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JavaScript APIs

Supported JS APIs

Golem’s JavaScript runtime uses wasm-rquickjs . This reference follows its current API inventory. It provides Web APIs and Node.js-compatible modules, not a complete browser or Node.js runtime. Read the limitations below before choosing a library.

Feature Flags

The runtime generated by wasm-rquickjs has optional features. These are runtime build options, not settings in an agent definition. Availability depends on the runtime included in your SDK build.

FeatureDefaultDescription
logging✅ OnRoutes the console API through host logging
http✅ OnEnables fetch and the HTTP client APIs
sqlite❌ OffEnables node:sqlite with embedded SQLite
timezone✅ OnEnables IANA timezones for Intl.DateTimeFormat
typescript-runtime❌ OffStrips TypeScript types when loading runtime modules
typescript-transform-runtime❌ OffAlso transforms TypeScript syntax such as enums and runtime namespaces

Runtime TypeScript support is separate from compiling a TypeScript agent with the SDK’s normal build tools.

WIT–JS Type Mappings

WIT TypeJS TypeNotes
charstring—
stringstring—
s8, u8, s16, u16, s32, u32number—
s64, u64bigint—
f32, f64number—
option<T>T | undefinedNested options encoded differently
list<T>T[]—
result<T, E>{ tag: "ok", val: T } | { tag: "err", val: E }—
tuple<A, B, C>Array—
enum { a, b, c }"a" | "b" | "c"Matches WIT case names
flags { a, b, c }{ a: boolean, b: boolean, c: boolean }Keys are camelCase
record { .. }ObjectField names are camelCase
variant { .. }{ tag: "x", val: X }val is undefined for unit cases

An imported function with a result<T, E> return type returns T on success and throws E on failure, rather than returning the tagged object in the table. An asynchronous import rejects with the same error value. Structured errors retain their fields; string coercion renders their payload as JSON.

Mapping Limitations

  • Maximum of 26 function parameters
  • Anonymous interface exports/imports are not supported
  • Imported individual functions into the world are not supported (only whole interfaces)

Available JavaScript APIs

Web Platform APIs

Console

Depends on wasi:logging (if logging feature is enabled), otherwise core WASI.

  • assert, clear, count, countReset, debug, dir, dirXml, error, group, groupCollapsed, groupEnd, info, log, table, time, timeEnd, timeLog, trace, warn

HTTP (fetch)

Requires http feature flag. Depends on wasi:http.

  • fetch, Headers, Request, Response, FormData, Blob, File

URL

  • URL (including createObjectURL, revokeObjectURL)
  • URLSearchParams

Streams

Implemented via web-streams-polyfill .

  • ByteLengthQueuingStrategy, CountQueuingStrategy
  • ReadableStream, ReadableStreamDefaultReader, ReadableStreamBYOBReader, ReadableStreamDefaultController, ReadableByteStreamController, ReadableStreamBYOBRequest
  • WritableStream, WritableStreamDefaultController
  • TransformStream, TransformStreamDefaultController

Timers

  • setTimeout, clearTimeout, setInterval, clearInterval, setImmediate

Abort Controller

  • AbortController, AbortSignal, DOMException

Encoding

  • TextEncoder, TextDecoder, TextDecoderStream, TextEncoderStream

Messaging

  • MessageChannel, MessagePort

Events

  • Event, EventTarget, CustomEvent

Intl (Internationalization)

Minimal en-US implementation — all locale inputs are accepted but resolved to en-US. When the timezone feature is enabled (default), DateTimeFormat supports all ~590 IANA timezones via chrono-tz.

  • Intl.DateTimeFormat — format(), formatToParts(), resolvedOptions(), supportedLocalesOf()
  • Intl.NumberFormat — format(), formatToParts(), resolvedOptions(), supportedLocalesOf()
  • Intl.Collator — compare(), resolvedOptions(), supportedLocalesOf()
  • Intl.PluralRules — select(), selectRange(), resolvedOptions(), supportedLocalesOf()
  • Intl.getCanonicalLocales(), Intl.supportedValuesOf()

Crypto (global)

  • crypto.randomUUID, crypto.getRandomValues

Performance (global)

  • performance.now() uses a monotonic clock and is not affected by wall-clock adjustments.
  • performance.timeOrigin is the deployment wall-clock origin paired with that timeline.
  • The global object is shared with node:perf_hooks.

