---
title: "SSE (Server-Sent Events) | AgentRQ Glossary"
url: https://agentrq.com/glossary/sse
description: "Server-Sent Events (SSE) is a web technology that enables a server to push real-time updates to a client over a persistent HTTP connection, used by AgentRQ to deliver agent notifications instantly."
---

[Back to Glossary](https://agentrq.com/glossary/)

# SSE (Server-Sent Events)

**Server-Sent Events (SSE)** is a web technology that enables a server to push real-time, one-directional updates to a client over a persistent HTTP connection. Unlike traditional HTTP where the client must poll for updates, SSE maintains an open connection through which the server can stream data as it becomes available.

## How SSE Works

text

```text
Client                          Server
  │                               │
  │── GET /events (EventSource) ──▶│
  │                               │
  │◀── data: {"type":"task"} ─────│  (immediate push)
  │                               │
  │◀── data: {"type":"message"} ──│  (seconds later)
  │                               │
  │       [connection stays open] │
```

1. The client opens a persistent HTTP connection to the server's SSE endpoint
2. The server sends events as they occur — no polling required
3. The connection auto-reconnects if dropped

## SSE vs. WebSockets vs. Polling

| Method | Direction | Protocol | Use Case |
| --- | --- | --- | --- |
| Polling | Client pulls | HTTP | Simple, high-latency OK |
| SSE | Server pushes | HTTP | Real-time server-to-client |
| WebSockets | Bidirectional | WS | Full-duplex real-time |

SSE is simpler than WebSockets and works over standard HTTP/2 — making it ideal for server-to-agent event streaming.

## SSE in MCP

The [Model Context Protocol](https://agentrq.com/glossary/mcp) supports SSE as one of its transport options. When an [MCP server](https://agentrq.com/glossary/mcp-server) like AgentRQ is accessed remotely, it uses HTTP for tool calls and SSE for streaming responses and real-time events.

## SSE in AgentRQ

AgentRQ uses SSE to deliver real-time [notifications](https://agentrq.com/glossary/notification) and messages to connected clients. When a [Claude Code](https://agentrq.com/glossary/claude-code) agent calls the `task` [MCP tool](https://agentrq.com/glossary/mcp-tool) with the `reply` action, AgentRQ pushes the message to your [task board](https://agentrq.com/glossary/task-board) via SSE — appearing instantly without any refresh or polling on your end.

## Related Terms

- → [MCP](https://agentrq.com/glossary/mcp)
- → [MCP Server](https://agentrq.com/glossary/mcp-server)
- → [Notification](https://agentrq.com/glossary/notification)
- → [Channel](https://agentrq.com/glossary/channel)
- → [Task Board](https://agentrq.com/glossary/task-board)