writeSseFrame

SUPPORT · function · 运行时值

Write one encoded frame and wait for drain when the writer reports backpressure.

The signal is re-checked around the write and the drain wait, so cancellation does not leave a pending write considered successful.

导入

TypeScript

import { writeSseFrame } from '@jangts/agent-core/sse';

JavaScript

import { writeSseFrame } from '@jangts/agent-core/sse';

其他公开入口：@jangts/agent-core、@jangts/agent-core/types、@jangts/agent-core/sse、@jangts/agent-core/support。

定义

调用

writeSseFrame({ writer, frame }: { writer: SseWriter; frame: string; }, { signal }: import("../../structs/common.js").ExecutionContext): Promise<void>

Write one encoded frame and wait for drain when the writer reports backpressure.

The signal is re-checked around the write and the drain wait, so cancellation does not leave a pending write considered successful.

参数	类型	传递	说明
__0	{ writer: SseWriter; frame: string; }	必需	—
__1	ExecutionContext	必需	—

__0 的字段

字段	类型	必需	说明
writer	SseWriter	必需	见类型定义及调用场景。
frame	string	必需	见类型定义及调用场景。

__1 的字段

字段	类型	必需	说明
logger	SubFlowLog | undefined	可省略	只读。Explicit optional recorder for this operation; never inferred from diagnostics.
signal	AbortSignal	必需	只读。Non-optional cancellation signal; never undefined once execution has started.
diagnostics	DiagnosticContext | undefined	可省略	只读。Diagnostic scope of the enclosing call, when recording is enabled.

返回： Promise<void>。

等待后的值： void。

使用示例

• SSE、JSON 帧与有界事件流：复用传输机制，保持取消和背压；协议解析与业务校验仍各自负责。

在本地解析一帧 SSE

入门 · Node.js

TypeScript

import { Support } from '@jangts/agent-core';
const frame = Support.encodeSseEvent({ event: 'status', data: JSON.stringify({ phase: 'thinking' }) });
const body = new Response(frame).body!;
for await (const event of Support.readSse(body)) console.log(event.event, event.data);

JavaScript

import { Support } from '@jangts/agent-core';
const frame = Support.encodeSseEvent({ event: 'status', data: JSON.stringify({ phase: 'thinking' }) });
const body = new Response(frame).body;
for await (const event of Support.readSse(body))
    console.log(event.event, event.data);

生产者等待每一次事件交付

配置 · Node.js

TypeScript

import { Support } from '@jangts/agent-core';
const signal = new AbortController().signal;
const stream = Support.streamEvents<{ phase: string }>(async emit => {
  await emit({ phase: 'preparing' });
  await emit({ phase: 'complete' });
}, { signal });
for await (const event of stream) console.log(event.phase);

JavaScript

import { Support } from '@jangts/agent-core';
const signal = new AbortController().signal;
const stream = Support.streamEvents(async (emit) => {
    await emit({ phase: 'preparing' });
    await emit({ phase: 'complete' });
}, { signal });
for await (const event of stream)
    console.log(event.phase);

显式限制 JSON 帧数量和外围内容

扩展 · Node.js

TypeScript

import { Support } from '@jangts/agent-core';
const text = '{"kind":"reply","answer":"服务正常"}';
console.log(Support.scanJsonObjectFrames(text));
console.log(Support.parseJsonFrames(text, { maxFrames: 1, maxExtraClosings: 0 }));
const sent: string[] = [];
await Support.writeSseFrame({
  writer: { write(frame) { sent.push(frame); return true; }, async waitForDrain() {} },
  frame: Support.encodeSseEvent({ event: 'answer', data: text }),
}, { signal: new AbortController().signal });
console.log(sent);

JavaScript

import { Support } from '@jangts/agent-core';
const text = '{"kind":"reply","answer":"服务正常"}';
console.log(Support.scanJsonObjectFrames(text));
console.log(Support.parseJsonFrames(text, { maxFrames: 1, maxExtraClosings: 0 }));
const sent = [];
await Support.writeSseFrame({
    writer: { write(frame) { sent.push(frame); return true; }, async waitForDrain() { } },
    frame: Support.encodeSseEvent({ event: 'answer', data: text }),
}, { signal: new AbortController().signal });
console.log(sent);

相关策略源码

• 事件流单槽交接与背压

相关定义

• ExecutionContext
• SseWriter