Foundations of Component Based Development
Proposal for an ARTIST_ACTION draft 17/10/2001
A BRIEF RATIONALE
Component based design is perceived as a key technology for developing
advanced real-time systems in a both cost- and time effective manner. Already
today, component based design is seen to increase software productivity,
by reducing the amount of effort needed to update and maintain systems,
by packaging solutions for re-use, and easing distribution. In an ideal
scenario, application development could follow a "drop & glue" approach,
picking components from a library incorporating the intellectual property
of the system house as well as standardized components, giving to the system
developer a range of re-usable components supporting all layers of a system
architecture. The OMG´s Model-Driven Architecture approach is an
initiative to enhance re-use across multiple implementation platforms,
by separating functional modeling from deployment architectures
Given the perceived range of advanced real-time systems as outlined
in the introduction, there are many challenges ahead to lift the component
technology from current capabilities to reaching the level of maturity
of an engineering discipline.
Visions in Application Domains
Let us look into particular application domains to highlight the challenges.
The below paragraphs might be shortened
Within automotive industry, the recent mergers have further multiplied
the number of platforms to be supported by car manufacturers. A vision
for system development is that key functional "ingredients" of electronic
control units (ECUs), sometimes called atoms or features,
will be kept and maintained in a proprietary design repository, allowing
model- and platform based variations to be constructed from such atoms
using the above mentioned "drop & glue" approach. To support such a
vision, component models must carry information for all system development
processes: the system- design and possibly safety analysis process, for
production and for maintenance. Let us consider concrete examples. To support
power-management, component models must explicate operation modes which
allow the system to be deactivated. To transition from an application independent
model to deployment on a concrete network of ECUs, memory/CPU/bandwidth
requirements of components must be known. Interfaces for diagnostic processes
both integration testing, manufacturing, and maintenance must be visible.
To support safety- analysis, component failure modes and failure rates
must be accessible. These sample question highlight the need to maintain
with each component an (application-specific) range of viewpoints,
which jointly cover the life cycle of automotive applications. The elaboration
of such an approach is further complicated by the need to support not only
distributed development across multiple sites, but also various forms of
interplay between manufactures and supplier companies, in particular allowing
the integration of "atoms" from multiple sources (e.g. multiple suppliers)
while protecting their IP. The need to ensure non-interference of such
atoms when coming from multiple suppliers is obvious, taking into account
legal issues such as liability. Hence strong encapsulation and rigid measures
to assure this are a must in supporting component based design in this
domain. It should be pointed that current industrial practice is far from
this vision. We only begin to see today deployment of model-based development
processes, and current methods and tool support are available for single
ECU based implementations only. However, already the next generation development
tools supporting distributed applications are in the pipeline, and companies
are analyzing library based approaches.
The challenge for the telecommunication domain for the future
is to enable the ubiquitous "anything, anytime, anywhere" concept. It means
that a service should be seen for an end user as a black box respecting
functional and non functional (Quality of Service) properties (or goals)
independently of the underlying architecture. For that, we need innovative
and consistent development methodology from high level specification towards
design. Telecommunication applications, and similarly, new concepts such
as VHE (Virtual Home Environment), are built from a set of service or service
features (high level component), which could be new features but also existing
features. Formal validation is necessary to obtain a consistent composition
of such distributed components respecting their interface specification
but also their properties as specified on the system view (user view for
example). Real time aspects (performances for example) is also a critical
problem, in particular, for the next mobile generation (UMTS), where quality
of service is the subject of negotiation between the user terminal and
the core network.
