Introduction - benefits of object-orientation, object-oriented programming and BETA introduction to basic concepts - perspectives on programming, object-oriented programming objects and patterns - overview, reference attributes, pattern attributes repetitions - reallocation, assignment and slice, the text pattern imperatives - introduction to evaluations, for-imperative, if-imperative, labels and jump imperatives, a large example, assignment and equality, computed references and computed remote name, detailed description of evaluations, block structure and scope rules, object kinds and construction modes sub-patterns - specialization by simple inheritance, specialization of actions, enter/exit-parts for sub-patterns, the object patterns, summary, qualifications and scope rules virtual procedure patterns, continued extension of a virtual patterns, more examples of using virtual patterns, benefits of virtual patterns, summary block structure - simple block structure, class grammar, flight reservation example virtual class patterns - directly qualified virtual class patterns, general parameterized class patterns part objects and reference attributes - part objects, reference attributes pattern variables - declaration of pattern variables, example procedural programming - functional classes, higher order procedure patterns, virtual classes and genericity deterministic alternation - execution stacks, generators, components and recursive procedure patterns, abstract super-patterns concurrency - concurrent execution of components, monitors, direct communication between components, compound systems, readers and writers problem non-determinstic alternation - alternating execution of components, a distributed calendar, bounded buffer, a simple game exception handling - simple exceptions, recovery, partial recovery, handlers for procedure patterns, system exceptions, language-defined exceptions, advanced design of exception patterns modularization - fragments, separation of interface and implementation, alternative implementations, programme variants, using several libraries, visibility and binding rules (part contents).

http://cs-exhibitions.uni-klu.ac.at/fileadmin/template/documents/text/betabook.pdf

Object-Oriented Programming in the Beta Programming Language

Finite state description of communication protocols

This paper summarizes the current state of the art and recent trends in software engineering economics. It provides an overview of economic analysis techniques and their applicability to software engineering and management. It surveys the field of software cost estimation, including the major estimation techniques available, the state of the art in algorithmic cost models, and the outstanding research issues in software cost estimation.

Software engineering economics

The production of error-free protocols or complex process interactions is essential to reliable communications. This paper presents techniques for both the detection of errors in protocols and for prevention of errors in their design. The methods have been used successfully to detect and correct errors in existing protocols. A technique based on a reachability analysis is described which detects errors m a design. This "perturbation technique" has been implemented and has successfully detected inconsistencies or errors in existing protocol designs including both X.21 and X.25. The types of errors handled are state deadlocks, unspecified receptions, nonexecutable interactions, and state smbiguities. These errors are discussed and their effects considered. An interactive design technique is then described that prevents design errors. The technique is based on a set of production rules which guarantee that complete reception capability is provided in the interacting processes. These rules have been implemented in the form of a tracking algorithm that prevents a designer from creating unspecified receptions and nonexecutable interactions and monitors for the presence of state deadlocks and ambiguities.

Towards Analyzing and Synthesizing Protocols

This article surveys techniques used in structured and object-oriented software specification methods. The techniques are classified as techniques for the specification of external interaction and internal decomposition. The external specification techniques are further subdivided into techniques for the specification of functions, behavior, and communication. After surveying the techniques, we summarize the way they are used in structured and object-oriented methods and indicate ways in which they can be combined. This article ends with a plea for simplicity in diagram techniques and for the use of formal semantics to define these techniques. The appendices show how the reviewed techniques are used in 6 structured and 19 object-oriented specification methods.

/pdf/a-survey-of-structured-and-object-oriented-software-2qrgdygec5.pdf

A survey of structured and object-oriented software specification methods and techniques

The paper presents OSDL, an object-oriented extension of SDL. SDL is an acronym for Specification and Description Language. It is recommended as the standard specification language for telecommunication purposes by the International Telecommunication Union CCITT. The paper gives an introduction and overview of object-orientation in general. The object-oriented features of OSDL is presented in the form of a tutorial. It is demonstrated, that by a few extensions SDL becomes object-oriented. At last the rationale for object-orientation in general and OSDL in special is given.

Rationale and tutorial on OSDL : an object-oriented extension of SDL

During the last year recommendation X.25 [1] of the CCITT specifying a packet mode interface between a DTE and a DCE has been the subject of study and discussion. X.25 defines a link access and a packet level protocol the latter of which is of interest here. According to X.25 a number of logical connections, called virtual calls, may share one physical link between DTE and DCE. The sharing is achieved by asynchronous time-division multiplexing of so-called logical channels. For each channel, call setup and clearing, data transfer, and flow control takes place by the exchange of packets. There are different types of packets for the different tasks mentioned. A scheme involving a number of states for logical channels is used in the protocol.In this paper we discuss two aspects of the packet level protocol which we feel are insufficiently or erroneously specified in X.25. First, the insufficient description of the DTE-to-DTE packet level protocol which X.25 implies. Second, some problems relating to the states and state transitions for logical channels as specified by X.25. These problems we consider to be the result of erroneous design, and repair is suggested.

Some problems with the X.25 packet level protocol

A simple extension of Pascal for quasi-parallel processing

Publisher Summary In this chapter M is considered a Turing machine (TM). An instantaneous description (ID) of M is a triple 〈q,X,n〉 where q∈K, X∈ ∑∞ and n≥1. describes that M is in state q with the read-write head scanning square no. n and that the tape T contains X. M is to stop if M tries to go off the tape at the left end. M is called a non-writing TM if it contains no write-instructions. The immortality problem (IP) associated with a set of TM-s is the problem of deciding, for a given TM in the set, whether or not there exists an immortal ID. It is shown that IP for non-erasing TM-s is decidable, if the tape is allowed to contain ultimately periodic words. If, however, the tape is restricted to contain only a finite number of non-blanks, then the IP for the set of nonerasing TM-s is recursively undecidable (of degree 0").

Dag Belsnes

Papers

Rationale and tutorial on OSDL : an object-oriented extension of SDL

Some problems with the X.25 packet level protocol

A simple extension of Pascal for quasi-parallel processing

The Immortality Problem for Non-Erasing Turing Machines