Allow registering multiple ContentCodecs per media type with optional scheme support by Pranav-0440 · Pull Request #1484 · eclipse-thingweb/node-wot

Pranav-0440 · 2026-02-15T18:41:44Z

Add example and explanation for configuring PSK security scheme in CoapsClient. Closes eclipse-thingweb#954 Signed-off-by: Pranav Ghorpade <pranavghorpade61@gmail.com>

…ssary-condition rule Signed-off-by: Pranav Ghorpade <pranavghorpade61@gmail.com>

…ith optional scheme support Signed-off-by: Pranav Ghorpade <pranavghorpade61@gmail.com>

Copilot

Pull request overview

This PR aims to extend ContentSerdes to support registering multiple ContentCodecs for the same media type (with an additional “scheme” dimension), and includes several CoAP binding cleanups plus DTLS/PSK documentation for CoAPs.

Changes:

Refactors ContentSerdes codec registry to map mediaType -> (scheme -> codec) and adds an optional scheme parameter to addCodec.
Updates CoAP binding code paths (content-type handling, request routing, internal refactors) and adds a package-local ESLint config.
Documents PSK usage for coaps:// in the CoAP binding README.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
packages/core/src/content-serdes.ts	Refactors codec storage to support multiple codecs per media type and introduces optional scheme registration.
packages/binding-coap/src/mdns-introducer.ts	Simplifies iteration over network interfaces.
packages/binding-coap/src/coaps-client.ts	Tightens undefined checks and minor cleanup in security and content handling.
packages/binding-coap/src/coap-server.ts	Refactors routing and multiple-properties read behavior; adjusts type handling and content-type defaults.
packages/binding-coap/src/coap-client.ts	Makes Content-Format parsing more defensive (non-string headers).
packages/binding-coap/eslint.config.mjs	Adds binding-local ESLint override for `no-unnecessary-condition`.
packages/binding-coap/README.md	Adds documentation for DTLS/PSK usage with `coaps://`.

Comments suppressed due to low confidence (3)

packages/binding-coap/src/coap-server.ts:860

handleEventRequest() assumes thing.events[affordanceKey] exists. For requests like /events (missing key) or /events/<unknown>, event will be undefined and event.forms / event.uriVariables will throw. Add an explicit not-found check (and validate affordanceKey) before using the event.

    private async handleEventRequest(
        thing: ExposedThing,
        affordanceKey: string,
        req: IncomingMessage,
        res: OutgoingMessage,
        contentType: string
    ) {
        const event = thing.events[affordanceKey];

        if (req.method !== "GET") {
            this.sendMethodNotAllowedResponse(res);
            return;
        }

        const observe = req.headers.Observe as number | undefined;

        if (observe === undefined) {
            debug(
                `CoapServer on port ${this.getPort()} rejects '${affordanceKey}' event subscription from ${Helpers.toUriLiteral(
                    req.rsinfo.address
                )}:${req.rsinfo.port}`
            );
            this.sendResponse(res, "4.00", "No Observe Option");
            return;
        }

        if (observe === 0) {
            this.avoidDuplicatedObserveRegistration(res); // TODO: Get rid of this workaround

            const interactionOptions = this.createInteractionOptions(
                event.forms,
                thing,
                req,
                contentType,
                event.uriVariables
            );

packages/binding-coap/src/coap-server.ts:563

handlePropertyRequest() no longer handles an unknown affordanceKey. If thing.properties[affordanceKey] is undefined, subsequent accesses (property.forms, property.readOnly, etc.) will throw and likely crash the request handler instead of returning 4.04. Add an explicit not-found check before switching on the method.

