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A communication infrastructure to ease the development of mobile collaborative applications

Mobile workers doing loosely coupled activities typically perform on demand collaboration in the physical workplace. Communication services available in such work scenarios are uncertain, therefore mobile collaborative applications supporting those activities must provide ad hoc communication mechanisms in order to use each cooperation opportunity. Typically, the complexity of implementing such mobile ad hoc communication mechanisms becomes a challenge that jeopardizes the development of mobile collaborative solutions. This article presents a communication infrastructure named HLMP API dealing with that challenge. HLMP API intends to ease the development of such applications through the reuse of communication services. The infrastructure is an application programming interface that implements the HLMP routing protocol and also some awareness mechanisms that are required for mobile loosely coupled work. Developers using this infrastructure do not have to perform low-level programming.

Wildfire monitoring using a mixed air-ground mobile network

Forest fires are a challenging problem for many countries. They often cause economical lost and ecological damage, and they can sometimes even cost human lives. Finding hot spots immediately after a fire is an important part of fighting forest fires. The main objective is to obtain a temperature map of the burned area, to locate the most critical embers. This information can help firefighter managers make the correct decisions about ground crew movements. The pervasive application described in this article lets firefighters obtain images of hot spots directly from an unmanned aircraft and receive commands from their manager through a communication network. Every firefighter holds a personal electronic device (PED), which includes a touch screen, Wi-Fi connectivity, a GPS receiver, and temperature sensors. Because terrain conditions such as abrupt ravines, rocks, and dense vegetation can introduce obstacles to connectivity, a balloon with a Wi-Fi device is tethered to every firefighters truck to improve communication. In addition, a fixed-wing unmanned aircraft augments the number of communication layers to three. This article studies the quality of this three-layered network in maintaining the applications bandwidth requirements.

Decentralized vs. centralized economic coordination of resource allocation in grids

Application layer networks are software architectures that allow the provisioning of services requiring a huge amount of resources by connecting large numbers of individual computers, like in Grid or Peer-to-Peer computing. Controlling the resource allocation in those networks is nearly impossible using a centralized arbitrator. The network simulation project CATNET will evaluate a decentralized mechanism for resource allocation, which is based on the economic paradigm of the Catallaxy, against a centralized mechanism using an arbitrator object. In both versions, software agents buy and sell network services and resources to and from each other. The economic model is based on self-interested maximization of utility and self-interested cooperation between agents. This article describes the setup of money and message flows both for centralized and decentralized coordination in comparison.

Communication and coordination patterns to support mobile collaboration

Wireless communication and mobile computing technologies have brought new opportunities and challenges to the CSCW area. Traditional CSCW solutions concerning communication and coordination support are not applicable to mobile collaboration scenarios. Therefore, new reusable solutions have to be proposed in order to ease the development of mobile collaborative applications. This paper presents a set of design patterns to support communication and coordination in mobile ad-hoc scenarios. These two aspects are the basis to support mobile collaboration.

Building real-world ad-hoc networks to support mobile collaborative applications: lessons learned

Mobile collaboration is required in several work scenarios, i.e. education, healthcare, business and disaster relief. The features and capabilities of the communication infrastructure used by mobile collaborative applications will influence the type of coordination and collaboration that can be supported in real work scenarios. Developers of these applications are typically unaware of the constraints the communication infrastructure imposes on the collaborative system. Therefore, this paper presents an experimental study of how ad-hoc networks can effectively support mobile collaborative work. The article analyzes several networking issues and it determines how they influence the collaborative work. The paper also presents the lessons learned and it provides recommendations to deal with the networking issues intrinsic to adhoc networks.

ULabGrid, an Infrastructure to Develop Distant Laboratories for Undergrad Students over a Grid

There has been a lot of discussion and study in the recent past about how distance learning could be improved using emerging technologies. Collaborative tools based on the web/internet infrastructure such as e-mail, discussion groups, video/audio conferencing and virtual campuses have been proposed and implemented in many areas of distance learning. We had proposed [3] ULabGrid as a new architecture that enables educators to design collaborative, distant laboratories for undergraduate students using the Grid infrastructure. We describe here some of the changes we have made to the proposed architecture and the prototype that is being developed and present the results of our efforts to date.

Sharing hardware resources in heterogeneous computer-supported collaboration scenarios

There currently are many mobile computing devices with various properties and capabilities. These devices may need to collaborate among them to allow nomad workers to perform a common activity. Unfortunately software developers in charge of creating infrastructures or applications allowing these devices to cooperate among them, do not count with clear guidelines to design such software components; particularly when these components must work in a scenario involving heterogeneous devices. This paper presents a study that tries to understand how to address collaboration among heterogeneous mobile devices, by exploring several variables affecting the process. In particular, this study explores various strategies to borrow CPU slots from peer mobile computing devices and return the favor back later on. The study outcomes indicate there is a short list of computing and network variables affecting the collaboration capability of the mobile devices. These findings have been verified using data mining techniques. Based on these findings and the lessons learned, the article presents a simulation method of computing scenarios that can help developers to determine which computing configuration would be suitable to be used in each particular work scenario. Software designers can take advantage of this simulation method and the design guidelines reported in this paper in order to develop applications able to work appropriately in heterogeneous computing scenarios.

HLMP API: A software library to support the development of mobile collaborative applications

Mobile collaborative applications are usually deployed in work scenarios where the existence of fixed communication infrastructure is hard to predict. For that reason, these applications use Mobile Ad hoc Networks (MANETs) to support communication between mobile users. The complexity involved in such communication infrastructures make that developers avoid developing software for mobile work scenarios. However, it is possible to provide a reusable abstraction of such communication mechanisms, in order to avoid that developers have to deal with low-level programming. This article presents HLMP API, which is an application programming interface that provides access to a HLMP implementation. This API is organized as a fully distributed mobile communication infrastructure, able to run on MANETs. This infrastructure provides an important set of services, which are required to support mobile collaboration. The reuse of these services allows developers to reduce the complexity, times and cost of these development projects.

Topology-aware group communication middleware for MANETs

We believe that any MANET middleware should be aware of the underlying multi-hop routing protocol to improve communication efficiency. In general, existing MANET middleware either ignore the underlying routing protocol or create specific cross-layer solutions that break the strict layering of the network stack. This problem is even more severe in the case of traditional group communication middleware (GC) where membership protocols, failure detection mechanisms or flow control layers can considerably harm the overall performance of the network. We propose to move the routing logic to the application layer in order to achieve a smooth and clean integration between the middleware and the underlying MANET topology. In this line, we have modified a well-known GC toolkit (JGroups) in order to adapt membership protocols, failure detectors and flow control mechanisms to the underlying MANET topology. We have implemented the MANET OLSR protocol in the application layer using UDP (jOLSR). On top of it, we have developed an overlay Multicast protocol (OMOLSR) that directly benefits from the OLSR protocol to improve communication efficiency. As a consequence, in our middleware group membership is obtained from OMOLSR, failure detection from the jOLSR protocol, and our modified flow control protocol benefits from jOLSR topology information. We validate our approach in a real test-bed to demonstrate the feasibility and efficiency of our middleware.

Group Prediction in Collaborative Learning

We propose an approach for predicting group formations, to address the problem of automating the incorporation of group awareness into CSCL applications. Contextual information can enable the construction of applications that effectively assist the group members to automatically communicate in synchronous and collocated collaborative learning activities. We used data traces collected from the study of students’ behavior to train and test an intelligent system. Results have shown that context-information can be effectively used as a basis for a middleware for a dynamic group management. Inferring group membership is technically viable and can be used in real world settings.