Custom Payload Transformer (WebAssembly Support) [ Fixed Issue #257 ] by Juwonlo · Pull Request #366 · EDOHWARES/EventHorizon

Juwonlo · 2026-04-28T00:47:07Z

Closes #257

Fixed Issue #257

drips-wave · 2026-04-28T00:47:42Z

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Pull request overview

Implements a custom payload transformation runtime that executes user-provided WebAssembly (Wasm) against event payloads, and wires it into the BullMQ worker so triggers can optionally transform payloads before dispatching actions.

Changes:

Added a worker-thread-based Wasm payload transformer with timeout support.
Integrated optional Wasm transformation into the action processor (including batch handling) and added a benchmark script.
Added GraphQL subscriptions/pubsub scaffolding intended to publish execution logs.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 13 comments.

Show a summary per file

File	Description
backend/src/worker/wasmTransformer.js	Adds worker-thread Wasm execution and payload transformation logic.
backend/src/worker/wasm.benchmark.js	Adds a benchmark script to measure transformation/thread overhead.
backend/src/worker/processor.js	Invokes the Wasm transformer before executing trigger actions; adds failure pubsub publishing.
backend/src/worker/server.js	Adds an Apollo + graphql-ws subscription server configuration.
backend/src/worker/typeDefs.js	Adds GraphQL schema definitions for execution log subscriptions.
backend/src/worker/resolvers.js	Adds subscription resolver using `withFilter` and pubsub iterator.
backend/src/worker/pubsub.js	Adds Redis-backed GraphQL pubsub implementation.

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Copilot · 2026-04-28T00:51:40Z

+const { ApolloServer } = require('@apollo/server');
+const { ApolloServerPluginDrainHttpServer } = require('@apollo/server/plugin/drainHttpServer');
+const { makeExecutableSchema } = require('@graphql-tools/schema');
+const { WebSocketServer } = require('ws');
+const { useServer } = require('graphql-ws/lib/use/ws');
+const jwt = require('jsonwebtoken');


This file introduces imports for packages that are not listed in backend/package.json (e.g., @apollo/server, @apollo/server/plugin/drainHttpServer, @graphql-tools/schema, ws, graphql-ws). Add the missing dependencies (or remove the code) so the backend workspace can install and start successfully.

Copilot · 2026-04-28T00:51:41Z

+        transformPayload: async (wasmBase64, payload, timeoutMs = 1000) => {
+            return new Promise((resolve, reject) => {
+                const worker = new Worker(__filename, {
+                    workerData: { wasmBase64, payload }
+                });
+
+                const timer = setTimeout(() => {
+                    worker.terminate();
+                    reject(new Error(`WASM execution timed out after ${timeoutMs}ms`));
+                }, timeoutMs);
+
+                worker.on('message', (msg) => {
+                    clearTimeout(timer);
+                    if (msg.error) reject(new Error(msg.error));
+                    else resolve(msg.result);
+                });
+
+                worker.on('error', (err) => {
+                    clearTimeout(timer);
+                    reject(err);
+                });
+
+                worker.on('exit', (code) => {
+                    clearTimeout(timer);
+                    if (code !== 0) reject(new Error(`Worker stopped with exit code ${code}`));
+                });


New transformation behavior is introduced here (worker thread execution, timeouts, ABI export validation, output decoding/JSON parsing), but there are no unit/integration tests added alongside it. Given the repo uses node --test with backend/__tests__, please add tests for success/failure cases (invalid base64, missing exports, timeout, invalid JSON, large output) to prevent regressions.

Copilot · 2026-04-28T00:51:41Z

+const { RedisPubSub } = require('graphql-redis-subscriptions');
+const Redis = require('ioredis');


This module depends on graphql-redis-subscriptions (and ioredis), but graphql-redis-subscriptions isn’t listed in backend/package.json right now. Add it to the backend workspace dependencies so installs don’t fail.

Copilot · 2026-04-28T00:51:41Z

+const { withFilter } = require('graphql-subscriptions');
+const pubsub = require('./pubsub');
+


graphql-subscriptions is imported here, but it’s not currently declared in backend/package.json. Add the missing dependency (or replace this with the project’s existing subscription utilities) to avoid runtime/module resolution failures.

