In early 2001, I wrote a white paper about Web Services and component models. At that time SOAP was all new and shiny and we were using it at Orchestra Networks to build the first version of the EBX platform. SOAP, and its usage as an RPC technology for the Web was one of the main subjects of the paper.
Shortly after publication, I got a short email from Mark Baker saying something like: «Sorry but your paper is completely uninteresting. RPC for the Web isn’t what you want» and pointing me at something mysterious called REST. I looked at REST and quickly added a new chapter about it, titled "RPC is not the only model". And from that time on, I’ve been happily doing consulting and teaching on REST, helping a number of people to get out of the SOAP/WS-* train wreck along the way. I did some writing too, including a white paper on architectural options for Web services (in french) and some contributions to the Restlet in Action book.
After all these years of fun and fascinating work with REST, I can say that Mark’s email is one of the most useful I ever got in my life. And I’m grateful for that.