This document discusses an architecture for multi-tenant SOA middleware for cloud computing. It proposes isolating tenants through unique security domains, storing tenant data separately in databases, and maintaining separate execution contexts. The WSO2 Carbon platform is presented as implementing this approach, with the Stratos cloud platform allowing scalable deployment. Challenges discussed include tenant partitioning, application descriptions, discovery, and hybrid cloud support.

1. Multi-Tenant SOA Middleware for
Cloud Computing
July 2010
Srinath Perera, Ph.D.,
Architect, WSO2 Inc.

2. Outline
● What does a Cloud Native Platform needs?
● Multi-tenancy
● Challenges of Multi-tenancy
● Carbon Platform
● Multi-tenancy Architecture
● Stratos
● Conclusion

3. Outsourcing IT through Cloud
● Ideally users want to just outsources their non-
competitive IT parts.
● They want to buy IT aspects as a Utility (like
water or electricity), making Niclous Carr's “IT
does not matter” prediction a reality

4. Cloud Computing
For end-users
For developers, integrators, architects
For infrastructure specialists

5. What does Cloud a Native Platform
Needs(1/2)?
● Distributed/Dynamically Wired (works properly in
the cloud)
– Supports deploying in a dynamically sized cluster
– Finds services across applications even when they
move
● Elastic (Uses the cloud efficiently)
– Scales up and down as needed
– Works with the underlying IaaS
● Multi-tenant (Only costs when you use it)
– Virtual isolated instances with near zero incremental
cost
– Implies you have a proper identity model

6. What does Cloud a Native Platform
Needs(1/2)?
● Self-service (in the hands of users)
– De-centralized creaton and management of tenants
– Automated Governance across tenants
● Granularly Billed and Metered (pay for just what
you use)
– Allocate costs to exactly who uses them
● Incrementally Deployed and Tested (seamless live
upgrades)
– Supports contnuous update, side-by-side operaton, in-
place testng and incremental producton

7. What Multi-tenancy ?
● Many Parties shared same set of resources,
while giving each an his own space

8. Multi-tenancy is for Maximizing
Resource Sharing
● Possible SaaS Implementations
– First generation: Machine for User
– Second Generation: VM per User
– Third Generation: Using multi-tenancy to share
same server/machine/VM across users.
rd
●
Efficient implementations of SaaS needs 3
generation multi-tenancy

9. Multi-tenant SOA Platform
● Data multi-tenancy is great – most of the focus
has been there
● But we need multi-tenancy in other layers as
well.
– E.g. Google apps provides a Servelt as a
Service.
● Mosts apps, SOA handles most
logic/executions. A Multi-tenant SOA platform
will ease the development of Apps as a Service
to a greater extent.

10. To Understand Multi-tenant SOA
platform, you have to first
understand Our SOA Platform

11. WSO2 Carbon Platform

12. WSO2 Carbon Platform

13. Our Goal
● Developing an architecture to provide SOA
Container (s)/ Platform as a Service.
● Let users run their single tenet apps (Services,
Business processes, Web applications,
Mediation logic, Rules etc. ) in this multi-tenant
environment without any change.

14. Understanding Multi-tenancy
● Goal of multi-tenancy is to provide different users
of the system (which we shall call tenants)
isolation in each of these spaces while
maximizing resource sharing.
● Resource sharing and isolation are a tradeoff.
● Furthermore, Chang et al. [4] has proposed three
properties for multi-tenancy in addition to
isolation:
– Scalable,
– Multi-tenant-efficient: same instance hosts
multiple tenants
– configurable.

15. Challenges of Multi-tenancy
● Isolation between tenants
● Admin view vs tenants views and programming
model, maximum configuration without
compromising isolation.
● Scalability: multi-tenancy tend to accumulate
load so it has to be scalable.

16. SOA Multi-tenancy
● We break multi-tenancy at SOA in to three parts (Based on
Chang et al.).
– Execution: Business Processes, Workflows and Mashups
– Security: ownership and authorization of both data, as well as
executions in the framework
– Data

17. Multi-tenancy Architecture

18. Achieving Tenant Isolation
● Each Tenant is given a Security Domain
● Each domain may have its own User Store and Permissions,
thus have a set of users and permissions enabling users to access
resources
● Each domain is isolated and do not have access to other
domains

19. Achieving Data Isolation
● All data access to the Carbon platform is done
through Registry interface.
● At Multi-tenant environments, system loads with
multi-tenant implementation of the registry,
which enforces isolation
● Multi-tenancy options at Database level
● Separate database
● Separate tables
● Shared tables ** [We use this]

20. Achieving Execution Isolation
● All executions are based on Axis2
● Axis2 have stateless executions and keep all state in a
Context.
● So if we create different context for each tenant, they
are isolated.

21. Achieving Execution Isolation (Contd.)

22. Extending this to Products

23. Extending this to Products
● WSAS (Web Services Application Server) ,
Registry, Identity Server directly get Multi-
tenancy once security, data, and execution,
● BPS keeps all the data either in Context or in
registry, and each tenet see a specific view.
● Some products need some work, but in general
they are implemented using registry for data
and services for executions So the
aforementioned model covers most usecases.

24. Performance

25. WSO2 Stratos

26. http://cloud.wso2.com

27. AppServer

28. Open Questions/Challenges
● Scaling Up beyond simple Clustering: Tenant partitioning
strategy combined with tenant aware load balancing
● Archival Formats that describe applications that uses
different parts of the SOA (Services, BPEL, Workflows,
Rules, CEP etc).
● Bringing in discovery: WS-Discovery based deployment
● Monitoring and Managing Stratos Deployment
● Making Sessions work with Scalability Solutions
● Tenant-aware JDBC driver
● Supporting Hybrid Cloud Architectures, and on demand
scaling out to Public Cloud.
● Incremental deployment and versioning

29. Conclusion
● We discussed an architecture to enable multi-
tenancy in an SOA platform
● We discussed how architecture handle three
aspects, Security, data, and execution and how
those three aspects can yield a Multi-tenet SOA
platform

30. More Info
 Corporate website: http://wso2.com
 Developer portal: http://wso2.org
 Business development team: bizdev@wso2.com
 srinath@wso2.com