feat: add local file storage and stdio transport support

.env.exmaple

@@ -1,6 +1,9 @@
 SERVER_PORT=8081
 
-# Cloud Storage Configuration
+# Storage mode: 'local' (saves to ./images/) or 'cloud' (uploads to BaiduBCE BOS)
+STORAGE_MODE=local
+
+# Cloud Storage Configuration (only needed when STORAGE_MODE=cloud)
 BOS_AK=...
 BOS_SK=...
 BOS_ENDPOINT=...

package.json

@@ -5,6 +5,7 @@
     "main": "src/index.js",
     "scripts": {
         "dev": "nodemon src/index.js",
+        "start:stdio": "node src/index.js --stdio",
         "inspect": "mcp-inspector node ./src/index.js"
     },
     "keywords": ["echarts", "mcp", "data-visualization"],

src/index.js

@@ -20,9 +20,9 @@
 import express from 'express';
 import { Server } from '@modelcontextprotocol/sdk/server/index.js';
 import { SSEServerTransport } from '@modelcontextprotocol/sdk/server/sse.js';
+import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
 import { CallToolRequestSchema, ErrorCode, ListToolsRequestSchema, McpError } from '@modelcontextprotocol/sdk/types.js';
 import dotenv from 'dotenv';
-import fs from 'fs';
 
 import { getChartBase64 } from './chart.js';
 import { isTreelike, seriesTypes } from './util.js';
@@ -32,11 +32,6 @@ dotenv.config();
 
 class EChartsServer {
     constructor() {
-        // Throw an error if there is no .env file
-        if (!fs.existsSync('.env')) {
-            throw new Error('Missing .env file. Please create a .env file with your configuration. See .env.example for reference.');
-        }
-
         this.server = new Server(
             {
                 name: 'echarts',
@@ -173,38 +168,46 @@ class EChartsServer {
     }
 
     async run() {
-        const app = express();
-        const transports = {};
+        const useStdio = process.argv.includes('--stdio');
 
-        app.get('/', (_, res) => {
-            res.send('Apache ECharts MCP Server is running');
-        });
+        if (useStdio) {
+            const transport = new StdioServerTransport();
+            await this.server.connect(transport);
+            console.error('ECharts MCP Server running on stdio');
+        } else {
+            const app = express();
+            const transports = {};
 
-        app.get('/sse', async (_, res) => {
-            const transport = new SSEServerTransport('/messages', res);
-            transports[transport.sessionId] = transport;
-            res.on('close', () => {
-                delete transports[transport.sessionId];
+            app.get('/', (_, res) => {
+                res.send('Apache ECharts MCP Server is running');
+            });
+
+            app.get('/sse', async (_, res) => {
+                const transport = new SSEServerTransport('/messages', res);
+                transports[transport.sessionId] = transport;
+                res.on('close', () => {
+                    delete transports[transport.sessionId];
+                });
+                await this.server.connect(transport);
             });
-            await this.server.connect(transport);
-        });
 
-        app.post('/messages', async (req, res) => {
-            const sessionId = req.query.sessionId;
-            const transport = transports[sessionId];
-            if (!transport) {
-                if (!res.headersSent) {
-                    res.status(400).send('No transport found for sessionId. Please establish SSE connection first.');
+            app.post('/messages', async (req, res) => {
+                const sessionId = req.query.sessionId;
+                const transport = transports[sessionId];
+                if (!transport) {
+                    if (!res.headersSent) {
+                        res.status(400).send('No transport found for sessionId. Please establish SSE connection first.');
+                    }
+                    return;
                 }
-                return;
-            }
-            await transport.handlePostMessage(req, res);
-        });
+                await transport.handlePostMessage(req, res);
+            });
 
-        const port = process.env.SERVER_PORT || 8081;
-        app.listen(port, () => {
-            console.log(`Server is running on port ${port}`);
-        });
+            const port = process.env.SERVER_PORT || 8081;
+            app.listen(port, () => {
+                console.log(`Server is running on port ${port}`);
+            });
+        }
     }
 }
 

src/storage.js

@@ -17,74 +17,113 @@
 * under the License.
 */
 
-import bos from '@baiducloud/sdk';
-import dotenv from 'dotenv';
 import fs from 'fs';
 import path from 'path';
 import { fileURLToPath } from 'url';
 
-dotenv.config();
-
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = path.dirname(__filename);
-const tmpDir = path.join(__dirname, '../tmp');
 
-// Create tmp directory if not exists
-if (!fs.existsSync(tmpDir)) {
-    fs.mkdirSync(tmpDir);
+/**
+ * Storage mode: 'local' or 'cloud'
+ * Set via STORAGE_MODE env variable. Defaults to 'local'.
+ */
+const storageMode = process.env.STORAGE_MODE || 'local';
+
+export async function saveImage(base64) {
+    if (storageMode === 'cloud') {
+        return saveImageToCloud(base64);
+    }
+    return saveImageLocally(base64);
 }
 
