We use WebAPI to pull the data into our application. The speed issue in here as calling the directly from Poster in Firefox takes 3 minutes.

IbmISql.cs

        /// <summary>
        /// Gets the data from the IBM i.
        /// </summary>
        /// <param name="connString">The connection string</param>
        /// <param name="sqlStatement">The SQL statement</param>
        /// <param name="parameters">The parameters (iDB2Parameter)</param>
        /// <returns>DataTable</returns>
        public DataTable GetData(string sqlStatement, Action<iDB2ParameterCollection> parameters)
        {
            DataTable dt = new DataTable();

            using (iDB2Command cmd = new iDB2Command(sqlStatement, conn))
            {
                if (parameters != null) { parameters(cmd.Parameters); }
                try
                {
                    using (iDB2DataAdapter da = new iDB2DataAdapter(cmd)) { da.Fill(dt); }
                }
                catch (iDB2SQLErrorException e)
                {
                    if (!EventLog.SourceExists(_LOG_SOURCE))
                        EventLog.CreateEventSource(_LOG_SOURCE, _LOG_APPLICATION);

                    EventLog.WriteEntry(_LOG_SOURCE, "**ERROR** on da.Fill(dt): " + e.Message, EventLogEntryType.Error);
                    throw e;
                }
                catch (Exception e)
                {
                    if (!EventLog.SourceExists(_LOG_SOURCE))
                        EventLog.CreateEventSource(_LOG_SOURCE, _LOG_APPLICATION);

                    EventLog.WriteEntry(_LOG_SOURCE, "**ERROR** on da.Fill(dt): " + e.Message, EventLogEntryType.Error);
                    throw e;
                }
            }

            return dt;
        }

LeaveHistoryController.cs

        // GET api/<controller>/5
        public IEnumerable<LeaveRequest> Get(string supervisorId)
        {
            return lrRepository.GetLeaveRequestHistory(supervisorId);
        }

LeaveRequestRepository.cs

        /// <summary>
        /// Gets the leave requests by supervisor. This list will only bring requests in the past.
        /// </summary>
        /// <param name="supervisorId">The supervisor id.</param>
        /// <returns></returns>
        public IEnumerable<LeaveRequest> GetLeaveRequestHistory(string supervisorId)
        {
            /*
                SELECT REQUEST_ID, EMPLOYEE_ID, EMPLOYEE_NAME, FIRST_DATE, TOTAL_HOURS, EMPLOYEE_SIGNATURE, EMPLOYEE_SIGNED_DATE, 
                    EMPLOYEE_SIGNED_TIME, WORKSTATION, EMPLOYEE_COMMENT, SIGNED_BY, SUPERVISOR_ID, SUPERVISOR_SIGNED_DATE, SUPERVISOR_SIGNED_TIME, 
                    SUPERVISOR_WORKSTATION, SUPERVISOR_COMMENT, HR_SIGNED_DATE, HR_SIGNED_TIME, HR_WORKSTATION, HR_COMMENT, NEED_HR_APPROVAL
                FROM MPRLRREQP, MPRTCSP 
                WHERE MPRLRREQP.EMPLOYEE_ID = MPRTCSP.EM_UNIQUE_KEY AND UPPER(EM_SUPV_USERID) = UPPER(@id) AND SUPERVISOR_SIGNED_DATE <> '0001-01-01' 
                ORDER BY FIRST_DATE 
            */

            StringBuilder sb = new StringBuilder();
            sb.Append("SELECT REQUEST_ID, EMPLOYEE_ID, EMPLOYEE_NAME, FIRST_DATE, TOTAL_HOURS, EMPLOYEE_SIGNATURE, EMPLOYEE_SIGNED_DATE, ");
            sb.Append("EMPLOYEE_SIGNED_TIME, WORKSTATION, EMPLOYEE_COMMENT, SIGNED_BY, SUPERVISOR_ID, SUPERVISOR_SIGNED_DATE, SUPERVISOR_SIGNED_TIME, ");
            sb.Append("SUPERVISOR_WORKSTATION, SUPERVISOR_COMMENT, HR_SIGNED_DATE, HR_SIGNED_TIME, HR_WORKSTATION, HR_COMMENT, NEED_HR_APPROVAL ");
            sb.Append("FROM MPRLRREQP, MPRTCSP ");
            sb.Append("WHERE MPRLRREQP.EMPLOYEE_ID = MPRTCSP.EM_UNIQUE_KEY AND UPPER(EM_SUPV_USERID) = UPPER(@id) AND SUPERVISOR_SIGNED_DATE <> '0001-01-01' ");
            sb.Append("ORDER BY FIRST_DATE DESC");

            //iSql.OpenConn();

            var leaveRequests = from i in iSql.GetData(sb.ToString(), p => p.Add("@id", iDB2DbType.iDB2Decimal).Value = supervisorId).AsEnumerable()
                                select new LeaveRequest()
                                {
                                    RequestId = Convert.ToInt32(i.Field<decimal>("REQUEST_ID")),
                                    EmployeeId = Convert.ToInt32(i.Field<decimal>("EMPLOYEE_ID")),
                                    EmployeeName = i.Field<string>("EMPLOYEE_NAME"),
                                    FirstDateOfRequest = i.Field<DateTime>("FIRST_DATE"),
                                    EmployeeSignature = i.Field<string>("EMPLOYEE_SIGNATURE"),
                                    EmployeeSignedDateTime =
                                        Convert.ToDateTime(String.Format("{0} {1}",
                                                            i.Field<DateTime>("EMPLOYEE_SIGNED_DATE").ToShortDateString(),
                                                            i.Field<DateTime>("EMPLOYEE_SIGNED_TIME").ToShortTimeString())),
                                    Workstation = i.Field<string>("WORKSTATION"),
                                    EmployeeComment = i.Field<string>("EMPLOYEE_COMMENT"),
                                    SupervisorId = i.Field<string>("SUPERVISOR_ID"),
                                    SupervisorSignedDateTime =
                                        Convert.ToDateTime(String.Format("{0} {1}",
                                                            i.Field<DateTime>("SUPERVISOR_SIGNED_DATE").ToShortDateString(),
                                                            i.Field<DateTime>("SUPERVISOR_SIGNED_TIME").ToShortTimeString())),
                                    SupervisorComment = i.Field<string>("SUPERVISOR_COMMENT"),
                                    SignedByUser = i.Field<string>("SIGNED_BY"),
                                    TotalHours = i.Field<decimal>("TOTAL_HOURS"),
                                    SupervisorWorkstation = i.Field<string>("SUPERVISOR_WORKSTATION"),
                                    HrSignedDateTime =
                                        Convert.ToDateTime(String.Format("{0} {1}",
                                                            i.Field<DateTime>("HR_SIGNED_DATE").ToShortDateString(),
                                                            i.Field<DateTime>("HR_SIGNED_TIME").ToShortTimeString())),
                                    HrWorkstation = i.Field<string>("HR_WORKSTATION"),
                                    HrComment = i.Field<string>("HR_COMMENT"),
                                    IsHrApprovalRequired = Convert.ToBoolean(i.Field<decimal>("NEED_HR_APPROVAL")),
                                    LeaveType = GetLeaveType(i.Field<decimal>("REQUEST_ID"))
                                };

            iSql.CloseConn();

            return leaveRequests;
        }