No, edit-on Pro is a XHTML editor, so server side scripting languages like PHP, ASP or JSP can of course not be edited as they generally are represented by code enclosed through special tags which are not well-formed XHTML. However, to be able to edit pages containing server side code, you could enclose the code elements of the pages in comments or CDATA sections, which will not be removed or edited by the applet, and thus remain as-is. Following some examples of special tags of a server side scripting language enclosed in comments and in a CDATA section:

JSP code in comments:

<!-- <%= myVariable %> -->

JSP in a CDATA section:

<![CDATA[<%= myVariable %>]]>

In both of these examples, the JSP code represented will be executed correctly. The only drawback to this is that any code that should be displayed in the browser will not be displayed, as the output of those JSP scripts will still remain in comments, e.g. the first script would evaluate to

<!-- the value of the variable myVariable -->

whereas the second would evaluate to

<![CDATA[ the value of the variable myVariable ]]>

Content edited with edit-on Pro would have to be preprocessed and postprocessed if the comments or CDATA sections are not acceptable.