6. Run the Journey in your app

Your host app reaches Journeys through the JourneyService. The recommended path is SDK-provided UI: the SDK renders the Journey's screens itself in a styleable WebView, so your app only needs to fetch the Journey by name and run it.

The two functions you need are:

• JourneyService.getJourneys(tags?, statuses?) — list available Journeys, optionally filtered by tag.
• JourneyService.runJourney(name, data) — run a Journey by its programmatic name. data is an object whose keys are seeded into the JourneyContext before the first step.

iOS

let journeyService = DataSapien.getJourneyService()

// Either look it up by tag…
let journeys = try await journeyService.getJourneys(tags: ["getting-started"])

// …or just run it directly by programmatic name.
let result = try await journeyService.runJourney(
    name: "hello_world",
    data: [:]
)

Android

val journeyService = DataSapien.getJourneyService()

lifecycleScope.launch {
    // Either look it up by tag…
    val journeys = journeyService.getJourneys(tags = listOf("getting-started"))

    // …or just run it directly by programmatic name.
    val result = journeyService.runJourney(
        name = "hello_world",
        data = emptyMap()
    )
}

Flutter

final journeyService = DataSapien.getJourneyService();

// Either look it up by tag…
final journeys = await journeyService.getJourneys(tags: ['getting-started']);

// …or just run it directly by programmatic name.
final result = await journeyService.runJourney(
  name: 'hello_world',
  data: {},
);

React Native

const journeyService = DataSapien.getJourneyService();

// Either look it up by tag…
const journeys = await journeyService.getJourneys(['getting-started']);

// …or just run it directly by programmatic name.
const result = await journeyService.runJourney('hello_world', {});

Programmatic name

A Journey's programmatic name is the unique identifier you set on the Basics section in build the Journey (we used hello_world). It's what every API call refers to — not the display title.

Exact signatures

The native API surface is nearly identical to the JavaScript one shown above; Android methods may take an extra Context. See the JourneyService API reference for per-platform signatures.

Build and run your app on a device. Trigger the call above and the SDK will, in order:

1. Show the favorite_color question.
2. Show the "What's your name?" question.
3. Run the Script step silently to build greeting.
4. Show the Screen displaying Hello, <name>! Your favourite colour is <colour>.
5. Complete.

[#10] The Hello World Journey running on a device

---

What just happened

In a single Journey you used four of the five step types, defined a custom MeData, persisted a value to the on-device data vault, and ran user-authored logic — all without sending any personal data to a backend. That's the whole platform in miniature.

Next steps

• Request the collected favorite_color as Zero-Party Data and watch it appear in the Journey Viewer after a run.
• Add a Conditional Flow that branches on the colour the user picked.
• Replace the static greeting with one generated by an on-device AI model called from the Script step.
• Restrict the Journey to a real Audience instead of All.