A design and verification technique for implementation schemes of distributed software is presented. In this technique, first, the specification is modelled by a concurrent object system, that is, one which is constit...
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ISBN:
(纸本)0897912845
A design and verification technique for implementation schemes of distributed software is presented. In this technique, first, the specification is modelled by a concurrent object system, that is, one which is constituted of computational agents with capability of concurrent execution and message passing. Then, such a concurrent object system is transformed into another concurrent object system, which models a sophisticated implementation scheme. Our transformation technique is mainly based on fusing and splitting concurrent objects. The correctness of transformation rules can be proven formally.
TS (Typed Smalltalk) is a portable optimizing compiler that produces native machine code for a typed variant of Smalltalk, making Smalltalk programs much faster. This paper describes the structure of TS, the kinds of ...
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ISBN:
(纸本)0897912845
TS (Typed Smalltalk) is a portable optimizing compiler that produces native machine code for a typed variant of Smalltalk, making Smalltalk programs much faster. This paper describes the structure of TS, the kinds of optimizations that it performs, the constraints that it places upon Smalltalk, the constraints placed upon it by an interactive programming environment, and its performance.
The programming of the interrupt handling mechanisms, process switching primitives, scheduling mechanisms, and synchronization primitives of an operating system for a multiprocessor require both efficient code in orde...
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ISBN:
(纸本)0897912845
The programming of the interrupt handling mechanisms, process switching primitives, scheduling mechanisms, and synchronization primitives of an operating system for a multiprocessor require both efficient code in order to support the needs of high-performance or real-time applications and careful organization to facilitate maintenance. Although many advantages have been claimed for object-oriented class hierarchical languages and their corresponding design methodologies, the application of these techniques to the design of the primitives within an operating system has not been widely demonstrated. To investigate the role of class hierarchical design in systemsprogramming, the authors have constructed the Choices multipxocessor operating system architecture using the C++ programming language. During the implementation, it was found that many operating system design concerns can be represented advantageously using a class hierarchical approach, including: the separation of mechanism and policy;the organization of an operating system into layers, each of which represents an abstract machine;and the notions of process and exception management. In this paper, we discuss an implementation of the low-level primitives of this system and outline the strategy by which we developed our solution.
作者：
Sridhar, S.Tektronix
Inc. P.O. Box 500 M.S: 50-470 BeavertonOR97077 United States
The Smalltalk-80 programming environment, though powerful for prototyping applications, does not have any mechanisms for constructing a stand-alone version of an application. Traditionally, the application is bundled ...
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ISBN:
(纸本)0897912845
The Smalltalk-80 programming environment, though powerful for prototyping applications, does not have any mechanisms for constructing a stand-alone version of an application. Traditionally, the application is bundled with an image including the entire development environment. Production applications frequently require that the only interface visible to the end user be that of the application. A common misperception among Smalltalk- application developers is that it is impossible to: l develop and deliver applications containing proprietary algorithms, - prevent inspection and modification of the application, l separate the development environment from the delivered application, l provide annotation of the application classes and methods without actually revealing the source code to the end user. In this paper, we introduce various techniques and mechanisms for meeting these requirements.
We describe the design of a constraint-based window system for Smalltalk. This window system uses constraints to specify attributes of windows and relationships between them. Three classes of constraints are supported...
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ISBN:
(纸本)0897912845
We describe the design of a constraint-based window system for Smalltalk. This window system uses constraints to specify attributes of windows and relationships between them. Three classes of constraints are supported, one of which is implicit and not available for general use. The system extends the current Smalltalk system, providing support for both fixed-size and fixedscale windows. It also provides the capability to dynamically reorganize the layout of a window. A goal of the design is to produce a system with real-time response that is fast enough to be substituted for the existing system. A prototype with response times of approximately l/4 second has been implemented to demonstrate the feasibility of the design as well as to point out several important optimizations.
Kyma is an 'object-oriented environment for music composition written in Smalltalk-80. which, in conjunction with a microprogrammable digital signal processor called the Platypus, provides the composer with a mean...
