An explanation of Eric Brewer's CAP theorem, which says you cannot have more than two of Consistency, Availability and Partition-tolerance in web-based distributed systems.
R. Straeten, T. Mens, J. Simmonds, and V. Jonckers. UML 2003 – The Unified Modeling Language, volume 2863 of Lecture Notes in Computer Science, page 326--340. Springer, (2003)