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The Flow Builder is the centerpiece of Devset. It gives you a visual, drag-and-drop canvas for assembling event-driven workflows — sequences of pipeline stages that emit messages to Kafka or RabbitMQ according to the logic you define. Every stage, field value, and expression lives in a portable DSL that you can import, export, and version however you like. Open the Flow Builder at http://localhost:8082/flow-builder.

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The Manage View

Before you open the canvas, the Manage view at /flow-builder/manage gives you a table of every workflow you have saved. From here you can open a workflow in the editor, clone it to use as a starting point, or delete it entirely. You can also bring in a workflow from outside Devset using the Import button. Paste any valid DSL JSON and Devset will load it as a new workflow ready for editing.

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Creating a New Workflow

1

Open the Manage view

Navigate to http://localhost:8082/flow-builder/manage and click New Workflow. The canvas editor opens with a blank workflow.
2

Configure the Workflow Panel

In the right-hand sidebar, the Workflow Panel shows the current workflow’s ID field. Enter a unique Workflow ID to identify this workflow. To configure the other top-level properties — message type, content type, producer name, topic or exchange, routing key, schema ID, and execution count — open the Payload Editor from the Workflow Panel and edit those fields directly in the DSL JSON.
3

Add pipeline stages

Click the Add Step button on the canvas toolbar. If your workflow has a schema attached, you can pick fields from it when configuring the new stage. A colored stage node appears on the canvas connected to the previous node by an arrow.Repeat this step until you have all the stages your workflow requires.
4

Configure each stage

Click a stage node to select it. The Stage Inspector panel opens in the right sidebar. Use it to configure:
  • Set fields — static or computed values written into the message payload.
  • State fields — values read from or written to the shared workflow state.
For more complex logic on any individual field, use Function Studio (see below).
5

Save your workflow

When you are happy with the canvas, save the workflow. If you try to navigate away with unsaved changes, Devset will prompt you to confirm before discarding them.
Setting a schemaId in the workflow DSL (via the Payload Editor) unlocks field autocomplete throughout the editor, including in the Stage Inspector and Function Studio. Add your schemas to the Schema Repo first to get the most out of this feature.

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Using Function Studio for Per-Field Expressions

Function Studio is a per-field expression editor that opens as a full-screen drawer from the sidebar. It lets you go beyond static values and write dynamic expressions for any field in a stage.
1

Open Function Studio

With a stage node selected on the canvas, click the Open Function Studio button in the sidebar. The Function Studio drawer slides open with a field tree picker on the left and an expression editor on the right.
2

Pick the field

Use the field tree on the left to navigate to the field you want to set. If a schema is attached to the workflow, the tree reflects its structure.
3

Choose a field mode

Select the mode that matches your intent:
ModeDescription
LITERALA static, hard-coded value.
FNA function call such as uuid() or int(1, 100).
REFA relative reference to another field in the same message.
PATHAn absolute path into the shared workflow state.
WHENA conditional expression — returns different values based on a condition.
4

Write and confirm the expression

Type your expression in the editor on the right, then confirm to save it back to the stage.

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Importing and Exporting Workflows

Devset workflows are stored as a JSON DSL, which makes them easy to share, version-control, or migrate between environments. To export a workflow, open the canvas editor and click Payload Editor in the Workflow Panel sidebar. This modal displays the raw DSL JSON for the current workflow. Copy the contents to share or commit the workflow to source control. To import a workflow, go to the Manage view and click Import. Paste the DSL JSON into the dialog and confirm. The workflow is loaded into Devset as a new entry in your workflow list.
The Payload Editor also lets you edit the DSL directly. This is useful for bulk edits that would be tedious to make field by field in the canvas UI.

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Managing Workflows from the Manage View

The Manage view table shows every saved workflow alongside three actions:

Open

Load the workflow in the canvas editor to view or modify it.

Clone

Create a duplicate of the workflow with a new ID. Useful for creating variations without modifying the original.

Delete

Permanently remove the workflow from Devset. This action cannot be undone.

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Defining Initial Workflow State

Open the Workflow State Editor modal from the Workflow Panel in the sidebar to define the initial state shape for the workflow. State values are accessible in Function Studio using the PATH mode and can be read or updated by any stage during execution.