-const config = {
-    endpoint: process.env.BOS_ENDPOINT,
-    credentials: {
-        ak: process.env.BOS_AK,
-        sk: process.env.BOS_SK,
-    },
-};
+// ─── Local Storage ───────────────────────────────────────────────────────────
 
-const client = new bos.BosClient(config);
-const bucket = process.env.BOS_BUCKET;
-const basePath = '/upload/echarts';
+const imagesDir = path.join(__dirname, '../images');
+
+function ensureImagesDir() {
+    if (!fs.existsSync(imagesDir)) {
+        fs.mkdirSync(imagesDir, { recursive: true });
+    }
+}
+
+async function saveImageLocally(base64) {
+    ensureImagesDir();
 
-export async function saveImage(base64) {
     const fileName = getFilePrefix() + '.png';
-    const key = `${basePath}/${fileName}`;
-    const tmpPath = path.join(tmpDir, fileName);
+    const filePath = path.join(imagesDir, fileName);
 
     try {
-        // Remove Base64 prefix if exists
         const base64Data = base64.replace(/^data:image\/\w+;base64,/, '');
-        // Save base64 to tmp file
-        fs.writeFileSync(tmpPath, Buffer.from(base64Data, 'base64'));
+        fs.writeFileSync(filePath, Buffer.from(base64Data, 'base64'));
+        return filePath;
+    } catch (error) {
+        console.error('Failed to save image locally:', error);
+        throw error;
+    }
+}
+
+// ─── Cloud Storage (BaiduBCE BOS) ────────────────────────────────────────────
 
-        // Upload file
-        await client.putObjectFromFile(bucket, key, tmpPath);
-        return process.env.BOS_CDN_ENDPOINT + key;
+async function saveImageToCloud(base64) {
+    const { BosClient } = await import('@baiducloud/sdk');
+
+    const bosConfig = {
+        endpoint: process.env.BOS_ENDPOINT,
+        credentials: {
+            ak: process.env.BOS_AK,
+            sk: process.env.BOS_SK,
+        },
+    };
+
+    const bucket = process.env.BOS_BUCKET || 'echarts-mcp';
+    const cdnEndpoint = process.env.BOS_CDN_ENDPOINT;
+
+    if (!bosConfig.endpoint || !bosConfig.credentials.ak || !bosConfig.credentials.sk) {
+        throw new Error(
+            'Cloud storage requires BOS_ENDPOINT, BOS_AK, and BOS_SK environment variables. ' +
+            'Set STORAGE_MODE=local to use local storage instead.'
+        );
+    }
+
+    const client = new BosClient(bosConfig);
+    const fileName = getFilePrefix() + '.png';
+    const key = `charts/${fileName}`;
+
+    try {
+        const base64Data = base64.replace(/^data:image\/\w+;base64,/, '');
+        const buffer = Buffer.from(base64Data, 'base64');
+
+        await client.putObject(bucket, key, buffer, {
+            'Content-Type': 'image/png',
+        });
+
+        const url = cdnEndpoint
+            ? `${cdnEndpoint}/${key}`
+            : `${bosConfig.endpoint}/${bucket}/${key}`;
+
+        return url;
     } catch (error) {
-        console.error('Upload failed:', error);
+        console.error('Failed to save image to cloud:', error);
         throw error;
-    } finally {
-        // Remove tmp file
-        if (fs.existsSync(tmpPath)) {
-            fs.unlinkSync(tmpPath);
-        }
     }
 }
 
+// ─── Utils ───────────────────────────────────────────────────────────────────
+
 function getFilePrefix() {
-    // Datetime + 10 random characters
     const date = new Date();
     const year = date.getFullYear();
-    const month = date.getMonth() + 1;
-    const day = date.getDate();
-    const hour = date.getHours();
-    const minute = date.getMinutes();
-    const second = date.getSeconds();
+    const month = String(date.getMonth() + 1).padStart(2, '0');
+    const day = String(date.getDate()).padStart(2, '0');
+    const hour = String(date.getHours()).padStart(2, '0');
+    const minute = String(date.getMinutes()).padStart(2, '0');
+    const second = String(date.getSeconds()).padStart(2, '0');
 
     const chars = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
     let result = '';
     for (let i = 0; i < 10; i++) {
         result += chars[Math.floor(Math.random() * chars.length)];
     }
-    return `${year}${month}${day}${hour}${minute}${second}${result}`;
+    return `${year}${month}${day}_${hour}${minute}${second}_${result}`;
 }