> ## Documentation Index > Fetch the complete documentation index at: https://langchain-zh.cn/llms.txt > Use this file to discover all available pages before exploring further. # 消息队列 > 在智能体顺序处理的同时，对多条消息进行排队和管理 export const PatternEmbed = ({pattern, theme, height, minHeight = 400, maxHeight = 700, className, defaultView = "preview", defaultSdk = "react", defaultLanguage = "js", showCodeTab = true, agentServer = "prod", onError, onReady}) => { var VALID_GUEST_TYPES = new Set(["READY", "RESIZE", "ERROR", "RUN_STARTED", "TRACE_URL", "THREAD_CLEARED"]); function stub() { return { safeParse: data => ({ success: true, data }), optional: () => stub(), min: () => stub(), url: () => stub() }; } var z = { object: _shape => stub(), literal: _value => stub(), string: () => stub(), number: () => stub(), boolean: () => stub(), enum: _values => stub(), array: _el => stub(), union: _schemas => stub(), record: (_key, _value) => stub(), discriminatedUnion: (_key, _schemas) => ({ safeParse(data) { if (data != null && typeof data === "object" && ("type" in data) && typeof data.type === "string" && VALID_GUEST_TYPES.has(data.type)) { return { success: true, data }; } return { success: false }; }, optional: () => stub(), min: () => stub(), url: () => stub() }) }; var SetThemeMessageSchema = z.object({ type: z.literal("SET_THEME"), theme: z.enum(["light", "dark"]) }); var SetPatternMessageSchema = z.object({ type: z.literal("SET_PATTERN"), slug: z.string() }); var ResetMessageSchema = z.object({ type: z.literal("RESET") }); var SetViewMessageSchema = z.object({ type: z.literal("SET_VIEW"), view: z.enum(["preview", "code"]) }); var SetLanguageMessageSchema = z.object({ type: z.literal("SET_LANGUAGE"), language: z.enum(["js", "python"]) }); var CodeFileSchema = z.object({ filename: z.string(), content: z.string() }); var UpdateCodeMessageSchema = z.object({ type: z.literal("UPDATE_CODE"), files: z.array(CodeFileSchema).min(1), entryFile: z.string() }); var TrackEventMessageSchema = z.object({ type: z.literal("TRACK_EVENT"), name: z.string(), properties: z.record(z.string(), z.union([z.string(), z.number(), z.boolean()])).optional() }); var HostToGuestMessageSchema = z.discriminatedUnion("type", [SetThemeMessageSchema, SetPatternMessageSchema, ResetMessageSchema, UpdateCodeMessageSchema, SetViewMessageSchema, SetLanguageMessageSchema, TrackEventMessageSchema]); var ReadyMessageSchema = z.object({ type: z.literal("READY"), framework: z.enum(["react", "vue", "angular", "svelte"]) }); var ResizeMessageSchema = z.object({ type: z.literal("RESIZE"), height: z.number() }); var ErrorMessageSchema = z.object({ type: z.literal("ERROR"), message: z.string(), stack: z.string().optional() }); var RunStartedMessageSchema = z.object({ type: z.literal("RUN_STARTED"), runId: z.string() }); var TraceUrlMessageSchema = z.object({ type: z.literal("TRACE_URL"), url: z.string().url(), runId: z.string() }); var ThreadClearedMessageSchema = z.object({ type: z.literal("THREAD_CLEARED") }); var GuestToHostMessageSchema = z.discriminatedUnion("type", [ReadyMessageSchema, ResizeMessageSchema, ErrorMessageSchema, RunStartedMessageSchema, TraceUrlMessageSchema, ThreadClearedMessageSchema]); var PreviewMessageSchema = z.union([HostToGuestMessageSchema, GuestToHostMessageSchema]); function isOriginAllowed(origin, allowedOrigins) { return allowedOrigins.includes("*") || allowedOrigins.includes(origin); } function createPreviewHost(iframe, options) { const {allowedOrigins} = options; const targetOrigins = options.targetOrigins ?? allowedOrigins; const listeners = new Map(); function postToGuest(message) { if (!iframe.contentWindow) return; for (const origin