---
# @generated by sylphx-gen 0.1.0 from contracts@e145cc7cf1bc9605f2b27439e5e17ed76a1a2fd7e7021906a013f7565e4a0cd5. Do not edit.
title: "Publish a realtime channel"
description: "`events.realtime_channels.publish` (POST /v1/{name}:publish): Publishes one message to the channel: it is appended to the channel's history and pushed to every connected client."
type: reference
product: realtime
summary: "Publishes one message to the channel: it is appended to the channel's history and pushed to every connected client."
updated: 2026-09-28
nav: false
---

Publishes one message to the channel: it is appended to the channel's history and pushed to every connected client. A retry with the same Idempotency-Key returns the first message.

- **Path** `POST https://api.sylphx.com/v1/orgs/acme/projects/shop/envs/production/realtime_channels/realtime-channel:publish`
- **Scope** `events:publish`
- **Effect** `write` — a successful call changes state.
- **Collection** [realtime_channels](/docs/api/realtime_channels)

## Request

| Field | Type | What it is |
| --- | --- | --- |
| `name` | `string` | The name of the realtime channel. Required. |
| `message_type` | `string` | The message name, 1 to 255 of `[A-Za-z0-9._:-]`. Required. |
| `data` | `value` | The payload; at most 64 KiB as JSON. |
| `client_id` | `string` | The publisher's client id, shown to subscribers. |

## Response

| Field | Type | What it is |
| --- | --- | --- |
| `realtime_message` | `RealtimeMessage` | The message as the channel appended it. |

### RealtimeMessage

| Field | Type | What it is |
| --- | --- | --- |
| `name` | `string` | `…/realtime_channels/{realtime_channel}/realtime_messages/{realtime_message}`. |
| `uid` | `string` | `rtm_<cell><ulid>`; never reused. Output only. |
| `meta` | `ResourceMeta` | Resource metadata. |
| `cursor` | `string` | The message's place in the channel; send it back as `after_cursor` (or `Last-Event-ID`) to resume after it. Output only. |
| `sequence` | `int64` | The position in the channel, from 1, gap-free. Output only. |
| `message_type` | `string` | The message name (`chat.message`, `presence.enter`, …). Required. |
| `data` | `value` | The payload. |
| `client_id` | `string` | The publisher's client id, when it named one. |
| `publish_time` | `timestamp` | When the channel appended it. Output only. |

### ResourceMeta

| Field | Type | What it is |
| --- | --- | --- |
| `generation` | `int64` | Increases by one on every change to `spec`. Output only. |
| `etag` | `string` | Strong ETag (AIP-154): changes on any change to spec, status, or metadata. Send it back as `If-Match` or `etag` to make Update and Delete conditional; a mismatch fails with ABORTED / 409 `ETAG_MISMATCH`. Output only. |
| `create_time` | `timestamp` | When the Resource was created. Output only. |
| `update_time` | `timestamp` | When the Resource last changed. Output only. |
| `delete_time` | `timestamp` | Set while the Resource is being deleted. Output only. |
| `labels` | `map<string, string>` | Caller-writable, indexed labels (AIP-122 label rules). |
| `annotations` | `map<string, string>` | Caller-writable, unindexed annotations. |
| `display_name` | `string` | Caller-writable human-readable name. |
| `creator` | `string` | The principal that created the Resource. Output only. |

## Errors

- [`UNAUTHENTICATED`](/docs/api/errors/UNAUTHENTICATED) — No valid key or token was presented.
- [`PERMISSION_DENIED`](/docs/api/errors/PERMISSION_DENIED) — The key lacks the method's permission.
- [`RESOURCE_NOT_FOUND`](/docs/api/errors/RESOURCE_NOT_FOUND) — The named Resource does not exist or is not visible.
- [`INVALID_FIELD`](/docs/api/errors/INVALID_FIELD) — A field failed validation.
- [`IDEMPOTENCY_KEY_REUSED`](/docs/api/errors/IDEMPOTENCY_KEY_REUSED) — An Idempotency-Key was reused with another body.
- [`IDEMPOTENCY_IN_PROGRESS`](/docs/api/errors/IDEMPOTENCY_IN_PROGRESS) — The first call with this Idempotency-Key is still running.

Every error arrives in the body [Errors](/docs/platform/errors) describes.

## Examples

**cURL**

```curl
curl -X POST "https://api.sylphx.com/v1/orgs/acme/projects/shop/envs/production/realtime_channels/realtime-channel:publish" \
  -H "Authorization: Bearer $SYLPHX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"message_type":"…"}'
```

**TypeScript**

```ts
const response = await sylphx.events.realtimeChannels.publish({ messageType: '…', name: 'orgs/acme/projects/shop/envs/production/realtime_channels/realtime-channel' })
```

**Rust**

```rust
let mut req = sylphx::events::PublishRealtimeMessagesRequest::default();
req.message_type = "…".to_string();
req.name = "orgs/acme/projects/shop/envs/production/realtime_channels/realtime-channel".to_string();
let response = sx.events().realtime_channels().publish(req).await?;
```

**CLI**

```bash
sylphx events realtime-channels publish orgs/acme/projects/shop/envs/production/realtime_channels/realtime-channel
```

**MCP**

```json
{ "method_id": "events.realtime_channels.publish", "args": {"message_type":"…","name":"orgs/acme/projects/shop/envs/production/realtime_channels/realtime-channel"} }
```