As the Grid proliferates as the next-generation computing infrastructure, a user interface in the form of "Grid Portals" is becoming increasingly important, especially for computational scientists and engineers. Although several Grid Portal toolkits have been proposed, the portal developer still must build and deploy both the user interface and the application, which results in considerable programming efforts. We aim to ease this burden by generating the portal frontend (that constitutes of JSP and Java Servlets) from an XML document for the former, and a GridRPC system, Ninf-G for easily "gridifying" existing applications for the latter, and realizing their seamless integration. The resulting system, which we call the Ninf Portal, allowed concise description and easy deployment of a real Grid application with greatly small programming efforts.