In factory automation the process of transformation from building
monolith proprietary systems to component-based systems is already active
several years. The process started from componentisation of applications
in common platforms and additional components using software product-line
approach. The second step, ongoing today, is decomposition of basic platform
and further decomposition of different applications, using new component-based
technologies, and mixing in-house developed components with COTS. These
trends come from market requirements (reduced time-to-market, flexibility,
lower development costs, and in the same time increase of Quality of Services,
managing much larger amount of information, and finally integration with
information and application from other domains). To be able to meet these
requirements the automation industry is focusing on core-business, outsourcing,
the reuse of components and buying COTS. However, there are many problems
related to this approach that still remain to be solved, valid for component-based
development in general and in particular in process automation (component
technology, development processes, understanding system complexity, reliability
of COTS and component-based systems, maintainability, flexibility, ability
for integration, predictability of integration, trusted components etc.).
A typical challenge of industrial process automation is integration. We
can distinguish between vertical integration in which data and processes
at different process levels are integrated, and horizontal integration
in which similar types of data and processes from different domains are
integrated. Typical examples of vertical and horizontal integration can
be found in industrial process automation. At the lowest levels of management
(Field Management), data collected from the process and controlled directly,
is integrated on the plant level (Process Management), then is further
processed for analysis and combination with data provided from the market
and finally published on the Web (Business Management). To successfully
obtain integration of different type of data and different type of application
the integration process, as a part of the development process, must be
seamless, reliable and predictive. Predictive integration is a challenge
for itself. The main question of a predictive integration is if it is possible
to predict the behaviour of component compositions from known behaviour
of components (is. known functional and non-functional attributes). Automation
industry is very well aware of advantages of component-based development
approach, but also about the disadvantages. In many cases industry does
not have solutions and is interested in finding them in collaboration with
The above visions of future component based technology can only
be realized, if major technological challenges are met. Today, component
technology is supported merely by syntactic definition of interfaces.
It is a challenge to develop technology for
semantic support, which
includes the following challenges:.
Life-cycle-complete component models
The identification and characterization of a set of component viewpoints
supporting the full life cycle of components, and covering such viewpoints
as e.g., timing, resource utilization, interface specifications, failure
models, .... Demonstrators of such component models for selected application
domains, including automotive and telecom.
Verification and Validation
Of all viewpoints across all design steps against requirements. Both
formal verification and testing. The challenge and the must here is for
component based V&V.
Component integration technology
To (automatically) propagate the impact across a component configuration
across all viewpoints. To check consistency of viewpoints of a component
configuration, analyzing potential interferences between conflicting viewpoints.
Encapsulating target architecture. Providing services supporting all
viewpoints in making intelligent decisions for deployment architectures,
optimizing the various cost-functions related to viewpoints. Providing
strong encapsulation between safety- and non-safety related parts of the
system. Supporting mix of soft- and hard real-time constraints. Automatic
mapping of middleware based deployment architectures to executables on
Synthesis and Deployment
Such as knowledge based component retrieval based on requirement specifications.
Automatic "glue" synthesis. Automatic construction of deployment architectures.
The objective of this action is to assess the current technical
state of the art with respect to this vision, to identify scientific challenges
for its realization. The action will be the result of collaboration between
leading research teams with key competence on the foundations of the above
topics. The action will rely on industrial guidance, as represented by
an industrial advisory board involving key decision makers in different
It is important to relate the technology developments with emerging
and new standards, such as promoted by the OMG or within STEP. Partners
of the action, supported by the industrial advisory board, are in close
contact with relevant bodies of standardization organizations, and will
assess current and emerging standards wrt to their potential in supporting
such a component design process. Example of questions to be analyzed are
the aptness of UML and in particular RT UML in supporting the component
technology vision of this action.
The challenges outlined above will be addressed along the following
Task 1. Component Models: which includes the
Identifying aspects, such as functional behaviour, timing, interfaces,
resource utilization, mobility, etc. which must be expressed in a component
model in order to capture the essentials of component dynamics, without
constraining the details of its implementation, The work will consider
the impact of constraints arising from selected application domains.
Reviewing potential for formalization of these aspects, considering use
of such formalization for component integration, verification and validation,
middleware, deployment, etc. in different application domains.
Component Models will be the focus during Year 1. Part of the work will
be carried out by interaction and interviews with industrialists, an activity
which is shared with WP1, Task 1.
