A Controller manages the state of a single Resource (Application, Infrastructure, or Network). It executes the Resource's configuration and instantiation, and is the primary player in ongoing management, e.g. control loop actions, migration, and scaling. All of these actions involve executing workflows (recipes) obtained from ASDC. In addition, the Controller reports the status of each workflow execution to both A&AI and MSO.
In effect, each Controller instance supports a form of orchestration to manage operations within its scope. This low-level orchestration is done outside the MSO.
The MSO is responsible for ensuring that the Controller successfully completes its Resource configuration as defined by the recipe.
OpenECOMP uses three distinct Controller types to manage Resources in the execution environment, corresponding to their assigned controlled domain:
- cloud computing resources (Infrastructure Controller, typically within the cloud layer)
- network configuration (Network Controller)
- application (Application Controller).
Infrastructure Controllers
Infrastructure Controllers typically execute OpenStack requests for the creation of virtual machines (VMs), and load the Virtual Function (VF) software into the new VM container. To do this, the Infrastructure Controller obtains the Virtual Function's Resource recipe from the ASDC. The Resource recipe will define VM sizing, including compute, storage, and memory. When the Infrastructure Controller completes the request, it will pass the virtual resource identifier and access (IP) information back to the MSO to provide to the Network and Application controllers.
If the Resource recipe requires multiple VMs, the MSO will repeat the process, requesting each Infrastructure Controller to spin up one or more VMs and load the appropriate VFs.
An Infrastructure Controller also has its own recipe, which specifies...?
To create an Infrastructure Resource controller, see ?
Network Controllers
A Network Controller instantiates a Virtual Network Function, by carrying out its network configuration workflow and reporting the resulting status (to both A&AI and MSO).
Application Controllers
Application Controllers will be requested by the MSO to obtain the application-specific component of the Service recipe from ASDC and execute the orchestration workflow. The MSO continues to be
responsible for ensuring that the Application Controller successfully completes its Resource configuration as defined by the recipe.
Note that not all changes in network or service behavior are the result of orchestration. For example, Application Virtual Functions can change network behavior by changing rules or policies associated with Controller activities. These policy changes can dynamically enable service behavior changes.
To create an Application controller, see ?