Java glacier2 callback

java/Glacier2/callback/.gitignore

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+# Gradle generated build files
+bin
+build
+.gradle

java/Glacier2/callback/README.md

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+# Glacier2 Callback
+
+This demo shows how to write a client that establishes a session with a Glacier2 router. It also shows how to implement
+callbacks in this client.
+
+This demo is similar to the [Ice Callback][1] demo, except all communications go through the Glacier router.
+
+The connection between the client and the Glacier2 router is a "bidir" connection, like in the [Ice Bidir][2] demo:
+
+```mermaid
+flowchart LR
+    c[Client<br>hosts AlarmClock] --bidir connection--> g[Glacier2 router:4063]
+    g --connection1--> s[Server:4061<br>hosts WakeUpService] --connection2--> g
+```
+
+## Ice prerequisites
+
+- Install Glacier2. See [Ice service installation].
+
+## Building the demo
+
+The demo has two Gradle projects, **client** and **server**, both using the [application plugin].
+
+To build the demo, run:
+
+```shell
+./gradlew build
+```
+
+## Running the demo
+
+Start the Server program in its own terminal:
+
+```shell
+./gradlew :server:run --quiet
+```
+
+Next, start the Glacier2 router in its own terminal:
+
+```shell
+glacier2router --Ice.Config=config.glacier2
+```
+
+> [!TIP]
+> You can also start the Glacier2 router before the server. The order does not matter: the server is identical to the
+> server provided in the [Ice Greeter][1] demo and does not depend on Glacier2.
+
+Finally, in a separate terminal, start the client application:
+
+```shell
+./gradlew :client:run --quiet
+```
+
+[Application plugin]: https://docs.gradle.org/current/userguide/application_plugin.html
+
+[1]: ../callback
+[2]: ../bidir

java/Glacier2/callback/client/build.gradle.kts

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+// Copyright (c) ZeroC, Inc.
+
+plugins {
+    // Apply the application plugin to tell gradle this is a runnable Java application.
+    id("application")
+
+    // Apply the Slice-tools plugin to enable Slice compilation.
+    id("com.zeroc.slice-tools") version "3.8.+"
+
+    // Pull in our local 'convention plugin' to enable linting.
+    id("zeroc-linting")
+}
+
+dependencies {
+    // Add Ice and Glacier2 as implementation dependencies.
+    implementation("com.zeroc:ice:3.8.+")
+    implementation("com.zeroc:glacier2:3.8.+")
+    implementation(project(":util"))
+}
+
+sourceSets {
+    main {
+        // Add the AlarmClock.ice file from the parent slice directory to the main source set.
+        slice {
+            srcDirs("../slice")
+        }
+    }
+}
+
+application {
+    // Specify the main entry point for the application.
+    mainClass.set("com.example.glacier2.callback.client.Client")
+}

java/Glacier2/callback/client/src/main/java/com/example/glacier2/callback/client/Client.java

