DO, Java Servlet (.do)
The DO Website file format
A file that has the extension of DO (filename.do) can have several different origins and purposes. However, the most common use of the DO file extension is associated with files that are necessary to generate dynamic web pages on the internet. When the DO files are created, they are usually built using a Java program or code. The page that contains that information (the DO document) is then placed on the server for the web page, along with the other website files. The live website pulls information from the server in order to show the page online and show people the page that resulted from the code on the DO document.
Technical details of DO files
Server files that use the DO file extension function in much the same way as a file with a PHP extension. In some circles, the DO file extension is sometimes referred to as Java Struts Application Files. This is due to the fact that the DO files frequently give the user an associated URL that also has the ability to create a mapped function to the Struts action that is specified. There are also a few programs that create and manage webinars that make use of the DO file extension. If you are having trouble with a DO file that is a webinar, you may be able to change the name of the file extension to VCS in order to use it.