Migrating Java to the Cloud

Chapter 1. An Introduction to Cloud Systems

Somewhere around 2002, Jeff Bezos famously issued a mandate that described how software at Amazon had to be written. The tenets were as follows:

• All teams will henceforth expose their data and functionality through service interfaces.

• Teams must communicate with each other through these interfaces.

• There will be no other form of interprocess communication allowed: no direct linking, no direct reads of another team’s data store, no shared-memory model, no backdoors whatsoever. The only communication allowed is via service interface calls over the network.

• It doesn’t matter what technology they use.

• All service interfaces, without exception, must be designed from the ground up to be externalizable. That is to say, the team must plan and design to be able to expose the interface to developers in the outside world. No exceptions.

• Anyone who doesn’t do this will be fired.

The above mandate was the precursor to Amazon Web Services (AWS), the original public cloud offering, and the foundation of everything we cover in this book. To understand the directives above and the rationale behind them is to understand the motivation for an enterprise-wide cloud migration. Jeff Bezos understood the importance of refactoring Amazon’s monolith for the cloud, even at a time when “the cloud” did not yet exist! Amazon’s radical success since, in part, has been due to their decision to lease their infrastructure to others and create an extensible ...