Alexander L. Wolf's research while affiliated with University of California, Santa Cruz and other places

Publications (184)

Preprint
Full-text available
We are concerned with reliably harvesting data collected from service-based systems hosted on a mobile ad hoc network (MANET). More specifically, we are concerned with time-bounded and time-sensitive time-series monitoring data describing the state of the network and system. The data are harvested in order to perform an analysis, usually one that r...
Article
Full-text available
We present a method to locate faults in service-based software systems hosted on mobile ad hoc networks (MANETs). In such systems, computations are structured as interdependent services distributed across the network, collaborating to satisfy client requests. Faults, which may occur at either or both the service and network layers, propagate by cas...
Conference Paper
Modern servers have become heterogeneous, often combining multi-core CPUs with many-core GPGPUs. Such heterogeneous architectures have the potential to improve the performance of data-intensive stream processing applications, but they are not supported by current relational stream processing engines. For an engine to exploit a heterogeneous archite...
Article
Full-text available
Data centre networks are increasingly programmable, with $\textit{application-specific}$ network services proliferating, from custom load-balancers to middleboxes providing caching and aggregation. Developers must currently implement these services using traditional low-level APIs, which neither support natural operations on application data nor pr...
Conference Paper
Heterogeneous architectures that combine multi-core CPUs with many-core GPGPUs have the potential to improve the performance of data-intensive stream processing applications. Yet, a stream processing engine must execute streaming SQL queries with sufficient data-parallelism to fully utilise the available heterogeneous processors, and decide how to...
Technical Report
Full-text available
The emerging use of ad hoc wireless networks combined with current trends in the use of Web Services-based systems pose new challenges to accurate emulation of these systems. Current network simulators lack the ability to replicate the complex message exchange behavior of services while service simulators do not accurately capture mobile network pr...
Technical Report
Full-text available
The emerging use of mobile ad hoc networks combined with current trends in the use of service-based systems pose new challenges to accurate simulation of these systems. Current network simulators lack the ability to replicate the complex message exchange behaviour of services, while service simulators do not accurately capture of mobile network pro...
Conference Paper
Full-text available
The dynamic environment of hybrid mobile and fixed wireless networks used in military operations poses significant challenges in the efficient provisioning of software functionality to application clients. With their transient topology, the software services hosted on mobile nodes may become temporarily unavailable or the cost of transferring data...
Conference Paper
The heterogeneous and dynamic nature of tactical coalition networks poses several challenges to common network management tasks, due to the lack of complete and accurate network information. In this paper, we consider the problem of redeploying services in mobile tactical networks. We propose M-iTop, an algorithm for inferring the network topology...
Conference Paper
Full-text available
We are concerned with reliably harvesting data used to monitor a service-based system hosted in a mobile ad hoc network (MANET) environment. These data are time-bounded, time-sensitive time-series data recorded by individual hosts in the network. Harvesting is used to gather the data for global time-series analyses, such as fault localization. The...
Article
We present a cost model for analyzing the memory efficiency of algorithms expressed in a simple functional language. We show how some algorithms written in standard forms using just lists and trees (no arrays) and requiring no explicit memory layout or memory management are efficient in the model. We then describe an implementation of the language...
Article
Full-text available
The dependencies among the components of service-oriented software applications hosted in a mobile ad hoc network (MANET) are difficult to determine due to the inherent loose coupling of the services and the transient communication topologies of the network. Yet understanding these dependencies is critical to making good management decisions, since...
Conference Paper
Full-text available
Data centre applications for batch processing (e.g. map/reduce frameworks) and online services (e.g. search engines) scale by distributing data and computation across many servers. They typically follow a partition/aggregation pattern: tasks are first partitioned across servers that process data locally, and then those partial results are aggregate...
Conference Paper
I began my career in software engineering research and now find myself working more in software systems research. Is there a difference? In this talk I reflect on this question by recalling the stream of ideas, students, and colleagues that have shaped my path. I present an overview of the current projects in which I am involved to understand at a...
Conference Paper
Routing in information-centric networking remains an open problem. The main issue is scalability. Traditional IP routing can be used with name prefixes, but it is believed that the number of prefixes will grow too large. A related problem is the use of per-packet in-network state (to cut loops and return data to consumers). We develop a routing sch...
Conference Paper
The dynamic environment of Hybrid Wireless Networks used in military operations, poses significant challenges to efficient provisioning of functionality of service-based systems to client applications. With the transient topology, the services hosted on mobile nodes may become temporality unavailable or the cost of transferring data across distant...
Conference Paper
The management of large scale service based systems hosted in dynamic environments of hybrid wireless networks is a complex task. Such systems are designed as composite services integrating heterogeneous service components such as sensor, software and data services. In this paper, we propose a new situational aware framework which allows the networ...
Conference Paper
Full-text available
The combination of service-oriented applications, with their run-time service binding, and mobile ad hoc networks, with their transient communication topologies, brings a new level of complex dynamism to the structure and behaviour of software systems. This complexity challenges our ability to understand the dependence relationships among system co...
Conference Paper
We present the design, implementation, and evaluation of B4, a private WAN connecting Google's data centers across the planet. B4 has a number of unique characteristics: i) massive bandwidth requirements deployed to a modest number of sites, ii) elastic ...
Conference Paper
We have argued that an information-centric network should natively support publish/subscribe event notification in addition to on-demand content delivery. We have also argued that both primitives could use the same forwarding information base and, furthermore, that both primitives can easily support addresses that are more expressive than simple hi...
Conference Paper
We have argued that an information-centric network should natively support publish/subscribe event notification in addition to on-demand content delivery. We have also argued that both primitives could use the same forwarding information base and, furthermore, that both primitives can easily support addresses that are more expressive than simple hi...
Conference Paper
In this paper, we consider a problem related to service management and deployment in tactical military networks. Tactical networks are typically hybrid wireless networks in which there are both static and mobile nodes with several wireless interfaces, such as 802.11, 3G, satellite, etc. In tactical networks, performance degradation in services coul...
Conference Paper
Full-text available
Fault localization in general refers to a technique for identifying the likely root causes of failures observed in systems formed from components. Fault localization in systems deployed on mobile ad hoc networks (MANETs) is a particularly challenging task because those systems are subject to a wider variety and higher incidence of faults than those...
Conference Paper
Cloud computing realises the vision of utility computing. Tenants can benefit from on-demand provisioning of computational resources according to a pay-per-use model and can outsource hardware purchases and maintenance. Tenants, however, have only limited visibility and control over network resources. Even for simple tasks, tenants must resort to i...
Conference Paper
An important concern in the design of a publish/subscribe system is its expressiveness, which is the ability to represent various types of information in publications and to precisely select information of interest through subscriptions. We present an enhancement to existing content-based publish/subscribe systems with support for a 2D spatial data...
Conference Paper
Full-text available
Variability is a means for evolution of component-based architectures, driving flexible and adaptive architectures. In recent years, researches have emphasized the need for documenting architectural knowledge to maintain and evolve software, i.e. the need for documenting not only the design of the solution, but also the decisions driving the design...
Article
Full-text available
We propose a novel algorithm to determine the availability or the states of services considering the dynamics and scale of the networks. Our approach is based on network tomog-raphy and spatial correlation of the services. We use service-layer dependency graphs and e2e client-service measurements in a dynamic network to evaluate the internal states...
Article
On-line information comes in different forms and is accessed in different ways and for different purposes. For example, a recording of Beethoven's Ninth Symphony differs from a storm warning from the local weather service. Beethoven's Ninth is a large media file with perpetual validity that is typically accessed on demand by users. By contrast, a s...
Chapter
Software engineering research can trace its roots to a small number of highly influential individuals. Among that select group is Prof. Leon J. Osterweil, whose work has fundamentally defined or impacted major directions in software analysis, development tools and environments, and software process. His exceptional and sustained contributions to th...
Book
Software engineering research can trace its roots to a few highly influential individuals. Among that select group is Leon J. Osterweil, who has been a major force in driving software engineering from its infancy to its modern reality. For more than three decades, Prof. Osterweil's work has fundamentally defined or significantly impacted major dire...
Conference Paper
Full-text available
The emerging use of mobile ad hoc networks com-bined with current trends in the use of service-based systems pose new challenges to accurate simulation of these systems. Current network simulators lack the ability to replicate the complex message exchange behaviour of services and service simulators do not provide accurate simulation of mobile netw...
Conference Paper
Change impact analysis is fundamental in software evolution, since it allows one to determine potential effects upon a system resulting from changing requirements. While prior work has generically considered change impact analysis at architectural level, there is a distinct lack of support for the kinds of architectures used to realize software pro...
Conference Paper
New technologies have recently emerged to challenge the very nature of computing: multicore processors, virtualized operating systems and networks, and data-center clouds. One can view these technologies as forming levels within a new, global computing platform. We aim to open a new area of research, called multiplicity computing, that takes a radi...
