Aspect] is a simple and practical aspect-oriented extension to Java With just a few new constructs, AspectJ provides support for modular implementation of a range of crosscutting concerns. In AspectJ's dynamic join point model, join points are well-defined points in the execution of the program; pointcuts are collections of join points; advice are special method-like constructs that can be attached to pointcuts; and aspects are modular units of crosscutting implementation, comprising pointcuts, advice, and ordinary Java member declarations. AspectJ code is compiled into standard Java bytecode. Simple extensions to existing Java development environments make it possible to browse the crosscutting structure of aspects in the same kind of way as one browses the inheritance structure of classes. Several examples show that AspectJ is powerful, and that programs written using it are easy to understand.

An overview of AspectJ

A computerized method of presenting information from a variety of sources on a display device. Specifically the present invention describes a graphical user interface for organizing the simultaneous display of information from a multitude of information sources. In particular, the present invention comprises a graphical user interface which organizes content from a variety of information sources into a grid of tiles, each of which can refresh its content independently of the others. The grid functionality manages the refresh rates of the multiple information sources. The present invention is intended to operate in a platform independent manner.

System and method for simultaneous display of multiple information sources

Application development for distributed computing "Grids" can benefit from tools that variously hide or enable application-level management of critical aspects of the heterogeneous environment. As part of an investigation of these issues, we have developed MPICH-G2, a Grid-enabled implementation of the Message Passing Interface (MPI) that allows a user to run MPI programs across multiple computers, at the same or different sites, using the same commands that would be used on a parallel computer. This library extends the Argonne MPICH implementation of MPI to use services provided by the Globus Toolkit for authentication, authorization, resource allocation, executable staging, and I/O, as well as for process creation, monitoring, and control. Various performance-critical operations, including startup and collective operations, are configured to exploit network topology information. The library also exploits MPI constructs for performance management; for example, the MPI communicator construct is used for application-level discovery of, and adaptation to, both network topology and network quality-of-service mechanisms. We describe the MPICH-G2 design and implementation, present performance results, and review application experiences, including record-setting distributed simulations.

MPICH-G2: A Grid-Enabled Implementation of the Message Passing Interface

MPICH-G2: a Grid-enabled implementation of the Message Passing Interface

Performance is a pervasive quality of software systems; everything affects it, from the software itself to all underlying layers, such as operating system, middleware, hardware, communication networks, etc. Software Performance Engineering encompasses efforts to describe and improve performance, with two distinct approaches: an early-cycle predictive model-based approach, and a late-cycle measurement-based approach. Current progress and future trends within these two approaches are described, with a tendency (and a need) for them to converge, in order to cover the entire development cycle.

/pdf/the-future-of-software-performance-engineering-1gznpsm01s.pdf

The Future of Software Performance Engineering

Distributed applications are difficult to build and maintain and are even more difficult when the applications are distributed over wide-area networks. Distributed Object Computing middleware has emerged to simplify the building of distributed applications by hiding implementation details behind functional interfaces. However, critical applications have non-functional requirements, such as real-time performance, dependability, or security, that are as important as the functional requirements, but are also hidden by the middleware. Because current distributed object middleware doesn't support these aspects of critical applications, application developers often find themselves bypassing the distributed object systems, effectively gaining little or no advantage from the middleware. We have developed Quality Objects (QuO), a framework for including Quality of Service (QoS) in distributed object applications. QuO supports the specification of QoS contracts between clients and service providers, runtime monitoring of contracts, and adaptation to changing system conditions. A crucial aspect of QuO is a suite of Quality Description Languages for describing states of QoS, system elements that need to be monitored to measure the current QoS, and notification and adaptation to trigger when the state of QoS in the system changes. This paper gives a brief overview of QuO and describes the syntax and semantics of CDL, the component of QDL for describing QoS contracts.

Specifying and measuring quality of service in distributed object systems

Two limitations of the current implementations of adaptive QoS behaviors are complexity associated with inserting them into common application contexts and lack of reusability across applications. What is needed is a way of bundling all the specification for systemic behavior into one place, and making it feasible to insert the collection of related QoS management artifacts into applications as a single, reusable behavior. As a means of addressing these issues, we have developed a new abstraction intended specifically to bundle together the lower level abstractions, specifications and implementations associated with providing adaptive QoS behaviors in a manner which is both easier to package and makes the behavior bundle reusable in a variety of applications and styles of use. We introduce the concept of "qoskets" as reusable systemic behaviors, lay out elements of our design for qoskets within the QuO framework, and use a case study example to highlight the issues of using qoskets in practice.

Packaging quality of service control behaviors for reuse

Recent work in opening up distributed object systems to make them suitable for applications needing quality of service control has had the side effect of increasing the complexity in setting up, configuring, and initializing such applications. Configuration of distributed applications is more complicated than that of non-distributed applications, simply because of the heterogeneous and distributed nature of the application's components. CORBA and other distributed object middleware simplifies the configuration of distributed object applications, but hides much of the information and control necessary to achieve quality of service (QoS). We describe the techniques and tools that we have developed within our Quality Objects (QuO) framework for simplifying the configuration of distributed applications with QoS attributes. We describe a QuO configuration language, as well as the specific configuration needs of particular QoS properties-real-time, security, and dependability-and the support we provide for them.

Using QDL to specify QoS aware distributed (QuO) application configuration

The Quality Objects (QuO) middleware is a set of extensions to standard distributed object computing middleware that is used to control and adapt the quality of service in a number of distributed application environments, from wide-area to embedded distributed applications This paper compares and contrasts the characteristics of key use cases and the variations in QuO implementations that have emerged to support them We present these variations in the context of several actual applications being developed using the QuO middleware

https://www.cse.wustl.edu/~cdgill/PDF/ICDCS01.pdf

Comparing and contrasting adaptive middleware support in wide-area and embedded distributed object applications

While providing some resistance against cyberattacks, current approaches to securing networked and distributed information systems are mainly concerned with static prevention measures. For example, signature-based systems can only detect known attacks and tend to provide brittle, all-or-nothing protection. New work in survivability and intrusion tolerance focuses on augmenting existing information systems with adaptive defenses. A middleware-based survivability toolkit lets applications use network-and host-based mechanisms in their own defense.

Joseph Loyall

Papers

Specifying and measuring quality of service in distributed object systems

Packaging quality of service control behaviors for reuse

Using QDL to specify QoS aware distributed (QuO) application configuration

Comparing and contrasting adaptive middleware support in wide-area and embedded distributed object applications

Adaptive cyberdefense for survival and intrusion tolerance