Structured Clone

Via ungap/structured-clone :

  • structuredClone

Node.js-Compatible Modules

⚠️ Golem does not support node:net, node:dgram and node:dns. These modules use WASI sockets, which the worker executor refuses by default: every TCP connect, UDP send, bind and DNS lookup fails. Only an operator can turn WASI sockets on, with the executor setting agent_sockets.enabled. For HTTP, use fetch or the node:http client, which do not use WASI sockets.

node:assert

  • ok, equal, notEqual, strictEqual, notStrictEqual
  • deepEqual, notDeepEqual, deepStrictEqual, notDeepStrictEqual, partialDeepStrictEqual
  • throws, doesNotThrow, rejects, doesNotReject
  • ifError, match, doesNotMatch, fail
  • AssertionError, CallTracker
  • strict — strict mode variant

node:async_hooks

  • AsyncLocalStorage — run, exit, getStore, enterWith, disable, snapshot, bind
  • AsyncResource — runInAsyncScope, asyncId, triggerAsyncId, bind
  • createHook — stub (returns enable/disable no-ops)
  • executionAsyncId, triggerAsyncId, executionAsyncResource — stubs

Context propagates through Promise.prototype.then, catch, and finally, and through setTimeout and setInterval.

⚠️ Limitation: Context is not propagated across await boundaries.

node:buffer

  • Buffer, Blob, File, SlowBuffer
  • resolveObjectURL, isAscii, isUtf8
  • INSPECT_MAX_BYTES, kMaxLength, kStringMaxLength, constants

node:child_process

The runtime cannot create operating-system subprocesses. A limited compatibility adapter runs JavaScript targets invoked through process.execPath inline, with separate argument, environment, and working-directory views. It also recognizes npm’s literal sh -c form for plain Node commands and executable Node shebang files.

Other executables, unsupported shells and shell syntax, and unsupported shebangs fail with ENOSYS. Inline execution does not create a fresh JavaScript runtime or a subprocess.

  • ChildProcess, exec, execFile, fork, spawn, execSync, execFileSync, spawnSync

node:cluster (stub)

Clustering not supported in WASM.

  • isPrimary, isMaster, isWorker, fork, disconnect, setupPrimary

node:constants

Merged constants from os.constants, fs.constants, and crypto.constants (signal numbers, errno values, file flags, etc.)

node:crypto

  • Hashing: createHash, createHmac, hash, getHashes
  • Ciphers: createCipheriv, createDecipheriv, getCiphers
    • Supported ciphers: aes-128/256-cbc, aes-128/256-ctr, aes-128/256-gcm, aes-128/192/256-wrap, id-aes128/192/256-wrap, id-aes128/192/256-wrap-pad, des-ede3-cbc, des3-wrap, chacha20-poly1305
  • Signing: createSign, createVerify (Ed25519, ECDSA with P-256, P-384, secp256k1)
  • Keys: createPublicKey, createPrivateKey, createSecretKey, KeyObject, generateKeyPairSync, generateKeyPair
  • ECDH: createECDH, ECDH, diffieHellman, getCurves
  • Certificate: Certificate (verifySpkac, exportPublicKey, exportChallenge)
  • Random: randomBytes, randomFillSync, randomFill, randomInt, randomUUID, pseudoRandomBytes, prng, rng
  • KDF: pbkdf2, pbkdf2Sync, scrypt, scryptSync, hkdf, hkdfSync
  • Primes: generatePrime, generatePrimeSync, checkPrime, checkPrimeSync
  • Other: timingSafeEqual, getFips, setFips, secureHeapUsed

node:dgram (not supported)

UDP datagram sockets built on WASI sockets. Golem does not support this module: the worker executor refuses WASI sockets by default, so binds and sends fail.

