add a simple READ to DemoMain, and document usage for demos in README

see also etcd-io/etcd#10102

README.md

@@ -80,7 +80,9 @@ If you used etcd before you may [want to completely wipe it](https://github.com/
     sudo systemctl start etcd
     etcdctl ls
 
-Beware that `etcdctl ls -r` [does not seem to show unprintable keys](https://github.com/etcd-io/etcd/issues/10102).
+Beware that `etcdctl ls -r` [does not seem to show unprintable keys](https://github.com/etcd-io/etcd/issues/10102), so better use our own:
+
+    java -jar demo/target/*.jar read http://localhost:2379
 
 
 ### RESTCONF
@@ -102,6 +104,7 @@ Note how there is no `karaf/target/assembly/etc/org.opendaylight.controller.clus
     echo '<HelloWorldContainer xmlns="urn:opendaylight:etcd:test"><name>hello, world</name></HelloWorldContainer>' >put.xml
     http -v -a admin:admin PUT :8181/restconf/config/opendaylight-etcd-test:HelloWorldContainer @put.xml
     http -a admin:admin GET :8181/restconf/config/opendaylight-etcd-test:HelloWorldContainer
+    java -jar demo/target/*.jar read http://localhost:2379
     http -a admin:admin DELETE :8181/restconf/config/opendaylight-etcd-test:HelloWorldContainer
     http -a admin:admin GET :8181/restconf/config/opendaylight-etcd-test:HelloWorldContainer
 
@@ -112,13 +115,15 @@ Here is how to run [the asciinema POC v0.1](https://asciinema.org/a/DShFpWOXFmaQ
 
 Now run this project's demo:
 
-    java -jar demo/target/*.jar http://localhost:4001
+    java -jar demo/target/*.jar write http://localhost:4001
 
 or if you started `etcd` directly without systemd then:
 
-    java -jar demo/target/*.jar http://localhost:2379
+    java -jar demo/target/*.jar write http://localhost:2379
+
+and have a closer look at the logs this will print to understand what happened, and read it via:
 
-and have a closer look at the logs this will print, to understand what happened.
+    java -jar demo/target/*.jar read http://localhost:2379
 
 
 ## FAQ

demo/src/main/java/org/opendaylight/etcd/demo/DemoMain.java

@@ -7,12 +7,23 @@
  */
 package org.opendaylight.etcd.demo;
 
-import static org.opendaylight.mdsal.common.api.LogicalDatastoreType.OPERATIONAL;
+import static com.google.common.base.Charsets.US_ASCII;
+import static io.etcd.jetcd.options.GetOption.SortOrder.ASCEND;
+import static io.etcd.jetcd.options.GetOption.SortTarget.KEY;
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static org.opendaylight.mdsal.common.api.LogicalDatastoreType.CONFIGURATION;
 
+import com.google.common.collect.Lists;
 import io.etcd.jetcd.Client;
-import java.util.Arrays;
+import io.etcd.jetcd.data.ByteSequence;
+import io.etcd.jetcd.data.KeyValue;
+import io.etcd.jetcd.options.GetOption;
+import java.util.List;
 import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeoutException;
+import org.opendaylight.etcd.ds.impl.EtcdDataStore;
 import org.opendaylight.etcd.testutils.TestEtcdDataBrokerProvider;
+import org.opendaylight.etcd.utils.KeyValues;
 import org.opendaylight.mdsal.binding.api.DataBroker;
 import org.opendaylight.mdsal.binding.api.WriteTransaction;
 import org.opendaylight.yang.gen.v1.urn.opendaylight.etcd.test.rev180628.HelloWorldContainer;
@@ -34,29 +45,46 @@ public final class DemoMain {
     private static void write(DataBroker dataBroker) throws InterruptedException, ExecutionException {
         InstanceIdentifier<HelloWorldContainer> iid = InstanceIdentifier.create(HelloWorldContainer.class);
         WriteTransaction tx = dataBroker.newWriteOnlyTransaction();
-        tx.put(OPERATIONAL, iid, new HelloWorldContainerBuilder().setName("hello, world").build());
+        tx.put(CONFIGURATION, iid, new HelloWorldContainerBuilder().setName("hello, world").build());
         tx.commit().get();
     }
 
     public static void main(String[] args) {
-        if (args.length < 1) {
-            System.err.println("USAGE: etcd server host:port (list of)\nEXAMPLE: http://localhost:2379");
+        if (args.length < 2) {
+            System.err.println("USAGE: write|read etcd-server-host:port (list of)\nEXAMPLE: write http://localhost:2379");
             return;
         }
-        System.out.println("Connecting to etcd server/s on: " + Arrays.toString(args));
-        try (Client client = Client.builder().endpoints(args).build()) {
-            try (TestEtcdDataBrokerProvider dbProvider = new TestEtcdDataBrokerProvider(client, "demo")) {
-                DataBroker dataBroker = dbProvider.getDataBroker();
+        String operation = args[0];
+        List<String> endpoints = Lists.newArrayList(args).subList(1, args.length);
 
-                write(dataBroker);
-
-            } catch (Exception e) {
-                LOG.error("Demo failed", e);
-            } finally {
-                client.close();
-                // TODO find out why non-daemon thread "pool-2-thread-1" causes hung exit without this hack..
-                System.exit(0);
+        System.out.println("Operation: " + operation + "; connecting to etcd server/s on: " + endpoints);
+        try (Client client = Client.builder().endpoints(endpoints.toArray(new String[0])).build()) {
+            if ("write".equalsIgnoreCase(operation)) {
+                try (TestEtcdDataBrokerProvider dbProvider = new TestEtcdDataBrokerProvider(client, "demo")) {
+                    DataBroker dataBroker = dbProvider.getDataBroker();
+                    write(dataBroker);
+                    // read(client);
+                } finally {
+                    client.close();
+                }
+            } else {
+                read(client);
             }
+        } catch (Exception e) {
+            LOG.error("Demo failed", e);
+        }
+        // TODO find out why non-daemon thread "pool-2-thread-1" causes hung exit without this hack..
+        System.exit(0);
+    }
+
+    private static void read(Client client) throws InterruptedException, ExecutionException, TimeoutException {
+        ByteSequence prefix = EtcdDataStore.CONFIGURATION_PREFIX;
+        // TODO huh, the sorting by key doesn't seem to work?  Running this after restconf demo has aaa interspersed
+        GetOption getOpt = GetOption.newBuilder().withPrefix(prefix).withSortField(KEY).withSortOrder(ASCEND).build();
+        List<KeyValue> kvs = client.getKVClient().get(prefix, getOpt).get(3000, MILLISECONDS).getKvs();
+        System.out.println(kvs.size() + " key/values in etcd under prefix " + prefix.toString(US_ASCII) + "/ :");
+        for (KeyValue kv : kvs) {
+            System.out.println(KeyValues.asString(kv));
         }
     }