Checkpointing the Message Processing

Summary

Let’s start by asking you two questions. What Super Frog has to do with messaging? When was the last time you wrote if statements in SQL? If it’s been a long time, have you at least seen them? If not, (don’t) worry, you’ll see them today. Will it be a post about weird SQL usage? Not necessarily. We’ll talk today about checkpointing our processing. I’ve started my relationship with computers with games. I still have my Amiga 500. In those days, computers didn’t always have a hard disk. You’ve got a bunch of diskettes with different chapters of the game. Not all of them were simple games; many were quite sophisticated, and it took some time to finish them. Yet they were dealing with limited diskette space, so it was best if they didn’t have to use any of it. How can you then allow you to stop playing and return to the previous state? Or how to not force you to start from the beginning of the game when you fell from the platform, and well, you died? You died in the game, ofc, that at least you should be able to recover, right? As mentioned earlier, the limited space on diskettes and the additional complexity that came with it led many game makers to adopt a simple solution: checkpoints with codes. After you passed a level, you got a code you could type when you started the game, and instead of starting from the beginning, you could go directly to the place where you left off. That worked pretty well for the platform and race car games, since your game’s storyline was always the same, immutable. If you had to go to level 27, the starting point and your character would always look the same. Of course, for RPG and strategy games, that’s a different story. Surprisingly, this parallel also matches the recovery from a business process failure. Let’s say we’re using message-based communication to streamline and make it more resilient. We don’t want to make it vulnerable to scenarios where we store information in one system, our process dies, and we don’t manage to notify the ...