13. A program storage device readable by computer, tangibly embodying a program of instructions executable by said computer to perform a method of automated data integration, said method comprising: establishing extensible markup language (XML) mappings between XML source schemas and an XML target schema, wherein said XML source schemas comprise data; and wherein said XML target schema comprises a set of constraints, said set of constraints comprising: data merging rules for integrating said data from multiple said XML source schemas comprising overlapping information; and nested equality-generating dependencies (NEGDs), said NEGDs comprising rules specifying that fields in two different data tuples must be merged; querying multiple XML source schemas through a common XML target schema, wherein said common XML target schema defines a set of terms and a structure that a target query refers to; rewriting said target query in terms of said XML source schemas based on said XML mappings; integrating said data based on said set of constraints evaluating a union of a set of source queries, wherein said evaluating occurs at query run-time; and displaying results of said rewriting and said integrating to a user.
13. A program storage device readable by computer, tangibly embodying a program of instructions executable by said computer to perform a method of automated data integration, said method comprising: establishing extensible markup language (XML) mappings between XML source schemas and an XML target schema, wherein said XML source schemas comprise data; and wherein said XML target schema comprises a set of constraints, said set of constraints comprising: data merging rules for integrating said data from multiple said XML source schemas comprising overlapping information; and nested equality-generating dependencies (NEGDs), said NEGDs comprising rules specifying that fields in two different data tuples must be merged; querying multiple XML source schemas through a common XML target schema, wherein said common XML target schema defines a set of terms and a structure that a target query refers to; rewriting said target query in terms of said XML source schemas based on said XML mappings; integrating said data based on said set of constraints evaluating a union of a set of source queries, wherein said evaluating occurs at query run-time; and displaying results of said rewriting and said integrating to a user. 14. The program storage device according to claim 13 , further comprising rewriting said target query into a set of source queries comprising said source XML schemas.