Coordinator of Task 1: Jean-Marc
Task 2. Component integration and Verification and Validation.
This includes verification of a component against its specification, across
all viewpoints as mentioned above, checking consistency for particular
configurations, analyzing potential interferences between conflicting requirements,
and compositional verification and testing of components integration. Attention
should be given to assessing usability and scalability of potential techniques,
including testing and formal verification.
Coordinator of Task 2: Ed Brinksma, U. of Twente
Task 3. Soft Real Time, including the formalization and reasoning
about soft real-time and Quality-of-Service requirements, and the combination
of hard and soft real-time requirements. This task has strong links to
actions 1 and 3.
Coordinator of Task 3: Gordon Blair, Lancaster U.
Task 4. Link to Standardization. Particular attention will be to
assess and give input to the current development of UML extensions
for real time and component based engineering and to the new Model Driven
Architecture approach pushed by the OMG.
Coordinator of Task 4: Andy Evans, York.
TYPES OF ACTIVITIES
Interaction with Industrials An important part of the Work Package
is to better understand the challenges and bottlenecks that face industrial
practice. Interaction with strategically placed industrialists will be
organized in the forms of interviews and seminars, and analysis of case
studies. This task will be shared with WP1, Task 1.
Coordinator of industrial interviews: Jan Tretmans, Twente.
Workshops The work package brings together experience and expertise
from different backgrounds. At least 3 meetings of the technical group
will be organized annually, with invitations given to prominent industrialists
and contributors with other relevant expertise. The meetings will be organized
in connection with other major conference events, such as FLOC02, ACM/IFIP
Middleware, ETAPS and UML Conference series, FTRTFT 2002, etc.
The deliverables per year and task are as follows. The major technical
deliverables are annual technical reports (white papers), which collects
and synthesizes the experience and findings by partners in the activites
outline above. The technical reports typically report on the state of the
art, and outline directions for major research efforts.
Technical report which provides a report on the state of the
component models: (task 1) from a semantical viewpoint, considering
What aspects (from a semantic point of view) are covered by current proposals
for component models, including current standardization work (task 4)
What aspects of the UML standard are relevant for defining Component models
What are desiderata, from application perspectives, for life-cycle complete
component models, in view of visions for future development technology?
How useful is current technology, considered in Tasks 2 and 3 to cope with
Workshop Proceedings:, from one of the organized meetings.
Technical report which provides
a report on the state of the art concerning
Component Integration, and Verification and Validation (Task 2)
considering the findings in Task 1
Soft Real Time (task 3) will also be assessed, considering also
output from actions 1 and 3.
Update on tasks 1 and 4 as compared with the report of year 1. This includes
using the results of other tasks to identify overlap with existing UML
component model and identify additional requirements.
Workshop Proceedings:, from one of the organized meetings.
Technical report which for all tasks provides
Outline of potential research directions to advance the state of the art
towards the vision outlined in the beginning of this document.
For Task 4, the report will outline a skeleton of metamodel for components.
Workshop:, summarizing results of the action.
The following technical areas are important for addressing the above challenges.
Modeling and Specification of Components in Real-Time Systems. There
is a large body of work on the specification of components, modules, processes,
objects, or other units of software in real-time systems.
Contracts as a specification paradigm is promoted, among others,
Trusted Components initiative, in which the Triskell Group
of Jean-Marc Jezequel at IRISA participate
Real-Time Object based modeling as support of high level specification
and rapid prototyping methods as proposed by ACCORD development platform
developed by the LLSP team at CEA,
The semantics group at OFFIS develops different forms of formal semantics
for parallel and distributed systems, together with integration of specification
techniques for different viewpoints.
VERIMAG develops a tool box supporting component based development
of real time systems, based on the modeling language IF
The Uppaal toolbox supports modeling and verification of control
and timing properties of parallel systems
Formal Verification and Checking of consistency between component
LSV conducts a number of approaches to the formal verification of real-time
and embedded systems
OFFIS is developing formal verification techniques for UML within the
Wooddes project http://wooddes.intranet.gr
The UPPAAL, Kronos, and IF toolboxes support automated verification.