of targetOrigins) { iframe.contentWindow.postMessage(message, origin); } } function addListener(type, callback) { if (!listeners.has(type)) { listeners.set(type, new Set()); } listeners.get(type).add(callback); return () => { listeners.get(type)?.delete(callback); }; } function handleMessage(event) { if (!isOriginAllowed(event.origin, allowedOrigins)) return; const result = GuestToHostMessageSchema.safeParse(event.data); if (!result.success) return; const msg = result.data; const cbs = listeners.get(msg.type); if (!cbs) return; for (const cb of cbs) { switch (msg.type) { case "READY": cb(msg.framework); break; case "RESIZE": cb(msg.height); break; case "ERROR": cb(msg.message, msg.stack); break; case "RUN_STARTED": cb(msg.runId); break; case "TRACE_URL": cb(msg.url, msg.runId); break; case "THREAD_CLEARED": cb(); break; } } } window.addEventListener("message", handleMessage); return { setTheme(theme) { postToGuest({ type: "SET_THEME", theme }); }, setPattern(slug) { postToGuest({ type: "SET_PATTERN", slug }); }, setView(view) { postToGuest({ type: "SET_VIEW", view }); }, setLanguage(language) { postToGuest({ type: "SET_LANGUAGE", language }); }, updateCode(files, entryFile) { postToGuest({ type: "UPDATE_CODE", files, entryFile }); }, reset() { postToGuest({ type: "RESET" }); }, trackEvent(name, properties) { postToGuest({ type: "TRACK_EVENT", name, properties }); }, onReady(callback) { return addListener("READY", callback); }, onResize(callback) { return addListener("RESIZE", callback); }, onError(callback) { return addListener("ERROR", callback); }, onRunStarted(callback) { return addListener("RUN_STARTED", callback); }, onTraceUrl(callback) { return addListener("TRACE_URL", callback); }, onThreadCleared(callback) { return addListener("THREAD_CLEARED", callback); }, destroy() { window.removeEventListener("message", handleMessage); listeners.clear(); } }; } var PROD_BASE = "https://ui-patterns.langchain.com"; var SDK_LABELS = { react: "React", vue: "Vue", svelte: "Svelte", angular: "Angular" }; var SDK_LOCAL_HOSTS = { react: "http://localhost:4100", vue: "http://localhost:4200", svelte: "http://localhost:4300", angular: "http://localhost:4400" }; var SDK_PROD_HOSTS = { react: `${PROD_BASE}/react`, vue: `${PROD_BASE}/vue`, svelte: `${PROD_BASE}/svelte`, angular: `${PROD_BASE}/angular` }; var SDK_LOGOS = { react: ``, vue: ``, svelte: ``, angular: `` }; var PROD_AGENT_API_BASE = `${PROD_BASE}/api/langgraph`; function normalizeAgentServerBase(agentServer, useLocalPreview) { const trimmed = agentServer.trim(); if (useLocalPreview) { return "http://localhost:2024"; } if (trimmed === "prod") { return PROD_AGENT_API_BASE; } if (trimmed === "local") { return PROD_AGENT_API_BASE; } return PROD_AGENT_API_BASE; } function isLocalhost() { if (typeof window === "undefined") return false; const {hostname} = window.location; return hostname === "localhost" || hostname === "127.0.0.1" || hostname === "[::]"; } function detectPageTheme() { if (typeof document === "undefined") return "light"; const el = document.documentElement; if (el.classList.contains("dark")) return "dark"; if (el.getAttribute("data-theme") === "dark") return "dark"; if (el.style.colorScheme === "dark") return "dark"; return "light"; } var CACHE_KEY = "__lcPlaygroundIframeCache"; var iframeCache = globalThis[CACHE_KEY] ?? (() => { const m = new Map(); globalThis[CACHE_KEY] = m; return m; })(); var SDK_CACHE_KEY = "__lcPlaygroundSdkCache"; var sdkCache = globalThis[SDK_CACHE_KEY] ?? (() => { const m = new Map(); globalThis[SDK_CACHE_KEY] = m; return m; })(); var LANG_CACHE_KEY = "__lcPlaygroundLangCache"; var langCache = globalThis[LANG_CACHE_KEY] ?? (() => { const