1. A receiving apparatus comprising: a memory configured to store service information including search criteria set in a memory device and a connection method for connecting with the memory device, the memory device storing attribute information including attributes of contents in a searchable condition and being connectable via a network, the service information is defined on a service-by-service basis; a first generator configured to generate a common search query that expresses search conditions used in searching content and at least a pair of a common search condition attribute and a common search condition attribute value, the common search condition attribute having a common mode of expression of a search condition attribute that represents any of the attributes, the common search condition attribute value being a value taken by the common search condition attribute; a second generator configured to generate a search query according to the search criteria specified in the service information with the use of the generated common search query; a transmitter configured to transmit the generated search query to the memory device based on the connection method specified in the service information; and a receiver configured to receive, from the memory device, the attribute information obtained as a result of executing the search query, wherein the attribute information is metadata, the service information further includes a metadata attribute that is an attribute represented by the metadata which is provided as a result of executing the search query and a metadata description format that is a description format of the metadata, includes a search condition attribute representing the metadata attribute that is specifiable as a search condition in the search query, the search conditional attribute is defined on the service-by-service basis, includes a search query description format representing a description format of the search query that can be processed by the memory device, and includes a metadata attribute conversion table representing a correspondence relationship between the metadata attributes, the search condition attributes, and the common search condition attributes, and the second generator generates the search query that includes the search condition attributes and that is written in the search query description format, the search condition attributes being obtained by conversion of the common search condition attributes included in the common search query with the use of the metadata attribute conversion table, wherein the common search query has, as a common search condition attribute, a service identifier for identifying the service information, and, when a plurality of the memory devices has a hierarchical relationship therebetween, has, as a common search condition attribute, hierarchical relationship information for identifying the hierarchical information, the apparatus further comprises a determining unit configured to, based on the search query description format specified in the service information, determine whether to generate a single of the search query including the hierarchical information as the search condition attribute or to generate the search query according to the memory device for which hierarchical relationship is identified with the hierarchical relationship information, wherein the second generator generates the search query according to determination of the determining unit by using the generated common search query.