Table Of ContentD
Developing Multi-tenant applications for the clouD, ev
3rD eDition patterns & practices el
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How can you create an application that has truly global reach, and can scale Proven practices for predictable results p Third Edition
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rapidly to meet sudden massive spikes in demand? Historically, companies n
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had to invest in an infrastructure capable of supporting such an application Save time and reduce risk on your
themselves, and plan for peak demand—which often means that much of the software development projects by M D
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capacity sits idle for much of the time. Typically, only large companies would incorporating patterns & practices, u
have the available resources to risk such an enterprise. Microsoft’s applied engineering lt
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The cloud has changed the rules of the game. By making infrastructure guidance that includes both production -t M -
quality source code and documentation. e u lt i t e n a n t
available on a “pay as you go” basis, creating a massively scalable, global n
application is within the reach of both large and small companies. Yes, by a
The guidance is designed to help n
moving applications to the cloud you’re giving up some control and autonomy,
software development teams: t a
but you’re also going to benefit from reduced costs, increased flexibility, and a p p l i c at i o n s
scalable computation and storage. Make critical design and technology p
selection decisions by highlighting p
This guide is the third release of the second volume in a series about Windows the appropriate solution architectures, lic for the
Azure. It demonstrates how you can create from scratch a multi-tenant, Software technologies, and Microsoft products a
as a Service (SaaS) application to run in the cloud by using the Windows Azure t
tools and the increasing range of capabilities of Windows Azure. for common scenarios io c
n lo u D
Understand the most important s
The Tailspin Scenario concepts needed for success by f
Motivations, constraints, o
and goals of a SaaS ISV explaining the relevant patterns and r
building an application on prescribing the important practices t on Microsoft
Windows Azure h
Hosting a Multi-tenant Application e
on Windows Azure Get started with a proven code base c Windows Azure™
Selecting a single or a multi-tenant by providing thoroughly tested l
architecture, stability, scalability, o
software and source that embodies
SLAs, authentication, ALM, monitoring, u
customization Microsoft’s recommendations D
Partitioning Multi-tenant
Applications
The patterns & practices team consists
Partitioning for tenants,
session state management, of experienced architects, developers, t
caching, using MVC Maximizing Availability, Scalability, writers, and testers. We work openly h
and Elasticity ir
ChoosiDnga taa MAruclhtii-tteecntuanret Gexeeoc-uloticoanti, oanu,t CoDscNa,l iansgy rnoclhersonous winidthu stthrey edxepveerlotsp, eorn c eovmemryu pnriotyje acnt,d t o eD Dominic Betts
Data models, partitioning, ensure that some of the best minds in D Alex Homer
extensibility and scalability. the industry have contributed to and it
Using Windows Azure SQL reviewed the guidance as it is being io Alejandro Jezierski
Database, Windows Azure Securing Multi-tenant Applications developed. n
blobs and tables, data Masashi Narumoto
paging, and data analysis Protecting sensitive data, protecting
session tokens, authentication and
We also love our role as the bridge Hanz Zhang
authorization
between the real world needs of our
customers and the wide range of
Managing and Monitoring
Multi-tenant Applications products and technologies that
ALM, endpoint protection, provisioning Microsoft provides.
new tenants, customization, billing
The guide focuses on both good
practice design and the practicalities
of implementation for multi-tenant
applications, but also contains a
wealth of information on factors
For more information explore:
such as security, scalability, availability,
msdn.microsoft.com/practices
and elasticity that are relevant to all
types of cloud hosted applications.
Software Architecture and
Software Development
Developing Multi-tenant
Applications for the Cloud
3rd Edition
Dominic Betts
Alex Homer
Alejandro Jezierski
Masashi Narumoto
Hanz Zhang
978-1-62114-023-8
This document is provided “as-is.” Information and views expressed in this
document, including URL and other Internet website references, may change
without notice. You bear the risk of using it. Some examples depicted herein
are provided for illustration only and are fictitious. No real association or
connection is intended or should be inferred.
© 2012 Microsoft. All rights reserved.
Microsoft, Microsoft Dynamics, Active Directory, MSDN, SharePoint, SQL
Server, Visual C#, Visual C++, Visual Basic, Visual Studio, Windows, Windows
Azure, Windows Live, Windows PowerShell, Windows Server, and Windows
Vista are trademarks of the Microsoft group of companies.