m = new Map(); globalThis[LANG_CACHE_KEY] = m; return m; })(); var VIEW_EYE_SVG = ``; var VIEW_CODE_SVG = ``; var CHEVRON_DOWN_SVG = ``; var TRACE_ICON_SVG = ``; var TRACE_SPINNER_SVG = ``; var EXTERNAL_LINK_SVG = ``; var DOWNLOAD_SVG = ``; var EXPAND_SVG = ``; var CLOSE_SVG = ``; var LANG_TS_SVG = ``; var LANG_PYTHON_SVG = ` `; var SDK_OPTIONS = Object.keys(SDK_LABELS).map(k => [k, SDK_LABELS[k]]); var EMBED_CSS = ` [data-lc-pe] .lc-tab{font-size:13px;font-family:inherit} [data-lc-pe] .lc-sdk-option{font-size:13px} [data-lc-pe] .lc-border{border-color:#B8DFFF} [data-lc-pe].dark .lc-border{border-color:#1A2740} [data-lc-pe] .lc-bg-surface{background-color:white} [data-lc-pe].dark .lc-bg-surface{background-color:#0B1120} [data-lc-pe] .lc-bg-wash{background-color:#F2FAFF} [data-lc-pe].dark .lc-bg-wash{background-color:#030710} [data-lc-pe] .lc-tab-active{background-color:#7FC8FF;color:#030710} [data-lc-pe] .lc-tab-inactive{background-color:transparent;color:#6B8299} [data-lc-pe] .lc-tab-inactive:hover{background-color:#E5F4FF;color:#030710} [data-lc-pe].dark .lc-tab-inactive:hover{background-color:#1A2740;color:#C8DDF0} [data-lc-pe] .lc-tab-trace{background-color:#FFF3E0;color:#E65100} [data-lc-pe].dark .lc-tab-trace{background-color:#3E2723;color:#FFB74D} [data-lc-pe] .lc-tab-trace:hover{background-color:#FFE0B2} [data-lc-pe].dark .lc-tab-trace:hover{background-color:#4E342E} [data-lc-pe] .lc-tab-trace-loading{background-color:transparent;color:#6B8299;cursor:not-allowed} [data-lc-pe] .lc-sdk-btn{border-color:#B8DFFF;background-color:white;font-size:13px;color:#030710} [data-lc-pe].dark .lc-sdk-btn{border-color:#1A2740;background-color:#0B1120;color:#C8DDF0} [data-lc-pe] .lc-sdk-btn:hover{background-color:#E5F4FF} [data-lc-pe].dark .lc-sdk-btn:hover{background-color:#1A2740} [data-lc-pe] .lc-dropdown{border-color:#B8DFFF;background-color:white;min-width:120px} [data-lc-pe].dark .lc-dropdown{border-color:#1A2740;background-color:#0B1120} [data-lc-pe] .lc-sdk-selected{background-color:#E5F4FF;color:#030710} [data-lc-pe].dark .lc-sdk-selected{background-color:#1A2740;color:#C8DDF0} [data-lc-pe] .lc-sdk-unselected{color:#6B8299} [data-lc-pe] .lc-sdk-unselected:hover{background-color:#F2FAFF;color:#030710} [data-lc-pe].dark .lc-sdk-unselected:hover{background-color:#1A2740;color:#C8DDF0} [data-lc-pe] .lc-spinner{border-color:#B8DFFF;border-top-color:#7FC8FF} [data-lc-pe].dark .lc-spinner{border-color:#1A2740;border-top-color:#7FC8FF} [data-lc-pe] .lc-error{background-color:rgb(178 125 117/0.1);border-color:rgb(178 125 117/0.3);color:#B27D75} [data-lc-pe] .lc-error-btn{border-color:rgb(178 125 117/0.3);background-color:white;color:#B27D75} [data-lc-pe].dark .lc-error-btn{background-color:#0B1120} [data-lc-pe] .lc-lang-switcher .lc-tab{padding:4px 8px} @media(max-width:639px){ [data-lc-pe] .lc-toolbar{flex-wrap:wrap;gap:8px} [data-lc-pe] .lc-tab-label{display:none} [data-lc-pe] .lc-tab{padding-left:10px;padding-right:10px} [data-lc-pe] .lc-sdk-btn{margin-left:auto} } [data-lc-pe] .lc-expand-btn{border:none;background:transparent;cursor:pointer;padding:6px;border-radius:6px;display:inline-flex;align-items:center;justify-content:center;color:#6B8299;transition:background-color 0.15s,color 0.15s} [data-lc-pe] .lc-expand-btn:hover{background-color:#E5F4FF;color:#030710} [data-lc-pe].dark .lc-expand-btn:hover{background-color:#1A2740;color:#C8DDF0} .lc-pe-backdrop{position:fixed;inset:0;z-index:9998;background:rgba(0,0,0,0.4);backdrop-filter:blur(4px);-webkit-backdrop-filter:blur(4px)} `; const slotRef = useRef(null); const cardRef = useRef(null); const placeholderRef = useRef(null); const cachedRef = useRef(null); const useLocalPreview = agentServer === "local" || agentServer === "prod" && isLocalhost(); const agentQuery = agentServer !