The Internet has made tremendous progress since its inception. The kingpin has been the transmission control protocol (TCP), which supports a large fraction of communication. With the Internet's wide-spread access, users now have increased expectations. The demands have evolved to an extent which TCP was never designed to support. Since network stacks do not provide the necessary functionality for modern applications, developers are forced to implement them over and over again --- as part of the application or supporting libraries. Consequently, application developers not only bear the burden of developing application features but are also responsible for building networking libraries to support sophisticated scenarios. This leads to considerable duplication of effort. The challenge for TCP in supporting modern use cases is mostly due to limiting assumptions, simplistic communication abstractions, and (once expedient) implementation shortcuts. To further add to the complexity, the limited TCP options space is insufficient to support extensibility and thus, contemporary communication patterns. Some argue that radical changes are required to extend the networks functionality; some researchers believe that a clean slate approach is the only path forward. Others suggest that evolution of the network stack is necessary to ensure wider adoption --- by avoiding a flag day. In either case, we see that the proposed solutions have not been adopted by the community at large. This is perhaps because the cost of transition from the incumbent to the new technology outweighs the value offered. In some cases, the limited scope of the proposed solutions limit their value. In other cases, the lack of backward compatibility or significant porting effort precludes incremental adoption altogether. In this dissertation, we focus on the development of a communication model that explicitly acknowledges the context of the conversation and describes (much of) modern communications. We highlight how the communication stack should be able to discover, interact with and use available resources to compose richer communication constructs. The model is able to do so by using session, flow and endpoint abstractions to describe communications between two or more endpoints. These abstractions provide means to the application developers for setting up and manipulating constructs, while the ability to recognize change in the operating context and reconfigure the constructs allows applications to adapt to the changing requirements. The model considers two or more participants to be involved in the conversation and thus enables most modern communication patterns, which is in contrast with the well-established two-participant model. Our contributions also include an implementation of a framework that realizes such communication methods and enables future innovation. We substantiate our claims by demonstrating case studies where we use the proposed abstractions to highlight the gains. We also show how the proposed model may be implemented in a backwards compatible manner, such that it does not break legacy applications, network stacks, or middleboxes in the network infrastructure. We also present use cases to substantiate our claims about backwards compatibility. This establishes that incremental evolution is possible. We highlight the benefits of context awareness in setting up complex communication constructs by presenting use cases and their evaluation. Finally, we show how the communication model may open the door for new and richer communication patterns. / PHD

Approved for public release, distribution is unlimited / The use of specialized single-level networks in current military operations is inadequate to meet the need to share information envisioned by the Global Information Grid (GIG). Multilevel security (MLS) is a key Information Assurance enabler for the GIG vision. The Monterey Security Architecture (MYSEA), a distributed MLS network, eliminates the need to use separate equipment to connect to many networks at different classification levels. It allows users to view data at different sensitivities simultaneously. MYSEA also allows commercial software and hardware to be used at clients. To address the threat of residual data on the client after a user session change in security state, the MYSEA clients are required to be "stateless", i.e., there is no non-volatile writable memory. Hence the MYSEA server must provide the clients with the ability to execute server-resident client-side applications to access data at different security levels over the MLS Local Area Network (LAN). The MYSEA server currently does not support such capability. This thesis addresses this limitation. A new trusted process family is introduced to provide a pseudo-socket interface for the single level remote application to access the MLS LAN interface. Detailed design specifications were created to facilitate implementation of the remote application support. / Lieutenant, United States Navy

