Negotiation of information contracts between information providers and consumers
A method for automatically supplying or locating data over a communication network comprising: configuring a data source to provide source data over the communication network, the source data being identified by a data identifier in a domain of identifiers; receiving a machine-readable description, the machine-readable description specifying at least one predicate that must be satisfied by the data; labeling data identified by the data identifier with labels at least in part indicative of data predicates that hold true for the data identified by the data identifier or that are satisfiable for the data identified by the data identifier; searching for the data based at least in part on the machine-readable description and the labels; obtaining a solution satisfying the predicate based on the search; and supplying the solution over the communication network to a data consumer.
1 . A method for automatically supplying or locating data over a communication network, the method comprising:
configuring, by a system, at least one data source comprising a field device to provide source data over the communication network, the source data being identified by at least one data identifier in a domain of identifiers, wherein the at least one data identifier comprises one or more memory locations;
receiving, by a first subsystem of the system, a machine-readable description, the machine-readable description specifying at least one predicate that must be satisfied by the source data, wherein the at least one predicate provides semantical information about the source data, wherein the at least one predicate comprises one or more binary or n-ary predicates with a truth value fixed by pairs or tuples;
labeling, by a second subsystem of the system, the source data identified by the at least one data identifier with one or more labels indicative of data predicates that hold true for the source data identified by the at least one data identifier or that are satisfiable for the source data identified by the at least one data identifier;
searching, by a third subsystem of the system, for the source data based on the machine-readable description and the labels;
obtaining, by a fourth subsystem of the system, at least one solution in a solution set satisfying the at least one predicate based on the search; and
supplying, by the system, the at least one solution over the communication network to a data consumer, wherein the at least one solution comprises access to at least one of the one or more memory locations over the communication network;
wherein the at least one predicate is obtained based on an information model.
2 . The method of claim 1 , wherein the at least one solution comprises at least a data identifier that allows access to the source data for at least one of reading and writing.
3 . The method of claim 1 , wherein the at least one solution identifies an information model or where the data predicates are obtained from an information model.
4 . The method of claim 3 , wherein the information model is an OPC UA information model from which predicates are extracted.
5 . The method of claim 1 , wherein the at least one predicate or the data predicates are expressed with an expression that is then translated to intermediate representations of the predicates based on translation rules.
6 . The method of claim 5 , wherein the predicates are expressed based on an information model.
7 . The method of claim 1 , wherein equivalence between predicates or likely equivalence between predicates is automatically detected.
8 . The method of claim 7 , wherein the equivalence or likely equivalence between predicates is determined based on syntactic or semantic characteristics.
9 . The method of claim 8 , wherein the equivalence between predicates is determined based on strings matching regular expressions.
10 . The method of claim 1 , wherein the search is a parallel distributed search and the data identifier identifies a path in a graph to a node storing the identified source data.