  • dgram.createSocket(type[, listener]) — udp4 or udp6
  • socket.bind, socket.send, socket.sendto, socket.connect, socket.disconnect, socket.close
  • socket.address(), socket.remoteAddress()
  • socket.setTTL, socket.setRecvBufferSize/getRecvBufferSize, socket.setSendBufferSize/getSendBufferSize
  • socket.ref()/socket.unref() — no-op
  • Events: message, listening, close, error, connect

⚠️ Multicast operations throw ENOSYS.

node:diagnostics_channel

  • channel, subscribe, unsubscribe, hasSubscribers, tracingChannel
  • Channel — subscribe, unsubscribe, publish, bindStore, unbindStore, runStores, hasSubscribers, name
  • TracingChannel — subscribe, unsubscribe, hasSubscribers, traceSync, tracePromise, traceCallback
  • Built-in HTTP diagnostics channels: http.client.request.created, http.client.request.start, http.client.request.error, http.client.response.finish

node:dns (not supported)

DNS resolution via WASI sockets. Golem does not support this module: the worker executor refuses WASI sockets by default, so lookups fail.

  • lookup, lookupService, resolve, resolve4, resolve6
  • resolveAny, resolveCname, resolveCaa, resolveMx, resolveNaptr, resolveNs, resolvePtr, resolveSoa, resolveSrv, resolveTxt, resolveTlsa
  • reverse, setServers, getServers, setDefaultResultOrder, getDefaultResultOrder
  • Resolver class
  • promises — promise-based API
  • Error constants: NODATA, FORMERR, SERVFAIL, NOTFOUND, NOTIMP, REFUSED, BADQUERY, BADNAME, BADFAMILY, BADRESP, CONNREFUSED, TIMEOUT, EOF, FILE, NOMEM, DESTRUCTION, BADSTR, BADFLAGS, NONAME, BADHINTS, NOTINITIALIZED, LOADIPHLPAPI, ADDRGETNETWORKPARAMS, CANCELLED, ADDRCONFIG, V4MAPPED, ALL

node:domain

Deprecated error-handling domains.

  • domain.create()/domain.createDomain(), domain.active, domain._stack
  • Domain class (extends EventEmitter): run, add, remove, bind, intercept, enter, exit, dispose, members, parent
  • process.domain — reflects active domain
  • Error decoration: error.domain, error.domainEmitter, error.domainBound, error.domainThrown
  • EventEmitter integration and propagation through process.nextTick, setTimeout, and setInterval

⚠️ Only synchronous errors and explicitly bound callbacks are captured. There is no general asynchronous context propagation through async_hooks.

node:events

  • EventEmitter — on, once, off, addListener, removeListener, removeAllListeners, emit, listenerCount, eventNames, listeners, rawListeners, prependListener, prependOnceListener, setMaxListeners, getMaxListeners
  • Static: once, on, getEventListeners, getMaxListeners, setMaxListeners, addAbortListener, errorMonitor, captureRejections
  • Event, EventTarget, CustomEvent

node:fs

Comprehensive filesystem API on WASI filesystem.

Symbolic links persist in the filesystem. Targets must be relative; absolute targets fail with EINVAL without creating a link. Windows local development requires Developer Mode or equivalent symlink privileges. This restriction does not affect non-link filesystem operations.

  • Sync: readFileSync, writeFileSync, appendFileSync, openSync, closeSync, readSync, writeSync, ftruncateSync, fsyncSync, fdatasyncSync, statSync, lstatSync, fstatSync, statfsSync, readdirSync, accessSync, existsSync, realpathSync, truncateSync, copyFileSync, linkSync, symlinkSync, readlinkSync, chmodSync, fchmodSync, lchmodSync, chownSync, fchownSync, lchownSync, utimesSync, futimesSync, lutimesSync, unlinkSync, renameSync, mkdirSync, rmdirSync, rmSync, mkdtempSync, opendirSync, readvSync, writevSync, cpSync
  • Async (callback): readFile, writeFile, appendFile, open, close, read, write, stat, lstat, fstat, statfs, ftruncate, fsync, fdatasync, readdir, access, exists, realpath, truncate, copyFile, link, symlink, readlink, chmod, fchmod, lchmod, chown, fchown, lchown, utimes, futimes, lutimes, unlink, rename, mkdir, rmdir, rm, mkdtemp, opendir, watch, watchFile, unwatchFile, readv, writev, cp, openAsBlob
  • Streams: createReadStream, createWriteStream
  • Classes: Stats, Dirent, Dir, FSWatcher, StatWatcher, ReadStream, WriteStream
  • Constants: F_OK, R_OK, W_OK, X_OK, O_RDONLY, O_WRONLY, O_RDWR, O_CREAT, O_EXCL, O_TRUNC, O_APPEND, and more

