35. A computer-implemented method, comprising: receiving service requests from a plurality of client applications on a web service interface to a searchable data service, wherein the service requests comprise query requests and storage requests, and wherein said receiving comprises receiving the query requests and storage requests at a common message endpoint provided by the web service interface to the plurality of client applications to send the query requests and storage requests; forwarding each service request from the web service interface to one of a plurality of nodes configured to participate in the searchable data service; processing received storage requests on the plurality of nodes to store searchable data service objects specified in the 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, and wherein the attributes include a unique entity identifier for locating the particular entity in the particular data store; processing each received query request on the plurality of nodes to locate a set of one or more searchable data service objects from the searchable indexes that satisfy the query request, wherein the received query requests specify one of the searchable indexes; and returning at least the entity identifiers from the set of one or more searchable data service objects that satisfy the query request to the client applications in accordance with the web service interface.
35. A computer-implemented method, comprising: receiving service requests from a plurality of client applications on a web service interface to a searchable data service, wherein the service requests comprise query requests and storage requests, and wherein said receiving comprises receiving the query requests and storage requests at a common message endpoint provided by the web service interface to the plurality of client applications to send the query requests and storage requests; forwarding each service request from the web service interface to one of a plurality of nodes configured to participate in the searchable data service; processing received storage requests on the plurality of nodes to store searchable data service objects specified in the 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, and wherein the attributes include a unique entity identifier for locating the particular entity in the particular data store; processing each received query request on the plurality of nodes to locate a set of one or more searchable data service objects from the searchable indexes that satisfy the query request, wherein the received query requests specify one of the searchable indexes; and returning at least the entity identifiers from the set of one or more searchable data service objects that satisfy the query request to the client applications in accordance with the web service interface. 49. The computer-implemented method as recited in claim 35 , wherein the plurality of nodes comprises two or more storage nodes, and wherein the method further comprises: communicating between the storage nodes to locate a volunteer storage node that volunteers to receive a replica of a partition of a particular searchable index persistently stored by one of the storage nodes; and performing a cooperative operation between the storage node and the volunteer storage node to replicate the partition to the other storage node.