A SOA promotes federation. Federation in an organization is an environment in which the software applications and resources work together while simultaneously maintaining their autonomy. Federation gives organizations the freedom not to be required to replace all of their existing systems that must work together. As long as there is a common, open, and standardized framework, legacy and non-legacy applications can work together. Organizations have the flexibility to choose whether they want to replace certain systems, allowing them to use a phased approach to migration.