Multi-tenancy is part of the OutSystems platform for a long time but has not often been used. In this session, Tiago will first explain what multi-tenancy exactly is. But very fast, we'll leave the theoretical aspect and dive into the practice. No better way to learn than from real-life cases. You'll get insight on when to use - and perhaps when not to use - the built-in mechanism and tip and trick to avoid pitfalls.

1. Multi-tenancy
A practical example
Tiago Bernardo
OutSystems Consultant @ Creetion
tiagobernardo@creetion.com

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Agenda 1. Quick introduction to Multi-tenancy
a. What is Multi-tenant?
b. It’s all about context!
c. What are User Providers?
d. Module, Entities, Timers, Site Properties in Multi-
tenant
2. Practical example (demo)
3. Final considerations
Goal: Hopefully, at the end you will understand a little
better how multi-tenant works.

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Is the capability of providing each Customer (Tenant) with his own isolated set of
computing resources (data, end-users), while using a single Application Server and
Database Server.
What is multi-tenant?

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Context!
All logic and data are executed and accessed always within a certain context.
It is important that the developer understands, and controls in certain ways (for example
accessing the data of all Tenants), the Tenant context that is applied in certain parts of the
application.
It’s all about Tenant context!

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Using the system action TenantSwitch.
"Change the context to the given tenant identifier. When switching tenant, the session is
cleared (equivalent to an implicit logout, before changing the tenant), the OnSessionStart
(Traditional) actions are executed, and the current transaction is committed."
The User_Login action from the module Users executes inside a TenantSwitch.
How to change Tenant context?

6. User Providers are modules that make context available for:
End-users, sessions, and tenants (if the User Provider is multi-tenant).
By default the platform has 2 User Provider modules:
1) Users
2) Service Center
A User Provider module always has a Default Tenant.
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What are User Providers?

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System User entity
User entity, and User Providers
User Provider,
Not multi-tenant:
ServiceCenter
Default tenant:
ServiceCenter
User Provider,
Multi-tenant:
Users
Default tenant:
Users
Tenant ONE
Tenant
TWO
User Provider,
Multi-tenant:
UsersClone
Default tenant:
UsersClone

8. 1) Module
a) Sets the default for the other elements inside the module.
2) Entities
a) Have a visual clue to help distinguish
3) Site Properties
4) Timers
BPTs (run in the context of a Tenant)
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Elements for Multi-Tenancy

9. A practical example
Customer Management

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1) Security:
a) Avoid expose the Tenant_Id, only when necessary, and isolate the usage.
b) Also control the use of TenantSwitch.
2) Monitor performance with the increase of Tenants (Timers and BPT have limited
threads to run)
3) Monitor database usage.
4) Try to avoid logic that depends on the Tenant. Makes code more complex and
difficult to maintain.
5) Anonymous screens for generation of PDFs need to controlled.
6) Etc.
Final considerations

11. Q&A
Thank you! Hope it was interesting.
Now for Q&A.

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End