A system for constructing a view provided by a web application is provided. The system includes a viewer component that is used to compose at least a portion of a web application. The viewer component enables web applications to generate a hypertext markup language file containing input fields for communication to a web server. The viewer component includes an input field file, a script file and a java server page template. The input filed file defines a plurality of constraints on the input fields and the script file reads the input field file and places instructions into the hypertext markup language file. The instructions validate an input to one of the input fields based on the input field file. The java server page template is extendable to create a java server page that is operable to generate a part of the hypertext markup language file.