Approaches that focus on finding inconsistencies between different
descriptions of a component include
The UMLAUT tool
and work on Feature interaction
Testing of RealTime/Embedded systems
The teams of Twente and Aalborg are developing techniques for
based testing and conformance testing of real-time systems.
The team LLSP of CEA is adapting the AGATHA tool box for automatic
test generation from UML specifications, http://wooddes.intranet.gr
Soft Real Time.
The distributed multimedia group at Lancaster has an extensive experience
in the area of managing resources on behalf of the component to provide
the necessary (soft) real-time guarantees.
The group at Twente has extended approaches to verification of real-time
systems to handle soft real-time properties
semantics of the emerging UML standards.
The pUML group
is concerned with clarifying and making precise the semantics of UML. Contributorsparticipants
the action includes key partners of the pUML (precise UML) group, as well
as partners involved in developing RT profiles of the UML standard.
PARTNERS AND KEY PERSONS
Aalborg University (or Brics group)
Research Prof. Dr. Anders Peter Ravn, BRICS, Deparment of Computer
Science, Aalborg University, Fredrik Bajersvej 7E, 9220 Aalborg, Denmark.
Phone: +4596358887, Fax: +4598159889, E-mail firstname.lastname@example.org.
CEA/Saclay, DRT/LIST/DTSI/SLA, F-91191 GIF sur Yvette Cedex France
Francois Terrier, Phone/Fax: +33 (0)1 69 08 62 59 / 20 82, E-Mail:
INRIA, BP 105, 78153 Le Chesnay Cedex, France
Benoit Caillaud, IRISA, Campus de Beaulieu 35042 RENNES Cedex, FRANCE,
Tel +33 (0)2 99 84 74 07, Fax +33 (0)2 99 84 25 32, email: Benoit.Caillaud@irisa.fr,
VERIMAG, Centre Equation, 2 avenue de Vignate, F-38610 GIERES, France
Susanne Graf, E-mail: email@example.com, Tel : +33 - 4 76 63 48
52, Fax : +33 - 4 76 63 48 50,
Distributed Multimedia Group, Lancaster University, Lancaster
Gordon Blair, E-mail: firstname.lastname@example.org Tel : +44 - 1524 593809
Fax : +44 - 1524 593608,
LSV, CNRS UMR 8643, Ecole Normal Superieure de Cachan, 61, Avenue du President
Wilson, 94235 Cachan Cedex, France,
Michel Bidoit, Tel: +33 - 1 47 40 28 68 Fax: +33 - 1 47 40 24 64, E-mail:
Univ. of Twente, PO Box 217, 7500 AE Enschede, The Netherlands, VERIMAG,
Centre Equation, 2 avenue de Vignate, F-38610 GIERES, France
Ed Brinksma, E-mail: email@example.com, Tel : +31 - 53 489 3676
Fax : +31 - 53 489 3247,
Uppsala University, Department of Computer Systems. Box 325, S-751 05 Uppsala,
Bengt Jonsson, firstname.lastname@example.org , Phone: office: +46 18 4713157. mobile:
+46 70 4 250 240 Fax: +46 18 550225. Email: email@example.com,
OFFIS R&D Division of Embedded Systems, Escherweg 2, D-26121 Oldenburg,
Prof.Dr.Werner Damm, Department of Computer Science, Carl von Ossietzky
Universität Oldenburg, Ammerländer Heerstraße 114-118,
D-26129 Oldenburg, Phone +49-441-798-4502, e-mail firstname.lastname@example.org,
Mälardalen University, Västerås, Sweden.
p Ivica Crnkovic, Tel: +46 - 21 103183, Fax: +46 - 21 101460, E-mail:
Department of Computer Science, University of York, Heslington, York, UK,
Andy Evans: email@example.com,