Using Google App Engine

264 Pages·2009·3.03 MB·English

by  Charles Severance

Using Google App Engine

Using Google App Engine
Charles Severance
Beijing • Cambridge • Farnham • Köln • Sebastopol • Taipei • Tokyo
Using Google App Engine
by Charles Severance
Copyright © 2009 Charles Severance. All rights reserved.
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May 2009: First Edition.
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ISBN: 978-0-596-80069-7
[M]
1241457704
Table of Contents
Preface ..................................................................... xi
1. Programming on the Web ................................................ 1
The Request/Response Cycle 3
What Is Google App Engine? 5
What Is a “Cloud”? 6
Why Did Google Build App Engine and Give It Away for Free? 7
What Is the Google Infrastructure Cloud? 8
Enter the Application Engine 9
Your Application Must Be a Good Citizen in the Google Cloud 10
How the Cloud Runs Your Application 11
Why You Really Want to Run in the Cloud 12
The Simplest App Engine Application 13
Summary 14
Exercises 15
2. HTML and CSS ......................................................... 17
A Brief History of HTML and CSS 18
HyperText Markup Language (HTML) 18
A Well-Formed HTML Document 20
Validating Your HTML 22
HyperText Links (Anchor Tags) 23
Multiple Files 25
Lists in HTML 26
Specifying Styles Using CSS 27
Styling Tags with CSS 27
Exerting More Control over Markup 30
Validating CSS 32
Tools to Help You Work with CSS 33
Building the Navigation Menu 34
The CSS Box Model 37
Adding Navigation Hints for Users 39
v
Summary 40
Exercises 42
3. Python ............................................................... 43
What Is Programming? 43
About Python 44
Installing Python 45
The Essence of Programming 46
Input, Processing, and Output 47
Conditional Steps: A Number-Guessing Web Application 48
Variables and Expressions 52
Naming Variables 53
Constants 54
Handling Text Data Using Strings 55
Using the String Library 56
Types and Conversion 57
Variables with Many Values at the Same Time: Lists 59
Repeated Code: Loops 60
Python’s Backpack: Dictionaries 63
Looping Through a Dictionary 64
Stored and Reused Code: Python Functions 65
Turning Traceback to Our Advantage Using Try and Except 68
Object-Oriented Python 70
Comments in Python 71
The Tao of Programming 71
Summary 72
Exercises 72
4. Sending Data to Your Application ......................................... 75
Making an HTTP Request 75
Hacking the HTTP Protocol 77
The HTTP Protocol Standards 79
Watching HTTP in Action 79
HTML: Building a Form 81
Sending Form Data to the Server Using POST 82
Handling Form Data in the App Engine Server 83
Sending Form Data to the Server Using GET 87
App Engine Log 88
Looking at All the Data Available on an HTTP Request 89
Advanced: Multipart POST Data with File Upload 93
Summary 96
Exercises 96
vi | Table of Contents
5. The App Engine webapp Framework ...................................... 99
A Trivial App Engine Application 99
An Equivalent Trivial webapp Application 100
The Handler Callback Pattern 102
Looking at the Handler Code 102
What Is “self” and Why Is It There? 103
Number Guessing Using the webapp Framework 105
Web Server Logs 109
Summary 112
Exercises 112
6. Templates ........................................................... 113
Template Syntax 113
Using the Templates from Python 114
The Number-Guessing Game Using Templates 116
Abstraction and Separation of Concerns: “Model View Controller” 118
Building a Multiscreen Application 118
Static Files in App Engine 120
Referencing Static Files 121
Generalizing Template Lookup with Multiple Templates 121
Extending Base Templates 123
Conditional Processing Templates 125
Replacing More Than One Block in the Base Template 129
Extending Our Application 131
Syntax Errors 139
More on Templates 141
Summary 141
Exercises 141
7. Cookies and Sessions .................................................. 143
HTTP Cookies 143
Logging In and Logging Out Using Sessions 145
Installing the Simple Session Utility 146
Using the Session to Mark Login and Logout 146
Changing the User Interface for a Logged-In User 148
Summary 150
Exercises 150
8. App Engine Datastore ................................................. 153
The Model-View-Controller Pattern 153
Defining Models 154
Adding a New Account Form 155
Adding a User Account 156
Table of Contents | vii
Looking Through the Datastore 159
Logging In and Checking Accounts and Passwords 160
Retrieving and Displaying Many Objects 161
Terminology: Different Types of Keys 164
References Between Data Models 165
Interactions Between Models 166
Putting the Primary Key into Session 168
Adding the Chat Feature 169
Summary 174
Exercises 174
9. JavaScript, jQuery, and AJAX ............................................ 177
jQuery 178
Create a View of the Chat Messages in HTML 178
Asynchronously Updating a <div> Using AJAX 181
Summary 183
Exercises 183
10. Running Your Application on the Google Infrastructure ..................... 185
Application Engine Accounts 185
Creating an Application on App Engine 186
Uploading Your Application 187
Testing Your Application 187
Logs, Statistics, and Other Features 188
Uploading New Versions 190
Collaboration on Applications 191
Summary 192
Exercises 192
11. Memory Cache ....................................................... 193
The Rules of Memory Cache 194
Using the Memory Cache 195
Using the Application Console to Examine Memory Cache 196
Using a Memory Cache in Your Application 197
Building a Session Store Using Memory Cache 198
Sessions and Memory Cache 202
Summary 204
Exercises 204
A. Installing and Running Google App Engine on Windows XP .................. 205
B. Installing and Running Google App Engine on Windows Vista ................ 213
viii | Table of Contents