I’m trying to understand the limitations of using GPL software within a proprietary (closed source) software application. According to this you can distribute the GPL software with your proprietary as long as they communicate “at arms length”. What exactly does this mean? If you communicate using a COM server? How about a ROAP server? What about good old fashioned Unix like pipes? What about simply batching jobs to the GPL software?
Can anyone more familiar with the legalese of the GPL shed some light?