== "local" && agentServer !== "prod" ? `?agentServer=${encodeURIComponent(agentServer)}` : ""; const sdkCacheKey = `${agentServer}|${pattern}`; const [sdk, setSdkRaw] = useState(() => { const fromCache = sdkCache.get(sdkCacheKey); if (fromCache) return fromCache; const hosts = useLocalPreview ? SDK_LOCAL_HOSTS : SDK_PROD_HOSTS; let best = null; for (const [s, url] of Object.entries(hosts)) { const entry = iframeCache.get(`${url}|${agentQuery}`); if (entry?.lastActiveAt && (!best || entry.lastActiveAt > best.at)) { best = { sdk: s, at: entry.lastActiveAt }; } } if (best) return best.sdk; return defaultSdk; }); const setSdk = useCallback(s => { sdkCache.set(sdkCacheKey, s); setSdkRaw(s); }, [sdkCacheKey]); const [sdkDropdownOpen, setSdkDropdownOpen] = useState(false); const langCacheKey = `${agentServer}|${pattern}`; const [agentLang, setAgentLangRaw] = useState(() => langCache.get(langCacheKey) ?? defaultLanguage); const setAgentLang = useCallback(l => { langCache.set(langCacheKey, l); setAgentLangRaw(l); }, [langCacheKey]); const previewUrl = useLocalPreview ? SDK_LOCAL_HOSTS[sdk] : SDK_PROD_HOSTS[sdk]; const cacheKey = `${previewUrl}|${agentQuery}`; const [ready, setReady] = useState(() => iframeCache.get(cacheKey)?.ready ?? false); const [iframeHeight, setIframeHeight] = useState(() => iframeCache.get(cacheKey)?.lastHeight ?? minHeight); const [error, setError] = useState(null); const [activeView, setActiveView] = useState(() => iframeCache.get(cacheKey)?.lastView ?? defaultView); const [traceUrl, setTraceUrl] = useState(null); const [traceLoading, setTraceLoading] = useState(false); const [expanded, setExpanded] = useState(false); const expandedRef = useRef(false); expandedRef.current = expanded; const [pageTheme, setPageTheme] = useState(detectPageTheme); useEffect(() => { setPageTheme(detectPageTheme()); const observer = new MutationObserver(() => setPageTheme(detectPageTheme())); observer.observe(document.documentElement, { attributes: true, attributeFilter: ["class", "data-theme", "style"] }); return () => observer.disconnect(); }, []); const effectiveTheme = theme ?? pageTheme; useEffect(() => { if (document.getElementById("lc-pe-css")) return; const style = document.createElement("style"); style.id = "lc-pe-css"; style.textContent = EMBED_CSS; document.head.appendChild(style); }, []); const onErrorRef = useRef(onError); onErrorRef.current = onError; const onReadyRef = useRef(onReady); onReadyRef.current = onReady; const patternRef = useRef(pattern); patternRef.current = pattern; const themeRef = useRef(effectiveTheme); themeRef.current = effectiveTheme; const activeViewRef = useRef(activeView); activeViewRef.current = activeView; const agentLangRef = useRef(agentLang); agentLangRef.current = agentLang; useEffect(() => { let cached = iframeCache.get(cacheKey); if (cached?.hideTimer) { clearTimeout(cached.hideTimer); cached.hideTimer = void 0; } if (!cached) { const iframe2 = document.createElement("iframe"); iframe2.src = `${previewUrl}/${agentQuery}#/${patternRef.current}`; iframe2.setAttribute("sandbox", "allow-scripts allow-same-origin allow-forms"); iframe2.setAttribute("allow", "clipboard-write"); iframe2.title = `${patternRef.current} pattern`; iframe2.setAttribute("data-cache-key", cacheKey); Object.assign(iframe2.style, { position: "fixed", border: "none", visibility: "hidden", pointerEvents: "auto", zIndex: "1", borderRadius: "0 0 15px 15px" }); document.body.appendChild(iframe2); let iframeOrigin; try { iframeOrigin = new URL(previewUrl).origin; } catch { iframeOrigin = previewUrl; } const host2 = createPreviewHost(iframe2, { allowedOrigins: [iframeOrigin] }); cached = { iframe: iframe2, host: host2, ready: false, lastHeight: minHeight, lastView: defaultView, lastActiveAt: 0 }; iframeCache.set(cacheKey, cached); } cachedRef.current = cached; const {iframe, host} = cached; if (cached.ready) { setReady(true); setIframeHeight(cached.lastHeight); host.setTheme(themeRef.current); host.setPattern(patternRef.current); host.setLanguage(agentLangRef.current); if (activeViewRef.current !