Recent industry focus may lead one to believe extreme transaction processing is a new concept. The concept isn't new, but we have new tools that make building XTP-classified systems easier. XTP is a fuzzy classification of software architecture and performance. XTP systems have three main responsibilities. They must offer high performance, scalability, and manageability. Other definitions exist, but these three things are consistent across all XTP definitions.
We have covered enough IMDG features, and the WebSphere eXtreme Scale APIs, to compare in-memory data grids with in-memory databases. In-memory databases were popular in the late-90s and early-00s as a way to build XTP-style applications. As we have seen, storing data in memory has a much lower latency than storing data on disk. An in-memory database allows SQL access to data since it's stored in rows and columns just like any other SQL-based database. In-memory databases are popular for smaller datasets...