SharePoint Content Search

Content searching in documents write this code snippet in ASP.NET WCF service.

public MethodResponse<ClientResult<ResultTableCollection>> SearchDocuments(string text, string token)
 
        {
 
            MethodResponse<ClientResult<ResultTableCollection>> response = new MethodResponse<ClientResult<ResultTableCollection>>();
 
            UserCredential userCredential = new UserCredential();          
 
          
            try
            {
                userCredential = VerifyToken(token);
                if (userCredential != null)
                {
                    _ctx = GetClientContext(userCredential);
                    if (_ctx != null)
                    {
                        KeywordQuery keywordQuery = new KeywordQuery(_ctx);
                        keywordQuery.QueryText = Convert.ToString(text);
                        SearchExecutor searchExecutor = new SearchExecutor(_ctx);
                        ClientResult<ResultTableCollection> results = searchExecutor.ExecuteQuery(keywordQuery);
                        _ctx.ExecuteQuery();
                        response.ErrorCode = "200";
                        response.ErrorDescription = "No Error";
                        response.Response = results;
                    }
                }
            }

            catch (Exception ex)
            {              
               
                response.ErrorCode = "400";
                response.ErrorDescription = ex.Message;
                response.Response = null;
            }
            return response;
       }