Using the Saga Screen

Opening the Saga screen from Devops app menu or navigation bar, you will come across a visual graph editor, allowing design of flows step by step.

Sagas are listed on the left side of this screen, grouped by their domain and path information. It is possible to assign multiple saga flows to the same path (i.e. URL endpoint), under the following conditions:

• Either only 1 saga has active status - typically used when older or alternate versions are kept for reference or disaster recovery

• More than 1 sagas are active, but they are allowed on different streams - typically used for allowing same endpoint with different flows between development, test and production environments

• If more than 1 saga is set to active on the same stream, only the first record is used

The saga screen has similar functionalities as any other UI screen, such as save, delete, duplicate, item import and export actions and menus. Saga flow designed on this screen is stored in JSON format, the same as any other data source.

On top of this screen, you will notice that the saga ID is editable, this allows you to assign a meaningful unique ID to each saga for your reference. Since these IDs will be recorded within event logs, this approach makes them more manageable than assigning random or sequential IDs.

Icon Bar

Below the ID field, you can find the icon bar, which allows construction of a saga flow as well as changing its layout.

If you click on the edit icon on the left of this bar, you will see the pop-up editor for defining saga details.

At the center of the icon bar, you can see different types of saga steps, which you can and drop on to the grid to add new steps to the saga flow.

Each saga must have a single Start step, but can have multiple Fail or Success steps if that makes your flow easier to follow. Between these steps, you can add any number of steps or conditional logic to build your API flow.

At the right side, you can see the icons for changing the layout of saga flow after you've added its steps, such as automatically aligning steps, hiding / displaying the grid as well as changing its size.

Once you create a new saga or update an existing one, it is automatically updated on the respective runners - as long as the change data capture is not disabled. This update changes API flow for the saga's URL endpoint in real-time. This change can affect still ongoing requests to this URL endpoint (e.g. requests started just milliseconds before you save your saga) as follows:

• If they are running on another saga record (i.e. with a different id), they continue and finish using that previous saga flow, regardless of whether their saga is set to inactive status or not, effectively having no impact on these requests

• If you've updated the design of the currently active saga, they start using this new saga flow for completion. If you've done drastic changes on the saga flow, such as removing some steps, this can cause some of these requests to fail. In such cases, we recommend creating a new version of the saga or switching to a back-up saga flow for a few seconds to make sure there are no active requests on your saga.