[core] Support opt-in Expect: 100-continue in Node HTTP/1 transport by jeremymeng · Pull Request #40258 · Azure/azure-sdk-for-js

Jeremy Meng (jeremymeng) · 2026-10-08T22:47:04Z

Copilot agent (on behalf of Jeremy Meng (@jeremymeng)):

Packages impacted by this PR

@typespec/ts-http-runtime (existing unreleased 0.3.10).
@azure/core-rest-pipeline (tooling-managed patch increment to 1.25.1; runtime minimum updated to ^0.3.10). Publish the runtime before or together with the core package.

Issues associated with this PR

Describe the problem that is addressed by this PR

The built-in Node transport starts body factories, stream consumption, and upload progress before a server can decide whether to accept a potentially large upload. It also needs to preserve existing HTTP/1.1 streaming behavior, retries, redirects, authentication challenges, and caller-owned stream semantics when an early response arrives.

This PR adds opt-in Expect: 100-continue support when the caller explicitly supplies the header. It does not automatically add Expect or introduce a public option.

Changes in this PR:

Negotiation gate: sends headers first, then starts the body exactly once after HTTP 100 or a fixed 1,000 ms fallback. The fallback starts only after socket assignment and an ordered header-write callback, excluding agent queueing and DNS/TCP/TLS setup.
Effective headers and framing: honors replacement header objects and raw arrays, preserves automatic Host generation when omitted, and derives Content-Length or chunked framing before ClientRequest construction.
Lazy body production: defers body factories, multipart part factories, Blob conversion, source reads, and upload progress until the upload is permitted. Known-empty bodies end immediately without waiting.
Response/upload lifecycle: keeps early final responses readable; stops unfinished uploads for rejection, redirect, and challenge responses; preserves successful full-duplex 2xx uploads and explicit-length streams with asynchronous EOF; preserves original upload errors while the response remains open; retires sockets with interrupted outgoing framing.
Stream ownership and replay: leaves direct streams caller-owned, disposes factory-created sources and SDK wrappers, waits for .pipe() drain before resuming a multipart part or invoking the next factory, preserves readable-mode backpressure, and rejects every previously started, ended, closed, or disturbed one-shot source with REQUEST_BODY_NOT_REPLAYABLE.
Retry and policy integration: removes obsolete negotiation/framing on body-removing redirects, disposes abandoned streamed responses before retry/redirect/authentication resends on a best-effort basis, keeps legacy abort forwarding active until both upload and response completion, and preserves non-retryable errors for unsupported body types.
Documentation and package integration: documents the behavior in the runtime README and updates @azure/core-rest-pipeline to consume the new runtime version.

HTTP 417 is returned normally before or after upload starts; there is no automatic 417 recovery. This PR does not add HTTP/2/Undici support, a configurable continue timeout, or transport-specific behavior to Fetch/XHR/React Native.

What are the possible designs available to address the problem? If there are more than one possible design, why was the one in this PR chosen?

Public Node APIs instead of internals: the implementation uses header, socket, write-callback, and request events rather than TLS readiness heuristics or private ClientRequest state.
Deferred Expect header write: withholding Expect during construction and restoring it after agent header rewrites supports forward proxies and custom agents.
Ordered client-side flush boundary: an empty write callback after flushHeaders() provides a practical fallback boundary across fresh/reused connections, delayed DNS/TLS, HTTP forward proxies, and HTTPS CONNECT. It does not claim that the remote server has received the headers.
Private identity tracking instead of a public replay abstraction: sources are marked only when actually started. Untouched direct sources remain reusable after an early response; started one-shot sources require a factory that returns a fresh stream.
Ownership-aware cleanup: caller-provided streams are detached and paused, while request-owned factory results and wrappers may be destroyed. Successful full-duplex responses are allowed to finish their uploads.

Are there test cases added in this PR? (If not, why?)

Yes. Coverage includes:

Continue/fallback ordering, duplicate and late 100 responses, ignored 102/103 responses, timeout/abort/error/close races, and exactly-once body dispatch.
Effective object/flat/pair-array headers, automatic Host behavior, explicit and inferred framing, known-empty bodies, UTF-8, Buffer, ArrayBuffer, DataView, and typed-array windows.
Lazy multipart, Blob, FormData, and createFileFromStream factories; readable-mode backpressure; .pipe() pause/drain with single- and multi-chunk parts; direct/factory ownership; replay protection across negotiated and non-negotiated attempts.
Early rejection responses, active upload shutdown, readable streamed/compressed/HEAD responses, compressed-stream cancellation races, successful full-duplex responses, upload failures after successful response headers, explicit-length async EOF, keep-alive reuse, and interrupted-framing retirement.
Retries, redirects, authentication challenges, abandoned response disposal, legacy abort signals, unsupported body classification, forward proxies, HTTPS CONNECT, delayed lookup/TLS, and custom agents.