node:fs/promises

  • FileHandle, open, readFile, writeFile, appendFile, unlink, rename, mkdir, rmdir, rm, stat, lstat, readdir, opendir, access, realpath, truncate, copyFile, link, symlink, readlink, chmod, lchmod, chown, lchown, utimes, lutimes, mkdtemp, cp, watch, statfs, constants

node:http / node:https

Requires http feature flag. Client uses wasi:http (TLS transparent). Socket-backed servers use WASI sockets and are not supported; to serve HTTP with an http.createServer request listener, mount the server as a custom HTTP router with nodeHttpHandler from @golemcloud/golem-ts-sdk/http-router.

  • http.request, http.get, http.METHODS, http.STATUS_CODES, http.maxHeaderSize, http.validateHeaderName, http.validateHeaderValue
  • http.Agent, http.globalAgent
  • http.OutgoingMessage, http.ClientRequest, http.IncomingMessage
  • https.request, https.get
  • http.createServer, http.Server, http.ServerResponse
  • http.ServerResponse.writeContinue, writeProcessing, writeEarlyHints
  • Server-side IncomingMessage with method, url, headers, rawHeaders, httpVersion, socket, etc.
  • node:_http_common — _checkIsHttpToken, _checkInvalidHeaderChar
  • Supports: keep-alive, chunked transfer encoding, content-length bodies, sequential pipelining, idle connection cleanup

⚠️ Not yet supported: HTTP Upgrade, CONNECT tunnels, client-side 1xx events, server-side timeout enforcement, https.createServer(), client lookup / autoSelectFamily options, and custom per-request createConnection transports. Custom Agent createConnection hooks are ignored with a warning: they cannot route or isolate traffic. All outbound requests use the host HTTP client.

node:http2 (stub)

  • connect, createServer, createSecureServer, Http2ServerRequest, Http2ServerResponse

node:inspector (stub)

No V8 inspector in WASM.

  • Session, open, close, url, waitForDebugger, console, Network

node:module

  • require, require.resolve, createRequire, builtinModules, isBuiltin, runMain, _nodeModulePaths
  • stripTypeScriptTypes — strip and transform modes, when runtime TypeScript support is enabled

Package resolution supports package.json main, exports, and imports, including subpaths and wildcard patterns. CommonJS resolution recognizes golem, node, require, module-sync, and default conditions. ES module resolution uses import instead of require.

With runtime TypeScript support, .mts files are ES modules and .cts files are CommonJS. .ts files follow the nearest package type and Node-style syntax classification. ES module imports require explicit file extensions. The runtime does not type-check, read tsconfig.json, strip types inside node_modules, or support .tsx. Syntax that needs transformation, such as enums and runtime namespaces, requires typescript-transform-runtime.

node:net (not supported)

TCP sockets and servers on WASI sockets. Golem does not support this module: the worker executor refuses WASI sockets by default, so connects and listens fail.

  • net.createServer, net.createConnection, net.connect
  • net.isIP, net.isIPv4, net.isIPv6
  • net.getDefaultAutoSelectFamily/net.setDefaultAutoSelectFamily — stubs
  • net.Socket (extends stream.Duplex): connect, write, end, destroy, resetAndDestroy, setTimeout, setNoDelay, setKeepAlive, address, ref, unref; properties: remoteAddress, remotePort, remoteFamily, localAddress, localPort, localFamily, bytesRead, bytesWritten, connecting, pending, readyState; events: connect, ready, data, end, close, error, timeout, drain, lookup
  • net.Server (extends EventEmitter): listen, close, address, getConnections, ref, unref; properties: listening, maxConnections; events: listening, connection, close, error, drop
  • net.BlockList, net.SocketAddress, net.Stream

⚠️ Not supported: IPC/Unix domain sockets, Happy Eyeballs / autoSelectFamily, cluster integration.

