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Variability in Multi-tenant SaaS Applications

Jaap Kabbedijk, MSc.Utrecht University, the Netherlands

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What will we discuss?

Introduction

Explanation SaaS history

Explanation Multi-tenancy

Case Studies

Conclusion

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Who am I?

Bachelor Information Sciences @UU

Master Business Informatics @UU

PhD. Candidate on variability in multi-tenant SaaS implimentations

Train for marathon of Paris

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What do all those terms mean?!

Runtime Variability

Multi-tenancy

Software as a Service (SaaS)

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First something completely different!

Based on work of dr. Andy Zaidman (TUDelft)

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Pros and Cons

House Apartment

Effective use of land - +

Privacy + -

Infrastructure sharing - +

Maintenance cost sharing - +

Freedom + -

House: Privacy en freedomApartment: Cost efficiency

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What does this have to do with software?

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Traditional Delivery Life Cycle

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Traditional Deployment Model

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Traditional - Characteristics

Think about the ‘House’ example

Customers have to install and update their own software

Customers manage their own data

Every customers needs his own server to deploy the product

Customizations can easily be done per customer

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Traditional – Disadvantages

High initial costs for customers

Hard to keep up with updates

Lack of expert knowledge

High change of data loss

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Application Server Provider

Data not responsibility customer

Application is hosted at a third party

Multiple products are hosted on the same machine

More efficient use of server compared to the traditional way

Every customer has his own product on the server

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Different Environments

Data not responsibility customer

Everyone uses the same product, but gets his own environment and database

Only one codebase

Reasonably scalable

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Multi-user Solution

Software as a Service (think about the ‘apartment ‘ example)

Data not responsibility customer

A product is offered completely as a ‘service’

Comparable to water or energy

Possibility to serve large number of customers with a limited amount of servers

Facebook, Grooveshark, etc.

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Perfect Solution?

Lower cost for customers

Higher safety of data for the customer

Efficient server use for the hosting provider

But…where are the customizations?

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Multi-tenancy

Data not responsibility customer

A product is offered completely ‘as a service’

Possibility to serve large number of customers with a limited amount of servers

Tenants (customers) can have specific functionality

Combination between the ‘house’ and ‘apartment’ example

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Overview ASP to Multi-tenancy

(Kwok et al., 2008)

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Multi-tenancy: Holy grail?

A hosted solution

Sharing of: Hardware Software Development cost Deployment cost Maintenance cost

Possibility for variability in the product

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Why is not everything multi-tenant?

It is a hype, but many people do not know what it is exactly

Great flexibility in a product can make it difficult to maintain

Single point of failure

Safety

But most of all…most companies don’t know HOW to implement variability!

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What is variability?

Possibility to adapt a software product to a specific situation

Different platform

Different country

Specific customer wishes

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Variability moments

During design Different product for Linux than for Windows

During compilation Point to different sections of code while compiling software for

a specific phone

Linking at installation Linking a product to several additional modules

Run-time When a user of an on-line system wants to change something

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Runtime variability

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Case Studies

Two large product software vendors from the Netherlands Exact AFAS

ERP software

Examine the software architecture of both

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Case 1 - Exact

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Case 1 – Exact

Had (and have) an on-premises solution

Started Exact Online a few years ago

15.000 customers

Database change

All customers (in principle) use the same database and software instance.

Customizations per customer are difficult

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Architecture Exact Online

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Overview ASP to Multi-tenancy

(Kwok et al., 2008)

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Case 2 - AFAS

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Case 2 - AFAS

Originally an on-premises solution

Since a few years: Profit Web

10.000 customers

Every customer has his own environment on the server

Customizations per customer are possible, but are hard to maintain

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Overview ASP to Multi-tenancy

(Kwok et al., 2008)

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My research

Answering the question: “how can variability be implemented in a multi-tenant SaaS

environment?”

My research aims at finding patterns the enable a software vendor to successfully implement variability in a multi-tenant SaaS system

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Questions