Asynchronous State Change Events

TNC-O emits events when the state of an assembly and its components changes. Messages that are sent asynchronously are put onto a Kafka bus. The exact topics can be configured. These are emitted in response to Intent Requests causing the state of the Assembly Instance, or its associated components, to change. In the event of a failure to change state, an event will also be emitted.

Associated with each example is a table explaining the fields in the example. This includes the name of the field, a brief description and whether the field is mandatory. Whether a field is required or not is based on the context of the examples. The underlying API definition may mark a field as optional, but in some contexts, the fields must be supplied.

In the examples below field names shown in italics are example names and not the real one to be used in messages.

ProcessStateChangeEvent

These events are associated with the process that performs the Intent request. These are sent out at the Start of the processing and when completed or failed.

ProcessStateChangeEvent Examples

Example of an initial state change event:

{
   "processId": "e29b86a8-ca75-413b-921b-c4b895996c12",
   "assemblyId": "e4c198d1-2dbb-4557-baae-b5891fa258cf",
   "assemblyName": "example2",
   "assemblyDescriptorName": "assembly::t_single::1.0",
   "intentType": "CreateAssembly",
   "intent": {
      "assemblyName": "example2",
      "descriptorName": "assembly::t_single::1.0",
      "intendedState": "Active",
      "properties": {
         "data": "example data",
         "deplomentLocation": "admin@local"
      }
   },
   "processState": "In Progress",
   "processStartedAt": "2017-09-14T13:06:17.499Z",
   "eventId": "e08039e7-7efd-4b7e-86a3-9d39c48c2dd7",
   "eventCreatedAt": "2017-09-14T13:06:17.499Z",
   "eventType": "ProcessStateChangeEvent"
}

The example above shows the first message sent when an intent has been received by TNC-O. The processId will be used in all subsequent state change events. These happen when the process changes state.

Example of the final message on successful completion of the Intent:

{
   "processId": "e29b86a8-ca75-413b-921b-c4b895996c12",
   "assemblyId": "e4c198d1-2dbb-4557-baae-b5891fa258cf",
   "assemblyName": "example2",
   "assemblyDescriptorName": "assembly::t_single::1.0",
   "intentType": "CreateAssembly",
   "intent": {
​      "assemblyName": "example2",
​      "descriptorName": "assembly::t_single::1.0",
​      "intendedState": "Active",
​      "properties": {
​         "data": "example data",
​         "deplomentLocation": "admin@local"
​      }
   },
   "processState": "Completed",
   "processStartedAt": "2017-09-14T13:06:17.499Z",
   "processFinishedAt": "2017-09-14T13:06:19.648Z",
   "eventId": "405cf14c-752e-4030-8a4e-6706e04b50f5",
   "eventCreatedAt": "2017-09-14T13:06:19.649Z",
   "eventType": "ProcessStateChangeEvent"
}

Example of the final message indicating Intent Failed:

{
   "processId": "8c922ec6-7589-4ba8-8b4e-d7841b9a9654",
   "assemblyId": "42ecbe49-0069-41f5-ac38-595b090c3d65",
   "assemblyName": "example3",
   "assemblyDescriptorName": "assembly::t_single::1.0",
   "intentType": "CreateAssembly",
   "intent": {
​      "assemblyName": "example3",
​      "descriptorName": "assembly::t_single::1.0",
​      "intendedState": "Active",
​      "properties": {
​         "data": "Example Data",
​         "deplomentLocation": "admin@local"
​      }
   },
   "processState": "Failed",
   "processStateReason": "Exception …",
   "processStartedAt": "2017-09-14T13:13:58.966Z",
   "processFinishedAt": "2017-09-14T13:13:59.616Z",
   "eventId": "11acf385-e6f9-41cf-9651-38dc3ed6a53a",
   "eventCreatedAt": "2017-09-14T13:13:59.616Z",
   "eventType": "ProcessStateChangeEvent"
}

Field Details

ComponentStateChangeEvent

These events are sent when the root assembly changes state and when each of its associated resources successfully transitions to a new state. In the event of a failure of the process no events will be sent.

ComponentStateChangeEvent Examples

First message sent indicating first component transitioning to the Installed State:

{
   "eventId": "901d4794-7734-4511-8e24-6035ee5cb22a",
   "eventCreatedAt": "2017-09-14T13:06:18.37Z",
   "rootAssemblyId": "e4c198d1-2dbb-4557-baae-b5891fa258cf",
   "rootAssemblyName": "example2",
   "resourceId": "7a03bc63-bccf-4731-b6b2-9389609d9fa5",
   "resourceName": "example2__A",
   "resourceManager": "test-rm",
   "deploymentLocation": "admin@local",
   "externalId": "06d20929-a1c0-44cf-8009-aee47bac3f99",
   "processId": "f4538d94-4c42-4b3b-993a-530f7862120f",
   "previousState": null,
   "newState": "Installed",
   "eventType": "ComponentStateChangeEvent"
}

The above message is an example of a resource transitioning to the Installed state. The previous state is null indicating the resource did not exists before.

An event indicating the root assembly has transitions to Installed State:

{
   "eventId": "33a63fca-2bed-49c3-8615-56e5b35aa3bb",
   "eventCreatedAt": "2017-09-14T13:06:18.572Z",
   "rootAssemblyId": "e4c198d1-2dbb-4557-baae-b5891fa258cf",
   "rootAssemblyName": "example2",
   "processId": "f4538d94-4c42-4b3b-993a-530f7862120f",
   "previousState": null,
   "newState": "Installed",
   "eventType": "ComponentStateChangeEvent"
} 

The example above will be sent when all resources associated with the root assembly have successfully transitioned to the Installed State.

Field Details

‡ When TNC-O is requested to heal a component, TNC-O will indicate this with a set of state transitions from Active to Broken and then Broken to Inactive.