Tests use ephemeral loopback endpoints and existing trusted test certificates and require no Azure service. Linux/macOS and minimum-Node coverage remain part of CI. Already-flowing sources and bytes queued inside Node cannot be made lazy or unsent retroactively.

Defer upload sources until continue or the fixed flush-based fallback, preserve early responses, and retire incomplete outgoing framing. Integrate lazy multipart factories, one-shot replay protection, redirects, and streamed legacy cancellation. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: f15004e9-d812-46bf-abcf-2a9bb184fcae

azure-pipelines · 2026-10-08T22:47:38Z

Azure Pipelines: Successfully started running 2 pipeline(s). 9 pipeline(s) were filtered out due to trigger conditions. There may be pipelines that require an authorized user to comment /azp run to run.

Use the absolute repository URL required by Verify Links. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: f15004e9-d812-46bf-abcf-2a9bb184fcae

…inue-production

Jeremy Meng (jeremymeng) · 2026-10-13T18:42:09Z

/azp run js - storage-blob - tests

azure-pipelines · 2026-10-13T18:42:27Z

Azure Pipelines: Successfully started running 1 pipeline(s).

Jeremy Meng (jeremymeng) · 2026-10-13T18:42:32Z

/azp run js - storage-file-share - tests

Jeremy Meng (jeremymeng) · 2026-10-13T18:42:39Z

/azp run js - storage-file-datalake - tests

azure-pipelines · 2026-10-13T18:42:45Z

Azure Pipelines: Successfully started running 1 pipeline(s).

azure-pipelines · 2026-10-13T18:42:51Z

Azure Pipelines: Successfully started running 1 pipeline(s).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: feef5cbc-ea2d-48f7-916c-c481f4742476

Copilot

🟡 Changes recommended

Confirmed stream-lifecycle regressions block approval, and the shared transport changes warrant final human review.

2 open findings

What changed in this PR

Adds opt-in Node HTTP/1 upload negotiation to the shared runtime and integrates it with core-rest-pipeline.

Changes:

Defers uploads until HTTP 100 or a fixed fallback.
Adds lazy multipart handling, replay protection, and response cancellation cleanup.
Adds regression coverage, documentation, and coordinated package metadata updates.

File	Description
sdk/core/ts-http-runtime/test/snippets.spec.ts	Adds negotiation example.
sdk/core/ts-http-runtime/test/public/node/expectContinueState.spec.ts	Tests negotiation state transitions.
sdk/core/ts-http-runtime/test/public/node/expectContinue.spec.ts	Tests wire behavior and lifecycle.
sdk/core/ts-http-runtime/test/internal/node/httpServer.ts	Adds loopback server and proxy helpers.
sdk/core/ts-http-runtime/test/internal/node/concat.spec.ts	Tests lazy multipart streams.
sdk/core/ts-http-runtime/test/internal/expectContinue.spec.ts	Tests effective header handling.
sdk/core/ts-http-runtime/src/util/nodeBody.ts	Tracks stream ownership and replay.
sdk/core/ts-http-runtime/src/util/expectContinue.ts	Handles negotiation headers.
sdk/core/ts-http-runtime/src/util/concat.ts	Makes multipart consumption lazy.
sdk/core/ts-http-runtime/src/policies/redirectPolicy.ts	Clears negotiation on body removal.
sdk/core/ts-http-runtime/src/policies/multipartPolicy.ts	Preserves factory size metadata.
sdk/core/ts-http-runtime/src/nodeHttpClient.ts	Implements negotiation and lifecycle handling.
sdk/core/ts-http-runtime/README.md	Documents negotiation behavior.
sdk/core/ts-http-runtime/CHANGELOG.md	Records runtime support.
sdk/core/core-rest-pipeline/test/public/node/expectContinue.spec.ts	Tests core integration.
sdk/core/core-rest-pipeline/src/util/file.ts	Retains lazy file factories.
sdk/core/core-rest-pipeline/src/util/abortSignalCleanup.ts	Defers response-stream cleanup.
sdk/core/core-rest-pipeline/src/policies/wrapAbortSignalLikePolicy.ts	Extends legacy cancellation forwarding.
sdk/core/core-rest-pipeline/src/policies/multipartPolicy.ts	Passes lazy factories to runtime.
sdk/core/core-rest-pipeline/src/defaultHttpClient.ts	Preserves streamed-response cancellation.
sdk/core/core-rest-pipeline/src/constants.ts	Updates SDK version.
sdk/core/core-rest-pipeline/README.md	Documents integration behavior.
sdk/core/core-rest-pipeline/package.json	Updates version and runtime minimum.
sdk/core/core-rest-pipeline/CHANGELOG.md	Records integration changes.
pnpm-lock.yaml	Updates dependency resolution metadata.

