Catálogo de publicaciones - libros

Model driven engineering is a popular attempt to deal with the complexity of modern software systems. For the telecommunication sector a model driven approach means that you have to handle several ITU-T modelling languages in a single process to cover all aspects of telecommunication system development. Unfortunately, this is a difficult task, because the ITU-T languages are hard to use together. That is why the ITU-T started the Unified Language Family (ULF) initiative with the goal to unify the ITU-T language definitions and allow an easier alignment and integrated use of these languages.

We present a tooling framework for those ULF languages: ULF-ware. Our framework uses metamodelling and a shared use of common language concepts for a tight language integration. Around these language models it incorporates a set of tools to cover the various responsibilities of development environments such as program parsing, model checking, model transformation and code generation.

This paper shows work in progress. We demonstrate our ideas on a tool chain for a subset of SDL. But the overall goal is an open framework that is extendable with other languages, even beyond ULF, and with tools for other software engineering tasks such as model simulation or software deployment.

Security is a crucial aspect in any modern software system. We consider access control as a concern in the sense of Aspect Oriented Programming and present a design language for access control aspects in distributed systems, called View Policy Language. The specification of the View Policy Language for a given application is integrated into a model-driven software engineering approach to support the designer throughout the entire software process. We give a graph-based formal semantics to the design models in order to reason about model transformations. In particular, we can formally ensure the preservation of model constraints in the transformation process, and hence prove the reusability of security aspects in dynamic models for different platforms.

The Object Constraint Language (OCL) offers so-called non-deterministic constructs which are often only poorly understood even by OCL experts. They are widely ignored in the OCL literature, their semantics given in the official language description of OCL is ill-defined, and none of today’s OCL tools support them in a consistent way.

The source of the poor understanding and ill-defined semantics is, as identified in this paper, OCL’s attempt to adopt the concept of non-determinism from other specification languages with fundamentally different semantical foundations. While this insight helps to improve the understanding of non-deterministic constructs it also shows that there are some formidable obstacles for their integration into OCL.

However, in some cases, non-deterministic constructs can be read as abbreviations for more complex deterministic constructs and can help to formulate a specification in a more understandable way. Thus, we suggest to integrate non-deterministic constructs in other specification languages such as Z, JML, Eiffel whose semantical foundations are similar to those of OCL.

The usage of formal description techniques (FDTs), and specifically SDL, has arisen as a promising way of dealing with the increasing complexity of embedded real time distributed systems. An important issue that must be taken into account is the predictability of the temporal behaviour of this kind of system including communications. In this sense, RT-CORBA is an interesting alternative as a middleware for real time distributed applications because, unlike standard CORBA, it guarantees predictable temporal response on particular invocations to remote objects and assures a bounded priority inversion. In order to control the predictability of the complete system we propose the design in SDL of RT-CORBA. It provides three important results: first, it is possible to include the behaviour of the communication middleware in the design of the applications and then the simulation of the whole system can be carried out; second, the implementation stage is simplified because the integration of the RT-CORBA middleware allows generation of code from the design; finally, a schedulability analysis for real time distributed systems can be included reducing the development time. In order to apply our proposal we present the design in SDL of a nuclear power plant simulator.

The development of software systems in general and software components in particular becomes a more and more challenging task. The key solution for handling the complexity in the development process is the modeling of software systems and the transformation into implementation. The authors show an application of OMG’s Model Driven Architecture (MDA) in the context of component development, where different languages such as eODL, SDL, CIDL and C++ are involved. The application of model transformation is based on eODL as a platform independent modeling (PIM) language and CIDL as the platform specific modeling (PSM) language. We used type based mapping rules to define the transformation. The paper shows the concrete implementation of these rules based on MOF repositories as model storage and the use of Java to perform the transformation actions. The Java technology Meta Data Repository (MDR) builds the base for an on-demand MOF repository creation in our approach. The handling of syntax based language is considered for integration purposes.

Current trends in distributed computing and e-business processing suggest that many applications are evolving towards Service Oriented Computing (SOC) with technologies such as Web services. Services are autonomous platform-independent computational elements, and we observe an increasing need for core SOC technologies for dynamic discovery, selection, and composition of services. However, such technologies are often based on syntactic descriptions of the services and of their interfaces, which are insufficient to ensure that desired liveness properties are satisfied. In this paper, we propose an approach for the description, discovery, and selection of services based on role modeling and goal expressions that enables the definition of semantic interfaces and the evaluation of liveness properties. The same mechanisms also enable component reuse. We discuss how UML 2.0 can support the modeling of both the services and the desired properties. The approach is illustrated with telephony services.

Today, simulators for the performance evaluation of networked systems are seldom integrated with tool environments used for system development and maintenance. This requires the system developer to establish and maintain separate code bases for simulation and production purposes, a tedious and error-prone task. In this paper, we present +SDL, an extension of the network simulator -2 to combine SDL design specifications with -2 network models. +SDL enables the developer to use SDL design specifications as a common base for the generation of simulation and production code. Furthermore, the same SDL-to-C code generator is used to generate this code. Both measures increase confidence that the results of the performance evaluation hold for the networked system in operation. Another important aspect is the composition of SDL systems and existing -2 simulation components, in particular, components implementing detailed timed models of existing communication technologies. We illustrate the application of +SDL by a simulation of DSDV, the Destination-Sequenced Distance-Vector routing protocol, over WLAN.

The language of MSC diagrams is widely used for the specification of communicating systems, the design of software and hardware for real time and reactive systems, and other industrial applications. Often it is used as an abstraction of systems specified in SDL or UML (in the form of sequence diagrams). In this paper, a novel representation of the semantics of message sequence charts is described. This formulation has been developed to enable the implementation of tools aimed at the verification of requirements for interactive systems. Our definition of the formal semantics of the language of MSC diagrams relies on the theory of interaction of agents and environments. This approach helped to simplify the definition of the semantics in comparison to other approaches based on highly sophisticated process algebras and it brought the definition of the semantics closer to possible implementations.

With the introduction of UML 2.0, many improvements to diagrams have been incorporated into the language. Some of the major changes were applied to sequence diagrams, which were enhanced with most of the concepts from ITU-T’s Message Sequence Charts, and more. In this paper, we introduce a formal semantics for most concepts of sequence diagrams by means of Petri nets as a formal model. Thus, we are able to express the partially ordered and concurrent behaviour of the diagrams natively within the model. Moreover, the use of coloured high-level Petri nets allows a comprehensive and efficient structure for data types and control elements. The proposed semantics is defined compositionally, based on basic Petri net composition operations.

This paper presents the design of the open shortest path first (OSPF) protocol for the wireless private network using the specification and description language (SDL). Simulations are run in many scenarios to show that our design is excellent in the aspects of both function and performance. In addition, SDL is proven to be an efficient tool in the development of communication software.