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+// Copyright (c) ZeroC, Inc.
+
+package com.example.glacier2.callback.client;
+
+import java.time.ZoneOffset;
+import java.time.ZonedDateTime;
+import java.util.concurrent.ExecutionException;
+
+import com.example.earlyriser.AlarmClockPrx;
+import com.example.earlyriser.WakeUpServicePrx;
+import com.example.util.Time;
+import com.zeroc.Glacier2.CannotCreateSessionException;
+import com.zeroc.Glacier2.PermissionDeniedException;
+import com.zeroc.Glacier2.RouterPrx;
+import com.zeroc.Glacier2.SessionPrx;
+import com.zeroc.Ice.Communicator;
+import com.zeroc.Ice.Identity;
+import com.zeroc.Ice.ObjectAdapter;
+import com.zeroc.Ice.Util;
+
+class Client {
+    public static void main(String[] args) {
+        // Create an Ice communicator. We'll use this communicator to create proxies and manage outgoing connections.
+        try (Communicator communicator = Util.initialize(args)) {
+
+            // Create a proxy to the Glacier2 router. The addressing information (transport, host and port number) is
+            // derived from the value of Glacier2.Client.Endpoints in the glacier2 router configuration file.
+            RouterPrx router = RouterPrx.createProxy(communicator, "Glacier2/router:tcp -h localhost -p 4063");
+
+            // Create a session with the Glacier2 router. In this demo, the Glacier2 router is configured to accept any
+            // username/password combination. This call establishes a network connection to the Glacier2 router; the
+            // lifetime of the session is the same as the lifetime of the connection.
+            SessionPrx session;
+            try {
+                session = router.createSession(System.getProperty("user.name"), "password");
+            } catch (PermissionDeniedException | CannotCreateSessionException e) {
+                System.out.println("Could not create session: " + e.getMessage());
+                return;
+            }
+
+            // The proxy returned by createSession is null because we did not configure a SessionManager on the Glacier2
+            // router.
+            assert session == null;
+
+            // Obtain a category string from the router. We need to use this category for the identity of
+            // server->client callbacks invoked through the Glacier2 router.
+            String clientCategory = router.getCategoryForClient();
+
+            // Create an object adapter with no name and no configuration, but with our router proxy. This object
+            // adapter is a "bidirectional" object adapter, like the one created by the Ice/Bidir client application.
+            // It does not listen on any port and it does not need to be activated.
+            ObjectAdapter adapter = communicator.createObjectAdapterWithRouter("", router);
+
+            // Register the MockAlarmClock servant with the adapter. It uses the category retrieved from the router.
+            // You can verify the Ring callback is never delivered if you provide a different category.
+            var mockAlarmClock = new MockAlarmClock();
+            AlarmClockPrx alarmClock = AlarmClockPrx.uncheckedCast(
+                adapter.add(mockAlarmClock, new Identity("alarmClock", clientCategory)));
+
+            // Create a proxy to the wake-up service behind the Glacier2 router. Typically, the client cannot connect
+            // directly to this server because it's on an unreachable network.
+            WakeUpServicePrx wakeUpService = WakeUpServicePrx.createProxy(
+                communicator,
+                "wakeUpService:tcp -h localhost -p 4061");
+
+            // Configure the proxy to route requests using the Glacier2 router.
+            wakeUpService = WakeUpServicePrx.uncheckedCast(wakeUpService.ice_router(router));
+
+            // Schedule a wake-up call in 5 seconds. This call establishes the connection to the server; incoming
+            // requests over this connection are handled by the communicator's default object adapter.
+            wakeUpService.wakeMeUp(alarmClock, Time.toTimeStamp(ZonedDateTime.now(ZoneOffset.UTC).plusSeconds(5)));
+            System.out.println("Wake-up call scheduled, falling asleep...");
+            try {
+                // Wait until the user presses the stop button on the alarm clock.
+                mockAlarmClock.stopPressed().get();
+                System.out.println("Stop button pressed, exiting...");
+            } catch (InterruptedException | ExecutionException ex) {
+                System.err.println(ex);
+            }
+
+        }
+    }
+}

java/Glacier2/callback/client/src/main/java/com/example/glacier2/callback/client/MockAlarmClock.java

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+// Copyright (c) ZeroC, Inc.
+
+package com.example.glacier2.callback.client;
+
+import java.util.concurrent.CompletableFuture;
+
+import com.example.earlyriser.AlarmClock;
+import com.example.earlyriser.ButtonPressed;
+import com.zeroc.Ice.Current;
+
+/**
+ * MockAlarmClock is an Ice servant that implements Slice interface AlarmClock.
+ */
+class MockAlarmClock implements AlarmClock {
+    private boolean _needMoreTime = true;
+
+    private final CompletableFuture<Void> _stopPressed;
+
+    public MockAlarmClock() {
+        _stopPressed = new CompletableFuture<>();
+    }
+
+    public CompletableFuture<Void> stopPressed() {
+        return _stopPressed;
+    }
+
+    // Implements the method ring from the AlarmClock interface generated by the Slice compiler.
+    @Override
+    public ButtonPressed ring(String message, Current current) {
+        System.out.println("Dispatching ring request { message = '" + message + "' }");
+        if (_needMoreTime) {
+            System.out.println("Returning " + ButtonPressed.Snooze + " to request more time.");
+            _needMoreTime = false; // we only snooze one time
+            return ButtonPressed.Snooze;
+        } else {
+            _stopPressed.complete(null);
+            System.out.println("Returning " + ButtonPressed.Stop + " to stop the alarm.");
+            return ButtonPressed.Stop;
+        }
+    }
+}

java/Glacier2/callback/config.glacier2

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+# Config file for glacier2router
+
+# The client-visible endpoint of the Glacier2 router.
+Glacier2.Client.Endpoints=tcp -p 4063
+
+# The server-visible endpoint of the Glacier2 router.
+# You need to configure this endpoint only when your servers make callbacks (call objects implemented by the clients).
+# If you don't use callbacks, don't set this property.
+Glacier2.Server.Endpoints=tcp -h 127.0.0.1
+
+# This Glacier router accepts any username/password combination.
+Glacier2.PermissionsVerifier=Glacier2/NullPermissionsVerifier
+
+# Turn on tracing.
+Glacier2.Client.Trace.Request=1
+Glacier2.Server.Trace.Request=1
+Glacier2.Trace.Session=1
+Glacier2.Trace.RoutingTable=1

java/Glacier2/callback/gradle/wrapper/gradle-wrapper.properties

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+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.12.1-all.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists