# Shared Api

Activity, Process, and Definition elements share the same api interface. The element must not necessarely implement listeners for all the api calls.

The Api is composed from the element event message.

Api properties:

- `id`: element id
- `type`: element type
- `name`: element name
- `executionId`: current execution id
- `environment`: shared [environment](/docs/Environment.md)
- `fields`: message fields
  - `routingKey`: message routing key
- `content`: message content
  - `id`: element id
  - `type`: element type
  - `executionId`: element execution id
  - `parent`: element parent
    - `id`: element parent id
    - `type`: element parent type
    - `executionId`: element parent unique execution id
      - `path`: list of parent parents
- `messageProperties`: message properties,
  - `messageId`: message id
- `owner`: api owner, i.e. the owning element instance
  - `broker`: element [broker](https://github.com/paed01/smqp)

### `cancel([message, options])`

Cancel run. Publishes cancel message via element broker on element broker `api` exchange.

Arguments:

- `message`: optional object sent as message
- `options`: optional object with broker message options
  - `delegate`: optional boolean to delegate the cancel to all interested parties

### `discard()`

Discard run. Publishes discard message on element broker `api` exchange.

### `signal(message[, options])`

Signal activity. Publishes signal message on element broker `api` exchange.

Arguments:

- `message`: signal message
- `options`: optional object with broker message options
  - `delegate`: optional boolean to delegate the signal to all interested parties

### `fail(error)`

Fail activity with error. The purpose is to fail user-/signal tasks waiting for user input. The behaviour differs between different type of activities.

### `stop()`

Stop element run. Publishes stop message on element broker `api` exchange.

### `resolveExpression(expression)`

Resolve expression.

### `createMessage([overrideContent])`

Utility function to create new message content from the api message.

### `sendApiMessage(action[, content, options])`

Utility function to publish message with element broker.

Arguments:

- `action`: message action, will be prefixed with the element type, e.g. `signal` will be sent as `activity.signal` if used to signal activity
- `content`: optional message content
- `options`: optional object with broker message options