Suggested change

const { withFilter } = require('graphql-subscriptions');

const pubsub = require('./pubsub');

const pubsub = require('./pubsub');

const withFilter = (asyncIteratorFn, filterFn) => (...args) => {

const asyncIterator = asyncIteratorFn(...args);

const getNextFilteredValue = async () => {

while (true) {

const result = await asyncIterator.next();

if (result.done) {

return result;

}

const payload = result.value;

const variables = args[1] || {};

if (await filterFn(payload, variables, ...args)) {

return { value: payload, done: false };

}

}

};

return {

async next() {

return getNextFilteredValue();

},

return() {

if (typeof asyncIterator.return === 'function') {

return asyncIterator.return();

}

return Promise.resolve({ value: undefined, done: true });

},

throw(error) {

if (typeof asyncIterator.throw === 'function') {

return asyncIterator.throw(error);

}

return Promise.reject(error);

},

[Symbol.asyncIterator]() {

return this;

}

};

};

Copilot · 2026-04-28T00:51:41Z

        case 'webhook': {
            if (!actionUrl) {
                throw new Error('Missing actionUrl for webhook trigger');
            }

-            const payload = {
+            return await axios.post(actionUrl, {
                contractId,
                eventName,
                payload: eventPayload,
-            };
-
-            return await webhookService.sendSignedWebhook(
-                actionUrl,
-                payload,
-                trigger.webhookSecret
-            );
+            });


The webhook action was changed from webhookService.sendSignedWebhook(...) to a plain axios.post(...), which removes the HMAC signing and request options previously used for secure delivery. Please restore signed webhook delivery (or re-implement equivalent signature + timestamp headers) to avoid breaking existing webhook verification expectations.

Copilot · 2026-04-28T00:51:43Z

+/**
+ * Configures the Apollo Server with WebSocket Subscriptions support.
+ * 
+ * @param {Object} httpServer HTTP server instance from Express
+ * @returns {ApolloServer} the configured Apollo server instance
+ */
+async function configureGraphQLServer(httpServer) {
+    const schema = makeExecutableSchema({ typeDefs, resolvers });


The PR description/linked Issue #257 is specifically about adding a custom payload transformer (Wasm runtime + benchmarks). This PR also adds a GraphQL subscriptions server/pubsub/typeDefs/resolvers which isn’t mentioned in the description or acceptance criteria. Either update the PR description to explain this additional scope and how it relates, or move the subscriptions work into a separate PR.

Copilot · 2026-04-28T00:51:43Z

@@ -0,0 +1,16 @@
+c.onst typeDefs = `#graphql


Line 1 has a syntax error (c.onst) which will prevent the module from loading. Change it to a valid const declaration so the schema can be imported.

Suggested change

c.onst typeDefs = `#graphql

const typeDefs = `#graphql

Copilot · 2026-04-28T00:51:44Z

 const telegramService = require('../services/telegram.service');
-const webhookService = require('../services/webhook.service');
 const logger = require('../config/logger');
+const pubsub = require('../graphql/pubsub');


This import path looks incorrect: there is no src/graphql/pubsub directory in the backend workspace, but a new src/worker/pubsub.js file exists. Update the require to point at the actual pubsub module (e.g., ./pubsub) so the worker doesn’t crash on startup.

Suggested change

const pubsub = require('../graphql/pubsub');

const pubsub = require('./pubsub');

Copilot · 2026-04-28T00:51:44Z

                case 'webhook': {
                    if (!actionUrl) {
                        throw new Error('Missing actionUrl for webhook trigger');
                    }

-                    const payload = {
+                    await axios.post(actionUrl, {
                        contractId,
                        eventName,
                        payload: eventPayload,
                        batchIndex: i,
                        batchSize: eventPayloads.length,
                        batchPayloads: eventPayloads, // Send the full batch for webhooks
-                    };
-
-                    await webhookService.sendSignedWebhook(
-                        actionUrl,
-                        payload,
-                        trigger.webhookSecret
-                    );
+                    });


Same issue in the batch webhook path: sending unsigned requests via axios.post drops the webhook HMAC signature and related options. Please switch back to signed webhook delivery (or add equivalent signing headers) for batch webhooks as well.