Files not reviewed (1)

pnpm-lock.yaml: Generated file

🧠 Review effort: Balanced

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: feef5cbc-ea2d-48f7-916c-c481f4742476

…inue-production

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: feef5cbc-ea2d-48f7-916c-c481f4742476

Jeremy Meng (jeremymeng) · 2026-10-19T21:25:00Z

 import { logger as coreLogger } from "../log.js";
 import type { RestError } from "../restError.js";
 import { isRestError } from "../restError.js";
+import { disposeResponseBody } from "../util/responseBody.js";


Copilot : disposeResponseBody is needed when a policy receives one response but decides to send another request instead of returning that response—retry, redirect, or authentication challenge.

With streamed responses, ignoring the old body leaves its connection occupied. For an early final response during an unfinished upload, the socket is intentionally retired only when the response body closes. If the policy neither reads nor cancels that body, a one-socket agent can deadlock: the replacement request waits forever for the previous socket.

So these policies dispose the abandoned response before resending:

• Retry: before another attempt.
• Redirect: before following Location .
• Authentication: before resending after a challenge.

Disposal destroys/resumes Node streams or cancels browser streams. It is best-effort: cleanup failures are logged but must not replace the selected retry or resend. Responses returned to callers are not disposed.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: feef5cbc-ea2d-48f7-916c-c481f4742476

Jeremy Meng (jeremymeng) · 2026-10-20T00:19:34Z

/azp run js - storage-file-datalake - tests

azure-pipelines · 2026-10-20T00:19:48Z

Azure Pipelines: Successfully started running 1 pipeline(s).

Jeremy Meng (jeremymeng) · 2026-10-20T00:19:58Z

/azp run js - storage-file-share - tests

azure-pipelines · 2026-10-20T00:20:09Z

Azure Pipelines: Successfully started running 1 pipeline(s).

Jeremy Meng (jeremymeng) · 2026-10-20T00:20:11Z

/azp run js - storage-blob - tests

azure-pipelines · 2026-10-20T00:20:23Z

Azure Pipelines: Successfully started running 1 pipeline(s).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: feef5cbc-ea2d-48f7-916c-c481f4742476

* Simplify Expect: 100-continue implementation - Share disposeResponseBody from ts-http-runtime internal/util instead of duplicating it in core-rest-pipeline - Extract header preparation from NodeHttpClient.makeRequest into prepareExpectContinueHeaders - Deduplicate raw header pair normalization and body header stripping in expectContinue - Add shared toError and toRequestError helpers Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 1aa4c5c1-7005-4d8a-b7eb-2f63b8487ab2

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: f7f163d1-8382-4cbb-adc7-eeb36717d037

Jeremy Meng (jeremymeng) · 2026-10-20T21:23:22Z

/azp run js - storage-blob - tests

Jeremy Meng (jeremymeng) · 2026-10-20T21:23:34Z

/azp run js - storage-file-share - tests

azure-pipelines · 2026-10-20T21:23:36Z

Azure Pipelines: Successfully started running 1 pipeline(s).

Jeremy Meng (jeremymeng) · 2026-10-20T21:23:42Z

/azp run js - storage-file-datalake - tests

azure-pipelines · 2026-10-20T21:23:45Z

Azure Pipelines: Successfully started running 1 pipeline(s).

azure-pipelines · 2026-10-20T21:23:54Z

Azure Pipelines: Successfully started running 1 pipeline(s).

Copilot

🟡 Changes recommended

Legacy cancellation can disconnect during active uploads, and asynchronous response-disposal errors can escape handling.

2 open issues

2 resolved since last review

_{Review effort: Balanced}

+      if (readableStream.destroy) {
+        readableStream.destroy();
+      } else {
+        readableStream.resume();
+      }


+  if (!stream || !stream.readable) {
+    cleanup();
+    return;


Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 44d4b275-f5cc-4ad3-ada9-7ca9ad006dc6

Copilot

🟡 Changes recommended

Asynchronous response-disposal errors can escape error handling and terminate the process.

