If the code used to run your crypto coin node wants updating, how is it finished?
There is no such thing as a such factor as “wants updating”, or at the very least no entity that may determine this. Whereas protocol updates occur, it’s as much as particular person customers to determine whether or not to undertake the code adjustments for it. For invasive adjustments (“hardforks”), non-adoption does end in previous and new nodes to successfully function on completely different networks with completely different currencies, however Bitcoin hasn’t had any such adjustments since 2013 (and even that one was accidentally, see BIP50; the final deliberate laborious fork was very early in its historical past in 2010). For regular protocol adjustments, most customers can improve at their leisure – or in no way, resulting from backward compatibility.
Is the code despatched as a patch as a transaction?
Who would get to determine to ship such a patch? Would not that individual or entity not successfully determine what transactions are legitimate? That might run solely counter to the issue the system is designed to resolve.
Does the node code know find out how to obtain and apply this patch? Or does somebody simply say “Hey, replace your code.”
This occurs by means of regular software program upgrading practices. Developer groups for node software program will launch a brand new model, and customers can determine to put in the replace or not. The overwhelming majority of all adjustments to node software program is solely unrelated to protocol adjustments, however as defined above, even those that do embody protocol adjustments are typically not necessary.