Jaiganesh Balasubramanian

A platform-independent component modeling language for distributed real-time and embedded systems

This paper provides two contributions to the study of developing and applying domain-specific modeling languages (DSMLS) to distributed real-time and embedded (DRE) systems - particularly those systems using standards-based QoS-enabled component middleware. First, it describes the platform-independent component modeling language (PICML), which is a DSML that enables developers to define component interfaces, QoS parameters and software building rules, and also generates descriptor files that facilitate system deployment. Second, it applies PICML to an unmanned air vehicle (UAV) application portion of an emergency response system to show how PICML resolves key component-based DRE system development challenges. Our results show that the capabilities provided by PICML - combined with its design and deployment-time validation capabilities - eliminates many common errors associated with conventional techniques, thereby increasing the effectiveness of applying QoS-enabled component middleware technologies to the DRE system domain.

DAnCE: a qos-enabled component deployment and configuration engine

This paper presents two contributions to the study of component deployment for distributed real-time and embedded (DRE) systems. First, it uses an inventory tracking systems (ITS) as a case study to elicit challenges involved in deploying DRE systems to account for their quality of service requirements. Second, it describes how we designed and implemented the Deployment And Configuration Engine (DAnCE), which is QoS-enabled middleware that addresses the challenges that arose in the context of our ITS case study. Our experience shows that DAnCE provides an effective platform for deploying DRE system components using a standard runtime environment and metadata.

Evaluating the performance of middleware load balancing strategies

This work presents three contributions to research on middleware load balancing. First, it describes the design of Cygnus, which is an extensible open-source middleware framework developed to support adaptive and nonadaptive load balancing strategies. Key features of Cygnus are its ability to make load balancing decisions based on application-defined load metrics, dynamically (re)configure load balancing strategies at run-time, and transparently add load balancing support to client and server applications. Second, it describes the design of LBPerf, an open-source middleware load balancing benchmarking toolkit developed to evaluate load balancing strategies at the middleware level. Third, it presents the results of experiments that systematically evaluate the performance of adaptive load balancing strategies implemented using the Cygnus middleware framework using workloads generated by LBPerf. The workloads used in our experiments are based on models of CPU-bound requests that are representative of a broad range of distributed applications. Our experiments with LBPerf illustrate the need for evaluating different adaptive and nonadaptive load balancing strategies under different workload conditions. In addition to assisting in choosing a suitable load balancing strategy for a particular class of distributed applications, our empirical results help configure run-time parameters properly and analyze their behavior in the presence of different workloads. Our results also indicate that integrating Cygnus into distributed applications can improve their scalability, while incurring minimal run-time overhead. As a result, developers can concentrate on their core application behavior, rather than wrestling with complex middleware mechanisms needed to enhance the scalability of their distributed applications.

Model driven middleware: A new paradigm for developing distributed real-time and embedded systems

Distributed real-time and embedded (DRE) systems have become critical in domains such as avionics (e.g., flight mission computers), telecommunications (e.g., wireless phone services), tele-medicine (e.g., robotic surgery), and defense applications (e.g., total ship computing environments). These types of system are increasingly interconnected via wireless and wireline networks to form systems of systems. A challenging requirement for these DRE systems involves supporting a diverse set of quality of service (QoS) properties, such as predictable latency/jitter, throughput guarantees, scalability, 24x7 availability, dependability, and security that must be satisfied simultaneously in real-time. Although increasing portions of DRE systems are based on QoS-enabled commercial-off-the-shelf (COTS) hardware and software components, the complexity of managing long lifecycles (often ~15-30 years) remains a key challenge for DRE developers and system integrators. For example, substantial time and effort is spent retrofitting DRE applications when the underlying COTS technology infrastructure changes. This paper provides two contributions that help improve the development, validation, and integration of DRE systems throughout their lifecycles. First, we illustrate the challenges in creating and deploying QoS-enabled component middleware-based DRE applications and describe our approach to resolving these challenges based on a new software paradigm called Model Driven Middleware (MDM), which combines model-based software development techniques with QoS-enabled component middleware to address key challenges faced by developers of DRE systems - particularly composition, integration, and assured QoS for end-to-end operations. Second, we describe the structure and functionality of CoSMIC (Component Synthesis using Model Integrated Computing), which is an MDM toolsuite that addresses key DRE application and middleware lifecycle challenges, including partitioning the components to use distributed resources effectively, validating software configurations, assuring multiple simultaneous QoS properties in real-time, and safeguarding against rapidly changing technology.

A multi-layered resource management framework for dynamic resource management in enterprise DRE systems

Enterprise distributed real-time and embedded (DRE) systems can benefit from dynamic management of computing and networking resources to optimize and reconfigure system resources at runtime in response to changing mission needs and/or other situations, such as failures or system overload. This paper provides two contributions to the study of dynamic resource management (DRM) for enterprise DRE systems. First, we describe a standards-based multi-layered resource management (ARMS MLRM) architecture that provides DRM capabilities to enterprise DRE systems. Second, we show the results of experiments evaluating our ARMS MLRM architecture in the context of a representative enterprise DRE system for shipboard computing.