    private async handlePropertyRequest(
        thing: ExposedThing,
        affordanceKey: string,
        req: IncomingMessage,
        res: OutgoingMessage,
        contentType: string
    ) {
        const property = thing.properties[affordanceKey];

        switch (req.method) {
            case "GET":
                if (req.headers.Observe == null) {
                    this.handleReadProperty(property, req, contentType, thing, res, affordanceKey);
                } else {
                    this.handleObserveProperty(property, req, contentType, thing, res, affordanceKey);
                }
                break;
            case "PUT":
                if (property.readOnly === true) {

packages/binding-coap/src/coap-server.ts:788

handleActionRequest() assumes thing.actions[affordanceKey] exists. For requests like /actions (missing key) or /actions/<unknown>, action will be undefined and action.forms / action.uriVariables will throw. Please restore a not-found guard (and also validate affordanceKey before indexing).

    private async handleActionRequest(
        thing: ExposedThing,
        affordanceKey: string,
        req: IncomingMessage,
        res: OutgoingMessage,
        contentType: string
    ) {
        const action = thing.actions[affordanceKey];

        if (req.method !== "POST") {
            this.sendMethodNotAllowedResponse(res);
            return;
        }

        const interactionOptions = this.createInteractionOptions(
            action.forms,
            thing,
            req,
            contentType,
            action.uriVariables
        );

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Copilot · 2026-02-15T18:46:51Z

packages/binding-coap/src/coap-server.ts

+                    if (
+                        content.type !== ContentSerdes.DEFAULT &&
+                        content.type !== "application/json"


In handleReadMultipleProperties(), the JSON filter is too strict: it only accepts content.type exactly equal to application/json / ContentSerdes.DEFAULT. JSON content types with parameters (e.g. application/json; charset=utf-8) will be skipped even though they are JSON. Consider comparing ContentSerdes.getMediaType(content.type) against application/json (or just attempt JSON parsing inside the try/catch without the exact-type guard).

Suggested change

if (

content.type !== ContentSerdes.DEFAULT &&

content.type !== "application/json"

const mediaType = ContentSerdes.getMediaType(content.type);

if (

mediaType !== ContentSerdes.DEFAULT &&

mediaType !== "application/json"

Copilot · 2026-02-15T18:46:52Z

packages/core/src/content-serdes.ts

+    public addCodec(codec: ContentCodec, offered = false, scheme?: string) : void {
+        const mediaType = codec.getMediaType();
+
+        if (!this.codecs.has(mediaType)) {
+            this.codecs.set(mediaType, new Map());
+        }
+
+        const schemeMap = this.codecs.get(mediaType)!;
+
+        // store codec under specific scheme (or undefined for generic)
+        schemeMap.set(scheme, codec);
+
+        if (offered) {
+            this.offered.add(mediaType);
+        }
+    }
+    private getCodec(mediaType: string, scheme?: string): ContentCodec | undefined {
+        const schemeMap = this.codecs.get(mediaType);
+        if (!schemeMap) return undefined;
+
+        if (scheme !== undefined && schemeMap.has(scheme)) {
+            return schemeMap.get(scheme);
+        }
+
+        return schemeMap.get(undefined);
    }


There is existing automated test coverage for ContentSerdes (see packages/core/test/content-serdes-test.ts), but this change introduces new behavior (multiple codecs per media type and scheme handling) without adding/adjusting tests. Please add tests that register multiple codecs for the same media type (generic + scheme-specific) and verify the correct codec is selected/fallback behavior is correct.

Copilot · 2026-02-15T18:46:52Z

packages/core/src/content-serdes.ts

+    public addCodec(codec: ContentCodec, offered = false, scheme?: string) : void {
+        const mediaType = codec.getMediaType();
+
+        if (!this.codecs.has(mediaType)) {
+            this.codecs.set(mediaType, new Map());
+        }
+
+        const schemeMap = this.codecs.get(mediaType)!;
+
+        // store codec under specific scheme (or undefined for generic)
+        schemeMap.set(scheme, codec);
+
+        if (offered) {
+            this.offered.add(mediaType);
+        }
+    }
+    private getCodec(mediaType: string, scheme?: string): ContentCodec | undefined {
+        const schemeMap = this.codecs.get(mediaType);
+        if (!schemeMap) return undefined;
+
+        if (scheme !== undefined && schemeMap.has(scheme)) {
+            return schemeMap.get(scheme);
+        }
+
+        return schemeMap.get(undefined);
    }


The new scheme parameter in addCodec() is currently ineffective: getCodec() is private and every caller (isSupported, contentToValue, valueToContent) calls it without passing a scheme, so scheme-specific codecs can never be selected (and isSupported() will return false for a media type that only has a scheme-specific codec). To make this feature usable, expose scheme-aware lookup and thread the scheme through the serialization/deserialization entry points (or otherwise define how the correct codec is chosen).

