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Open Streams in the sidebar and click Create Stream. The builder is a three-step wizard; Next stays disabled while the current step has validation errors, so you always know where you stand.

Step 1 — Stream Properties

The stream’s identity and configuration:
  • application.id (required) — the Kafka Streams application id. It names the consumer group, prefixes the internal topics, and identifies the stream everywhere in Alginte (including its detail-page URL). Pick it deliberately: redeploying under the same id resumes from the same committed offsets and state.
  • bootstrap.servers (required) — usually your cluster’s default.
  • Serde defaults — the default key/value types records are read and written with; individual nodes can override them later.
  • Optional groups for resiliency (replication factor, standby replicas, state directory) and error handling (the dead-letter-queue topic), plus any other Kafka Streams property.

Step 2 — Stream Flow: the canvas

The node palette sits beside the canvas, grouped by category — Source, Stateless, Group, Aggregate, Window, Join, Branch / Merge, Convert, Suppress, Terminal. Drag an item onto the canvas to add it, then draw edges between node handles to define the record flow.
  • Start with a Source (Stream Source, Table Source, or Global Table Source) reading from a topic.
  • Add processors — Map, Filter, Group By, Aggregate, Join, windowing and the rest of the operator set (see the overview).
  • End each branch in a Terminal node — typically a Sink writing to a topic.
Every node carries a small toolbar: Show Properties Panel, Duplicate, Delete. The properties panel opens as a drawer: an optional collapsed Help section for the operator on top, the node’s SpEL expression editors always visible in the middle, and collapsed sections for editor type hints, windowing, and serde overrides around them.

Validation as you build

Nodes, wizard steps, and palette groups carry error badges while something is incomplete — a missing topic, an unconnected handle, an invalid expression. Hover a badge to read the messages. When the canvas is clean, Next unlocks.

Editing shortcuts

  • Copy / paste: Ctrl+C / Ctrl+V — works for multi-node selections, including their connections.
  • Undo / redo: Ctrl+Z / Ctrl+Y.
  • Multi-select: hold Shift and drag a box around nodes (box selection — not Shift+click).
  • Alignment toolbar for tidying the selected nodes.

Save your work: Download / Upload

The wizard header has Download (export the whole design — configuration and canvas layout — as JSON) and Upload (import one back, ready to edit or submit). Export is your durable copy: designs live in the file, not in the server. Download early, download often.

Step 3 — Submit Stream

Review and hit Submit. The topology is built server-side, deployed into your Alginte instance, and started. What happens next — lifecycle, state, and edition behaviour — is on Deploy & lifecycle.