Datalex, the Howth-based developer of software for the travel industry, yesterday said its chairman, Mr John F. Tierney, had resigned from the firm. The firm said Mr Tierney had decided it was the appropriate time to step down following the recent completion of a corporate restructuring . Founder Mr Neil Wilson will move from the chief executive position to take up a new role as executive chairman. The current chief operating officer, Mr Neil Beck, will become chief executive.