Landelijke Architectuur Congres 2011

Product as a Service: One Size doesn’t fit All prof.dr. Sjaak Brinkkemper dr. Slinger Jansen Jaap Kabbedijk, MSc. Utrecht University, the Netherlands

Outline
Introduction
Deployment Models
Traditional
Online
Concepts
Variability
Multi-tenancy
Case Example
Example Pattern
Conclusion and Future Research
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Research Project
Utrecht University
University of Groningen
Two large ERP product software vendors from the Netherlands
Exact
AFAS
www.productasaservice.org
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First something completely different! Based on work of dr. Andy Zaidman (TUDelft) LAC2011

Pros and Cons House : Privacy en freedom Apartment : Cost efficiency LAC2011 House Apartment Effective use of land - + Privacy + - Infrastructure sharing - + Maintenance cost sharing - + Freedom + -

Traditional Deployment Model
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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Overview Online Deployment Models (Kwok et al., 2008) LAC2011 Application Server Provider Multi-user Solution Different Environments Multi-tenancy

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
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)
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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Multi-tenancy
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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Multi-tenancy: Holy grail?
A hosted solution
Sharing of Hardware, Software, Development cost, Deployment cost, Maintenance cost
Possibility for variability in the product
Great flexibility in a product can make it difficult to maintain
Single point of failure
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
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 LAC2011

Case 1 - Exact LAC2011

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 LAC2011

Overview ASP to Multi-tenancy (Kwok et al., 2008) LAC2011

So, where are we now?
Software is increasingly offered ‘ as a Service ’ (Ma, 2007)
Customers want a product to do ‘what they want’
Complying to customer specific requirements in a SaaS environment has drawbacks:
Difficulty with scalability
Difficulty with maintainability
Architectural erosion
Multi-tenancy enables software vendors to offer a SaaS product in a cost efficient way (Guo et al., 2007)
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What are Design Patterns?
A pattern for software architecture describes a particular recurring design problem that arises in specific design contexts, and presents a well-proven generic scheme for its solution. The solution scheme is specified by describing its constituent components , their responsibilities and relationships , and the ways in which they collaborate (Buschmann et al., 1996)
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When do you need Multi-tenancy? LAC2011

Pattern Catalogue
Identify Run-time Variability Patterns currently used
Case study at AFAS
Case study at Exact
Identify RVPs in literature (literature study)
Come up with new RVPs (design science)
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Example Patterns
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Pattern Example
In a warehousing system, customer A wants an SMS to be send to the truck driver when an order is picked, after which the order is removed from the system . Customer B however does not want any SMS to be send, but does want an approval by a manager before a picked order is removed from the system.
How can we solve this workflow related problem?
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Pre/Post Update Hooks (1/3) LAC2011

Pre/Post Update Hooks (2/3)
Intent - To provide the possibility for tenants to have custom functionality just before or after an event
Motivation - To let the software product fit the tenants business processes best, extra actions could be made available to tenants before or after an event is called
Solution – The use of a component able of calling other components before and after the update of data. The tenant-specific modules are listed in a separate table
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Pre/Post Update Hooks (3/3)
Explanation – See image
Consequences - Extra optional components have to be available in the software system in order to be able to implement this pattern
Example - In a bookkeeping program, tenants can choose, whether they want to update a third party service as well by using a component that uses the API of a third party service to make changes there. If so, the FunctionalComponent can call the third party communicator after an internal update is requested
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Conclusion and Further Research
Design patterns are an appropriate way to document and communicate solutions to the variability problem
The proposed patterns should be evaluated
How are patterns really used ?
We need mor e patterns and feedback on existing patterns
We are looking for research partners
Mail: [email_address]
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Landelijke Architectuur Congres 2011

by Jaap Kabbedijk

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