== "preview") { host.setView(activeViewRef.current); } cached.lastActiveAt = Date.now(); iframe.style.visibility = "visible"; } const unsubReady = host.onReady(() => { cached.ready = true; cached.lastActiveAt = Date.now(); setReady(true); host.setTheme(themeRef.current); host.setPattern(patternRef.current); host.setLanguage(agentLangRef.current); if (activeViewRef.current !== "preview") { host.setView(activeViewRef.current); } iframe.style.visibility = "visible"; onReadyRef.current?.(); }); const unsubResize = host.onResize(h => { if (expandedRef.current) return; const clamped = Math.min(maxHeight, Math.max(minHeight, h)); cached.lastHeight = clamped; setIframeHeight(clamped); }); const unsubError = host.onError((message, stack) => { setError(message); iframe.style.visibility = "hidden"; onErrorRef.current?.(message, stack); }); const unsubRunStarted = host.onRunStarted(() => { setTraceUrl(null); setTraceLoading(true); }); const unsubTraceUrl = host.onTraceUrl((url, _runId) => { setTraceUrl(url); setTraceLoading(false); }); const unsubThreadCleared = host.onThreadCleared(() => { setTraceUrl(null); setTraceLoading(false); }); function syncPosition() { const slot2 = slotRef.current; if (!slot2) return; const rect = slot2.getBoundingClientRect(); const {style} = iframe; style.top = `${rect.top}px`; style.left = `${rect.left}px`; style.width = `${rect.width}px`; style.setProperty("height", `${rect.height}px`, "important"); if (expandedRef.current) { style.zIndex = "10000"; } else { style.zIndex = "1"; } } syncPosition(); const ro = new ResizeObserver(syncPosition); if (slotRef.current) ro.observe(slotRef.current); document.addEventListener("scroll", syncPosition, { passive: true, capture: true }); window.addEventListener("resize", syncPosition, { passive: true }); let frameCount = 0; let rafId = 0; function initialSync() { syncPosition(); if (++frameCount < 5) rafId = requestAnimationFrame(initialSync); } rafId = requestAnimationFrame(initialSync); return () => { cancelAnimationFrame(rafId); ro.disconnect(); document.removeEventListener("scroll", syncPosition, { capture: true }); window.removeEventListener("resize", syncPosition); unsubReady(); unsubResize(); unsubError(); unsubRunStarted(); unsubTraceUrl(); unsubThreadCleared(); cachedRef.current = null; cached.hideTimer = setTimeout(() => { iframe.style.visibility = "hidden"; }, 200); }; }, [cacheKey, previewUrl, agentQuery, defaultView, minHeight, maxHeight]); useEffect(() => { requestAnimationFrame(() => window.dispatchEvent(new Event("resize"))); if (!expanded) return; const card = cardRef.current; const placeholder = placeholderRef.current; if (!card || !placeholder) return; const wrapper = document.createElement("div"); wrapper.setAttribute("data-lc-pe", ""); wrapper.className = `${effectiveTheme === "dark" ? "dark" : ""}`; document.body.appendChild(wrapper); const backdrop = document.createElement("div"); backdrop.className = "lc-pe-backdrop"; backdrop.addEventListener("click", () => setExpanded(false)); wrapper.appendChild(backdrop); wrapper.appendChild(card); Object.assign(card.style, { position: "fixed", zIndex: "9999", top: "50%", left: "50%", transform: "translate(-50%, -50%)", width: "min(70vw, calc(100vw - 48px))", height: "85vh", display: "flex", flexDirection: "column" }); const handleKeyDown = e => { if (e.key === "Escape") setExpanded(false); }; document.addEventListener("keydown", handleKeyDown); const pageWrapper = document.body.children[0]; const savedFilter = pageWrapper?.style.filter ?? ""; const savedPointerEvents = pageWrapper?.style.pointerEvents ?? ""; if (pageWrapper && pageWrapper !