Dsm presentation (english)

DependencyStructure Matrix for software architecture
Han van Roosmalen Softwarediensten
P. Flintstraat 7, NL 7412 JV Deventer
06-10148933
0570-546083

Agenda
Introduction Han van Roosmalen
What is and Why use a Dependency Structure Matrix?
How to use a DSM for Software Architecture?
How can Lattix LDM/LDC help you?

Han van Roosmalen Softwarediensten
Self-employed software architect
Software development since 1984
Design software architectures/systems
Analyze legacy systems
Companies:
Philips Consumer Electronics/Medical Systems, ASML, Océ, Nucletron, Peek Traffic, Thales, Surfnet/Kennisnet, CRV, Fibor Packaging
Embedded, Administrative, Web-based
Promote simple engineering methods
Working with DSMs since 2005 and Lattix
…. voor Inzicht, Toezicht en Overzicht

Origin of DSM
Initial development on DSM theory in early seventies (MIT Boston)
Extensive usage in engineering for complex systems
Large adoption in assembly industry, such as:
Boeing, Airbus
Fiat, Ferrari, Rolce Royce, BMW, Audi, Mercedes
Nasa
BP
Since 2004 for management of software architecture

DSM has proven additional value, when:
Desired modifications cannot be done efficiently because there is a lack of in- and oversight of the system and subsystems.
Need for insight during distributed development. Need for communication about design and architectural concepts and decisions. (e.g. multi-site, off-shoring development)
Questions of complexity during migration and integration of (third-party) components, due to lack of insight in frameworks, libraries and off-the-shelf components.
Degradation of quality of (architectural) design, due to changes and addition of functionality, lack-off knowledge, increasing complexity.
Day-to-day Challenges

Types of DSMs

Applicability of DSM
Impact analysis
Software architecture management
Estimations
Architecture design
Architecture (re)discovery
Software integration
Testing

Definition of Software Architecture
It is the definition of its subsystems, their externally visible properties and how the subsystems relate to each other.
“A common language and shared vision”*
*SEI CMMI Tutorial “How is a Model Used?”

Concept
Initial DSM
The Diagonal
Partitioning
Hiearchy

Example: Java Applet
How bad can you build an applet???
Because – requirements:
Recoverable upload
Secure
Multi-language
Intended Architecture
Realised Architecture

Approach
Create initial DSM
What has to beloadedforinspection
Demonstrate how it should be
Create Intended Architecture
Which dependencies can be removed
Create structure
Improve build order
Identify possibilities for improvement
ExternalLibrariesLayering/
Components
Make rules and follow them
11

Partitioning algorithms (1)
Partitioning on Strength and Reach ability
Ordering in DSM is done by mineralizing the number of dependencies in the upper triangular (upper triangular weight)
Greedy algorithm makes sure that providers (are called by above laying callers) are put underneath
Supports layering of the system

Partitioning algorithms (2)
Ordering is done in such a way that providers and users are brought together, though partitioning based on strength is taken into account
Supports the separation of subsystems into packages and classes

Layered System
ArchitecturalPatterns (1)
Imperfectlylayered
System

ChangePropagator
Architectural Patterns (2)
Private Components
Notvisibleoutside “domain”

ExampleDependency View of Eclipse

Dependency Kinds
Dependency Kinds improveinsght in different kinds of dependencies:
Easier to understand the origing of each kind in isolation
Analyse the DSM forspecific types of dependencies (e.g. inheritance versus methodcall)
Insight in scope of refactoring (e.g. weakdependencies are easier to remove)
Specification of rulesbased on dependency kinds (e.g. do notallow inter-schema tablereferences)

Design Rules
DSM with Rules View
Green Triangle – Dependency Acceptable
Yellow Triangle – Dependency Unacceptable
Red Triangle – Rule Violation Discovered
Each cell in a DSM represents a “design intent”
Dependency Model = DSM + Design Rules

Metrics for Architecture
Instability, Abstractness and Distance (Robert Martin)
System Stability - average impact of change (IBM)
Deviation from Conceptual (Lattix)

Lattix Toolsuite

Lattix Support For..
Platform/technology support:
Ada
C/C++ (managed/unmanaged)
.NET
Java, Hibernate, Spring
Delphi Pascal
Oracle (database + PL/SQL)
Microsoft SQL Server 2000, 2005
Sybase
AdobeActionScript
XMI (System Architect, Rhapsody)
LDI
Lattix Software Development Kit (SDK)
SDK Kit containsexampledriverforretrievingdependencies
Lattix as plug-in for Eclipse/Visual Studio
Multi Environment DSM

Insight, governance and oversight
Decisions at
Implementation
Level
INZICHT
Accountability
Decisions at
Tactical Level
Reproducibility
TOEZICHT
Decisions at
Strategic Level
OVERZICHT
Innovative

Scenarios
Architecture Discovery
What is the complexity of the system?
What is the structure of the current system?
Which dependencies are there?
How can we teach a new teammember?
…
Architecture Refactoring
Which parts of the system must be modified?
Which includes/namespaces are being used, which are not?
How can a team member see how to move with the architecture?
…
Architecture Control
How can future modification to the architecture be controlled?
How can a team member see what is (dis)allowed?
…
Service/Component Extraction
Which parts of the system can be extracted into a service or a loosely coupled component?
How can a team member see which parts belong to a service/component?
…
Impact Analyse
What is the impact of a change?
Which parts of the system use the parts that is going to be changed?
How does a team member find out what the consequences of his activities are?
Test strategy/efficiency
Which parts of the system are easier (stand-alone) to be tested?
How can a team member develop better unit tests?

Nice Words
What is being said about DSM and Lattix:
"That´s what impressed me about the Lattix tool: ease of use, quick results, simple concept (DSM)...A DSM view on software is merciless in its clarity. You don´t get mired in tedious layout work, but rather the tool strips naked the software you throw at it."
Ralf Westphal, Long-time .NET Consultant/AuthorMicrosoft Visual Developer Solution Architect MVP
“If everyday I would learn as much as in one day with Lattix of our system. We would be out of trouble in a month."
WimSchonkeren, Principal Architect Embedded Optics Software
Marvell
“Lattix LDM intuitively lets you sort through the maze to disentangle even the worst results of system evolution.”
James Gosling VP and Fellow
Sun Microsystems
“I really woke up during your workshop and now I consider extending Lattix to put even more valuable information in the DSM."
Anton Lap, Architect
Universal Music Group
The eBay marketplace runs on a very large global software stack... We have worked with Lattix to incorporate new features in Lattix 4.0 that enables us to effectively modularize and maintain our large codebase.“
Vijay RaghavendraDirector of Platform Team, eBay, Inc.

Feedback and Questions
Applicable in your situation?
What could be an approach to try DSMs?
What could be objections from using it?
Han van Roosmalen
han@hanvanroosmalen.nl
+31 6-10148933
+31 570-546083

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Dsm presentation (english)

by HanVanRoosmalen on May 26, 2010

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