Aligning OCL with UML

OCL is widely used by UML and other languages to constrain meta-models and perform evaluations on models. Unfortunately no OCL 2.x specification has ever been aligned with any UML 2.x specification. This lack of alignment makes some OCL compliance points such as XMI interchange unachievable. This paper describes how introduction of an OCL Pivot Meta-Model and clear exposition of the Values package may provide a solution to the alignment and a variety of other specification issues

Model Instantiation and Type Checking in UMLX

OMG's MDA initiative encourages the use of meta-model based transformations and re-usable specifications. We discuss how Graphical Transformation Notations such as UMLX reduce opportunities for errors in this programming domain

Re-engineering Eclipse MDT/OCL for Xtext

The current tooling used for the Eclipse OCL project uses an LALR parser generator. Enhancing the tooling to support editing motivated a migration to exploit the inherently model-driven characteristics of Xtext. This paper summarizes the experiences of that migration, identifies the many benefits and discusses a few changes in implementation approach that were required. Objective performance and size comparisons between the old LALR and new Xtext approach are provided

Modeling the OCL Standard Library

OCL is widely used by UML and other languages to constrain meta-models and perform evaluations on models. The OCL specification is the result of diligent but time-constrained human endeavor and so contains many inconsistencies, most of which are relatively easy to ignore as obvious typographical mistakes. However the need to ignore minor discrepancies undermines rigorous treatment of more significant issues. The minor issues can be substantially eliminated by auto-generating the specification. This paper provides early community visibility of proposed solutions to a variety of issues that arose while developing a model for the OCL Standard Library that forms the core of the OCL specification

Safe Navigation in OCL

Abstract. The null object has been useful and troublesome ever since it was introduced. The problems have been mitigated by references in C++, annotations in Java or safe navigation in Groovy, Python and Xbase. Introduction of a safe navigation operator to OCL has some rather unpleasant consequences. We examine these consequences and identify further OCL refinements that are needed to make safe navigation useable

OCL Tools Report based on the IDE4OCL Feature Model

Previously we have developed the idea of an Integrated Development Environment for OCL (IDE4OCL). Based on the OCL community's feedback we have also designed and published an IDE4OCL feature model. Here we present a report on selected OCL tools developed by the authors and their teams. Each author gives an overview of their OCL tool, provides a top level architecture, and gives an evaluation of the tool features in a web framework. The framework can also be used by other potential OCL users and tool developers. For users it may serve as an aid to choose a suitable tool for their OCL use scenarios. For tool developers it provides a comparative view for further development of the OCL tools. Our plans are to maintain the collected data and extend this web framework by further OCL tools. Additionally, we would like to encourage sharing of OCL development resources

Report on the Aachen OCL meeting

As a continuation of the OCL workshop during the MODELS 2013 conference in October 2013, a number of OCL experts decided to meet in November 2013 in Aachen for two days to discuss possible short term improvements of OCL for an upcoming OMG meeting and to envision possible future long-term developments of the language. This paper is a sort of "minutes of the meeting" and intended to quickly inform the OCL community about the discussion topics

Meta-compilation for C++.

Software Engineering progresses as improvements are made in languages and methodologies. Significant advances have been made through the use of Object- Oriented Programming, exploiting the effective support available in C++. Further evolution of OOP involving the use of design patterns and aspects requires additional language support. Increased flexibility in the declaration of objects is proposed in the form of the FOG (Flexible Object Generator) language, which is a superset of C++ implemented by a translator to C++. FOG generalises C++ syntax and supports compile-time meta-programming and reflection. The syntax generalisations provide the freedom for programmers to organise code to suit programming concerns and eliminate the need for duplication between interfaces and implementations. Further generalisations define composition policies for repeated declarations so that classes, arrays, enumerations and functions may all be extended. These composition policies support the weaving necessary for re-useable implementation of design patterns and for Aspect Oriented Programming. A declarative form of meta-programming is supported by derivation rules, which specify how a declaration specified in a base class is to be reinterpreted in derived classes. Automated generation of derived functionality is important for a number of design patterns. More general meta-programming is provided by elevating most run-time concepts to the meta-level, allowing conditional and iterated manipulation of declarations at compile-time. Compile-time execution enables subsequent run-time code to be optimised to suit application requirements. The use of meta-variables and meta-functions together with a well-disciplined lexical context for meta-programming and meta-level execution provide a complete replacement for the traditional C preprocessor functionality, satisfying Stroustrup's goal of making Cpp redundant [Stroustrup97]. The new functionality is integrated with the language, fits within an Object-Oriented framework and provides adequate support for modern Software Engineering practices. The C++ grammar is known to pose a significant parsing challenge and to require context dependent type and template knowledge. This creates considerable difficulties when meta-programming occurs in unresolved contexts. A new approach to parsing C++ has therefore been developed that defers the use of type and template information. This approach leads to a simpler grammar implementation. An extended form of regular expression is presented and used to predict known ambiguities and then show that this simpler grammar covers the C++ grammar