物件導向軟體之架構(Object-Oriented Software Construction)探討

[서평]「The Unified Modeling Language User Guide」

One of the principal uses of UML is the modelling of synchronous object-oriented software systems, in which the behaviour of each of several classes is modelled using a state diagram. UML permits a transition of the state diagram to show both the event which causes the transition (typically, the fact that the object receives a message) and the object's reaction (typically, the fact that the object sends a message). UML's semantics for state diagrams is "run to completion". We show that this can lead to anomalous behaviour, and in particular that it is not possible to model recursive calls, in which an object receives a second message whilst still in the process of reacting to the first. Drawing on both ongoing work by the UML2.0 submitters and recent theoretical work [1, 6], we propose a solution to this problem using state diagrams in two complementary ways.

/pdf/modelling-recursive-calls-with-uml-state-diagrams-1vx9aencrd.pdf

Modelling recursive calls with UML state diagrams

Zb 2005: Formal Specification and Development in Z and B

We show how UML (the industry standard in object-oriented modelling) can be used to express security requirements during system development. Using the extension mechanisms provided by UML, we incorporate standard concepts from formal methods regarding multi-level secure systems and security protocols. These definitions evaluate diagrams of various kinds and indicate possible vulnerabilities.On the theoretical side, this work exemplifies use of the extension mechanisms of UML and of a (simplified) formal semantics for it. A more practical aim is to enable developers (that may not be security specialists) to make use of established knowledge on security engineering through the means of a widely used notation.

/pdf/towards-development-of-secure-systems-using-umlsec-1r0rjeiiqk.pdf

Towards Development of Secure Systems Using UMLsec

Business rules are often specified only implicitly by applications to express user-defined constraints. OCL provides the chance to explicitly and automatically deal with business rules when building object-oriented applications. We investigate how OCL constraints can be handled in database applications as one of the most important kind of business applications. Based on our OCL toolset prototype and earlier research work we particularly experiment with various strategies for the evaluation of OCL constraints in object-oriented applications which use relational databases. For this work, a flexible SQL code generator is needed which can be used and adapted for different relational database systems and different object-to-table mappings. We implement such a database tool as an additional module for our OCL toolset using XML techniques.

/pdf/ocl-as-a-specification-language-for-business-rules-in-4vlwjbu987.pdf

OCL as a Specification Language for Business Rules in Database Applications

We propose a precise definition of UML active classes through associated labelled transition systems using the algebraic specification language Casl. We are convinced that the first step to make UML precise is to find an underlying formal model for the systems modelled by UML, and we argue that labelled transition systems are a sensible choice. This modelization will help understanding the UML constructs and will improve their use in practice. One of our aims is, in the future, to use the powerful animation and verification tools available for algebraic specifications with UML specifications. We simplify the problem of the applicability of our semantics by restricting the state machine constructs considered. This restriction does not, however, narrow the UML subset in study because the restricted constructs can be replaced by equivalent combinations of other constructs. Because of some ambiguities in the UML official semantics, we discuss the several options at hand and choose, for each ambiguous case, the semantics that either makes more sense or that allows to simplify the problem the most.

/pdf/analysing-uml-active-classes-and-associated-state-machines-a-14p0dfttla.pdf

Analysing UML Active Classes and Associated State Machines - A Lightweight Formal Approach

When OCL is applied in concrete examples, many questions arise about the precise meaning of OCL constraints. The same kind of difficulties appears when automatic support tools for OCL are designed. These questions are due to the lack of a precise semantics of OCL constraints in the context of a UML model. The aim of this paper is to contribute to a clarification of several issues, like interpretation of invariants and pre- and postconditions, treatment of undefined values, inheritance of constraints, transformation rules for OCL constraints and computation of proof obligations. Our study is based on a formal, abstract semantics of OCL.

http://dresden-ocl.sourceforge.net/downloads/pdfs/ObjectModelingWithOCL.pdf

Heinrich Hußmann

Papers

OCL as a Specification Language for Business Rules in Database Applications

Analysing UML Active Classes and Associated State Machines - A Lightweight Formal Approach

On the Precise Meaning of OCL Constraints