O'Reilly：GoogleAppEngine开发

　　 即便你在编程或者Web开发方面只有很少或者没有任何经验，使用Google APP Engine和这本书就能快速并且充满自信地构建那些激动人心的可扩展Web应用。
　　 App Engine几乎是近年来引人注目的Web技术，它提供了一个简单易用的应用程序框架以及基本的Web工具。尽管Google自带的教程已经展示了主要的步骤，但是《Google App Engine开发》将会帮助任何人开始上手使用这个平台。读完本书你将学会如何构建完整的交互应用，并且将它们部署到和]Google搜索引擎使用同样服务器的云中。
　　 拥有这本书，你将会：纵览Google App Engine相关必备技术；学习如何使用Python、HTML、层叠样式表（CSS）、HTTP和IDataStore（App Engine的数据库）；领会创建高级动态web应用的必备技术要点；掌握部署应用的前提要件。
　　 《Google App Engine开发》同样也是那些想要获得Web开发技能的资深程序员的参考资源。构建Web应用曾是专家们独占的领地，但自从有了Google App Engine和这本书，任何人都能创建一个动态Web网站。

Charles Severance是密歇根大学信息学院的兼职助理教授。他也是IMS全球学习联合会的IMS开发者网络协调员。

　　 “《Google App EngiRe开发》使几乎不可能的事成为可能，帮助我这个老家伙学习一些难以置信的相关技术诀窍。我在过去整个职业生涯中一直想要更好地掌握Web开发，自从有了这本书，梦想终于成真。”
　　 ——Robert Glushko．学生，密歇根大学

Preface
1.Programming on the Web
The Request/Response Cycle
What Is Google App Engine？
What Is a "Cloud"？
Why Did Google Build App Engine and Give It Away for Free？
What Is the Google Infrastructure Cloud？
Enter the Application Engine
Your Application Must Be a Good Citizen in the Google Cloud
How the Cloud Runs Your Application
Why You Really Want to Run in the Cloud
The Simplest App Engine Application
Summary
Exercises

2.HTMLandCSS
A Brief History of HTML and CSS
HyperText Markup Language （HTML）
A Well-Formed HTML Document
Validating Your HTML
HyperText Links （Anchor Tags）
Multiple Files
Lists in HTML
Specifying Styles Using CSS
Styling Tags with CSS
Exerting More Control over Markup
Validating CSS
Tools to Help You Work with CSS
Building the Navigation Menu
The CSS Box Model
Adding Navigation Hints for Users
Summary
Exercises

3.Python
What Is Programming？
About Python
Installing Python
The Essence of Programming
Input， Processing， and Output
Conditional Steps： A Number-Guessing Web Application
Variables and Expressions
Naming Variables
Constants
Handling Text Data Using Strings
Using the String Library
Types and Conversion
Variables with Many Values at the Same Time： Lists
Repeated Code： Loops
Pythons Backpack： Dictionaries
Looping Through a Dictionary
Stored and Reused Code： Python Functions
Turning Traceback to Our Advantage Using Try and Except
Object-Oriented Python
Comments in Python
The Tao of Programming
Summary
Exercises

4.Sending Data to Your Application
Making an HTTP Request
Hacking the HTTP Protocol
The HTTP Protocol Standards
Watching HTTP in Action
HTML： Building a Form
Sending Form Data to the Server Using POST
Handling Form Data in the App Engine Server
Sending Form Data to the Server Using GET
App Engine Log
Looking at All the Data Available on an HTTP Request
Advanced： Multipart POST Data with File Upload
Summary
Exercises

5.The App Engine webapp Framework
A Trivial App Engine Application
An Equivalent Trivial webapp Application
The Handler Callback Pattern
Looking at the Handler Code
What Is "self" and Why Is It There？
Number Guessing Using the webapp Framework
Web Server Logs
Summary
Exercises

6.Templates
Template Syntax
Using the Templates from Python
The Number-Guessing Game Using Templates
Abstraction and Separation of Concerns： "Model View Controller"
Building a Multiscreen Application
Static Files in App Engine
Referencing Static Files
Generalizing Template Lookup with Multiple Templates
Extending Base Templates
Conditional Processing Templates
Replacing More Than One Block in the Base Template
Extending Our Application
Syntax Errors
More on Templates
Summary
Exercises

7.Cookies and Sessions
HTTP Cookies
Logging In and Logging Out Using Sessions
Installing the Simple Session Utility
Using the Session to Mark Login and Logout
Changing the User Interface for a Logged-In User
Summary
Exercises

8.AppEngineDatastore
The Model-View-Controller Pattern
Defining Models
Adding a New Account Form
Adding a User Account
Looking Through the Datastore
Logging In and Checking Accounts and Passwords
Retrieving and Displaying Many Objects
Terminology： Different Types of Keys
References Between Data Models
Interactions Between Models
Putting the Primary Key into Session
Adding the Chat Feature
Summary
Exercises

