Communication between a client and the Advanced SQL Engine is made up of Requests and Responses. Client always initiates the process by sending a Request and waiting for the Response. At any moment in time a single Request can be outstanding. For example, a long running query will hold up the connection as Client is waiting for the Response.

Response size, number of bytes sent to Client, is negotiated between Client and the SQL Engine. A single row has to fit in one Response. Therefore a Response can contain one or more rows of data.

Client and SQL Engine communication also conforms to a specific wire protocol format and Session Character Set. That is all character data is encoded and decoded into the specified Session Character Set. For example, UNICODE data is encoded and decoded into KANJISJIS (Code Page 932) when Session Character Set is KANJISSJIS_0S. Furthermore all Types (System.Int16, System.Int32, System.Decimal, System.DateTime and etc.) are marshaled to and from the SQL Engine external data type representation.