Copilot · 2026-04-28T00:51:44Z

+            let outLen = 0;
+            while (outArray[outLen] !== 0 && outLen < 5000000) outLen++; // 5MB limit max


The null-terminated output scan can run past the end of memory.buffer: new Uint8Array(memory.buffer, outPtr) has a finite length, but the loop only checks outLen < 5000000. If there’s no 0 byte before the end of the view, outLen keeps increasing and new Uint8Array(memory.buffer, outPtr, outLen) can throw a RangeError. Bound the loop by outArray.length (and fail if no terminator is found within the limit) before decoding/JSON parsing.

Suggested change

let outLen = 0;

while (outArray[outLen] !== 0 && outLen < 5000000) outLen++; // 5MB limit max

const maxOutLen = Math.min(outArray.length, 5000000); // 5MB limit max

let outLen = 0;

while (outLen < maxOutLen && outArray[outLen] !== 0) outLen++;

if (outLen === maxOutLen) {

throw new Error(

outArray.length > 5000000

? 'WASM output exceeds maximum allowed size or is missing null terminator'

: 'WASM output is missing null terminator'

);

}

Juwonlo added 2 commits April 28, 2026 02:38

Fixed Issue EDOHWARES#258

e34ae12

Fixed Issue EDOHWARES#257

466c3d3

Copilot AI review requested due to automatic review settings April 28, 2026 00:47

Copilot started reviewing on behalf of Juwonlo April 28, 2026 00:47 View session

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Custom Payload Transformer (WebAssembly Support) [ Fixed Issue #257 ]#366

Custom Payload Transformer (WebAssembly Support) [ Fixed Issue #257 ]#366
Juwonlo wants to merge 2 commits intoEDOHWARES:mainfrom
Juwonlo:Payload

Juwonlo commented Apr 28, 2026 •

edited

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		const { RedisPubSub } = require('graphql-redis-subscriptions');
		const Redis = require('ioredis');

		const { withFilter } = require('graphql-subscriptions');
		const pubsub = require('./pubsub');

-const { withFilter } = require('graphql-subscriptions');
-const pubsub = require('./pubsub');
+const pubsub = require('./pubsub');
+const withFilter = (asyncIteratorFn, filterFn) => (...args) => {
+    const asyncIterator = asyncIteratorFn(...args);
+    const getNextFilteredValue = async () => {
+        while (true) {
+            const result = await asyncIterator.next();
+            if (result.done) {
+                return result;
+            }
+            const payload = result.value;
+            const variables = args[1] || {};
+            if (await filterFn(payload, variables, ...args)) {
+                return { value: payload, done: false };
+            }
+        }
+    };
+    return {
+        async next() {
+            return getNextFilteredValue();
+        },
+        return() {
+            if (typeof asyncIterator.return === 'function') {
+                return asyncIterator.return();
+            }
+            return Promise.resolve({ value: undefined, done: true });
+        },
+        throw(error) {
+            if (typeof asyncIterator.throw === 'function') {
+                return asyncIterator.throw(error);
+            }
+            return Promise.reject(error);
+        },
+        [Symbol.asyncIterator]() {
+            return this;
+        }
+    };
+};

	const pubsub = require('../graphql/pubsub');
	const pubsub = require('./pubsub');

		let outLen = 0;
		while (outArray[outLen] !== 0 && outLen < 5000000) outLen++; // 5MB limit max

-            let outLen = 0;
-            while (outArray[outLen] !== 0 && outLen < 5000000) outLen++; // 5MB limit max
+            const maxOutLen = Math.min(outArray.length, 5000000); // 5MB limit max
+            let outLen = 0;
+            while (outLen < maxOutLen && outArray[outLen] !== 0) outLen++;
+            if (outLen === maxOutLen) {
+                throw new Error(
+                    outArray.length > 5000000
+                        ? 'WASM output exceeds maximum allowed size or is missing null terminator'
+                        : 'WASM output is missing null terminator'
+                );
+            }

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Juwonlo commented Apr 28, 2026 •

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