Object protocols as a tool for debugging method call sequencing constraints

Clearly conveying and enforcing the proper ordering of method calls on objects has become a common problem among developers and interface designers. Without the ability of the compilation environment to enforce these constraints, programmers must rely on clear documentation being provided and diligence in programming to ensure that a proper sequence of operations is performed. Commonly, though, type-checking becomes the only tool to help support the correctness of operation sequences as API documentation rarely describes inter-object communications. Thus, the likeliness of producing erroneous and buggy software increases. Object protocols provide a simple and straight-forward approach to solving this problem. They do so by providing simple grammatical constructs for expressing valid call sequences on objects. These constructs can be parsed by a compiler and then used for conformance analysis on subclasses and objects that implement interfaces. Once parsing is complete, the compiler will implement code in the target binaries for run-time enforcement of sequencing constraints. This thesis builds upon the foundation provided by Butkevich et al. to provide the design of a comprehensive tool for utilizing object protocols within the Java compilation and runtime environments. In addition to the existing work, we provide language constructs that allow the enforcement of object protocols on classes and the designation of objects and interfaces to be traced programmatically. We will consider the problems that are introduced when protocols are enforced upon classes and discuss the strategy for resolving these issues. We present the results of testing the object tracing framework to determine the impact of protocols on the performance of software. Baseline timings are drawn on the operations of data types and then protocols are manually added to the code in the same manner that would be done by the compiler in a fully working implementation; including the implementation of the tracing framework. We show that the overhead introduced is minimal, making the run-time monitoring of protocols practical. Along with support for basic sequencing constraints, we also show how other constraints, such as timing constraints, can be added to the framework with minimal adjustments. Such applications of constraints can help debug different environments, such as embedded, real-time, and near real-time environments

ART-Ada design project, phase 2

Interest in deploying expert systems in Ada has increased. An Ada based expert system tool is described called ART-Ada, which was built to support research into the language and methodological issues of expert systems in Ada. ART-Ada allows applications of an existing expert system tool called ART-IM (Automated Reasoning Tool for Information Management) to be deployed in various Ada environments. ART-IM, a C-based expert system tool, is used to generate Ada source code which is compiled and linked with an Ada based inference engine to produce an Ada executable image. ART-Ada is being used to implement several expert systems for NASA's Space Station Freedom Program and the U.S. Air Force

A gentle transition from Java programming to Web Services using XML-RPC

Exposing students to leading edge vocational areas of relevance such as Web Services can be difficult. We show a lightweight approach by embedding a key component of Web Services within a Level 3 BSc module in Distributed Computing. We present a ready to use collection of lecture slides and student activities based on XML-RPC. In addition we show that this material addresses the central topics in the context of web services as identified by Draganova (2003)

The PARSE Programming Paradigm. Part I: Software Development Methodology. Part II: Software Development Support Tools

The programming methodology of PARSE (parallel software environment), a software environment being developed for reconfigurable non-shared memory parallel computers, is described. This environment will consist of an integrated collection of language interfaces, automatic and semi-automatic debugging and analysis tools, and operating system —all of which are made more flexible by the use of a knowledge-based implementation for the tools that make up PARSE. The programming paradigm supports the user freely choosing among three basic approaches /abstractions for programming a parallel machine: logic-based descriptive, sequential-control procedural, and parallel-control procedural programming. All of these result in efficient parallel execution. The current work discusses the methodology underlying PARSE, whereas the companion paper, “The PARSE Programming Paradigm — II: Software Development Support Tools,” details each of the component tools

Applying Formal Methods to Networking: Theory, Techniques and Applications

Despite its great importance, modern network infrastructure is remarkable for the lack of rigor in its engineering. The Internet which began as a research experiment was never designed to handle the users and applications it hosts today. The lack of formalization of the Internet architecture meant limited abstractions and modularity, especially for the control and management planes, thus requiring for every new need a new protocol built from scratch. This led to an unwieldy ossified Internet architecture resistant to any attempts at formal verification, and an Internet culture where expediency and pragmatism are favored over formal correctness. Fortunately, recent work in the space of clean slate Internet design---especially, the software defined networking (SDN) paradigm---offers the Internet community another chance to develop the right kind of architecture and abstractions. This has also led to a great resurgence in interest of applying formal methods to specification, verification, and synthesis of networking protocols and applications. In this paper, we present a self-contained tutorial of the formidable amount of work that has been done in formal methods, and present a survey of its applications to networking.Comment: 30 pages, submitted to IEEE Communications Surveys and Tutorial

Using FoxNet for TCP/IP networking in ML/OS

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (leaves 42-43).by Alexander Vladimirov.M.Eng