11. A computer program product, the computer program product comprising a non-transitory computer readable storage medium having program code embodied therewith, the program code executable by at least one processor to perform: receiving, by the at least one processor, a query with keywords that each identify a key concept, relevant words that capture a context of the keywords, and one or more selected services; calculating, by the at least one processor, a general relevance indicator for each service among services in a category using: GRI Q = ∑ i = 1 M q ⁢ ⁢ k ⁢ KRI i + ∑ i = 1 M ⁢ ⁢ q r ⁢ α i 2 × RRI i ( ( M q ⁢ ⁢ k + ∑ i = 1 M ⁢ ⁢ q r ⁢ α i ) ⁢ ( ∑ i = 1 M s ⁢ ⁢ k ⁢ KRI i 2 + ( ∑ i = 1 M s ⁢ ⁢ r ⁢ α i 2 × RRI i 2 ) ) ) 1 2 , wherein KRI i is a Keyword relevance indicator of a keyword i, from the keywords, associated with a service of the services in the category, wherein M k is a total number of the keywords in the query, wherein RRI j is a relevant word relevance indicator of a relevant word i, from the relevant words, associated with the service, wherein Mr is a total number of the relevant words in the query, and wherein α i is a weight for the relevant word i; ranking, by the at least one processor, the services in the category based on the general relevance indicator for each service; and in response to determining that at least one of the selected services is not ranked high with reference to the ranked services in the category, recommending, by the at least one processor, synonyms to be used to substitute corresponding keywords and synonyms to be used to substitute relevant words in the query; recommending, by the at least one processor, new relevant words by: retrieving names of properties and names of relationships of a concept identified by a keyword among the keywords in an ontology database as candidate relevant words; and in response to determining that the candidate relevant words are not in the query and no synonyms are found, providing a recommendation that the candidate relevant words be included in the query as the new relevant words; and recommending, by the at least one processor, one or more additional services to be included in the query.
15. The computer program product of claim 11 , wherein the program code is executable by at least one processor to perform: identifying, by the at least one processor, keywords and relevant words that are candidates to be removed from the query; and recommending, by the at least one processor, that the keywords and relevant words be removed from the query.