feat: serverless examples (#11)

examples/nodejs-lambda-s3/README.md

@@ -0,0 +1,4 @@
+# NodeJS + Lambda + S3 Serverless Rules Engine
+
+Requirements:
+* ZenEngineNodeJS Lambda Layer

examples/nodejs-lambda-s3/index.mjs

@@ -0,0 +1,43 @@
+import { ZenEngine } from '@gorules/zen-engine';
+import { S3Client, GetObjectCommand } from '@aws-sdk/client-s3';
+
+const client = new S3Client({});
+const { BUCKET_NAME } = process.env;
+
+const streamToBuffer = (stream) => new Promise((resolve, reject) => {
+    const chunks = [];
+    stream.on('data', (chunk) => chunks.push(chunk));
+    stream.on('error', reject);
+    stream.on('end', () => resolve(Buffer.concat(chunks)));
+});
+
+const loader = async (key) => {
+    try {
+        const params = {
+            Bucket: BUCKET_NAME,
+            Key: key,
+        };
+
+        const command = new GetObjectCommand(params);
+        const response = await client.send(command);
+
+        const { Body } = response;
+
+        return streamToBuffer(Body);
+    } catch (e) {
+        console.error(e);
+    }
+};
+
+export const handler = async(event) => {
+    const { key, context } = event;
+    const engine = new ZenEngine({
+        loader
+    });
+    const decision = await engine.getDecision(key);
+    const result = await decision.evaluate(context);
+    return {
+        statusCode: 200,
+        body: result,
+    };
+};