== wrapper) { pageWrapper.style.filter = "blur(4px)"; pageWrapper.style.pointerEvents = "none"; } requestAnimationFrame(() => window.dispatchEvent(new Event("resize"))); return () => { document.removeEventListener("keydown", handleKeyDown); if (pageWrapper && pageWrapper !== wrapper) { pageWrapper.style.filter = savedFilter; pageWrapper.style.pointerEvents = savedPointerEvents; } card.style.cssText = ""; placeholder.appendChild(card); wrapper.remove(); requestAnimationFrame(() => window.dispatchEvent(new Event("resize"))); }; }, [expanded, effectiveTheme]); useEffect(() => { if (!ready || !cachedRef.current) return; setError(null); cachedRef.current.host.setPattern(pattern); }, [pattern, ready]); useEffect(() => { if (!ready || !cachedRef.current) return; cachedRef.current.host.setTheme(effectiveTheme); }, [effectiveTheme, ready]); useEffect(() => { if (!ready || !cachedRef.current) return; cachedRef.current.host.setLanguage(agentLang); }, [agentLang, ready]); const switchView = useCallback(view => { setActiveView(view); if (cachedRef.current) { cachedRef.current.lastView = view; if (cachedRef.current.ready) { cachedRef.current.host.setView(view); if (view === "code") { cachedRef.current.host.trackEvent("code_tab_clicked", { pattern }); } } } }, [pattern]); const sdkButtonRef = useRef(null); useEffect(() => { if (!sdkDropdownOpen || !sdkButtonRef.current) return; const isDark = effectiveTheme === "dark"; const rect = sdkButtonRef.current.getBoundingClientRect(); const dropdown = document.createElement("div"); Object.assign(dropdown.style, { position: "fixed", top: `${rect.bottom + 4}px`, right: `${window.innerWidth - rect.right}px`, zIndex: expandedRef.current ? "10001" : "10", minWidth: "120px", borderRadius: "8px", border: `1px solid ${isDark ? "#1A2740" : "#B8DFFF"}`, backgroundColor: isDark ? "#0B1120" : "white", boxShadow: "0 4px 12px rgba(0,0,0,0.15)", padding: "4px 0" }); for (const [value, label] of SDK_OPTIONS) { const isSelected = value === sdk; const btn = document.createElement("button"); btn.type = "button"; Object.assign(btn.style, { display: "flex", alignItems: "center", gap: "6px", width: "100%", textAlign: "left", padding: "6px 12px", fontSize: "13px", cursor: "pointer", border: "none", fontWeight: isSelected ? "500" : "normal", backgroundColor: isSelected ? isDark ? "#1A2740" : "#E5F4FF" : "transparent", color: isSelected ? isDark ? "#C8DDF0" : "#030710" : "#6B8299" }); btn.innerHTML = `${SDK_LOGOS[value]}${label}`; btn.addEventListener("mouseenter", () => { if (!isSelected) { btn.style.backgroundColor = isDark ? "#1A2740" : "#F2FAFF"; btn.style.color = isDark ? "#C8DDF0" : "#030710"; } }); btn.addEventListener("mouseleave", () => { if (!isSelected) { btn.style.backgroundColor = "transparent"; btn.style.color = "#6B8299"; } }); btn.addEventListener("click", () => { setSdk(value); setSdkDropdownOpen(false); cachedRef.current?.host.trackEvent("sdk_switched", { sdk: value, pattern }); }); dropdown.appendChild(btn); } document.body.appendChild(dropdown); const handleClose = e => { if (!dropdown.contains(e.target) && !sdkButtonRef.current?.contains(e.target)) { setSdkDropdownOpen(false); } }; const