To use the Rackspace Cloud Orchestration API effectively, you should understand several key concepts:
A Cloud Orchestration template is a portable file, written in a user-readable language, that describes how a set of resources should be assembled and what software should be installed in order to produce a working stack. The template specifies what resources should be used, what attributes can be set, and other parameters that are critical to the successful, repeatable automation of a specific application stack.
For details on using and customizing templates, see the Rackspace Cloud Orchestration Templates User Guide.
A resource is a template artifact that represents some component of your desired architecture (a Cloud Server, a group of scaled Cloud Servers, a load balancer, some configuration management system, and so forth).
A stack is a group of resources (servers, load balancers, databases, and so forth) combined to fulfill a useful purpose. Based on a template, Heat orchestration engine creates an instantiated set of resources (a stack) to run the application framework or component specified (in the template). A stack is a running instance of a template. The result of creating a stack is a deployment of the application framework or component.