php file strcture design

[mavera2]

I have a php file, call it "mypage.php"

it makes come calculations, create 5 different arrays,

and creates a table by using the arrays.

 

I found simpleXML to create XMLs easily.

I want to make an xml file by using the contents of mypage.php.

 

I want to do that with an argument like that "mypage?type=xml"

I'm aware that i should use "$_GET" or "$_POST"

But where should i put the php code in page,

so when i use argument "xml" it will create an xml file.

When i don't give argument it will create an html type file.

 

Or should i use another php that includes mypage.php??

And get arrays from that file?

 

Thank you.