All other trademarks are the property of their respective owners.
Contents
Foreword: Bill Hilf xi
Preface xiii
Who This Guide Is For xiii
Why This Guide Is Pertinent Now xiv
How This Guide Is Structured xiv
What You Need to Use the Code xv
Where to Go for More Information xvi
Who’s Who xvi
Acknowledgments xix
Acknowledgements of Contributors to the Third Edition xxi
The Tailspin Scenario 1
The Tailspin Company 1
Tailspin’s Strategy 1
The Surveys Application 2
Tailspin’s Goals and Concerns 3
The Surveys Application Architecture 5
More Information 7
Hosting a Multi-Tenant Application on Windows Azure 9
Goals and Requirements 9
The Tenant’s Perspective 9
The Provider’s Perspective 10
Single Tenant vs. Multiple Tenant 11
Multi-Tenancy Architecture in Windows Azure 13
Selecting a Single-Tenant or Multi-Tenant Architecture 14
Architectural Considerations 14
Application Stability 14
Making the Application Scalable 15
Resource Limitations and Throttling 18
Geo-location 19
v
vi
Service Level Agreements 19
The Legal and Regulatory Environment 19
Handling Authentication and Authorization 19
The Command Query Responsibility Segregation (CQRS)
Pattern 20
Application Life Cycle Management Considerations 20
Maintaining the Code Base 20
Handling Application Updates 21
Monitoring the Application 21
Using Third-Party Components 21
Provisioning for Trials and New Subscribers 22
Customizing the Application 22
Customizing the Application by Tenant 22
URLs to Access the Application 23
Financial Considerations 24
Billing Subscribers 24
Managing Application Costs 26
Engineering Costs 26
More Information 27
Choosing a Multi-Tenant Data Architecture 29
Storing Data in Windows Azure Applications 29
Windows Azure Table Storage 29
Windows Azure Blob Storage 30
Windows Azure SQL Database 30
Other Storage Options 31
Storage Availability 31
Multi-Tenant Data Architectures 32
Partitioning to Isolate Tenant Data 32
Shared Access Signatures 35
Data Architecture Extensibility 36
Data Architecture Scalability 38
An Example 39
Option 1 — Using a Single Table 40
Option 2 — Table per Tenant 40
Option 3 — Table per Base Entity Type 40
Option 4 — Table per Entity Type 41
Option 5 — Table per Entity Type per Tenant 41
Comparing the Options 42
Goals and Requirements 42
Isolation of Tenants’ Data 42
Application Scalability 43
Extensibility 43
Paging through Survey Results 43
Exporting Survey Data to SQL Database for Analysis 43
vii
Overview of the Solution 44
Storage Accounts 44
The Surveys Data Model 44
Storing Survey Definitions 45
Storing Tenant Data 49
Storing Survey Answers 50
Storing Survey Answer Summaries 51
Comparing Paging Solutions 52
Paging with Table Storage 52
Paging with Blob Storage 53
Comparing the Solutions 53
The SQL Database Design 53
Inside the Implementation 55
The Data Store Classes 55
SurveyStore Class 55
SurveyAnswerStore Class 55
SurveyAnswersSummaryStore Class 55
SurveySqlStore Class 55
SurveyTransferStore Class 55
TenantStore Class 56
Accessing Custom Data Associated with a Survey 56
Defining a Tenant’s Custom Fields 56
Writing Custom Fields to the Surveys Table 57
Reading Custom Fields from the Surveys Table 61
Implementing Paging 62
Implementing the Data Export 64
Displaying Questions 66
Displaying the Summary Statistics 68
More Information 69
Partitioning Multi-Tenant Applications 71
Partitioning a Windows Azure Application 71
Partitioning Web and Worker Roles 73
Identifying the Tenant in a Web Role 74
Identifying the Tenant in a Worker Role 77
Partitioning Queues 78
Partitioning Caches 80
Goals and Requirements 81
Isolation 81
Scalability 81
Accessing the Surveys Application 82
Premium Subscriptions 82
Designing Surveys 83
viii
Overview of the Solution 84
Partitioning Queues and Worker Roles 84
Tenant Isolation in Web Roles 84
DNS Names, Certificates, and SSL in the Surveys Application 85
https://tailspin.cloudapp.net 86
http://tailspin.cloudapp.net 87
Accessing Tailspin Surveys in Different Geographic
Regions 87
Maintaining Session State 87
Isolating Cached Tenant Data 89
Inside the Implementation 90
Prioritizing Work in a Worker Role 90
The BatchMultipleQueueHandler and the Related Classes 92
Using MVC Routing Tables 97
Web Roles in Tailspin Surveys 100
Implementing Session Management 102
Configuring a Cache in Windows Azure Caching 106
Configuring the Session State Provider in the TailSpin.Web
Application 107
Caching Frequently Used Data 108
More Information 111
Maximizing Availability, Scalability, and Elasticity 113
Maximizing Availability in Multi-Tenant Applications 113
Maximizing Scalability in Multi-Tenant Applications 114
Caching 115
SQL Database Federation 115
Shared Access Signatures 116
Content Delivery Network 116
Implementing Elasticity in Multi-Tenant Applications 116
Scaling Windows Azure Applications with Worker Roles 117
Example Scenarios for Worker Roles 118
Triggers for Background Tasks 119
Execution Model 120
The MapReduce Algorithm 123
Goals and Requirements 123
Performance and Scalability when Saving Survey
Response Data 123
Summary Statistics 124
Geo-location in the Surveys Application 125
Making the Surveys Application Elastic 126
Scalability 126
ix
Overview of the Solution 127
Options for Saving Survey Responses 127
Writing Directly to Storage 127
Using the Delayed Write Pattern 128
Comparing the Options 132
Options for Generating Summary Statistics 137
Scaling out the Generate Summary Statistics Task 139
Using Windows Azure Caching 139
Using the Content Delivery Network 140
Setting the Access Control for the BLOB Containers 141
Configuring the CDN and Storing the Content 141
Configuring URLs to Access the Content 142
Setting the Caching Policy 143
Hosting Tailspin Surveys in Multiple Locations 144
Synchronizing Survey Statistics 145
Autoscaling and Tailspin Surveys 147
Inside the Implementation 147
Saving the Survey Response Data Asynchronously 148
Calculating the Summary Statistics 150
Pessimistic and Optimistic Concurrency Handling 154
More Information 156
Securing Multi-Tenant Applications 157
Protecting Users’ Data in Multi-Tenant Applications 157
Authentication 157
Authorization 158
Protecting Sensitive Data 158
Splitting Sensitive Data across Multiple Subscriptions 160
Using Shared Access Signatures 161
Goals and Requirements 163
Authentication and Authorization 163
Privacy 163
Overview of the Solution 164
Identity Scenarios in the Surveys Application 164
Integrating a Subscribers Own Identity Mechanism 164
Providing an Identity Mechanism for Small Organizations 165
Integrating with Social Identity Providers 166
Windows Azure Access Control Service and Windows
Azure Active Directory 167
Configuring Identity Federation for Tenants 168
Encrypting Session Tokens in a Windows Azure Application 169
Inside the Implementation 169
Using Windows Identity Foundation 170
Protecting Session Tokens in Windows Azure 174
More Information 175
x
Managing and Monitoring Multi-Tenant Applications 177
ALM Considerations for Multi-Tenant Applications 177
Goals and Requirements 177
Overview of the Solution 179
Testing Strategies 179
Stress Testing and Performance Tuning 181
Application Deployment and Update Strategies 182
Application Management Strategies 182
Application Monitoring Strategies 185
Inside the Implementation 186
Unit Testing 186
Testing Worker Roles 191
Testing Multi-Tenant Features and Tenant Isolation 193
Performance and Stress Testing 194
Managing the Surveys Application 197
Monitoring the Surveys Application 198
ISV Considerations for Multi-Tenant Applications 199
Goals and Requirements 199
Overview of the Solution 200
Onboarding for Trials and New Subscribers 200
Configuring Subscribers 201
Supporting Per Tenant Customization 201
Financial Goals and Billing Subscribers 202
Inside the Implementation 204
Onboarding for Trials and New Subscribers 204
Customizing the Surveys Application for Each Subscriber 209
Billing Subscribers in the Surveys Application 212
More Information 213
Glossary 215
Index 219
