It seems a common gotcha is with XPath (which turns out to be a very complex language when used outside of XSLT); I was just working with a customer who was aggregating/correlating using XPaths and was actually returning a list of nodes to correlate on rather than creating a unique string.
As a quick band aid I added this change https://issues.apache.org/activemq/browse/CAMEL-1262 but I wonder what we can do to help this going forward. I just wanted to throw this out to see if others had any good ideas. e.g. maybe we need an expression tracing mechanism; so we can enable/disable tracing of all expressions (or maybe just for different languages or maybe just for different nodes - say filter versus aggregator correlation etc?). For sure we could make the expression evaluation a little more clever - such as to coerce to Strings more often etc. http://issues.apache.org/activemq/browse/CAMEL-1252 I just wondered if others had any thoughts? -- James ------- http://macstrac.blogspot.com/ Open Source Integration http://fusesource.com/
