Trends in Software Intensive Systems Development JACEK SZYMANSKI INFORMATION SYSTEMS CONSULTANCY

Transcription

1 Trends in Software Intensive Systems Development JACEK SZYMANSKI INFORMATION SYSTEMS CONSULTANCY

2 Outline Complexity of ICT Projects Origins Consequences Remedies Structural improvement SOA/SCA Methodological improvement agile methodologies 2

3 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 3

4 Origins of difficulties(1) 4 Complexity of railway systems universe heterogeneity need for integration of legacy components distribution evolutivity

5 User pressure: Origins of difficulties(2) 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 5

6 Functions are qualified according to three criteria: Functional level Spatial range Temporal range Railway system complexity cube 6

7 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 7

8 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 8

9 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 9

10 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 10

11 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 11

12 Guiding principles Ground SOA rules for system development Services identification and categorization Compliance to standards (both common and industryspecific). Reuse, granularity, modularity, Composability, componentization and interoperability 12

13 SOA principle of operation Basic paradigm of SOA: Publish (register), Find, Interact(Bind) 13

14 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 14

15 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 15 Modeling applications through the definition of SCA assembly meta-model Supporting system building processes by specification of tools which transform models to software

16 SCA approach SCA organizes building a service-oriented application in two major steps: 16 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.

17 Central SCA artefact - component 17 Components basic elements of business function combined into complete business solutions by SCA composites. Services Component Properties Implementation -JAVA -BEPL - Composite References

18 Service - Java Interface - WSDL Port Type SCA Composite 18 Properties Reference - Java Interface - WSDL Port Type Composite A Property setting Service Component A Component B Reference Promote Wire Promote Binding - JMS - Web service Binding - JMS - Web service

19 Ba INTEGRAIL an example of SOA 19 IGR Portal Flexible Communication Adaptor 19 KPI computation, Common data model, Service directory Flexible Communication Adaptor InteGRail Service Grid Railway Communication Framework Virtual services Flexible Communication Adaptor Virtual services Flexible Communication Adaptor Virtual services Flexible Communication Adaptor Infra -RIOM- Infra Sensor Infra Sensor BayNetworksSD Infra Sensor Infra Sensor Traffic Traffic Infrastructure manager Jacek Szymanski manager ICT Workshop, Prague manager Virtual services Flexible Communication Adaptor Train Sensors TCMS Sensors Modem RTR Radio TCMS -MPU- «Train» Backbone db22222 Train Operator DDU

20 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 20 This provides the basic difference with respect to prescriptive methodologies

21 Effective response to constant changes Organization of the life-cycle of the project around four basic principles : 21

22 Life cycle organized by iterations 22 Business Modeling Requirements Analysis and Design Inception Elaboration Construction Transition Production Implementation Tests Deployment Prel. Iter Iter Iter Iter Iter Iter Iter Iter Iterations

23 Principal targets Close collaboration of stakeholders and system providers in order to support: 23 Responsiveness to changes Direct communications Frequent contacts Team motivation Sustainable collaboration Mutual trust

24 Stakeholders and providers 24 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."

25 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 25

26 THANK YOU FOR YOUR KIND ATTENTION