node:os

  • arch, platform, type, release, version, machine, hostname, homedir, tmpdir, endianness
  • cpus, loadavg, freemem, totalmem, uptime, availableParallelism
  • networkInterfaces, userInfo, getPriority, setPriority
  • EOL, devNull, constants

node:path

  • sep, delimiter, basename, dirname, extname, isAbsolute, join, normalize, relative, resolve, parse, format, matchesGlob, toNamespacedPath, posix

node:perf_hooks

  • performance — now(), timeOrigin, mark(), measure(), getEntries(), getEntriesByName(), getEntriesByType(), clearMarks(), clearMeasures(), toJSON()
  • PerformanceEntry, PerformanceObserver
  • monitorEventLoopDelay, createHistogram, constants

node:process

  • Properties: argv, argv0, env, pid, ppid, platform ('wasi'), arch ('wasm32'), version, versions, config, features, execArgv, execPath, exitCode, stdout, stderr
  • Methods: exit, cwd, nextTick, hrtime, hrtime.bigint, uptime, cpuUsage, memoryUsage, kill, abort, emitWarning
  • User/Group: getuid, getgid, geteuid, getegid, getgroups, setuid, setgid
  • Extends EventEmitter — supports on('uncaughtException'), on('unhandledRejection'), etc.

node:punycode

  • decode, encode, toASCII, toUnicode, ucs2, version

node:querystring

  • stringify/encode, parse/decode, escape, unescape, unescapeBuffer

node:readline

  • createInterface, Interface, clearLine, clearScreenDown, cursorTo, moveCursor, emitKeypressEvents
  • readline/promises — promise-based API

node:repl (stub)

  • start, REPLServer, Recoverable, builtinModules

node:sqlite

Requires sqlite feature flag. Synchronous API with embedded SQLite engine.

  • DatabaseSync — prepare, exec, close, open, isOpen, isTransaction, createSession, applyChangeset, enableLoadExtension, function, aggregate, backup
  • StatementSync — run, get, all, iterate, columns, setReadBigInts, setAllowBareNamedParameters, sourceSQL, expandedSQL
  • Session — changeset, patchset, close
  • Constants: SQLITE_CHANGESET_OMIT, SQLITE_CHANGESET_REPLACE, SQLITE_CHANGESET_ABORT

⚠️ loadExtension() throws — native extensions cannot be loaded in WASM.

node:stream

  • Readable (with from, fromWeb, toWeb, wrap, map, filter, flatMap, take, drop, toArray, forEach, reduce, some, every, find)
  • Writable, Duplex, Transform, PassThrough, Stream
  • pipeline, finished, compose, duplexPair, addAbortSignal
  • getDefaultHighWaterMark, setDefaultHighWaterMark, isDisturbed, destroy
  • stream/consumers — arrayBuffer, blob, buffer, json, text
  • stream/promises — promise-based pipeline and finished

node:string_decoder

  • StringDecoder

node:test

Built-in test runner.

  • test, describe/suite, it, before, after, beforeEach, afterEach
  • mock — function mocking
  • run — programmatic test execution

node:timers

  • setTimeout, setInterval, setImmediate, clearTimeout, clearInterval
  • timers/promises — promise-based setTimeout, setInterval, setImmediate

node:tls (stub)

TLS is handled transparently by the WASI-HTTP layer.

  • SecureContext, TLSSocket, Server, connect, createServer, createSecureContext, checkServerIdentity, getCiphers, rootCertificates
  • DEFAULT_MIN_VERSION, DEFAULT_MAX_VERSION, DEFAULT_ECDH_CURVE

node:trace_events

  • createTracing({ categories }) — creates a Tracing handle
  • Tracing#enable()/Tracing#disable(), Tracing#enabled, Tracing#categories
  • getEnabledCategories()

⚠️ No native trace sink — API-surface compatibility only.

node:tty

  • isatty, ReadStream, WriteStream

node:url

  • URL, URLSearchParams
  • parse, resolve, format (legacy)
  • domainToASCII, domainToUnicode
  • fileURLToPath, pathToFileURL, urlToHttpOptions

node:util

  • format, inspect, deprecate, debugLog, log
  • Type checks: isArray, isBoolean, isNull, isNullOrUndefined, isNumber, isString, isSymbol, isUndefined, isRegExp, isObject, isDate, isError, isFunction, isPrimitive, isBuffer
  • promisify, callbackify
  • parseEnv, styleText, getCallSite, getCallSites, toUSVString, _extend
  • TextEncoder, TextDecoder

node:v8

  • getHeapStatistics, getHeapSpaceStatistics, getHeapSnapshot, getHeapCodeStatistics
  • setFlagsFromString, writeHeapSnapshot, takeCoverage, stopCoverage
  • serialize, deserialize, Serializer, Deserializer, DefaultSerializer, DefaultDeserializer

node:vm

  • runInNewContext, runInContext, runInThisContext, createContext, isContext, compileFunction
  • Script, createScript
  • SourceTextModule (experimental — limited export const/export let/export var support)

These are synchronous compatibility contexts within one JavaScript runtime. They are not a security sandbox: code shares the component’s capabilities and filesystem access. For asynchronous jobs in fresh runtimes, see Fresh-runtime execution.

node:worker_threads (stub)

Workers not supported in single-threaded WASM.