timer = setTimeout(() => document.addEventListener("mousedown", handleClose), 0); return () => { clearTimeout(timer); document.removeEventListener("mousedown", handleClose); dropdown.remove(); }; }, [sdkDropdownOpen, sdk, effectiveTheme, setSdk, pattern]); const handleReset = useCallback(() => { cachedRef.current?.host.reset(); if (cachedRef.current?.ready) { cachedRef.current.host.setPattern(pattern); } }, [pattern]); const resolvedHeight = height ?? Math.min(maxHeight, Math.max(minHeight, iframeHeight)); const heightStyle = typeof resolvedHeight === "number" ? `${resolvedHeight}px` : resolvedHeight; useEffect(() => { if (!expanded) { slotRef.current?.style.setProperty("height", heightStyle, "important"); } else { slotRef.current?.style.removeProperty("height"); } }, [heightStyle, expanded]); const tabBase = "lc-tab inline-flex items-center gap-1.5 px-3.5 py-1.5 rounded-lg border-none font-medium cursor-pointer transition-all duration-150"; const tabActiveClass = `${tabBase} lc-tab-active shadow-sm`; const tabInactiveClass = `${tabBase} lc-tab-inactive`; const tabTraceActiveClass = `${tabBase} lc-tab-trace`; const tabTraceLoadingClass = `${tabBase} lc-tab-trace-loading`; const toolbar = showCodeTab &&
{(traceUrl || traceLoading) && !useLocalPreview && { if (!traceUrl) e.preventDefault(); else cachedRef.current?.host.trackEvent("trace_tab_clicked", { pattern }); }} className={traceUrl ? tabTraceActiveClass : tabTraceLoadingClass} aria-disabled={!traceUrl}> Trace {traceUrl && } }
{activeView === "code" &&
}
{} {}
; const slot =
{!ready && !error &&
} {error &&
Preview Error

{error}

}
; return
{toolbar} {slot}
; }; 消息队列允许用户快速连续发送多条消息，而无需等待智能体完成当前消息的处理。每条消息都会在服务器端排队并按顺序处理，让您对等待队列拥有完全的可见性和控制权。 此功能需要 [LangGraph Agent Server](/langsmith/local-server)。使用 `langgraph dev` 在本地运行您的代理，或 [将其部署到 LangSmith](/langsmith/deployment) 以使用此模式。 ## 为什么需要消息队列？ 在典型的聊天界面中，用户必须等待智能体完成响应后才能发送下一条消息。这在以下几种场景中会造成不便： * **批量提问**：用户希望一次性提出五个相关问题，而不是等待每个答案 * **连续追问**：在智能体仍在处理时提交澄清或额外上下文 * **自动化测试序列**：以编程方式发送一系列提示以验证智能体行为 * **数据录入工作流**：逐个输入结构化数据以供处理 消息队列通过立即接受所有提交并按顺序处理来解决这个问题。 ## 工作原理 在底层，LangGraph 使用 `multitaskStrategy: "enqueue"` 来管理并发提交。当智能体已在处理时提交消息，该消息会被添加到服务器端队列。当前运行完成后，会自动选取下一个排队的消息。 `useStream` 钩子暴露了一个 `queue` 属性，提供对等待消息的实时可见性： | 属性 | 类型 | 描述 | | ------------------ | ------------------------------- | --------------- | | `queue.entries` | `QueueEntry[]` | 所有等待队列条目的数组 | | `queue.size` | `number` | 当前队列中的条目数量 | | `queue.cancel(id)` | `(id: string) => Promise` | 通过 ID 取消特定的排队条目 | | `queue.clear()` | `() => Promise` | 取消所有排队条目 | 每个 `QueueEntry` 对象包含： | 字段 | 类型 | 描述 | | ----------- | -------- | -------------- | | `id` | `string` | 此队列条目的唯一标识符 | | `values` | `object` | 提交的输入值（包括消息） | | `options` | `object` | 提交时传递的任何额外选项 | | `createdAt` | `string` | 条目创建时的 ISO 时间戳 | ## 设置 `useStream` 定义一个与您的智能体状态模式匹配的 TypeScript 接口，并将其作为类型参数传递给 `useStream`，以便对状态值进行类型安全访问。在下面的示例中，将 `typeof myAgent` 替换为您的接口名称： ```ts theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} import type { BaseMessage } from "@langchain/core/messages"; interface AgentState { messages: BaseMessage[]; } ``` ```tsx React theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} import { useStream } from "@langchain/react"; function Chat() { const stream = useStream({ apiUrl: "http://localhost:2024", assistantId: "message_queue", }); const handleSubmit = (text: string) => { stream.submit({ messages: [{ type: "human", content: text }], }); }; // 访问队列状态 const pendingCount = stream.queue.size; const entries = stream.queue.entries; return (
{pendingCount > 0 && }
); } ``` ```vue Vue theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} ``` ```svelte Svelte theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}}