<p>This thesis is a collection of seven papers reporting a research effort that started in January 1999. The theme of the thesis is interaction support for mobile CSCW (Computer Supported Cooperative Work). The interest in this theme is motivated by the trend towards a networked and nomadic society, the technical trends towards embedded, ubiquitous, and mobile technology, and the emergence of mobile CSCW settings. It is also motivated by current trends within the area of CSCW to focus on actual work practices, invisible and ubiquitous computer support, and mobile work settings where interaction with others is critical to get the work done.</p><p>For some time now mobile technology has been widely used to support dispersed mobile interaction, and recently the importance of co-located ”mobile meetings” to get the work done, has been recognized in the area of CSCW. However, current technology is not well suited when it comes to support interaction in mobile work settings across co-located and dispersed settings. Here, this problem is approached from an informatics perspective. Informatics can be described as a theory and design oriented study of information technology use. The scope of this thesis can be defined as understanding transformations of work practice through the use of mobile technology, and how it might be supported. The overall research question is: What are the specific needs of interaction support related to mobile meetings and dispersed interaction, how might these be supported, and what are the implications for current interaction models and support within CSCW? To answer this question several activities have been undertaken. This thesis contains empirical studies of mobile work among service technicians at Telia Nära, models of mobility and mobile meetings, and design and evaluations of a prototype system called RoamWare.</p><p>The overall conclusions related to the question stated in this thesis are that mobile interaction can be described as ongoing across mobile meetings, including both co-located face-to-face and dispersed interaction. Further, the interaction is maintained by the mobile workers through their efforts of re-establishing different threads of interaction across co-located and dispersed settings. Overall: There is a need to bridge co-located and dispersed meetings with sustained interaction support. Concerning the second part of the overall research question one conclusion is that sustained interaction across co-located and dispersed settings can be supported with mobile physical/virtual meetings support systems through the use of personal and public interaction histories. To illustrate and test this idea a prototype system called RoamWare was developed. However, evaluations of RoamWare revealed that synchronous support for sustained interaction divides users’ attention between co-located and dispersed interaction. As a consequence a second version of RoamWare was developed as an unobtrusive support for sustained interaction in between mobile meetings through seamless reestablishment of different threads of interaction, by offering support for converting interaction histories into project contexts. Finally, and according to the last part of the question stated above, this thesis concludes that current session management models need to be extended to handle sustained and dynamic sessions of interaction across co-located and dispersed mobile meetings and that, techniques for addressing groups need to be extended to enable dynamic addressing of participants in co-located mobile meeting. Finally, the exploration of how to support sustained interaction in between mobile meetings reveals important aspects to consider when trying to automatically frame spontaneous interaction with mobile technology.</p><p>Directions for future work include questions of how to design filters to support: maintenance, participation in, and negotiation about participation in between, different mobile meetings. Further, more work is needed related to how to capture spontaneous face-to-face interaction technically. Finally, new methods are needed to enable good evaluations of the impact of IT in mobile work settings.</p>

This thesis is a collection of seven papers reporting a research effort that started in January 1999. The theme of the thesis is interaction support for mobile CSCW (Computer Supported Cooperative Work). The interest in this theme is motivated by the trend towards a networked and nomadic society, the technical trends towards embedded, ubiquitous, and mobile technology, and the emergence of mobile CSCW settings. It is also motivated by current trends within the area of CSCW to focus on actual work practices, invisible and ubiquitous computer support, and mobile work settings where interaction with others is critical to get the work done. For some time now mobile technology has been widely used to support dispersed mobile interaction, and recently the importance of co-located ”mobile meetings” to get the work done, has been recognized in the area of CSCW. However, current technology is not well suited when it comes to support interaction in mobile work settings across co-located and dispersed settings. Here, this problem is approached from an informatics perspective. Informatics can be described as a theory and design oriented study of information technology use. The scope of this thesis can be defined as understanding transformations of work practice through the use of mobile technology, and how it might be supported. The overall research question is: What are the specific needs of interaction support related to mobile meetings and dispersed interaction, how might these be supported, and what are the implications for current interaction models and support within CSCW? To answer this question several activities have been undertaken. This thesis contains empirical studies of mobile work among service technicians at Telia Nära, models of mobility and mobile meetings, and design and evaluations of a prototype system called RoamWare. The overall conclusions related to the question stated in this thesis are that mobile interaction can be described as ongoing across mobile meetings, including both co-located face-to-face and dispersed interaction. Further, the interaction is maintained by the mobile workers through their efforts of re-establishing different threads of interaction across co-located and dispersed settings. Overall: There is a need to bridge co-located and dispersed meetings with sustained interaction support. Concerning the second part of the overall research question one conclusion is that sustained interaction across co-located and dispersed settings can be supported with mobile physical/virtual meetings support systems through the use of personal and public interaction histories. To illustrate and test this idea a prototype system called RoamWare was developed. However, evaluations of RoamWare revealed that synchronous support for sustained interaction divides users’ attention between co-located and dispersed interaction. As a consequence a second version of RoamWare was developed as an unobtrusive support for sustained interaction in between mobile meetings through seamless reestablishment of different threads of interaction, by offering support for converting interaction histories into project contexts. Finally, and according to the last part of the question stated above, this thesis concludes that current session management models need to be extended to handle sustained and dynamic sessions of interaction across co-located and dispersed mobile meetings and that, techniques for addressing groups need to be extended to enable dynamic addressing of participants in co-located mobile meeting. Finally, the exploration of how to support sustained interaction in between mobile meetings reveals important aspects to consider when trying to automatically frame spontaneous interaction with mobile technology. Directions for future work include questions of how to design filters to support: maintenance, participation in, and negotiation about participation in between, different mobile meetings. Further, more work is needed related to how to capture spontaneous face-to-face interaction technically. Finally, new methods are needed to enable good evaluations of the impact of IT in mobile work settings.