Copilot · 2026-02-15T18:46:52Z

packages/core/src/content-serdes.ts

-    public addCodec(codec: ContentCodec, offered = false): void {
-        ContentSerdes.get().codecs.set(codec.getMediaType(), codec);
-        if (offered) ContentSerdes.get().offered.add(codec.getMediaType());
+    public addCodec(codec: ContentCodec, offered = false, scheme?: string) : void {


Minor style: method signature spacing is inconsistent with the rest of the file (scheme?: string) : void). Please align to the existing ): void formatting to keep lint/formatting consistent.

Suggested change

public addCodec(codec: ContentCodec, offered = false, scheme?: string) : void {

public addCodec(codec: ContentCodec, offered = false, scheme?: string): void {

Copilot · 2026-02-15T18:46:52Z

packages/binding-coap/src/coap-server.ts

    public async expose(thing: ExposedThing, tdTemplate?: WoT.ExposedThingInit): Promise<void> {
        const port = this.getPort();
        const urlPath = this.createThingUrlPath(thing);

-        if (port === -1) {
-            warn("CoapServer is assigned an invalid port, aborting expose process.");
-            return;
-        }
-
        this.fillInBindingData(thing, port, urlPath);



expose() no longer guards against getPort() returning -1. Servient.addServer() can call server.expose() before the server has started, which would now generate forms/URLs containing port -1. Consider restoring the early return (or otherwise ensuring expose() only runs after start() has bound the socket).

Pranav-0440 added 4 commits February 12, 2026 17:57

docs(binding-coap): document PSK usage with CoAPs

d4fd2e5

Add example and explanation for configuring PSK security scheme in CoapsClient. Closes eclipse-thingweb#954 Signed-off-by: Pranav Ghorpade <pranavghorpade61@gmail.com>

docs(binding-coap): document PSK usage with CoAPs

477dc14

Add example and explanation for configuring PSK security scheme in CoapsClient. Closes eclipse-thingweb#954 Signed-off-by: Pranav Ghorpade <pranavghorpade61@gmail.com>

fix(binding-coap): align affordance forms typing and enable no-unnece…

bf19d2f

…ssary-condition rule Signed-off-by: Pranav Ghorpade <pranavghorpade61@gmail.com>

feat(core): allow registering multiple ContentCodecs per media type w…

10a117a

…ith optional scheme support Signed-off-by: Pranav Ghorpade <pranavghorpade61@gmail.com>

Copilot AI review requested due to automatic review settings February 15, 2026 18:41

Pranav-0440 requested review from JKRhb, danielpeintner and relu91 as code owners February 15, 2026 18:41

Copilot started reviewing on behalf of Pranav-0440 February 15, 2026 18:42 View session

Copilot AI reviewed Feb 15, 2026

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Allow registering multiple ContentCodecs per media type with optional scheme support#1484

Allow registering multiple ContentCodecs per media type with optional scheme support#1484
Pranav-0440 wants to merge 4 commits intoeclipse-thingweb:masterfrom
Pranav-0440:fix/allow-different-codecs-the-same-contentType

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-                    if (
-                        content.type !== ContentSerdes.DEFAULT &&
-                        content.type !== "application/json"
+                    const mediaType = ContentSerdes.getMediaType(content.type);
+                    if (
+                        mediaType !== ContentSerdes.DEFAULT &&
+                        mediaType !== "application/json"

	public addCodec(codec: ContentCodec, offered = false, scheme?: string) : void {
	public addCodec(codec: ContentCodec, offered = false, scheme?: string): void {

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