Conference Paper
Full-text available
Modern societies are pervaded by computerized, heterogeneous devices designed for specific purposes, but also more and more often capable of interacting with other devices for entirely different purposes. For example, a cell phone could be used to purchase a train ticket on-line that could later be printed by a vending machine at the train station....
Article
Full-text available
We address the problem that existing publish/subscribe messaging systems, including such commonly used ones as Apache’s ActiveMQ and IBM’s WebSphere MQ, exhibit degraded end-to-end throughput performance in a wide-area network setting. We contend that the cause of this problem is the lack of an appropriate routing protocol. Building on the idea of...
Article
Test adequacy criteria provide the engineer with guidance on how to populate test suites. While adequacy criteria have long been a focus of research, existing testing methods do not address many of the fundamental characteristics of distributed systems, such as distribution topology, communication failure, and timing. Furthermore, they do not provi...
Article
The enormous changes in software engineering practice make it prudent to consider the interplay between software engineering research and practice. Toward that end, the authors provide an overall view of the motivations behind the Impact Project, the research methodology followed, and the project's development plan. They also explore more specific...
Conference Paper
ABSTRACT Experimentation is an essential tool employed by the devel- opers of software systems, especially distributed systems. In prior work we developed a model-driven framework,for au- tomating various experimentation tasks, such as workload generation, and demonstrated that it gives the engineer a cost-effective means,to conduct large-scale exp...
Conference Paper
In the mid 1990s the Internet began to emerge as a communication and application platform for the masses, enabled by infrastructures from CORBA to the World Wide Web. Consequently, software engineering researchers began to address the many challenges and opportunities of engineering large-scale, highly networked distributed systems. At the same tim...
Conference Paper
The International Workshop on the Engineering of Software Services for Pervasive Environments (ESSPE) brings together researchers interested in the software engineering challenges found at the convergence of software services and pervasive environments. This summary presents the motivation for the workshop and a brief review of the papers appearing...
Conference Paper
Network processors provide an economical programmable platform to handle the high throughput and frame rates of modern and next-generation communication systems. How- ever, these platforms have exchanged general-purpose capa- bilities for performance. This paper presents an alternative; a software network processor (Soft-NP) framework using commodi...
Conference Paper
The International Workshop on the Engineering of Software Services for Pervasive Environments (ESSPE) brings together researchers interested in the software engineering challenges found at the convergence of software services and pervasive environments. This summary presents the motivation for the workshop and a brief review of the papers appearing...
Article
Software architecture specifications are predominantly concerned with describing the component structure of systems and how the components interact behaviorally. Little attention has been paid to formally relating those specifications to higher levels of specification, such as the system requirements. In this paper we present our progress toward ad...
Article
Developers of distributed systems routinely construct discrete-event simulations to help them un-derstand and evaluate the behavior of inter-component protocols. Typically written using an imperative programming language, these simulations capture basic algorithmic functionality at the same time as they focus attention on properties critical to dis...
Conference Paper
Developers of distributed systems routinely construct discrete-event simulations to help understand and evaluate the behavior of inter-component protocols. Simulations are abstract models of systems and their environments, captur- ing basic algorithmic functionality at the same time as they focus attention on properties critical to distribution, in...
Article
Abstract The high performance, low cost, and flexibility of commodity hardware systems make them appealing for network processing applications. However, the standard software architecture of such systems imposes,significant limitations. At high rates (e.g., Gigabit Ethernet) and small frame sizes (64 byte) each frame must be processed in less than...
Article
One of the characteristics of autonomic systems is self recovery from failures. Self recovery can be achieved through sensing failures, planning for recovery and executing the recovery plan to bring the system back to a normal state. For various reasons, however, additional failures are possible during the process of recovering from the initial fai...
Article
Distributed software systems are notoriously difficult to test. As in all software testing, the space of potential test cases for distributed systems is intractably large and so the efforts of testers must be directed to the scenarios that are most important. Unfortunately, there does not currently exist a general-purpose, disciplined, and effectiv...
Conference Paper
Engineering distributed systems is a challenging activity. This is partly due to the intrinsic complexity of distributed systems, and partly due to the practical obstacles that de- velopers face when evaluating and tuning their design and implementation decisions. This paper addresses the latter aspect, providing techniques for software engineers t...
Article
Engineering distributed systems is a challenging activity. This is partly due to the intrinsic complexity of dis-tributed systems, and partly due to the practical obstacles that developers face when evaluating and tuning their design and implementation decisions. This paper addresses the latter aspect, providing techniques for software engineers to...
