Required fields

In the TEN framework, only message schemas can include required fields. Extension properties cannot include required fields.

This means that schemas for cmd_in, cmd_out, data_in, data_out, audio_frame_in, audio_frame_out, video_frame_in, and video_frame_out can define required fields.

For message schemas, the required field is valid only in the following three locations:

• At the same level as property in foo_in or foo_out
• Inside the property of result in foo_in or foo_out
• Within a property of type object (for nested structures)

Examples of these scenarios are shown below.

{
  "api": {
    "cmd_in": [
      {
        "name": "foo",
        "property": {
          "a": {
            "type": "int8"
          },
          "b": {
            "type": "uint8"
          },
          "c": {
            "type": "array",
            "items": {
              "type": "string"
            }
          },
          "d": {
            "type": "object",
            "properties": {
              "e": {
                "type": "float32"
              }
            }
          },
          "exampleObject": {
            "type": "object",
            "properties": {
              "foo": {
                "type": "int32"
              },
              "bar": {
                "type": "string"
              }
            },
            "required": ["foo"] // 3.
          }
        },
        "required": ["a", "b"], // 1.
        "result": {
          "property": {
            "ccc": {
              "type": "buf"
            },
            "detail": {
              "type": "buf"
            }
          },
          "required": ["ccc"] // 2.
        }
      }
    ]
  }
}

Use of required

Message sent from an extension

When an extension calls send_foo(msg_X) or return_result(result_Y), the framework checks msg_X or result_Y against their respective schemas in the extension. If msg_X or result_Y is missing any of the fields marked as required in the schema, the schema check fails, indicating an error.

The handling of these three scenarios is identical, though they are discussed separately:

1. If send_foo is sending a TEN command and the schema check fails:

   send_foo returns false immediately. If an error parameter is provided, it includes the schema check failure error message.

2. If return_result fails the schema check:

   return_result returns false. If an error parameter is provided, it includes the schema check failure error message.

3. If send_foo is sending a general data-like TEN message, such as data, audio frame, or video frame:

   send_foo returns false. If an error parameter is provided, it includes the schema check failure error message.

Message received by an extension

Before TEN runtime passes msg_X or result_Y to an extension's on_foo() or result handler, it checks whether all required fields defined in the schema of msg_X or result_Y are present. If a required field is missing, the schema check fails.

1. If the incoming message is a TEN command:

   ten_runtime returns an error status_code result to the previous extension.

2. If the incoming message is a TEN command result:

   ten_runtime changes the status_code of the result to error, adds the missing required fields, and sets the values of these fields to their default values based on their type.

3. If the incoming message is a TEN data-like message:

   ten_runtime simply drops the data-like message.

Behavior of graph check

TEN Manager has a function called Graph Check, which is used to verify the semantic correctness of a graph. The checks related to required fields are as follows:

1. For a connection, the required fields of the source must be a superset of the required fields of the destination.
2. If the same field name appears in both the source and destination required fields, their types must be compatible.