Net-centric information spaces have become a necessary concept to support information exchange for tactical warfighting missions using a publish-subscribe-query paradigm. To support dynamic, mission-critical and time-critical operations, information spaces require quality of service (QoS)-enabled dissemination (QED) of information. This paper describes the results of research we are conducting to provide QED information exchange in tactical environments. We have developed a prototype QoS-enabled publish-subscribe-query information broker that provides timely delivery of information needed by tactical warfighters in mobile scenarios with time-critical emergent targets. This broker enables tailoring and prioritizing of information based on mission needs and responds rapidly to priority shifts and unfolding situations. This paper describes the QED architecture, prototype implementation, testing infrastructure, and empirical evaluations we have conducted based on our prototype.

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Unit testing component-based distributed systems traditionally involved testing functional concerns of the application logic throughout the development lifecycle. In contrast, testing non-functional distributed system concerns (e.g., end-to-end response time, security, and reliability) typically has not occurred until system integration because it requires both a complete system to perform such tests and sophisticated techniques to identify and analyze performance metrics that constitute non-functional concerns. Moreover, in a agile development environment, unit testing non-functional concerns is even harder due to the disconnect between high-level system specification and low-level performance metrics.This paper provides three contributions to research on testing techniques for component-based distributed systems, which is manifested in a technique called Understanding Non-functional Intentions via Testing and Experimentation (UNITE). First, we show how UNITE allows developers to extract arbitrary metrics from log messages using highlevel constructs, such as a human readable expressions that identify variable data. Second, we show how UNITE preserves data integrity and system traces without requiring a globally unique identifier for context identification. Third, we show how developers can formulate equations that represent unit tests of non-functional concerns and then use UNITE to evaluate the equation using metrics extracted from the log messages. The results from applying UNITE to a representative project show that we can unit test nonfunctional properties of a component-based distributed system during the early stages of system development.

The end-to-end evaluation of quality-of-service (QoS) properties (e.g., performance, reliability, and security) for distributed systems has historically occurred late in the software lifecycle. As a result, many design flaws that affect QoS are not found and fixed in a timely and costeffective manner. This article shows how model-driven engineering-particularly domain-specific modeling languages coupled with system execution modeling tools-can enable agile development of distributed systems and facilitate continuous system integration testing to improve quality assurance of QoS properties throughout the software lifecycle.

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