text: This paper presents a logic based approach to debugging Java programs. In contrast with traditional debugging we propose a debugging methodology for Java programs using logical queries on individual execution states and also over the history of execution. These queries were arrived at by a systematic study of errors in object-oriented programs in our earlier research. We represent the salient events during the execution of a Java program by a logic database, and implement the queries as logic programs. Such an approach allows us to answer a number of useful and interesting queries about a Java program, such as the calling sequence that results in a certain outcome, the state of an object at a particular execution point, etc. Our system also provides the ability to compose new queries during a debugging session. We believe that logic programming offers a significant contribution to the art of object-oriented programs debugging.
  @cite_12: A programmer attempting to understand and debug a distributed program deals with large volumes of trace data that describe the program's behaviour. Visualization is widely believed to help in this and similar tasks. We contend that visualization is indeed useful, but only if accompanied of powerful data management facilities to support abstraction and filtering. The Hy+ visualization system and GraphLog query language provide these facilities. They support not just a fixed way of visualizing data, but visualizations that can be specified and manipulated through declarative queries, like data are manipulated in a database. In this paper we show how the Hy+ GraphLog system can be used by distributed program debuggers to meet their information manipulation and visualization goals.
summary: Hy @math @cite_12 is a visual debugger for distributed programs. The system works as follows. The program is instrumented to obtain trace which is used to build database implemented in CORAL. Programmers can specify debugging queries and visualizations using a visual declarative query language called GraphLog. These visual queries once formulated can be saved and applied to other programs since these queries are application independent. This technique allows the programmere to visualize a specific program behavior pattern and filter out irrelevant events. Hy @math performs static trace analysis and has a simple postmortem dynamic trace analysis by animating the program trace.