9.JavaScript， jQuery， and AJAX
jQuery
Create a View of the Chat Messages in HTML
Asynchronously Updating a Using AJAX
Summary
Exercises

10.Running Your Application on the Google Infrastructure
Application Engine Accounts
Creating an Application on App Engine
Uploading Your Application
Testing Your Application
Logs， Statistics， and Other Features
Uploading New Versions
Collaboration on Applications
Summary
Exercises

11.Memory Cache
The Rules of Memory Cache
Using the Memory Cache
Using the Application Console to Examine Memory Cache
Using a Memory Cache in Your Application
Building a Session Store Using Memory Cache
Sessions and Memory Cache
Summary
Exercises
A. Installing and Running Google App Engine on Windows XP
B. Installing and Running Google App Engine on Windows Vista

Running an application in the cloud is kind of like flying business class across the PacificOcean between Australia and the United States. You are vaguely aware that you aregoing really fast inside of a highly complex device that you barely understand. Thepilots， crew， maintenance people， chefs， logistics staff， traffic controllers， and gateagents all are making sure that your trip happens efficiently and comfortably——and thatit is uneventful. All you know is that you sit in a recliner， watch a movie， eat a nice filetmignon， have a glass of red wine， lay the seat fiat， sleep for a few hours， and wake uprefreshed on a different continent.
Why You Really Want to Run in the Cloud
You might initially think that you dont want to run in the Google cloud because youwant to make your own decisions and control your own destiny. You might want torun your own servers in your own facility and make all the decisions about your ap-plication. Perhaps you just like walking into a server room and seeing the hardwarethat is running the application. Although this sense of control might sound appealingat first， it is really just a lot of trouble and energy that does not advance the cause ofyourapplication. Here are a few of the things that you have to worry about when yourun on your own servers： what operating system should I run？ What version of theoperating system is the most reliable？ When do I apply vendor patches （especially thosepesky security patches）？ How do I protect my system from intruders？ Do I need afirewall to protect my servers？ How do I monitor my servers to detect when an intrusionhappens and then how do I get notified？ How far do I have to drive to the server roomto reformat and reinstall the software at 4：00 a.m. so that it is back up by 10：00 a.m.？What database do I run？ What version？ What patches？ Should I upgrade the memoryof my database server， or should I add an additional disk to the RAID controller？ CanI use a single database server， or do I need to cluster several database servers？ How doesthe clustered database server get backed up？ How long does it take to restore mydatabase when there is a hardware problem with the database servers disk drives？ Howmany application web servers do I need？ I know that my applications peak usage isfrom 7：00 p.m. to 9：00 p.m. each day. Do I buy enough hardware to handle that peakload， or do I buy a little less hardware and just let the servers slow down a bit duringthe 7：00 p.m. to 9：00 p.m. period？ If my application is so popular that it is used bothin the United States and Europe， do I need to find a data center in Europe and put somehardware in Europe so that all the European users see a quick response time？ Whenshould I upgrade my hardware？ Should I add more hardware and keep the old hardwareor simply pitch the old hardware and install all new hardware？ How much energy doesmy hardware take？ Is there a way to reduce the energy footprint of my hardware？

　　The greatest single reason that the World Wide Web has been so widely used andadopted is because individuals are allowed to participate in the Web. People can pro-duce web Content and create a MySpace page or home pages provided by their schoolor organization and contribute their creativity and content to the Web. Free serviceslike Blogger， Flickr， Google Sites， Google Groups， and others have given us all an outletfor our creativity and presence on the Web——at no charge.
　　For most of the life of the Web， if you wanted to have your own rich software-backedwebsite with data storage， your only choice was to purchase hosting services from anInternet Service Provider （ISP） and learn database management and a programminglanguage like PHP to build or run your software. Learning and paying for this muchtechnology was just beyond the reach of most web users， who simply had to accept thelimited features of MySpace， Blogger， or whatever system hosted their web content.In April 2008， Google announced a product called App Engine. When you write aprogram for the Web that runs on App Engine， your software runs on the Google serverssomewhere in the Google "cloud." It is as if you are a Google employee and you haveaccess to the entire scalable Google infrastructure. App Engine captures much of Goo-gles experience of building fast， reliable， and scalable websites， and through App En-gine， Google is revealing many of the secrets about how its own applications scale to millions of users.
　　The most exciting part of the Google App Engine announcement is the fact that it isfree for moderate levels of use. Every person with a Gmail account can have a numberof free applications running on the Google infrastructure. If your application becomesextremely popular and your traffic goes above the allowed levels of the free account，you can pay to use more of Googles resources. As your appli~：ation scales， Googleengineers and operations staff take care of all the hardware， data storage， backup， andnetwork provisioning for you.