Synchronous groupware depends on the assumption that people are fully connected to the others in the group, but there are many situations (network delay, network outage, or explicit departure) where users are disconnected for various periods. There is little research dealing with disconnection in synchronous groupware from a user and application perspective; as a result, most current groupware systems do not handle disconnection events well, and several user-level problems occur. To address this limitation, we developed the Disco framework, a model for handling several types of disconnection in synchronous groupware. The framework considers how disconnections are identified, what senders and receivers should do during an absence, and what should be done with accumulated data upon reconnection. We have implemented the framework in three applications that show the feasibility, generality, and functionality of our ideas. Our framework is the first to deal with a full range of disconnection issues for synchronous groupware, and shows how groupware can better support the realities of distributed collaboration.

Programmers seek to answer questions as they investigate the functioning of a software system, such as "which execution path is being taken in this case?" Programmers attempt to answer these questions, which we call conceptual queries, using a variety of tools. Each type of tool typically highlights one kind of information about the system, such as static structural information or control-flow information. Unfortunately for the programmer, the tools seldom directly answer the programmer's conceptual queries. Instead, the programmer must piece together results from different tools to determine an answer to the initial query. At best, this process is time consuming and at worst, this process can lead to data overload and disorientation.

Programmers need tools to help explore large software systems when performing software evolution tasks. A variety of tools have been created to improve the effectiveness of such exploration. The usefulness of these tools has been argued largely on the basis of case studies, small narrowly-focussed experiments, or non-human-based experiments. In this paper, we report on a more rigorously controlled study of three specialized software exploration tools in which professional programmers used the tools to plan complex change tasks to a medium-sized code base. We found that the tools had little apparent effect; the effects observed instead appear to be dominated by individual styles and strategies of the programmers and characteristics of the tasks. In addition to presenting the results of the study, this paper introduces the use of two experimental evaluation aids: the NASA task load index (TLX) for assessing task difficulty and distance profiles for assessing the to which programmers remain on-track.

We report on a field study about how software developers experience disorientation when using the Eclipse Java integrated development environment. We analyzed the data using the theory of visual momentum, identifying three factors that may lead to disorientation: the absence of connecting navigation context during program exploration, thrashing between displays to view necessary pieces of code, and the pursuit of sometimes unrelated subtasks