1. A system, comprising: one or more computer devices configured to implement a web services platform configured to provide a web service interface to a searchable data service, wherein the web services platform is configured to receive service requests from a plurality of client applications in accordance with the web service interface, wherein the service requests comprise query requests and storage requests, and wherein the web service interface provides a common message endpoint to the plurality of client applications to send the query requests and storage requests; and a plurality of computer devices configured to implement a plurality of nodes configured to participate in the searchable data service to: store searchable data service objects specified in received storage requests in respective searchable indexes for a plurality of independent data stores used by the client applications, wherein the searchable indexes are on the plurality of nodes, wherein the data stores are on one or more storage devices each on a network and separate from the one or more computer devices that implement the plurality of nodes configured to participate in the searchable data service, wherein each searchable index stores searchable data service objects for a particular one of the plurality of independent data stores such that each searchable index provides a complete index for only one of the independent data stores, wherein each searchable data service object specifies two or more attributes of a particular entity in a particular data store, wherein the attributes include a unique entity identifier for locating the particular entity in the particular data store; locate sets of one or more searchable data service objects from the searchable indexes that satisfy received query requests, wherein the received query requests specify one of the searchable indexes; and return at least the entity identifiers from the sets of one or more searchable data service objects that satisfy the query requests to the client applications in accordance with the web service interface.
1. A system, comprising: one or more computer devices configured to implement a web services platform configured to provide a web service interface to a searchable data service, wherein the web services platform is configured to receive service requests from a plurality of client applications in accordance with the web service interface, wherein the service requests comprise query requests and storage requests, and wherein the web service interface provides a common message endpoint to the plurality of client applications to send the query requests and storage requests; and a plurality of computer devices configured to implement a plurality of nodes configured to participate in the searchable data service to: store searchable data service objects specified in received storage requests in respective searchable indexes for a plurality of independent data stores used by the client applications, wherein the searchable indexes are on the plurality of nodes, wherein the data stores are on one or more storage devices each on a network and separate from the one or more computer devices that implement the plurality of nodes configured to participate in the searchable data service, wherein each searchable index stores searchable data service objects for a particular one of the plurality of independent data stores such that each searchable index provides a complete index for only one of the independent data stores, wherein each searchable data service object specifies two or more attributes of a particular entity in a particular data store, wherein the attributes include a unique entity identifier for locating the particular entity in the particular data store; locate sets of one or more searchable data service objects from the searchable indexes that satisfy received query requests, wherein the received query requests specify one of the searchable indexes; and return at least the entity identifiers from the sets of one or more searchable data service objects that satisfy the query requests to the client applications in accordance with the web service interface. 4. The system as recited in claim 1 , wherein the plurality of nodes comprises one or more query nodes each configured to maintain a local query cache of responses to previous query requests.