Conference Paper
These days, if you say that you are doing research in the area of computer security you instantly receive attention. Sadly, the same cannot be said of software engineering. But are the two areas really so different? Both seem to be concerned with issues that range from the finely technical to the broadly social and that force us to make difficult t...
Article
The University of Colorado DASADA project provides an application architecture and associated automated infrastructure (FIRM) that can support the dynamic reconfiguration of a software system. Its intended use is to insert sensor probes and actuators into a target system and to support the reconfiguration of the target to improve its operation base...
Conference Paper
Failure recovery in distributed systems poses a difficult challenge because of the requirement for high availability. Failure scenarios are usually unpredictable so they can not easily be foreseen. In this research we propose a planning based approach to failure recovery. This approach automates failure recovery by capturing the state after failure...
Article
This paper presents an algorithm for content-based forwarding, an essential function in content-based networking. Unlike in traditional address-based unicast or multicast networks, where messages are given explicit destination addresses, the movement of messages through a content-based network is driven by predicates applied to the content of the m...
Article
Understanding the dynamic behavior of a workflow is crucial for being able to modify, maintain, and improve it. A particularly difficult aspect of some behavior is concurrency. Automated techniques which seek to mine workflow data logs to discover information about the workflows must be able to handle the concurrency that manifests itself in the wo...
Article
Full-text available
This paper presents the design and evaluation of a support service for mobile, wireless clients of a distributed publish/subscribe system. A distributed publish/subscribe system is a networked communication infrastructure where messages are published by senders and then delivered to the receivers whose subscriptions match the messages. Communicatio...
Article
The quality of software systems are determined in part by their optimal configurations. Optimal configurations are desired when the software is being deployed and during its lifetime. However, initial deployment and subsequent dynamic reconfiguration of a software system is difficult because of the interplay of many interdependent factors, includin...
Article
This paper proposes a routing scheme for content-based networking. A content-based network is a communication network that features a new advanced communication model where messages are not given explicit destination addresses, and where the destinations of a message are determined by matching the content of the message against selection predicates...
Conference Paper
A primary goal of generative programming and model-driven development is to raise the level of abstraction at which designers and developers interact with the software systems they are building. During initial development, the benefits of abstraction are clear. However, during testing and maintenance, increased distance from the implementation can...
Article
Keywords: Critical Infrastructure Survivability, Distributed System Fault Tolerance Submission category: Regular paper Word count: 6486 The material included in this paper has been cleared throughthe authors' affiliations Contact author: CARTER Award: No.
Article
Full-text available
this paper we summarize the Willow concepts and provide an overview of the Willow architecture. Finally we describe a demonstration application system that has been built on top of a prototype Willow implementation
Article
Nowadays, more and more often, complex systems are built by assembling together different system components. This technology also affects the construction of heterogeneous and/or hybrid systems where components can represent hardware sensors, software ...
Article
This fellowship was intended to increase the capabilities of the identified fellow with respect to the area of security and information assurance by placing the fellow at the University of California at Davis Computer Science Department. This process succeeded by a number of measures. The fellow was able to quickly get up-to-speed on security. He i...
Article
Military information systems, such as a JBI, have evolved to a point where military organizations rely heavily upon them. In fact, the ability of the Department of Defense to use its resources effectively is contingent on the proper operation of these information systems. Improving the survivability of critical military information systems is essen...
Article
this paper serves is to guide research in the area of mobile wireless infrastructure, in part to flesh out the infrastructure requirements all participants agreed upon, and also to cast light upon the areas where no agreement was reached. Relevant funding agencies and companies interested in research in this area should consider these unanswered qu...
Article
Software release management is the process through which software is made available to and obtained by its users. Until now, this process has been relatively straightforward. However, the emergence of component-based software is com- plicating software release management. Increasingly, software is constructed via the assembly of pre-existing, indep...
Conference Paper
Full-text available
We describe Lira, a lightweight infrastructure for managing dynamic reconfiguration that applies and extends the concepts of network management to component-based, distributed software systems. Lira is designed to perform both component-level reconfigurations and scalable application-level reconfigurations, the former through agents associated with...
Conference Paper
Full-text available
As the focus of software design shifts increasingly toward the architectural level, so too are its analysis techniques. Dependence analysis is one such technique that shows promise at this level. In this paper we briefly describe and illustrate the application of dependence analysis to architectural descriptions of software systems.
Article
This paper presents an algorithm for content-based forwarding, an essential function in content-based networking. Unlike in traditional address-based unicast or multicast networks, where messages are given explicit destination addresses, the movement of messages through a content-based network is driven by predicates applied to the content of the m...