Add server example

examples/express-app/config.json

@@ -0,0 +1,31 @@
+{
+  "feature_management": {
+    "feature_flags": [
+      {
+        "id": "Beta",
+        "enabled": true,
+        "conditions": {
+          "client_filters": [
+            {
+              "name": "Microsoft.Targeting",
+              "parameters": {
+                "Audience": {
+                  "Users": [
+                    "Jeff"
+                  ],
+                  "Groups": [
+                    {
+                      "Name": "Admin",
+                      "RolloutPercentage": 100
+                    }
+                  ],
+                  "DefaultRolloutPercentage": 40
+                }
+              }
+            }
+          ]
+        }
+      }
+    ]
+  }
+}

examples/express-app/package.json

@@ -0,0 +1,10 @@
+{
+    "scripts": {
+        "start": "node server.mjs"
+    },
+    "dependencies": {
+        "@azure/app-configuration-provider": "latest",
+        "@microsoft/feature-management": "latest",
+        "express": "^4.21.2"
+    }
+}

examples/express-app/server.mjs

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+import express from "express";
+import path from "path";
+
+import { load } from "@azure/app-configuration-provider";
+const connectionString = "<your-connection-string>";;
+const appConfig = await load(connectionString, {
+    featureFlagOptions: {
+        enabled: true,
+        selectors: [{
+            keyFilter: "*"
+        }],
+        refresh: {
+            enabled: true
+        }
+    }
+});
+
+appConfig.onRefresh(() => {
+    console.log("Configuration has been refreshed.");
+});
+
+import { ConfigurationObjectFeatureFlagProvider, ConfigurationMapFeatureFlagProvider, FeatureManager } from "@microsoft/feature-management";
+
+/*
+You can use either ConfigurationObjectFeatureFlagProvider or ConfigurationMapFeatureFlagProvider to provide feature flags.
+We recommend using Azure App Configuration as the source of feature flags.
+*/
+// const config = JSON.parse(await fs.readFile("config.json"));
+// const featureProvider = new ConfigurationObjectFeatureFlagProvider(config);
+
+const featureProvider = new ConfigurationMapFeatureFlagProvider(appConfig);
+const featureManager = new FeatureManager(featureProvider);
+
+const server = express();
+const PORT = 3000;
+
+// Use a middleware to achieve request-driven configuration refresh
+server.use((req, res, next) => {
+    // this call s not blocking, the configuration will be updated asynchronously
+    appConfig.refresh();
+    next();
+})
+
+
+server.get("/", (req, res) => {
+    appConfig.refresh();
+    res.send("Hello World!");
+});
+
+server.get("/Beta", async (req, res) => {
+    appConfig.refresh();
+    const { userId, groups } = req.query;
+
+    if (await featureManager.isEnabled("Beta", { userId: userId, groups: groups ? groups.split(",") : [] })) {
+        res.send("Welcome to the Beta page!");
+    } else {
+        res.status(404).send("Page not found");
+    }
+});
+
+// Start the server
+server.listen(PORT, () => {
+    console.log(`Server is running at http://localhost:${PORT}`);
+});