Lessons Learned: Building Multitenant Applications with the Windows Azure Platform Ben Riga

benriga@microsoft.com

SVC33

Phil Calvin

CTO

Sitemasher Corporation

Stephan Friedl

Chief Architect

Quark, Inc.

A Definition> For our purposes:

> Multitenancy refers to a principle in software architecture where a single instance of the software runs on a server, serving multiple client organizations (tenants).

> Multitenancy is contrasted with a multi-instance architecture where separate software instances (or hardware systems) are set up for different client organizations.

> Different Approaches to Data Isolation> Separate/Shared DBs, Separate/Shared

SchemasSource: Wikipedia: http://en.wikipedia.org/wiki/Multitenancy

Sitemasher

Phil CalvinCTOSitemasher Corporation

www.sitemasher.com

Sitemasher website platform

> Website Infrastructure platform built on ASP.NET in C#

> Initial Development began late 2006> Running live on private cloud since

2008> ASP.NET 3.5SP1, Server 2008, SQL

2008> Launching Azure version at PDC> “Shared Everything” multitenancy

model> 2 Axis – Service Providers and Individual

Sites> Try it:

http://www.sitemasheronazure.com

Multitenant Model

Request/Response General Model

Browser

Application (Azure Web Role)

Caching (Worker Role)

SQL Azure Database Servers

Same model for all request types

• AJAX Requests in Development

• Page Requests in Production

• Asset Requests within Pages

Request/Response Lifecycle

Application (Azure Web Role)

>Determine Current Site and Service Provider

>Determine SQL Connections

>Content

>Membership Provider

>Check Access

>Process Request

Web front end architecture

> Key design requirement – eliminate any per-web-server configuration.> No service-provider specific features or UI> No site specific features or UI

> Built the notion of “Pageless” webservers> ASP.NET and markup built dynamically

from component model> Web Services used to create design

studio> Any request for any site –

automatically> Caching architecture critical for

performance

Sitemasher Component Architecture> Self-similar component architecture

for sites> Sites, URLs> Pages, Page Items, Stylesheets, Style

Items> Actions and Events> Database Tables, Columns, Queries> External Data Sources

> Lots of small independent blobs that can be manipulated independently

Display Published Page

> Code walk through – page request> Request –

(http://www.sitename.com/page)> Code walk through – asset request

> Request – http://www.sitename.com/image.jpg)

> Code walk-through – development studio> Browser - WebService - Component -

Returned JSON> Code walk-through

> membership providers

Common Themes

> In all three of these cases there is a pattern that is worth explaining – because it is fairly core to our system> Minimal component access – not normally

an issue on traditional website deployments because they are page based

> For Sitemasher, we need to demand load components of a page as required> Caching and SQL Access critical> PROFILE with remote database often to

expose bottlenecks

Lessons Learned

> HttpRuntime.Cache an enemy> Not distributed – leads to invalid state

> Don’t develop against local SQL Servers> Put network distance between application

code and database – quick way to locate bottlenecks

> Test and debug extensively under freely load balanced local environments

> Upgrading your system – that means you are upgrading every one of your customers.

Quark Promote

Stephan FriedlChief ArchitectQuark, Inc.

http://quarkpromote.quark.com/

Quark, Inc.

• Primary Product: Quark XPress• Defined Desktop Publishing Market

• Also Has Line of Enterprise Products• Quark Publishing System (QPS)• Quark XPress Server• XML Author

• MS Word Plug-In for editing XML

Quark Promote

• New Service for SMB Market> Allows users to create high quality marketing

collateral from professionally designed templates> Professional printing provided by mail –or-

through a network of neighborhood print partners

• Composed of 4 Principal Components> Content: Hundreds of professionally designed

templates> Website: Allows browsing of template content> Lightweight Design Tool: .NET Application for

Template customization> Back Office Services: Catalog mgmt, billing,

fulfillment

Quark Promote

Stephan FriedlChief ArchitectQuark, Inc.

demo

Initial Promote Architecture

Business Opportunity: Multi-Tenancy

• During discussions with print partners, a number expressed great interest in white labeling Promote for their business

• Engineering challenge to support business development with a Multi-Tenant solution> Extensive branding> Solid data partitioning > Cost-effective development , QA and

hosting> We examined a number of cloud

platforms and Azure was the obvious business enabler

Multi-Tenancy Model

• ‘Hybrid’ Multi-Tenant model > Single-Instance, shared Core Services

> Utilize Azure compute elasticity to manage loading> DB Partitioned along tenant boundaries

> Utilize separate SQL Azure instances per tenant> Logical separation of all tenant transactional data

> Separate ASP .NET web site per tenant> Maximal branding and customization per tenant

> Combination of divide-the-cloud and grow-in-the-cloud multi-tenancy models

Architectural Considerations> Why this model?

> Primarily Cost Driven in Several Dimensions> Ongoing development/QA/management cost

containment> Single-instance core services; multi-instance DB

> No changes required to DB schema> Minor changes to Core Services

> No changes to any SQL statements or ORM bindings> ‘Defensive Design’ - risk of accidental disclosure of one

tenant’s data to a second is minimized> Minimizes scope of testing for coupling between tenants

> Multi-instance tenant websites permit ‘gratuitous flexibility’ in branding and integration to tenant’s IT> Changes to one tenant website will not impact others > Modifications to carved-off deployments could be

handled by SIs or a partner’s IT staff

Implementation

• Speed to market without impacting main-line development was critical

• Design choice was to use a custom SOAP header to transmit tenant ID > Inject an tenant ID into custom SOAP header> Extract tenant ID in services, store in TSS> DB connection factory returns tenant specific

SQL Azure connection

> Required about 1 engineer week

Slide for Developer’s Software Code

• Show Thread-Local Request Context Object

• Show WCF Override for Org ID Injection custom HTTP/SOAP Header

• Show WCF Override to Get Org ID from Header

• Show DB Connection Factory

Multi-Tenant Promote on Azure

Multi-Tenant Quark Promote

Stephan FriedlChief ArchitectQuark, Inc.

demo

>>FUTURE

Next Steps

> Replace ASP .NET Membership with .NET Services Access Control

> Refactor some database code to reduce number of SQL selects issued

> Create a solution specific monitoring and management console> Utilize Azure Service Management API

and monitoring APIs

Lessons Learned

• Designing and implementing with cutting-edge .NET frameworks pays big dividends> Makes transition to Azure very, very smooth> Start using WCF now to avoid headaches later

• Be prepared for some SQL Azure tuning> Existing schema support is very good, but not

complete > SQL Azure is a shared, hosted DB environment

> Slightly different performance profile than standard SQL Server> Expect slightly higher latency per DB operation

> SQL Azure ‘Slowness’ could be many small queries in code

• Tooling is still maturing> Expect to have a lot of trace logging in your app

Conclusion

• Azure is an excellent fit, economically and operationally for Quark’s new service> High availability is baked into the platform

• Our initial port to the Azure environment required only 8 engineer-weeks> Platform and tooling maturity will drive this effort

down

• Azure Platform is a key enabler for multi-tenancy in our application> Inexpensive, easily provisioned DB instances> Elastic compute services consumption> Easily deployed web roles for isolated tenant web

sites

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Questions?Ben Riga

benriga@microsoft.com

SVC33

Phil Calvin

CTO

Sitemasher Corporation

Stephan Friedl

Chief Architect

Quark, Inc.

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