The backbone of SmART is a Java servlet called "SmartSsa". The servlet accepts HTTP requests from a web browser and sends back a response each time it is called. This response consists of a (new) HTML page to be displayed by the browser unless the user has clicked the "Save" or the "Export" button. The servlet will send XML output (the SSA's internal representation) in the former case and some other output (JPG, PNG, TIFF, SVG, PDF) in the latter. In both cases the browser will ask the user where to save the servlet's response.

When sending HTML output the servlet has (in most cases) constructed a new SSA according to the user's input (e.g., connecting two propositions). Each SSA is internally represented as an XML structure. This structure is transformed to HTML by means of an XSLT stylesheet ("ssa2html.xsl"). The stylesheet displays propositions, relations, and the buttons which the user is supposed to click. But there is also a hidden text field containing the original XML structure representing the SSA. The field content is sent to the servlet when the "Connect" or "Disconnect" button is clicked and a new SSA structure is composed from the propositions to be (dis-)connected, the chosen relation, and the old structure. Likewise, the new structure is represented as XML and transformed to HTML.

In general, the HTML output depends on the action the user has chosen. Opening a file requires a different output than disconnecting propositions. Thus, the servlet has to communicate with the XSLT stylesheet, providing the right information so that the adequate output can be generated. This is achieved by means of a Finite Automaton model. The automaton's state (e.g., "openRequest", "open", "ssa") is represented in the stylesheet's HTML output by means of a hidden text field. When a button is clicked a JavaScript function writes the new state into the field which is evaluated by the servlet. Now the appropriate action (e.g., constructing a new SSA structure holding an additional relation) is performed and the new state is passed as a parameter to the stylesheet which will in turn evaluate the state and generate the approprioate HTML output.

Export into several graphic formats is performed via SVG (Scalable Vector Graphics). This is done by means of a second XSLT stylesheet, called "ssa2svg.xsl". A SVG stream can easily be converted to JPG, PNG, and TIFF using Apache Batik and to PDF using Apache FOP (Formatting Objects Processor).

The SmART project would not be possible without extensive use of many non-commercial tools which are distributed with the SmART package:

• XML manipulation in Java is done using the JDOM library.
• The Apache Batik library is used to convert SVG to JPG, PNG, and TIFF.
• PDF generation from a SVG stream is performed using Apache FOP (Formatting Objects Processor).
• The "Open File" functionality has been implemented by means of O'Reilly's com.oreilly.servlet package. The source code, object code, and documentation in the com.oreilly.servlet package is copyright and owned by Jason Hunter.
• Cardo is a Unicode font by David Perry. It has been converted to a SVG font file by means of Apache Batik and the font file has been included in the SmART package with kind permission of the author.
• The Unicode Classical Greek Inputter is distributed in the SmART package with kind permission of its author, James Naughton.
• The nice tooltips showing the semantics of the buttons when the mouse pointer is hovering over them have been created with Erik Bosrup's overLIB.