There are some key differences between commercial orchestrators, such as vRealize Automation and CIAC, and FOSS orchestrators, such as OpenStack. While both of them attempt to provide IaaS to users, it is important to understand the difference between both the types of orchestrator in order to appropriately design your Cloud.

Let's begin with commercial orchestrators; these provide a base IaaS to their users. They normally sit on top of a virtualized environment and enable an automated provisioning of compute, storage, and network, even though the extent of automation varies. As a part of the toolset, they also typically have a workflow engine, which in most cases provides us with an extensibility option.

The commercial orchestrators are a better choice when the entire orchestration needs to be plugged in to the current IT processes. They work wonderfully well when extensibility and integration are major tasks of the cloud environment, which is typically seen in large enterprises given the scale of operations, the type of business critical applications, and the maturity of IT processes.

In such large enterprises, in order to take full advantage of the private cloud, the integration and automation of the orchestrator in the IT systems of the company becomes necessary. This kind of orchestration is normally used when minimum changes are anticipated to be made to the applications. A primary use case of this is IaaS, where virtual machines are provisioned on a self-service basis and a very small learning curve is involved.

FOSS orchestrators are less extensible, but more standardized in terms of offerings. They offer standardized services that a user is expected to use as building blocks to offer a larger solution. In order to take full advantage of the FOSS orchestrators, some amount of recoding of applications is required as they need to make use of the newly offered services. The use cases here are both IaaS and PaaS (for example, Database as a Service, Message Queue as a Service, and so on).

For this reason, the APIs that are used among the FOSS orchestrators need to have some common ground. This common ground that we are talking about here is Amazon Web Services (AWS) API compatibility, as Amazon has emerged as the gold standard as far as the service-oriented cloud architecture is concerned. At the time of writing the book, OpenStack Nova still had AWS EC2 API compatibility, but this may be pushed out to the StackForge project.