Adaptive Failover for Real-Time Middleware with Passive Replication

Supporting uninterrupted services for distributed soft real-time applications is hard in resource-constrained and dynamic environments, where processor or process failures and system workload changes are common. Fault-tolerant middleware for these applications must achieve high service availability and satisfactory response times for client applications. Although passive replication is a promising fault tolerance strategy for resource-constrained systems, conventional client failover approaches are non-adaptive and load-agnostic, which can cause system overloads and significantly increase response times after failure recovery.This paper presents four contributions to the study of passive replication for distributed soft real-time applications. First, it describes how our Fault-tolerant Load-aware and Adaptive middlewaRe (FLARe) dynamically adjusts failover targets at runtime in response to system load fluctuations and resource availability. Second, it describes how FLARes overload management strategy proactively enforces desired CPU utilization bounds by redirecting clients from overloaded processors. Third, it presents the design and implementation of FLARes lightweight middleware architecture that manages failures and overloads transparently to clients. Finally, it presents experimental results on a distributed Linux testbed that demonstrate how FLARe adaptively maintains soft real-time performance for clients operating in the presence of failures and overloads with negligible runtime overhead.

The design and performance of component middleware for QoS-enabled deployment and configuration of DRE systems

Quality of Service (QoS)-enabled component middleware can help reduce the complexity of deploying and configuring QoS aspects, such as priorities and rates of invocation. Few empirical studies have been conducted, however, to guide developers of distributed real-time and embedded (DRE) systems in choosing among alternative designs and performance optimizations. Moreover, few empirical studies have been conducted to examine the performance and flexibility trade-offs between standards-based and domain-specific DRE middleware solutions. This paper makes three key contributions to research on QoS-enabled component middleware for DRE systems. First, it describes optimizations applied to an implementation of the OMGs Deployment and Configuration (D&C) of Components specification that enable performance trade-offs between QoS aspects of DRE systems. Second, it compares the performance of several dynamic and static configuration mechanisms to help guide the selection of suitable configuration mechanisms based on specific DRE system requirements. Third, it compares the performance of our static standards-based approach to an avionics domain-specific approach. Our results show that these optimizations (1) provide developers improved control over key trade-offs between flexibility and performance at different stages of the DRE system lifecycle, (2) enhance trustworthiness of component-based DRE systems by supporting greater customization of how they are configured to meet specific requirements of each application, and (3) offer greater flexibility at a reasonable performance cost, compared to a domain-specific approach.

A Platform-Independent Component Modeling Language for Distributed Real-time and Embedded Systems

This paper provides two contributions to the study of developing and applying domain-specific modeling languages (DSMLS) to distributed real-time and embedded (DRE) systems - particularly those systems using standards-based QoS-enabled component middleware. First, it describes the platform-independent component modeling language (PICML), which is a DSML that enables developers to define component interfaces, QoS parameters and software building rules, and also generates descriptor files that facilitate system deployment. Second, it applies PICML to an unmanned air vehicle (UAV) application portion of an emergency response system to show how PICML resolves key component-based DRE system development challenges. Our results show that the capabilities provided by PICML - combined with its design and deployment-time validation capabilities - eliminates many common errors associated with conventional techniques, thereby increasing the effectiveness of applying QoS-enabled component middleware technologies to the DRE system domain.

Middleware for Resource-Aware Deployment and Configuration of Fault-Tolerant Real-time Systems

Developing large-scale distributed real-time and embedded (DRE) systems is hard in part due to complex deployment and configuration issues involved in satisfying multiple quality for service (QoS) properties, such as real-timeliness and fault tolerance. This paper makes three contributions to the study of deployment and configuration middleware for DRE systems that satisfy multiple QoS properties. First, it describes a novel task allocation algorithm for passively replicated DRE systems to meet their real-time and fault-tolerance QoS properties while consuming significantly less resources. Second, it presents the design of a strategizable allocation engine that enables application developers to evaluate different allocation algorithms. Third, it presents the design of a middleware agnostic configuration framework that uses allocation decisions to deploy application components/replicas and configure the underlying middleware automatically on the chosen nodes. These contributions are realized in the DeCoRAM (Deployment and Configuration Reasoning and Analysis via Modeling) middleware. Empirical results on a distributed testbed demonstrate DeCoRAM’s ability to handle multiple failures and provide efficient and predictable real-time performance.

NetQoPE: A Model-Driven Network QoS Provisioning Engine for Distributed Real-time and Embedded Systems

This paper provides two contributions to the study of quality of service (QoS)-enabled middleware that supports the network QoS requirements of distributed real-time and embedded (DRE) systems. First, we describe the design and implementation of NetQoPE, which is a model-driven component middleware framework that shields applications from the details of network QoS mechanisms by (1) specifying per-flow network QoS requirements, (2) performing resource allocation and validation decisions (such as admission control), and (3) enforcing per-flow network QoS at runtime. Second, we evaluate the effort required and flexibility of using NetQoPE to provide network QoS assurance to end-to-end application flows. Our results demonstrate that NetQoPE can provide network-level differentiated performance to each application flow without modifying its programming model or source code, thereby providing greater flexibility in leveraging network-layer mechanisms.