A repository to demonstrate how message formats can be evolved over time, assuming you are in a position to get clients to upgrade.
Start the server in a repl:
$ lein repl
message-migrations.core=> (require '[message-migrations.server :as server])
nil
message-migrations.core=> (def http-server (server/run-in-repl))
#'message-migrations.core/http-server
You can stop the server by running (.stop http-server)
In another terminal window run git rebase -i --root and change "pick" to
"reword" for each line.
This will get git to step through each commit and show you the commit message
as you go.
The commit messages have curl commands that demonstrate each step of the
process.
At each step reload the message processing code to get the new behaviour In your repl run:
message-migrations.core=> (require 'message-migrations.core :reload)
nil