1. A system comprising: a server system, including one or more computers, which is configured to receive query messages from a client object, the server system asynchronously receiving and responding to the query messages from the client object over a network; the client object that, while a user is providing input comprising a lengthening string of characters, sends query messages to the server system; whereby the query messages represent the lengthening string as additional characters are being input by the user; and wherein the server system, while receiving said query messages, uses the input to query data available to the server system and send return messages to the client object containing results in response to the input; and wherein, upon receiving a return message of the return messages from the server system, the client object tests the usability of the results in the return message by checking that the return message corresponds to the latest query, and if usability is established, the client object displays or returns at least some result data to the user.