I have crude way of doing this "search for string " in a IBM BPM Process App which is not performed at backend. I use this approach to lookup for some string literals in a larg BPD that has too many services to inspect one at a time. This is a way of narrowing down the services that have string. This involves using grep command
1. Export the process App in which you want to lookup for string and unzip to a folder.
2. CD to "objects" folder in cygwin (windows linux kind of shell) and run following command
for f in *;do grep -q 'stringToSearch' $f && grep -i -H process\ id= $f; done >> ..\\..\\services-that-have-match.txt
Services that have the match are in the output file.