Azure App Services and Logic Apps have now hit public preview, and they have generated a lot of excitement (including with this writer).  It’s a bit like Microsoft has hit a reset button and now all the Microsoft integration specialists have to start from scratch (at least in the cloud, BizTalk Server isn’t going anywhere for awhile, thankfully since I would miss it), at least when it comes to tooling, concepts don’t really change…

One of the first proof of concepts I tried to work with (actually this was a team effort with a bunch of integration specialists excitedly fighting over the keyboard) was creating a Logic App that would pick up emails from a POP3 mailbox, and write the contents to a folder in my DropBox account, the file being named based on the subject of the email + .txt, and the contents of the file being based on the body of the email.  This is easy enough to do with the POP3 and the DropBox connectors as below.


We had quite a lot of difficulty trying to figure out how to set the filename in DropBox since it required a combination of hardcoded strings and the email subject which flowed out of the POP3 connector.  We tried a kazillion different combinations, and nothing seemed to work.

I reached out to the BizTalk Advisors Yammer forums hosted by Microsoft and got a helpful response from Stephen Siciliano at Microsoft in a snap (that’s Stephen!).  His suggestion is that if you’re mixing string constants and functions then you should not surround your function with quotes, and you should not use the @ escape character before the function.  Also, if you want to concatenate strings you must use the @concat function.  My final function looked like the below.

@concat(‘jc\’, triggers().outputs.body.Subject, ‘.txt’ )

This resulted in the email body being written to a file in a folder in the root path called jc, with the filename being based on the email subject + .txt.  Interestingly, if you view the code view you’ll notice that the slash after the folder name gets automatically escaped (so you don’t have to escape it, in fact if you do then you will end up with two escaped slashes).


I hope this helps others who are also struggling to learn the new syntax.  Just like with any new language, once you understand the rules the learning curve is a lot less steep.  Don’t take it for granted that this syntax will remain the same.  I imagine that by the end of the public preview Azure App Services might be a very different beast.

Happy AAS-ing.