Getting MEAN With Mongo, Express, Angular, and Node 2ed by Simon
Holmes, Manning 2019
With the advent of social web sites and apps there has been a big change in the design architecture of the sites. The volume of traffic is up, the response is expected to be near-immediate, and the cost of running the servers is expected to be lower. At the same time, the requirements are relaxed a bit for correct transactions: if one in a million posts to a social site go astray, that is not a big loss (compare that to the banks’ site’s requirements for correctness, c.f. ACID).