File Extension DO
File extension DO is a file format that represents a web-based Java application. It is operated by or supported by web servers such as the IBM Web Sphere program or Struts controller, which is a program that is used in generation of dynamic web pages.

The web servers that support extension DO files must be able to support JSP in order to be able to run. DO files are therefore mostly viewed as web pages although special programs can be used to convert the files into other more compatible formats.
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Many operating systems support DO files. In this context, the Macintosh operating system and Windows operate DO files in the manner that has previously been described i.e. they both require web server programs that support JSP. This means that if any of the operating systems fails to work with the DO files, there is need to troubleshoot if all the programs are correctly installed.

Most probably, failure to install all the prerequisite programs may result in total failure to open file extension DO. .DO files are played as a content of a playlists in much the same way as other files can be cued in the Windows Media Player. In the play list, most players can open and read .DO files. This is particularly true for players that are in a position to handle and play .ASX files. Any DO file is opened in the normal procedure as used with Windows Media Player.
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One way is to open the relevant playing program such as Struts controller or IBM Web Sphere. While in the program's window, you have to choose the particular file extension DO or files to be opened. Another option is to double click the file's icon or right click it and select "open". Alternatively, you can drag the file's icon and drop it on the icon representing the playing program.