tzilla elrad

Illinois Institute of Technology, Computer Science, Faculty Member

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Papers by tzilla elrad

Race Scheduling Controls for Object Systems

Springer eBooks, 1998

Concurrent object-oriented computing, a relatively new and rapid growing field, is the inevitable... more Concurrent object-oriented computing, a relatively new and rapid growing field, is the inevitable integration of object-oriented programming and concurrent computing technology. Concurrent Object-Oriented Programming is a programming methodology in which the system to be constructed is modeled as a collection of concurrently executable objects interacting by means of message passing. It is a powerful design methodology for modeling and implementing complex, concurrent systems [2,16,17,22]. Concurrency usually introduces non-deterministic behavior to concurrent computation within object systems. A synchronization mechanism is often required to ensure the proper coordination of communicating software components and to determine what operations can be done at a given time. It permits the specification of conditions by which all the concerned parties can perform their designated tasks in a synchronized fashion.

Intelligent Objects for Adaptive Resource Management

IASSE, 2003

Adaptive Scheduling Control Mechanisms For Concurrent Object Systems

Parallel and Distributed Processing Techniques and Applications, 1999

The use of Ada in reactive systems: A 3-dimensional model

Springer eBooks, Nov 23, 2005

Reflective decision controls for autonomous distributed objects

This paper presents a reflective decision control mechanism for dealing with synchronization and ... more This paper presents a reflective decision control mechanism for dealing with synchronization and scheduling issues in distributed computing environment. We present a component-based reflective architecture for assisting distributed objects in decision making. It enables autonomous entities to support reflective computation that requires a flexible means for managing the course of computation, resource allocation and scheduling. Such capability is critical to the successful implementation of distributed software that supports real-time and reactive/adaptive applications (e.g., robotics, manufacturing, and military systems). In many instances, these systems must be designed to monitor and manage complex systems in dynamic settings.

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9TH International Workshop on Aspect-Oriented Modeling

Model Driven Engineering Languages and Systems, Oct 1, 2006

This report summarizes the outcomes of the 9th Workshop on Aspect-Oriented Modeling (AOM) held in... more This report summarizes the outcomes of the 9th Workshop on Aspect-Oriented Modeling (AOM) held in conjunction with the 9th International Conference on Model Driven Engineering Languages and Systems-MoDELS 2006-in Genoa, Italy, on the 1st of October 2006. The workshop brought together approximately 25 researchers and practitioners from two communities: aspect-oriented software development and software model engineering. It provided a forum for discussing the state of the art in modeling crosscutting concerns at different stages of the software development process: requirements elicitation and analysis, software architecture, detailed design, and mapping to aspect-oriented programming constructs. This paper gives an overview of the accepted submissions and summarizes the results of the different discussion groups. Papers and presentation slides of the workshop are available at http://www.aspect-modeling.org/.

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Efficiently Controlling Communication in Ada using Preference Control

The need for simple, readable and efficient communication software in Ada is apparent. This paper... more The need for simple, readable and efficient communication software in Ada is apparent. This paper suggests an elegant and efficient solution for real time communication software that considers the urgency of a message and the security level associated with such messages. We propose the use of the preference control construct, "pref", for the explicit control of preferences among different entries within the select statement. The preference control construct makes our solution much more readable, understandable, easy to modify and more efficient. We argue the necessity for the preference control construct in Ada. We also give a possible solution without the use of explicit preference control; but the resulting software does not measure up to the high quality software engineering standards that are attained with the use of explicit preference control. An example of message routing software is included in this paper. The advantages of using explicit preference control are discussed from two complementary aspects. First, the run time analysis shows that the response time is much faster using explicit preference control. The response time is obviously a very important constraint on military communication software. Secondly, we state a general principle called the branching wide horizons principle, which captures the necessary expressive power needed for the efficient control of communication. The preference control used in our communication is a natural implementation of this principle.

A language adaptation architecture for reflective concurrent systems

IFIP advances in information and communication technology, 1998

To address new requirements, language designers must often add new notations to an existing langu... more To address new requirements, language designers must often add new notations to an existing language. The new features may be optimal for some applications but unacceptable in others. Once the features have been added, programmers will be restricted to that resulting language. An open language implementation offers a solution to this drawback. It permits users to tailor a language by either customizing the existing semantics or by modifying the syntax. We present a reflective architecture to support language adaptation capability. Our approach enables users (language designers/programmers) to satisfy new requirements in a base language without changing the compiler while promoting reuse of software components.

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A Two-Dimensional Composition Framework to Support Software Adaptability and Reuse

Lecture Notes in Computer Science, 2000

WB Frakes (Ed.): ICSR-6, LNCS 1844, pp. 388-401, 2000. © Springer-Verlag Berlin Heidelberg 2000 .... more

Periodic route optimization for handed-off connections in wireless ATM networks

In Wireless ATM networks, user connections need to be rerouted during handoff as mobile users mov... more In Wireless ATM networks, user connections need to be rerouted during handoff as mobile users move among base stations. The rerouting of connections must be done quickly with minimal disruption to traffic. In addition, the resulting routes must be optimal. A reasonable approach is to implement handoff in two phases. In the first phase connections are rapidly rerouted and in the second phase a periodic route optimization procedure is executed. The route optimization should impose minimal signaling and processing load on the ATM switches. In this paper, we propose and study a periodic execution of route optimization for a two-phase handoff scheme. We study two types of execution: non-adaptive and adaptive. For the adaptive optimization, we consider two adaptation schemes that are dependent on network conditions. A simulation model is developed to study system performance. The adaptive route optimization is shown to minimize signaling and processing load while maximizing utilization of reserved resources.

