VMware vCenter Orchestrator provides Web services APIs so that you can develop applications to access workflows through the Web. The main purpose of the Orchestrator Web services APIs is to allow you to integrate Orchestrator workflows in custom Web-based applications.

Orchestrator provides Web services APIs that are based on two types of technologies:

A representational state transfer (REST) API. The Orchestrator REST API exposes the objects in the Orchestrator inventory and the inventories of the installed plug-ins as resources that you can access at predefined URLs. HTTP requests at these URLs result in triggering operations over workflows. The Orchestrator REST API exposes inventory objects as resources through a set of RESTful Web services that you can use to retrieve the definitions of workflows, run workflows, check the status of the running workflows, cancel workflow runs, process waiting user interactions, retrieve the presentation of workflows, and so on.

A simple object access protocol (SOAP) service. The Orchestrator SOAP service API provides a set of Web service definition language (WSDL) object type definitions and a set of Web service operations, that obtain workflows, run workflows, refresh workflow states, and obtain their output parameter values. You can also use the SOAP service to implement tree viewers, based on the relations between objects obtained from plug-ins. The API has few complex object types and relatively few operations.