3 open issues

_{Review effort: Balanced}

+    const readableStream: unknown = response.readableStreamBody;
+    if (isNodeResponseBody(readableStream)) {
+      if (readableStream.destroy) {
+        readableStream.destroy();


github-actions Bot added the Azure.Core label Oct 8, 2026

Jeremy Meng (jeremymeng) added 3 commits October 8, 2026 15:54

Fix core upload negotiation documentation link

7287199

Use the absolute repository URL required by Verify Links. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: f15004e9-d812-46bf-abcf-2a9bb184fcae

use improved isArrayBuffer and isArrayBufferView helper

b6c7a3a

Merge remote-tracking branch 'upstream/main' into jeremymeng-100-cont…

1481581

…inue-production

Fix request stream replay and cleanup

3705dfb

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: feef5cbc-ea2d-48f7-916c-c481f4742476

Jeremy Meng (jeremymeng) requested a balanced review from Copilot October 16, 2026 18:29

Copilot started reviewing on behalf of Jeremy Meng (jeremymeng) October 16, 2026 18:30

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Comment thread sdk/core/ts-http-runtime/src/nodeHttpClient.ts

Comment thread sdk/core/ts-http-runtime/src/util/concat.ts

Jeremy Meng (jeremymeng) added 5 commits October 16, 2026 11:55

Harden HTTP stream lifecycle handling

3d75eac

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: feef5cbc-ea2d-48f7-916c-c481f4742476

update pnpm-lock.yaml

f0a88a4

Fix streamed gzip abort handling

434d289

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: feef5cbc-ea2d-48f7-916c-c481f4742476

Fix early response stream lifecycle

7572a87

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: feef5cbc-ea2d-48f7-916c-c481f4742476

Merge remote-tracking branch 'upstream/main' into jeremymeng-100-cont…

a57826e

…inue-production

aanubhav-msft mentioned this pull request Oct 19, 2026

[core] Unsupported request bodies receive a retryable error code #40387

Open

1 of 6 tasks

Jeremy Meng (jeremymeng) added 2 commits October 19, 2026 13:38

Preserve HTTP streaming semantics

1187a89

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: feef5cbc-ea2d-48f7-916c-c481f4742476

Merge upstream/main into jeremymeng-100-continue-production

6ec3755

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Jeremy Meng (jeremymeng) commented Oct 19, 2026

View reviewed changes

Jeremy Meng (jeremymeng) added 3 commits October 19, 2026 15:05

Stabilize multipart backpressure tracking

e2bfbc5

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: feef5cbc-ea2d-48f7-916c-c481f4742476

Use runtime stream high-water mark in test

0817c04

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: feef5cbc-ea2d-48f7-916c-c481f4742476

Fix multipart backpressure test lint

179806e

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aanubhav-msft mentioned this pull request Oct 20, 2026

[storage-file-datalake] Check the error name in the single-shot upload abort test #40404

Open

1 of 3 tasks

Fix multipart drain and upload errors

7cc9ba3

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Jeremy Meng (jeremymeng) mentioned this pull request Oct 20, 2026

[core] Simplify Expect: 100-continue implementation jeremymeng/azure-sdk-for-js#40

Merged

Jeremy Meng (jeremymeng) and others added 4 commits October 20, 2026 11:21

Refine stream completion and backpressure

53be380

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Merge upstream/main into jeremymeng-100-continue-production

6d61b90

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: feef5cbc-ea2d-48f7-916c-c481f4742476

Fix early response socket retirement

71740f0

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Jeremy Meng (jeremymeng) marked this pull request as ready for review October 20, 2026 22:06

Jeremy Meng (jeremymeng) requested review from a team as code owners October 20, 2026 22:06

Copilot AI balanced review requested due to automatic review settings October 20, 2026 22:06

Copilot started reviewing on behalf of Jeremy Meng (jeremymeng) October 20, 2026 22:07

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Jeremy Meng (jeremymeng) mentioned this pull request Oct 20, 2026

[core] Extract NodeRequestAttempt state machine from makeRequest jeremymeng/azure-sdk-for-js#41

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3 tasks done

[core] Extract NodeRequestAttempt state machine from makeRequest (#41)

1130d99

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Copilot AI balanced review requested due to automatic review settings October 20, 2026 23:58

Copilot started reviewing on behalf of Jeremy Meng (jeremymeng) October 20, 2026 23:59

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Comment thread sdk/core/ts-http-runtime/src/util/responseBody.ts

const readableStream: unknown = response.readableStreamBody;

if (isNodeResponseBody(readableStream)) {

if (readableStream.destroy) {

readableStream.destroy();

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