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The use of communication-closed layers to support imprecise scheduling for distributed, real-time programs

The concept of communication-closed layers (CCL) of distributed programs that was introduced by t... more The concept of communication-closed layers (CCL) of distributed programs that was introduced by the author (1989) is adapted for scheduling real-time tasks in a tightly-bound environment. A simple scheduling mechanism for tightly-bound concurrent programs based on CCL is proposed. This scheduling strategy supports an imprecise computation approach and hence it can be used for real-time systems where deadlines are met with acceptable precision. It is flexible because the priorities given to the tasks within a layer can be controlled by different factors and they are user defined. Logical units for scheduling are decided at the design phase using layering and hence the programmer has more control over scheduling of the program rather than writing programs that suit a particular scheduler. This scheduling mechanism is general and can be utilized for single or multi-processor systems in a centralized or distributed environment.<<ETX>>

Distributed Languages Design Constructs for Controlling Preferences

International Conference on Parallel Processing, 1986

Distributed languages design-Constructs for controlling preferences. TZILLA ELRAD, FRED MAYMIR-DU... more

Comprehensive scheduling controls for Ada tasking

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Handling reactive crosscutting concerns with aspect-oriented modeling, state machines, and scenarios

This thesis addresses the problem of dealing with crosscutting concerns in a reactive environment... more

Aclamate: An AOSD Security Framework for Access Control

ABSTRACT The development of secure software could be simplified if tooling were readily available... more ABSTRACT The development of secure software could be simplified if tooling were readily available to application developers. Improvements can be made to better support software developers to secure their applications, without requiring that security code be inserted throughout core application processing code. The Aclamate framework is introduced here for securing software that imposes little restrictions on the writing of software. Aclamate uses AOSD to secure applications in a non-invasive manner. Both the existing state of software security frameworks and what support already exists to assist application development are discussed. Emphasis is placed on access control and authorization - as these areas are particularly lacking with security tooling to support software development in a non-invasive manner. Finally, there is a critique of Aclamate, the challenges remain in its development, and the remaining opportunities that may exist to provide application developers with more tools to ease the development of secure software

Aspect Oriented Approach for Capturing and Verifying Distributed Properties

Springer eBooks, 2009

ABSTRACT Given an initial decomposition of a distributed program into processes we are faced with... more ABSTRACT Given an initial decomposition of a distributed program into processes we are faced with two classes of properties that are tightly bounded. One is the class of intra- process properties; these are relationships and requirements over a local state of a process. The second class is inter- processes properties; these are relationships and requirements over different processes local states that depict the consistencies and cooperation among a collection of cooperative processes that might be tightly bounded to achieve a certain collective goal. Both classes of system properties are crucial for system development and verification. The intra-process properties are relatively easier to define and carry on through system development life cycle. This paper concentrates on the challenges of expressing and imposing inter-processes properties during a distributed execution. The approach taken here is based on two completely independent areas of research The first is the CCL - Communication Closed Layers; a formal system for developing, maintaining, and verifying distributed programs [EF82] and the second is the aspect oriented software development [AOSD, CACM] that enables simplification and automation of CCL implementations. Aspect-oriented approach provides a natural framework to address inter-processes cooperation. The essence of aspect oriented software developments is the localization of crosscutting concerns. Under CCL constrains cooperative global properties can be considered as a special case of crosscutting concerns. (Note that this is not true in general; layers closeness, as defined in the following, is a necessary condition for the validity of cooperative global virtual assertions). Both CCL and AOSD are software development methodologies; their synergy for distributed systems development and runtime verification of system virtual global assertions is a promising match to handle the complexities of global system cooperation and consistencies. Both are centered on the notion of crosscutting concerns; CCL captures the semantics whereas AOSD provides the expressive tools. Together, it enables a design-by-contract discipline [M93] to be applicable to a wider range of distributed programs. There is still ongoing research to use the WEAVR , an aspect oriented model driven engineering [tool developed by Motorola, to automate code generation from precise behavioral models to express layers and global assertions. [CE1, CE2, CVE1, CVE2, CVE3].

Aspect-oriented programming

Communications of The ACM, Oct 1, 2001

together behavior and data into a single conceptual (and physical) entity. Object-orientation is ... more

Editorial: Experiences with Auto-adaptive and Reconfigurable Systems (Application Level Adaptation)

Software - Practice and Experience, 2006

ABSTRACT Change can be observed in our environment and in the technology we build. While changes ... more

Scenario based resolution of aspect interactions with aspect interaction charts

An enhanced reflective architecture for adaptation of the object-oriented language/software

To be effective in addressing specific requirements found in the intended computing domains of a ... more To be effective in addressing specific requirements found in the intended computing domains of a given object-oriented language, several researchers have tended to introduce new notation into current existing interface constructs. Current research that provides such interfaces can be classified into two categories: one embedding special purpose interface construct in language syntax and can not be adapted further by end-users; the other provides an open way that programmers can tailor new interface construct to their need. In either way, programmers suffer the inheritance anomaly and the inheritance exclusion. To handle such disadvantages, this paper presents our language adapter++, in which programmers can adapt the object model to different computing environments, and then reify the internal object state into a separated virtual interface, called virtual adapter. The virtual adapter along with traditional interface can be used to define an object as if using the integrated construct.

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