3.11.Dynamic Web Pages

Virtuoso provides an extensible array or dynamic methods for creating data driven web pages. Through runtime hosting Virtuoso can directly host, store and drive:

Natively - VSP and VSPX:

Virtuoso Server Pages (VSP) is Virtuoso's specification for creating dynamic database driven Web pages, these files have the extension ".vsp" and are identical in functionality to: ASP, PHP, and JSP pages. A fundamental difference between VSP pages and others (PHP, ASP. and JSP pages) is the fact that VSPs are specialized forms of Virtuoso Stored procedures which implies that data is in-process rather than out-of-process, you do not have to complete a client-server connection in order to actually bind to the data being used in a VSP page. The obvious benefit being significant performance improvements over ASP, PHP, and JSP pages (which all bind to data out-of-process).

Since VSP is essentially Virtuoso PL in a web page you can do anything that PL can from or part of a web page either directly or from interaction with the user. A massive advantage of using VSP is that you do not have to worry about making connections to the database or the overhead of RPC's because the HTTP server is built into Virtuoso. When you write a VSP page the connection is assumed since you are already in Virtuoso! VSP is server script and is therefore executed in the server as it is encountered on the page. For this reason client (JavaScript) and server script cannot directly interact but can supplement each other. You can call JavaScript inside a VSP loop, for example, to manipulate something that already exists on the page but you cannot pass variables by reference from VSP directly to JavaScript or vice versa. Page flow control is managed using FORMs. The state of the page is defined in form fields such as INPUT boxes and TEXTAREA boxes and then passed on to the next form or page using POST.

Virtuoso Server Pages for XML (VSPX) is an XML based framework and state-managed system similar to ASPX. Pages are written in XML to describe templates of data-aware web-widgets. This massively reduces the code-effort and avoids many bugs by providing the functionality for you, of which you specify the data-source, be it XML, SQL or other, and which predefined control you want it represented by. VSPX allows for custom-designed controls too. Since XML is a key factor for VSPX so does XSLT for providing total separation between the data, business logic and the layout on the web page.

[Tip] See Also:

The Web Application Development Chapter.