Initial commit

packages/server/.gitignore

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+# dependencies (bun install)
+node_modules
+
+# output
+out
+dist
+*.tgz
+
+# code coverage
+coverage
+*.lcov
+
+# logs
+logs
+_.log
+report.[0-9]_.[0-9]_.[0-9]_.[0-9]_.json
+
+# dotenv environment variable files
+.env
+.env.development.local
+.env.test.local
+.env.production.local
+.env.local
+
+# caches
+.eslintcache
+.cache
+*.tsbuildinfo
+
+# IntelliJ based IDEs
+.idea
+
+# Finder (MacOS) folder config
+.DS_Store

packages/server/Containerfile

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+# Stage 1: Builder
+# This stage installs all dependencies and builds all packages.
+FROM oven/bun:1 AS builder
+WORKDIR /app
+
+# Copy dependency manifests
+COPY package.json bun.lock ./
+COPY tsconfig.base.json ./
+
+# Copy package-specific manifests to leverage Docker cache
+COPY packages/shared/package.json packages/shared/tsconfig.json ./packages/shared/
+COPY packages/server/package.json packages/server/tsconfig.json ./packages/server/
+
+# Install ALL workspace dependencies
+RUN bun install
+
+# Copy source code
+COPY packages/shared ./packages/shared/
+COPY packages/server ./packages/server/
+
+# Build the server and its dependencies (i.e., 'shared')
+RUN bun run --filter=@hnu.de/hl7v2-shared build
+RUN bun run --filter=@hnu.de/hl7v2-server build
+
+
+#---------------------------------------------------------------------
+
+# Stage 2: Production
+FROM oven/bun:1-slim
+WORKDIR /app
+
+# Create the full directory structure first
+RUN mkdir -p packages/shared packages/server
+
+# Copy workspace configuration
+COPY --from=builder /app/package.json /app/bun.lock ./
+
+# Set up shared package with its dist directory
+COPY --from=builder /app/packages/shared/package.json ./packages/shared/
+COPY --from=builder /app/packages/shared/dist ./packages/shared/dist
+
+# Set up server package with its dist directory
+COPY --from=builder /app/packages/server/package.json ./packages/server/
+COPY --from=builder /app/packages/server/dist ./packages/server/dist
+
+# Install ONLY production dependencies
+ENV NODE_ENV=production
+RUN bun install \
+    --frozen-lockfile \
+    --production
+
+# Set environment variables from config.ts
+ENV PORT=8080 \
+    PREFIXES=STA \
+    POOL_SIZE=100
+
+EXPOSE 8080
+
+# Run the server from its package directory
+WORKDIR /app/packages/server
+CMD ["bun", "run", "dist/index.js"]

packages/server/config.ts

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+interface Config {
+    port: number;
+    prefixes: string[];
+    poolSize: number;
+}
+
+export const config: Config = {
+    port: parseInt(process.env.PORT || '8080', 10),
+    prefixes: (process.env.PREFIXES || 'STA').split(","),
+    poolSize: parseInt(process.env.POOL_SIZE || '100', 10),
+};
+
+if (isNaN(config.port) || config.port < 1024 || config.port > 49151) {
+    throw new Error('Invalid PORT environment variable (1024 - 49151)');
+}
+
+if (config.prefixes.length === 0) {
+    throw new Error('Invalid PREFIXES environment variable (length > 1)');
+}
+
+if (isNaN(config.poolSize) || config.poolSize < config.prefixes.length) {
+    throw new Error('Invalid PORT environment variable (poolSize >= prefix.length)');
+}

