trends in software intensive systems development - integrail szymanski - trends in ict... · jacek...

JACEK SZYMANSKI

INFORMATION SYSTEMS CONSULTANCY

Trends in Software Intensive Systems Development

Outline

� Complexity of ICT Projects� Origins

� Consequences

� Remedies

� Structural improvement – SOA/SCA

� Methodological improvement – agile methodologies

10/20/2011Jacek Szymanski ICT Workshop, Prague

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Context

� ICT projects develop software intensive systems� In such systems software components control and observe system’s status , interact with system users and system environments (other systems)

� Software components interact not only with other software components, but also with external systems, devices, sensors and with people� Large variety of software from in-the-tiny to in-the-large


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Origins of difficulties(1)

� Complexity of railway systems universe � heterogeneity

� need for integration of legacy components

� distribution

� evolutivity


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Origins of difficulties(2)

� User pressure:� User requires explicitly functions and qualities

� Complexity of required functions vary from simple stand alone to composite

� An implicit requirement imposed on software components is continuous and transparent operation

� Software components especially the embedded ones, need to be for the user invisible and highly dependable � example: ABS software


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Railway system complexity cube

Functions are qualified

according to three

criteria:

•Functional level

•Spatial range

•Temporal range


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Consequences of increase of complexity

� In such a system software has chances to become exceptionally complex in all aspects

� As the consequence all life cycle stages exhibit problems� Definition - partial

� Design – incomplete

� Production – error prone

� Commissioning – lengthy and delayed

� Exploitation – uncertain

� Maintenance – costly


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Software system project outbreaks

� Fragility of projects developing software intensive systems is well known� Difficult inception phase

� Incomplete design

� Painful development

� Delayed commissioning

� Costly curative maintenance


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What is wrong ?

� Inherent fragility of methodological approach to software development� methodologies inherited more or less directly from the waterfall or V-shaped process models

� The basic models exhibit structural fragility for any changes in the initial definition of fundamental system characteristics: � its structure

� its qualities


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Remedy

� Produce component based extensible software systems� Service Oriented Architecture pattern

� Put the change at the center of the software development process� Recent trends in software development processes known under collective name of agile methodologies


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SOA

� SOA -Service-oriented architecture � a flexible set of design principles used during the phases of systems development and integration .

� Service –independent unit of functionality

� A SOA based application associates services using orchestration� no direct bindings among services


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Guiding principles

� Ground SOA rules for system development� Services identification and categorization

� Compliance to standards (both common and industry-specific).

� Reuse, granularity, modularity,

� Composability, componentization and interoperability


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SOA principle of operation

� Basic paradigm of SOA:� Publish (register), Find, Interact(Bind)


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SOA vs Web Services

� Frequent misunderstanding of the two notions which are different

� SOA and WS are neither the same nor redundant

� Differences:� SOA is not bound to any specific technology

� Web Services are an instantiation of SOA with

� SOAP as the transport protocol ,

�WSDL as the service interface description

� UDDI as the service discovery and binding


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Service Component Architecture(SCA)

� Extension of SOA paradigm� Support for constructing systems obeying SOA rules

� Clear definition of reusable software component

� SCA provides the foundation for � Modeling applications through the definition of SCA assembly meta-model

� Supporting system building processes by specification of tools which transform models to software


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SCA approach


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� SCA organizes building a service-oriented application in two major steps:� The implementation of service components which provide services and consume the results produced by other services.

� The assembly of sets of components in to business applications, through the wiring of service references to services of other components.

Central SCA artefact - component

� Components � basic elements of business function

� combined into complete business solutions by SCA composites.

ComponentComponent

PropertiesServices

ReferencesImplementation-JAVA-BEPL- Composite


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SCA Composite

Component A Component BService Reference

Composite A

Service- Java Interface- WSDL Port Type

Binding- JMS- Web service

Promote

Reference- Java Interface- WSDL Port Type

Binding- JMS- Web service

PromoteWire

Property setting

Properties


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INTEGRAIL – an example of SOA


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Railway Communication Framework

InteGRail Service Grid

Virtual

servicesFlexible

CommunicationAdaptor

FlexibleCommunication

Adaptor


Adaptor

Flexible



Adaptor

Flexible


Infra-RIOM-

Infra Sensor Infra SensorInfra SensorInfra

Sensor

BayNetworksSD

Ba

802.11Modem

DDU

RadioTCMS-MPU-TCMSSensors

«Train» Backbone

RTRTrain Sensors

db22222

Trafficmanager

Trafficmanager

Infrastructuremanager

TrainOperator

KPI computation,Common data model,Service directory

IGRPortal

Virtualservices

Virtual

servicesVirtualservices

Jacek Szymanski ICT Workshop, Prague

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Agile Methodologies

� Family of development processes which provide alternative solution to waterfall of V-shaped model

� Offer improvement with respect to purely prescriptive process

� Incorporate smoothly changes into the process� This provides the basic difference with respect to prescriptivemethodologies


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Effective response to constant changes

� Organization of the life-cycle of the project around four basic principles :


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Life cycle organized by iterations

Inception Elaboration Construction Transition Production

Business Modeling

Requirements

Analysis and Design

Implementation

Tests

Deployment

Prel. Iter Iter Iter Iter Iter Iter Iter Iter

Iterations


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Principal targets

� Close collaboration of stakeholders and system providers in order to support:

Responsiveness to changes

Direct communications

Frequent contacts

Team motivation

Sustainable collaboration

Mutual trust


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Stakeholders and providers

A pig and a chicken are walking down a road. The chicken looks at the pig and says, "Hey, why don't we open a restaurant?" The pig looks back at the chicken and says, "Good idea, what do you want to call it?" The chicken thinks about it and says, “Why don't we call it 'Ham and Eggs'?" "I don't think so," says the pig, "I'd be committed but you'd only be involved."


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Conclusions

� Information and Communication Technology places railway systems into the category of software intensive systems� An appropriate architectural pattern allows better control of the design characteristics of the system

� Efficient production of high quality railway software needs the appropriate methodologies to organize the production process� Putting the change in the middle of the scene


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