UNIX for Dummies Questions & Answers

Hi have an xml file which is like:
<tag1>
<tag2>

<tag3>data3
</tag3>

<tag4>data4
</tag4>

</tag2>
</tag1>

i need to convert it to the standard xml format
<tag1>
<tag2>
<tag3>data3</tag3>
<tag4>data4</tag4>
</tag2>
</tag1>

coming to the point,i need to remove the new line character only for those fields which have data,
I used the reg nawk to remove new line but it is doing it for all the tags:

nawk '{ if ( $0 !~ /<\// && NR > 1 ) { printf "\n"; } printf $0; } END { printf "\n"; }' file.xml >abc.xml

and i am getting
<tag1>
<tag2>
<tag3>data3</tag3>
<tag4>data4</tag4></tag2></tag1>

I need to remove the new line character for lines having data.
could someone help me out here,
Thanks

Actually it would just help if someone would help me on how to replace <> with a /n<.
The sed command...
sed 's/<>/\
</g' < abc.xml > abcd.xml
does not work..