Building Multi Tenant Java Applications

1. Building Multi Tenant Java Applications Rajesh Venkatesan Senior Architect, HCL Technologies rajeshvn@hcl.com

2. Multi Tenancy – An Overview Ability to cater to multiple customers using a shared instance of Software/Hardware • Time Share • ASP • End User Web Apps • Inability of SOHO and SMB segments to adopt IT • Non IT Businesses getting entrenched in managing IT That’s what this session is about

3. Multi Tenancy Impact in the real world Single Vs MultiTenancy

4. Architectural Facets of Multi Tenancy inthe Software World • Virtualized Hardware • Database • Application Servers • Inbound • Outbound Shared Infrastructure Integration Configuration over Customization Security • Data Security • Application Security • Standardization of • UI • Data Model • Business Logic

5. Shared Infrastructure – Database Separate Database Traditional – Isolated Database Instance Per Customer Shared Database Separate Schema Customers get their own schema but are co-hosted in the same database Shared Database – Shared Schema Drives the highest efficiency. All Customers data is stored in the same database and schema with a tenant id qualifier Isolated Shared Separate DB Separate Schema Shared Schema Typically Multi Tenancy at the database level has 3 standard patterns Isolated Shared Source:Multi Tenant Data Architecture, Frederick Chong, Gianpaolo Carraro, and Roger Wolter Microsoft Corporation

6. Database Multi Tenancy Patterns – Pros and Cons Separate Database Trade Off Considerations • Compliance/Regulatory • Cost • Operations • Time to Market • Liability Shared Database – Separate Schema Shared Database – Shared Schema

7. Database Multi Tenancy Implementation Isolated Database and Shared Database – Separate Schema • From a JDBC Perspective this implies different connection strings based on the customer. • Typical Tenant Context is set by an intercepting filter and obtained at the DAO layer possibly via a ThreadLocal variable • For Hibernate implement a Tenant aware ConnectionProvider and switch off the second level cache. Standard Data Access simply returns the appropriate connection based on tenant context Shared Database Shared Schema Approach 1 • Business Logic and Data Access is aware of multi tenant context and therefore query appropriately • Pros – Easy to build • Cons – High Probability of bugs leading to data leakage For Hibernate • Use Filters • Use Hibernate Shards Approach 2 • Abstract Multi Tenancy concern to the Data Access Layer and write business logic without tenant context. • Data Access Layer automatically adds tenant context to all data calls

8. Integration ? How can I receive notification ? Is there standard integration ? How can I push data to the application ? How do I orchestrate my business process Familiar? SOA? Typical integration concerns when applications move out of customer premises include

9. Integration – Contd Fundamentally the application must support well defined interfaces for inbound Integration as well as Outbound Integration Inbound Integration Implementation • Expose “services” • Technology Independent • Standards Based • High Security • Multi Tenant Aware • SOAP • Well Defined Standard • WSS for Multi Tenant Security (Username/Token, X509 –Tenant Certificate, SAML, Kerberos) • REST • Easy Integration • Simplicity • Security to be built on top. • Axis, XFire WSS4J JAX-WS

10. Integration – Contd Outbound Integration • Allow Tenants to register for integration events. • Push Vs Pull • Push – Synchronous • Data can pushed to waiting WS endpoints • Publish Standard Web Service Interfaces that customers can implement. • Multi Tenant aware integration layer appropriately calls out the tenant specific interface. • Problem with availability of customer endpoints • Push Asynchronous • Expose Secure Asynchronous Messaging Infrastructure. • Heavy Vs Light Weight Events • For security reasons and other reasons, push non-critical information alone into the message. The listening party then calls back via standard web service inbound interface for the actual message. • Push the entire message with all relevant information. The Infrastructure is absolutely secure. • The messaging infrastructure takes responsibility of ensuring delivery.

11. Security Application Security Physical Security Data Security Security Facets of Security

12. Data Security JCA/JCE Data at Rest • Use tenant specific encryption when required. Decouple encryption awareness from the data layer allowing data leaks to still be harmless • TradeOffs • Database functions cannot be applied on encrypted fields • Performance • Tokenization of Data – Only a token reference is stored in the database. Actual data has to come from a high security data protection server Data in Transit • Use Secure means of transfer (https) and add authentication/ authorization layer on top. • Use In Wire Encryption for highly critical data JSSE

