# HppHostChannel

A model the API reference uses in a request or a response. The operation pages link every field typed as this model here.

Where the public hosted payment page delivers its lifecycle envelopes, and where it accepts
commands from: the embedding browser window (the historical iframe integration), or a handler
installed by a native app hosting the page in a WebView. This governs the transport only. The
envelope vocabulary, the envelope shape, the payload members and the command names are
identical on both channels.

## Values

| Value | Description |
| --- | --- |
| `ParentWindow` | The default, historical behavior: envelopes are posted to window.parent with the session's parent origin as the target origin, and inbound commands arrive as window messages from that same origin. Emission fails closed when the session carries no parent origin. null (legacy sessions) resolves here. |
| `NativeWebView` | The page is a top-level document inside a native app's WebView, so it has no parent window and no parent origin. Envelopes are delivered to the single message handler the host app installed under the protocol's handler name, and commands arrive through the protocol's entry-point function the host app calls. The host app is the trust boundary: there is no origin to validate, and the embedding-domain allow-list does not apply. |

## See also

- [All documentation](https://devportal.demo.winkpg.io/llms.txt): the machine-readable index of every public page on this site.