You must authenticate against Orchestrator in the HTTP requests that you make through the Orchestrator REST API. If you use the Orchestrator REST API to access resources on a third-party system, such as vCenter Server, you must authenticate against that system as well.
For example, to access all workflows in the Orchestrator inventory, you must authenticate against Orchestrator. However, to run a workflow in vCenter Server, you must authenticate against Orchestrator and vCenter Server.
Depending on whether you configure Orchestrator with LDAP or with vCenter Single Sign-On, the authentication scheme for the Orchestrator REST API is different. If Orchestrator uses LDAP, you must authenticate by using valid credentials. If Orchestrator uses vCenter Single Sign-On, you must authenticate by using a holder-of-key token issued by the vCenter Single Sign-On Server.
If you make HTTP requests at the top-level URL of the Orchestrator REST API, you do not need to authenticate against Orchestrator. The top level URL of the Orchestrator REST API is https://vcoHost:port/vco/api/.
The default port number is 8281.
A GET request at the top level URL of the REST API returns URLs to all resources that are accessible through the API. To make HTTP requests at these URLs, you must authenticate against Orchestrator or the third-party system where the resources are located.