13. Application Security • Application Security is not different from traditional applications but some aspects become a lot more critical. • Exposing the application on the web brings about a gamut of application security threats. • Be Aware of possible security vulnerabilities and address them. • The OWASP Top Ten Project (http://www.OWASP.org) is a good place to look. • A1: Injection • A2: Cross-Site Scripting (XSS) • A3: Broken Authentication and Session Management • A4: Insecure Direct Object References • A5: Cross-Site Request Forgery (CSRF) • A6: Security Misconfiguration • A7: Insecure Cryptographic Storage • A8: Failure to Restrict URL Access • A9: Insufficient Transport Layer Protection • A10: Unvalidated Redirects and Forwards

14. Application Security – Contd • Some of the security best practices for applications • Encrypt all communication between the browser and server via SSL. • Strong password policy enforcement using configurable password policy. • Passwords are stored after one way encryption in the database. It is impossible to know user passwords. Auto-Generated Passwords automatically expire after xx hours. • Use of token based authentication with zero trust on server side Sessions. All access to the application is authenticated and is either secured by an authentication token or via certificates. • Decoupled Authentication and Authorization and consolidation of concerns in order to establish a single point of control of user access. • RBAC ensuring there are no super-users who get access to the system. • Extensive Logging Capability ensuring every action is traceable to the user, request and session along with the actual change to the database. • Database credentials created with named permissions. • OS credentials created with named permissions • All Inbound and Outbound interface points must be secured by default. (SSL) • Additional Tenant Aware Security measures like • Tenant Specific Certificates

15. Application Security – Federated Identity Tenant 1 Sign In Corporate LDAP Multi Tenant Application Tenant n Sign In Corporate LDAP • With applications moving outside of customer premise, corporate users are forced to have multiple identities one corporate and other in-cloud application identity. • This poses a security problem for customers since a person moving out of the company still has access to corporate data. • Therefore it becomes necessary to allow identity to be federated from the corporate context. • Therefore the application has to be ready to • De-Couple Identity Management and Authentication • Support delegation of IdM and Authentication to corporate systems through established standards like SAML.

16. In order to drive efficiency, an application must standardize its features. However this results in not being able to accommodate customers with alternate business processes. This results in an architectural requirement: How to support customization via configuration? Configuration Over Customization Database • Allow extension of existing entities Business Logic • Business Logic Templates • Allow pluggable business logic. • Allow small changes to business process UI • Metadata driven UI • Customize • Look and Feel • Layout • Content

17. UI Customization • Depending on requirements UI customization is done at various depths • Look and Feel – The ability to change the font, color and style of existing UI • Layout – The ability to switch component layouts • Content – The ability to choose what content goes where. • Two Approaches • Both approaches require a metadata layer that can understand the customization done be specific tenants. • UI Rendering must take into account a standard layout as well as the metadata for rendering. • Accommodate tenant specific UI Data models that can extensions to standard data models.

18. Business Logic & Database Customization Business Process Customization Database Customization • Enable an application to be flexible in allowing changes to business logic • Allow different workflows to be configured per tenant. • At the application design level • Follow a highly de-coupled, pluggable component based design. • Standard IoC Pattern to plug new implementations • At the functional level • Decide on the smaller variations that a business process/logic can take. Make these configurable. • Allow ability to plugin newer processes as the application evolves. • Accommodate generic data models during processing to cater to extended schemas • Again a metadata layer is required to understand the configuration done by tenants at the business process level as well as newer business process that is available. • Ability to extend the schema as per specific requirement • In the Shared Database – Separate Schema and Separate Database pattern, this becomes trivial as the customization can be done directly. • In the Shared Database-Shared Schema, the following approaches are standard • To have a pre-determined set of fields for specific data models that can be used as extensions. • To have a generic extension schema that can accommodate customization to any entities and a data access and business logic layer that can bring in the tenant context when querying. Reference: Multi Tenant Data Architecture, Frederick Chong, Gianpaolo Carraro, and Roger WolterMicrosoft Corporation Spring

19. Scalability Data • In case of a RDBMS, Shared Database – Shared Schema use partitioning by tenantid (SHARD) • Give a thought about NoSQL Databases if dealing with multiples of TB of data(ACID vs BASE) Hadoop HBASE Application Server • Clustering • Make services as stateless as possible. Session Replication is a nightmare. • Avoid file system for data. Use a central datastore • De-Coupled Components • Conceptualize application features that can be de-coupled and scaled separately. • Allows a resource hogging feature to be separated out and scale strategy planned differently. • Cache data where possible (memory IS cheap) • Plan for failure – Auto Recovery. UI • With the current scope of browser capabilities (HTML5) pushing state to the browser has become easier. • Also frameworks like GWT has enabled complex applications to sit on the client side. • For applications using more sophisticated RIA clients (OpenLAZLO, FLEX or Silverlight), the same principle applies

20. Questions?