Merge pull request #750 from mderka/readme

README was added for DNS and the main README was updated accordingly.

Author: mderka

README.md

@@ -16,6 +16,7 @@ This client supports the following Google Cloud Platform services:
 
 -  [Google Cloud BigQuery] (#google-cloud-bigquery-alpha) (Alpha)
 -  [Google Cloud Datastore] (#google-cloud-datastore)
+-  [Google Cloud DNS] (#google-cloud-dns-alpha) (Alpha)
 -  [Google Cloud Resource Manager] (#google-cloud-resource-manager-alpha) (Alpha)
 -  [Google Cloud Storage] (#google-cloud-storage)
 
@@ -48,8 +49,10 @@ Example Applications
   - Read more about using this application on the [`BigQueryExample` docs page](http://googlecloudplatform.github.io/gcloud-java/apidocs/?com/google/gcloud/examples/bigquery/BigQueryExample.html).
 - [`Bookshelf`](https://github.com/GoogleCloudPlatform/getting-started-java/tree/master/bookshelf) - An App Engine app that manages a virtual bookshelf.
   - This app uses `gcloud-java` to interface with Cloud Datastore and Cloud Storage. It also uses Cloud SQL, another Google Cloud Platform service.
-- [`DatastoreExample`](./gcloud-java-examples/src/main/java/com/google/gcloud/examples/datastore/DatastoreExample.java) - A simple command line interface for the Cloud Datastore
+- [`DatastoreExample`](./gcloud-java-examples/src/main/java/com/google/gcloud/examples/datastore/DatastoreExample.java) - A simple command line interface for Cloud Datastore
   - Read more about using this application on the [`DatastoreExample` docs page](http://googlecloudplatform.github.io/gcloud-java/apidocs/?com/google/gcloud/examples/datastore/DatastoreExample.html).
+- [`DnsExample`](./gcloud-java-examples/src/main/java/com/google/gcloud/examples/dns/DnsExample.java) - A simple command line interface for Cloud DNS
+  - Read more about using this application on the [`DnsExample` docs page](http://googlecloudplatform.github.io/gcloud-java/apidocs/?com/google/gcloud/examples/dns/DnsExample.html).
 - [`ResourceManagerExample`](./gcloud-java-examples/src/main/java/com/google/gcloud/examples/resourcemanager/ResourceManagerExample.java) - A simple command line interface providing some of Cloud Resource Manager's functionality
   - Read more about using this application on the [`ResourceManagerExample` docs page](http://googlecloudplatform.github.io/gcloud-java/apidocs/?com/google/gcloud/examples/resourcemanager/ResourceManagerExample.html).
 - [`SparkDemo`](https://github.com/GoogleCloudPlatform/java-docs-samples/blob/master/managed_vms/sparkjava) - An example of using gcloud-java-datastore from within the SparkJava and App Engine Managed VM frameworks.
@@ -218,6 +221,71 @@ if (entity != null) {
 }
 ```
 
+Google Cloud DNS (Alpha)
+----------------------
+- [API Documentation][dns-api]
+- [Official Documentation][cloud-dns-docs]
+
+*Follow the [activation instructions][cloud-dns-activation] to use the Google Cloud DNS API with your project.*
+
+#### Preview
+
+Here are two code snippets showing simple usage examples from within Compute/App Engine. Note that you must [supply credentials](#authentication) and a project ID if running this snippet elsewhere.
+
+The first snippet shows how to create a zone resource. Complete source code can be found on
+[CreateZone.java](./gcloud-java-examples/src/main/java/com/google/gcloud/examples/dns/snippets/CreateZone.java).
+
+```java
+import com.google.gcloud.dns.Dns;
+import com.google.gcloud.dns.DnsOptions;
+import com.google.gcloud.dns.Zone;
+import com.google.gcloud.dns.ZoneInfo;
+
+Dns dns = DnsOptions.defaultInstance().service();
+String zoneName = "my-unique-zone";
+String domainName = "someexampledomain.com.";
+String description = "This is a gcloud-java-dns sample zone.";
+ZoneInfo zoneInfo = ZoneInfo.of(zoneName, domainName, description);
+Zone zone = dns.create(zoneInfo);
+```
+
+The second snippet shows how to create records inside a zone. The complete code can be found on [CreateOrUpdateDnsRecords.java](./gcloud-java-examples/src/main/java/com/google/gcloud/examples/dns/snippets/CreateOrUpdateDnsRecords.java).
+
+```java
+import com.google.gcloud.dns.ChangeRequest;
+import com.google.gcloud.dns.Dns;
+import com.google.gcloud.dns.DnsOptions;
+import com.google.gcloud.dns.DnsRecord;
+import com.google.gcloud.dns.Zone;
+
+import java.util.Iterator;
+import java.util.concurrent.TimeUnit;
+
+Dns dns = DnsOptions.defaultInstance().service();
+String zoneName = "my-unique-zone";
+Zone zone = dns.getZone(zoneName);
+String ip = "12.13.14.15";
+DnsRecord toCreate = DnsRecord.builder("www.someexampledomain.com.", DnsRecord.Type.A)
+    .ttl(24, TimeUnit.HOURS)
+    .addRecord(ip)
+    .build();
+ChangeRequest.Builder changeBuilder = ChangeRequest.builder().add(toCreate);
+
+// Verify that the record does not exist yet.
+// If it does exist, we will overwrite it with our prepared record.
+Iterator<DnsRecord> recordIterator = zone.listDnsRecords().iterateAll();
+while (recordIterator.hasNext()) {
+  DnsRecord current = recordIterator.next();
+  if (toCreate.name().equals(current.name()) &&
+      toCreate.type().equals(current.type())) {
+    changeBuilder.delete(current);
+  }
+}
+
+ChangeRequest changeRequest = changeBuilder.build();
+zone.applyChangeRequest(changeRequest);
+```
+
 Google Cloud Resource Manager (Alpha)
 ----------------------
 
@@ -359,6 +427,10 @@ Apache 2.0 - See [LICENSE] for more information.
 [cloud-datastore-activation]: https://cloud.google.com/datastore/docs/activate
 [datastore-api]: http://googlecloudplatform.github.io/gcloud-java/apidocs/index.html?com/google/gcloud/datastore/package-summary.html
 
+[dns-api]: http://googlecloudplatform.github.io/gcloud-java/apidocs/index.html?com/google/gcloud/dns/package-summary.html
+[cloud-dns-docs]: https://cloud.google.com/dns/docs
+[cloud-dns-activation]: https://console.cloud.google.com/start/api?id=dns
+
 [cloud-pubsub]: https://cloud.google.com/pubsub/
 [cloud-pubsub-docs]: https://cloud.google.com/pubsub/docs