  • isMainThread, parentPort, workerData, threadId, resourceLimits
  • Worker, BroadcastChannel, MessagePort, MessageChannel
  • markAsUntransferable, moveMessagePortToContext, receiveMessageOnPort
  • getEnvironmentData, setEnvironmentData

node:zlib

  • Classes: Deflate, Inflate, Gzip, Gunzip, DeflateRaw, InflateRaw, Unzip, BrotliCompress, BrotliDecompress
  • Factory: createGzip, createGunzip, createDeflate, createInflate, createDeflateRaw, createInflateRaw, createUnzip, createBrotliCompress, createBrotliDecompress
  • Async: gzip, gunzip, deflate, inflate, deflateRaw, inflateRaw, unzip, brotliCompress, brotliDecompress
  • Sync: gzipSync, gunzipSync, deflateSync, inflateSync, deflateRawSync, inflateRawSync, unzipSync, brotliCompressSync, brotliDecompressSync
  • crc32, constants, codes

Internal / Compatibility Modules

  • internal/url — isURL
  • internal/http — kOutHeaders symbol
  • base64-js — byteLength, toByteArray, fromByteArray
  • ieee754 — read, write

Fresh-runtime execution

The wasm-rquickjs:execution module runs JavaScript asynchronously in a fresh runtime:

  • startJavaScript(options) returns live stdout and stderr readable streams, a result promise resolving to { value, overflowed }, and cancel().
  • runJavaScript(options) collects output and resolves to { value, overflowed, stdout, stderr }.

Pass exactly one of entry (a module path) or source (an asynchronous function body). Inline source supports await and return, but not static import or export declarations. Results cross the runtime boundary through structured clone.

Options include cwd, argv, env, timeoutMs, maxBytes, and overflow. The environment is an explicit allowlist and defaults to empty; jobs do not inherit environment variables. Output is bounded to 1 MiB per stream by default, with a maximum of 64 MiB. Overflow rejects the job by default; overflow: "truncate" keeps bounded output and sets overflowed instead. TypeScript entry files and inline language: "typescript" require runtime TypeScript support.

Each job has fresh globals, timers, process state, and module caches. It is not a security sandbox: jobs share the enclosing component’s host capabilities and filesystem. cwd controls path resolution, not filesystem access.

Cancellation is cooperative and cannot interrupt a tight loop already running on the same thread. Use a positive timeoutMs for a best-effort execution budget, not an exact deadline. An unfinished job must be cancelled or given a timeout before the enclosing invocation can finish. At most eight jobs can be active, and jobs cannot start nested execution jobs.

See the upstream execution API  for the complete options and execution limits.

Built-in Language Features (from QuickJS)

These come from QuickJS itself and are available globally without any import:

Globals: parseInt, parseFloat, isNaN, isFinite, quickMicrotask, decodeURI, decodeURIComponent, encodeURI, encodeURIComponent, escape, unescape, Infinity, NaN, undefined

Full built-in objects with all standard methods: Object, Function, Error, Generator, Iterator, Array, Number, Boolean, String, Symbol, Map, Set, WeakMap, WeakSet, GeneratorFunction, Math, Reflect, RegExp, JSON, Promise, AsyncFunction, AsyncIterator, AsyncGeneratorFunction, AsyncGenerator, Date, BigInt, ArrayBuffer, SharedArrayBuffer

Typed Arrays: Int8Array, Uint8Array, Int16Array, Uint16Array, Int32Array, Uint32Array, BigInt64Array, BigUint64Array, Float32Array, Float64Array, Float16Array

Other: DataView, Atomics, Performance, WeakRef, FinalizationRegistry, Callsite, Proxy

Additional Resources

Streaming Protocol v1