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ISBN:
(纸本)0897912845
Kyma is an 'object-oriented environment for music composition written in Smalltalk-80. which, in conjunction with a microprogrammable digital signal processor called the Platypus, provides the composer with a means for creating and manipulating Sound objects graphically with real-time sonic feedback via software synthesis. Kyma draws no distinctions between the materials and the structure of a composition: both are Sound objects. When a Sound object receives a message to play, it tranorms itself into a microSound object, i.e. an object representation of itself in the microcode of the Platypus. Thus an object paradigm is used not only in the representation of Sound objects in Smalltalk- but also in the microcode representation of those Sound objects on the Platypus.
This paper describes the evolution of the Transportable applications Executive (TAJZ) (developed at NASA/Goddard Space Flight Center) from a traditional procedural menu and co-doriented system to an object-oriented, m...
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ISBN:
(纸本)0897912845
This paper describes the evolution of the Transportable applications Executive (TAJZ) (developed at NASA/Goddard Space Flight Center) from a traditional procedural menu and co-doriented system to an object-oriented, modeless user interface management system, known as TAE Plus. The impetus for developing this environment and early experiments which led to its current implementation are addressed. The current version of TAE Plus provides design and prototyping functions, working in tandem with a mature application management system. The main components are (1) a user interface designers' WorkBench that allows an application developer to interactively layout an application screen and define the static and/or dynamic areas of the screen;(2) an application programner subroutine package that provides runtime services used to display and control WorkBench-designed interaction objects" on the screen;and (3) an extension to the existing TAE corwnand language that provides cormnds for displaying and manipulating interaction objects, thus providing a means to quickly prototype an application's user interface. During TAE Plus develqment, many design and implementation decisions were based on the stateof- the-art within graphics workstations, windowing systems and object-oriented programning languages, and this paper shares some of the problems and issues experienced during implementation. Some of the topics discussed include: lessons learned in using the Smalltalkn' language to prototype the initial WorkBench;why C++ was selected (over other languages) to build the WorkBench;and experiences in using X Window SystemTM and Stanford's Interviews object library The paper concludes with open issues and a description of the next steps involved in implementing the "totally modem" TAE.
This paper describes an execution model being developed for distributed object-oriented computation in a message-passing multiple-instruction/multiple-data-stream (MIMD) cmimun. The objective is to execute an object-o...
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ISBN:
(纸本)0897912845
This paper describes an execution model being developed for distributed object-oriented computation in a message-passing multiple-instruction/multiple-data-stream (MIMD) cmimun. The objective is to execute an object-oriented pogrum S concurrently as possible. Some opportunities for cmmmenq can be identified explicitly by the programmer. Chehers can be identified at compile time. There are some opportunities for concumncy. however, that can only be discovered atnmtime because they are datadependent. The model of execution we describe attempts to discover and exploit the data-dependent concumncyrhatexistsina given program execution.
KSL (Knowledge Specification Language) is an object-orientedprogramming language that supports data abstraction, inheritance, and message-sending. KSL is also fully reflective, as a result of representing all of the ...
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ISBN:
(纸本)0818608749
KSL (Knowledge Specification Language) is an object-orientedprogramming language that supports data abstraction, inheritance, and message-sending. KSL is also fully reflective, as a result of representing all of the language constructs as objects. Reflectivity allows the object paradigm to be applied to: (1) the development, analysis, and translation of KSL;(2) the extension of KSL to implement additional programming paradigms;and (3) the development of applications that modify themselves. The authors provide an overview of KSL, its object representation, and how its reflectivity is achieved.
A description is given of a prototype persistent-object system, called DOOM (Data-orientedobject Manager), which was designed to explore issues in language-level persistence for object-oriented application platforms....
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ISBN:
(纸本)0818608420
A description is given of a prototype persistent-object system, called DOOM (Data-orientedobject Manager), which was designed to explore issues in language-level persistence for object-oriented application platforms. Language-level persitence presumes that the abstraction constructs for dealing with persistent data should be a well-integrated part of the underlying object-oriented language, rather than a separate language altogether. In its first iteration (DOOM-I), the language aspects of persistence were investigated, and a design which allowed the exchange of persistent objects between Commonobjects (an object-oriented extension to Common Lisp) and objective-C**2 (an object-oriented extension to C) was implemented. The system features a tight coupling between the languages' run-time support and a relational storage manager. In a second iteration (DOOM-II), the coupling between the database and the language was loosened, and more characteristics of the database were exposed to the applications programmer. The change was a result of disappointment on the part of trial users at the performance obtainable without caching of objects at the level of the language run-time system, and the desire to better support multiuser systems.
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