo
3. 修改demo的models:

class User(models.Model): # key是保留字 password = models.IntegerField() nick = models.CharField(max_length=255) create_time = models.DateTimeField(default=datetime.datetime.now) class User(models.Model): # key是保留字 password = models.IntegerField() nick = models.CharField(max_length=255) create_time = models.DateTimeField(default=datetime.datetime.now)

4. 在demo下新建serializers.py

from rest_framework import serializers
from models import User

class UserSerializer(serializers.ModelSerializer): class Meta: model = User from rest_framework import serializersfrom models import User class UserSerializer(serializers.ModelSerializer): class Meta: model = User

5. 在demo下修改views.py

from django.shortcuts import renderfrom rest_framework import viewsetsfrom serializers import UserSerializerfrom models import Userclass UserViewSet(viewsets.ModelViewSet): queryset = User.objects.all() serializer_class = UserSerializer from django.shortcuts import renderfrom rest_framework import viewsets from serializers import UserSerializerfrom models import User class UserViewSet(viewsets.ModelViewSet): queryset = User.objects.all() serializer_class = UserSerializer

6. 在demo下新建urls.py

import os.pathfrom django.conf.urls import patterns, include, urlfrom django.conf.urls.static import staticfrom django.conf import settingsimport viewsfrom rest_framework import routersappname = os.path.basename(os.path.dirname(os.path.abspath(__file__)))router = routers.DefaultRouter()router.register('users', views.UserViewSet, appname)urlpatterns = patterns('', url(r'^', include(router.urls)),) import os.pathfrom django.conf.urls import patterns, include, urlfrom django.conf.urls.static import staticfrom django.conf import settingsimport views from rest_framework import routers appname = os.path.basename(os.path.dirname(os.path.abspath(__file__))) router = routers.DefaultRouter()router.register('users', views.UserViewSet, appname) urlpatterns = patterns('', url(r'^', include(router.urls)),)

7. 在mysite.urls下include demo.urls和rest_framework.urls

urlpatterns = patterns('', url(r'^demo/', include('demo.urls')), url(r'^admin/', include(admin.site.urls)), url(r'^api-auth/', include('rest_framework.urls', namespace='rest_framework'))) urlpatterns = patterns('', url(r'^demo/', include('demo.urls')), url(r'^admin/', include(admin.site.urls)), url(r'^api-auth/', include('rest_framework.urls', namespace='rest_framework')))

8. 执行初始化数据操作:

python manage.py syncdb python manage.py syncdb

之后访问: http://127.0.0.1:8000/demo 即可看到如下界面了:

对应的测试代码如下:

import jsonimport requestsfrom urlparse import urljoinBASE_URL = 'http://127.0.0.1:16500/'AUTH = ('admin', 'admin')def test_get_user_list(): rsp = requests.get(urljoin(BASE_URL, '/demo/users/'), auth=AUTH, headers={ 'Accept': 'application/json' }) assert rsp.okdef test_post_user_list(): json_data = dict( password=0, nick='oo', create_time='2014-03-3T03:3:3' ) rsp = requests.post(urljoin(BASE_URL, '/demo/users/'), auth=AUTH, headers={ 'Accept': 'application/json', 'Content-Type': 'application/json', }, data=json.dumps(json_data)) assert rsp.okdef test_get_user(): rsp = requests.get(urljoin(BASE_URL, '/demo/users/1'), auth=AUTH, headers={ 'Accept': 'application/json', 'Content-Type': 'application/json', }) assert rsp.okdef test_put_user(): json_data = dict( password=100, nick='xx', create_time='2014-03-3T03:3:3' ) # 注意最后的 / rsp = requests.put(urljoin(BASE_URL, '/demo/users/1/'), auth=AUTH, headers={ 'Accept': 'application/json', 'Content-Type': 'application/json', }, data=json.dumps(json_data), ) assert rsp.ok, rsp.status_code

Django REST framework 是严格区分PUT和PATCH的，这一点和flask-restless 不一样，需要注意。

OK，就这样。