{#if $queue.size > 0} {/if} handleSubmit(e.detail)} />
``` ```ts Angular theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} import { Component } from "@angular/core"; import { useStream } from "@langchain/angular"; @Component({ selector: "app-chat", template: ` @if (stream.queue().size > 0) { } `, }) export class ChatComponent { stream = useStream({ apiUrl: "http://localhost:2024", assistantId: "message_queue", }); handleSubmit(text: string) { this.stream.submit({ messages: [{ type: "human", content: text }], }); } } ``` ## 显示队列 构建一个 `QueueList` 组件，显示每条等待消息及其取消按钮。这使用户能够看到正在等待的内容，并可以移除不再需要的项目。 ```tsx theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} function QueueList({ entries, queue }) { return (
排队消息 ({entries.length})
    {entries.map((entry) => { const text = entry.values?.messages?.[0]?.content ?? "未知"; return (
  • {text} {new Date(entry.createdAt).toLocaleTimeString()}
    • ); })}
); } ``` 显示每条排队消息的前几个字符作为预览，以便用户无需阅读完整消息即可快速识别要取消的项目。 ## 取消排队消息 您有两个级别的取消操作： ### 取消单个条目 通过其 ID 从队列中移除特定消息。智能体将跳过它并处理下一个条目。 ```ts theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} await queue.cancel(entryId); ``` ### 清空整个队列 一次性移除所有等待消息。当用户改变上下文或想要重新开始时非常有用。 ```ts theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} await queue.clear(); ``` 取消队列条目仅影响**尚未开始处理**的消息。如果智能体已经在处理某条消息，从队列中取消它不会产生影响。请使用 `stream.stop()` 来中断当前运行。 ## 使用 `onCreated` 链式提交后续消息 `onCreated` 回调在创建新运行时触发，为您提供了一个以编程方式提交后续消息的钩子。这对于构建多步骤工作流非常有用，其中下一个问题取决于前一个提交是否被接受。 ```ts theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} stream.submit( { messages: [{ type: "human", content: "什么是量子计算？" }] }, { onCreated(run) { console.log("运行已创建：", run.run_id); // 链式提交后续问题 stream.submit({ messages: [{ type: "human", content: "给我一个简单的类比。" }], }); }, } ); ``` 这种模式会自然地填充队列。第一条消息立即开始处理，后续问题则排在其后。 ## 开始新对话 当用户想要开始新的对话时，使用 `switchThread(null)` 来创建新线程。这将清除当前消息历史和队列。 ```tsx React theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} function NewThreadButton() { const stream = useStream({ /* ... */ }); return ( ); } ``` ```vue Vue theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} ``` ```svelte Svelte theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} ``` ```ts Angular theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} stream = useStream({ /* ... */ }); // 在模板中： // ``` ## 完整示例 将所有内容整合在一起，这是一个包含队列管理的完整聊天组件： ```tsx theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}} function QueueChat() { const stream = useStream({ apiUrl: "http://localhost:2024", assistantId: "message_queue", }); const [input, setInput] = useState(""); const handleSubmit = () => { if (!input.trim()) return; stream.submit({ messages: [{ type: "human", content: input.trim() }], }); setInput(""); }; return (

队列聊天

{stream.messages.map((msg, i) => ( ))} {stream.isLoading && }
{stream.queue.size > 0 && (
排队中 ({stream.queue.size}) {stream.queue.entries.map((entry) => (
{entry.values?.messages?.[0]?.content}
))}
)}
{ e.preventDefault(); handleSubmit(); }}> setInput(e.target.value)} placeholder="输入消息（您可以发送多条！）" />
); } ``` ## 最佳实践 * **限制队列大小**：虽然客户端没有硬性的队列大小限制，但请注意非常大的队列可能会降低用户体验。当队列超过合理阈值（例如 10 个项目）时，考虑显示警告。 * **显示队列位置**：为每个排队项目编号，以便用户了解处理顺序。 * **保持输入焦点**：提交后保持输入字段聚焦，以便用户可以立即输入下一条消息。 * **动画过渡**：当项目开始处理时，平滑地将其从队列面板移动到消息列表中。 * **优雅处理错误**：如果排队消息失败，在不阻塞后续队列条目的情况下显示错误。 * **对快速提交进行防抖**：对于自动化或编程式提交，在消息之间添加小延迟，以避免服务器过载。 ***
[Edit this page on GitHub](https://github.com/langchain-ai/docs/edit/main/src/i18n\zh-CN\oss\langchain\frontend\message-queues.mdx) or [file an issue](https://github.com/langchain-ai/docs/issues/new/choose). [Connect these docs](/use-these-docs) to Claude, VSCode, and more via MCP for real-time answers.