Programming Claytronics with Locally Distributed Predicates (LDP)

Locally Distributed Predicates (LDP) approaches the distributed programming problem using pattern-matching techniques. LDP provides programmers the ability to specify distributed state configurations, based on combinations of the state found on connected subgroups of catoms. The LDP runtime automatically detects occurrences of these distributed configurations, and triggers user-specified actions in response to the detection event.

LDP also allows for the expression of distributed event sequences (through the use of automated history and temporal operators), as well as the expression of particular shapes (through topological restrictions). These facilities, combined with an array of mathematical and logical operators, allow programmers to express a wide variety of distributed conditions. As with Meld, LDP produces dramatically shorter code than traditional high-level languages (C++, Java, etc.).

LDP is descended from work on distributed debugging, and as such its strengths lie in the ability to efficiently detect conditions on variably-sized groups of modules, interface easily with existing low-level code, and easily express a large numbers of common distributed programming idioms. LDP has been used to implement several motion planning algorithms, as well as a variety of low-level utilities such as gradient fields and distributed aggregation.

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