Building the VPC Layer for Cloud
Virtual private clouds (VPCs) live at the molecular level of cloud architecture. Not quite atomic (core cloud services) or elemental (user-defined services), they define how which sets of services can talk to each other, They act as security boundaries and a networking layer for sets of services. But in the SaaS cloud era, VPCs take on even more importance. They are a deployment target for SaaS vendors – (see SaaS Isolation Patterns). These vendors "take ownership" of a VPC. Customers can ensu