packages/server/index.ts

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+import { WebSocketServer } from 'ws';
+import { type Message, MessageType } from '@hnu.de/hl7v2-shared';
+import 'dotenv/config';
+import { config } from './config';
+
+
+// ###########################################################################
+// ### ID Pool
+// ###########################################################################
+
+let availableIds: string[] = [];
+
+for (const prefix of config.prefixes) {
+    for (let i = 1; i <= config.poolSize / config.prefixes.length; i++) {
+        const number = i.toString().padStart(config.poolSize.toString().length, '0');
+        availableIds.push(`${prefix}-${number}`);
+    }
+}
+
+function shake(arr: any[]) {
+    for (let i = arr.length - 1; i > 0; i--) {
+        const j = Math.floor(Math.random() * (i + 1));
+        [arr[i], arr[j]] = [arr[j], arr[i]];
+    }
+    return arr;
+}
+
+availableIds = shake(availableIds);
+
+
+// ###########################################################################
+// ### Websocket Server
+// ###########################################################################
+
+const wss = new WebSocketServer({ port: config.port });
+
+const clients = new Map();
+
+console.log(`Starting WebSocket server ...`);
+
+console.log("Server configuration:", config);
+
+wss.on('connection', (ws) => {
+
+    // check for available IDs
+    if (availableIds.length === 0) {
+        console.log('Connection rejected: No available IDs.');
+        ws.close(1013, 'Server is full. Please try again later.'); // 1013: Try again later
+        return;
+    }
+
+    // get ID from pool and assign to user
+    const userId = availableIds.pop();
+    if (!userId) {
+        console.log('Connection rejected: Failed to retrieve ID.');
+        ws.close(1013, 'Server is full. Please try again later.'); // 1013: Try again later
+        return;
+    }
+
+    // store client in map
+    clients.set(userId, ws);
+
+    setTimeout(() => {
+        // send user ID to client
+        const welcomeMessage = {
+            type: 'assign_id',
+            payload: {
+                userId: userId,
+            },
+        } as Message;
+        ws.send(JSON.stringify(welcomeMessage));
+
+        console.log(`Client connected. Assigning ID: ${userId}`);
+    }, 0);
+
+    ws.on('message', (message) => {
+        try {
+
+            const parsedMessage: Message = JSON.parse(message.toString());
+            console.log(`Received message from ${userId}:`, parsedMessage);
+
+            // We only expect one type of message from clients: 'send_hl7v2'
+            if (parsedMessage.type === MessageType.send_hl7v2) {
+
+                const { message } = parsedMessage.payload;
+                // TODO: validate message
+
+                // get sender and recipient ID
+                const recipientId = parseMshField(message, 5);
+                if (!recipientId) {
+                    const errorMessage = {
+                        type: 'delivery_error',
+                        payload: {
+                            error: `Message is missing header field 5.`,
+                        },
+                    } as Message;
+                    ws.send(JSON.stringify(errorMessage));
+                }
+
+                // Find the recipient's WebSocket connection in our map.
+                const recipientWs = clients.get(recipientId);
+
+                if (recipientWs && recipientWs.readyState === WebSocket.OPEN) {
+
+                    // The recipient is connected. Forward the message.
+                    const forwardMessage = {
+                        type: MessageType.receive_hl7v2,
+                        payload: {
+                            message: message,
+                            timestamp: new Date().toISOString(),
+                        },
+                    } as Message;
+                    recipientWs.send(JSON.stringify(forwardMessage));
+                    console.log(`Forwarded message to ${recipientId}`);
+
+                } else {
+
+                    // The recipient is not connected or not found.
+                    console.log(`Recipient ${recipientId} not found or not connected.`);
+                    const errorMessage = {
+                        type: MessageType.delivery_error,
+                        payload: {
+                            error: `Station with ID ${recipientId} is not available.`,
+                        },
+                    } as Message;
+                    ws.send(JSON.stringify(errorMessage));
+                }
+            }
+        } catch (error) {
+            console.error(`Failed to process message from ${userId}:`, error);
+        }
+    });
+
+    // listen to disconnects to free IDs
+    ws.on('close', () => {
+        console.log(`Client ${userId} disconnected.`);
+        clients.delete(userId);
+        if (userId) {
+            availableIds.push(userId);
+        }
+        availableIds = shake(availableIds);
+    });
+
+    ws.on('error', (error) => {
+        console.error(`WebSocket error for client ${userId}:`, error);
+    });
+});
+
+function parseMshField(message: string, fieldIndex: number) {
+    try {
+        const mshLine = message.split(/[\r\n]+/)[0];
+        if (!mshLine || !mshLine.startsWith('MSH')) return null;
+        const fields = mshLine.split('|');
+        return fields[fieldIndex] || null;
+    } catch (e) {
+        return null;
+    }
+}
+
+console.log(`WebSocket server started on port ${config.port}`);

packages/server/package.json

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+{
+  "name": "@hnu.de/hl7v2-server",
+  "module": "index.ts",
+  "type": "module",
+  "private": true,
+  "scripts": {
+    "build": "tsc",
+    "dev": "bun --watch index.ts --watch config.ts",
+    "start": "bun index.ts"
+  },
+  "devDependencies": {
+    "@types/bun": "latest",
+    "@types/ws": "^8.18.1",
+    "typescript": "^5.8.3",
+  },
+  "dependencies": {
+    "@hnu.de/hl7v2-shared": "workspace:*",
+    "dotenv": "^17.2.0",
+    "ws": "^8.18.3"
+  }
+}

packages/server/tsconfig.json

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+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "outDir": "./dist",
+    "declaration": true,
+    "strict": true,
+    "skipLibCheck": true,
+    "noFallthroughCasesInSwitch": true,
+    "noUncheckedIndexedAccess": true,
+    "noImplicitOverride": true
+  },
+  "include": [
+    "*.ts"
+  ],
+  "exclude": [
+    "node_modules",
+    "dist"
+  ]
+}