Develop Reference

How to programmatically set external ip for Google Cloud virtual machine in Java?

I am trying to programmatically start Google Cloud virtual machine instances. It occurred to me that in order to have internet access, have to set an external IP address.
// Access Config
AccessConfig accessConfig = AccessConfig.newBuilder()
.setNatIP("foo")
.setType("ONE_TO_ONE_NAT")
.setName("External NAT")
.setExternalIpv6("bar")
.build();
// Use the network interface provided in the networkName argument.
NetworkInterface networkInterface = NetworkInterface.newBuilder()
.setName(networkName)
.setAccessConfigs(0, accessConfig)
.build();
That is my status quo. It is inspired by this article post. I hoped that would work in Java, too, but currently, I am stuck.
All I get is:
com.google.api.gax.rpc.InvalidArgumentException: Bad Request
Unfortunately, Google Cloud Compute Engine Docs doesn't really provide any further information, on how to set the external IP properly.
Thanks in advance.

I have encountered the answer. In the Google Cloud Compute Engine Docs it is explained for Windows Instances. It took me a while to recognize it because I've focused only Linux Instances' related questions.
The solution:
instanceResource = Instance.newBuilder()
.setName(instanceName)
.setMachineType(machineType)
.addDisks(disk)
// Add external internet to instance
.addNetworkInterfaces(NetworkInterface.newBuilder()
.addAccessConfigs(AccessConfig.newBuilder()
.setType("ONE_TO_ONE_NAT")
.setName("External NAT")
.build())
.setName("global/networks/default")
.build())
.setMetadata(buildMetadata())
.build();

How to verify that a queue exist on azure in java?

We have a service that receive the queue name and if the queue exist push data on the queue.
I'm looking to find a way to check if the queue exist on azure in java.
So far, using IQueueClient I can onl know if the queue exist when sending data via sendAsync with return a exception.
I want to found out when the client is created or even before.
The best answer I've found so far is using the NamespaceManager.
in this fashion:
Uri uri = ServiceManagementHelper.GetServiceUri();
TokenProvider tokenProvider = ServiceManagementHelper.GetTokenProvider(uri);
NamespaceManager nm = new NamespaceManager(uri, tokenProvider);
if (!nm.QueueExists("TestQueue")) return;
source:
http://www.cloudcasts.net/devguide/Default.aspx?id=12018
https://www.pmichaels.net/2017/06/11/reading-message-azure-service-bus-queue/
However this class seem not to be part of azure-core or azure-servicebus librairy and I can seem to find which lib to add to the project to have access to those class.

However this class seem not to be part of azure-core or azure-servicebus librairy and I can seem to find which lib to add to the project to have access to those class.
You mentioned code is related to .net SDK. For Java sdk we could use the following code check if the queue exist. ManagementClient seems only available in the 2.0.0-PREVIEW version. We also could get the source code from GitHub.
String connectionString = "Endpoint=sb://xxxx.servicebus.windows.net/;SharedAccessKeyName=SharedAccessKeyName;SharedAccessKey=xxxxxxxx=";
ConnectionStringBuilder connectionStringBuilder = new ConnectionStringBuilder(connectionString);
ManagementClient client = new ManagementClient(connectionStringBuilder);
boolean isExist = client.queueExists("queueName");
System.out.println(isExist);
Test Result:

Setting AWS region programmatically for SQS

I just started working on AWS SDK for Java and .net.
currently i am creating a AWS SQS Queue. I was able to Create a QUEUE, List the existing queues, and talk to the queues with .net SDK.
When i tried the same with the java i m getting following error.
Unable to find a region via the region provider chain. Must provide an
explicit region in the builder or setup environment to supply a
region.
I have set all the necessary access keys, Region and credentials in the aws preferences in eclipse.
This is how i am initializing SQS client in a Java maven project
AmazonSQS sqs = AmazonSQSClientBuilder.defaultClient();
I have googled and found that there is a key word called withregion() for S3 where i can specify the region but its not there for SQS.
I also tried setting region as
sqs.setRegion(Region.AP_Mumbai);
This shows up following exception
The method setRegion(com.amazonaws.regions.Region) in the type
AmazonSQS is not applicable for the arguments
(com.amazonaws.services.s3.model.Region)
i tried setting the same using com.amazonaws.regions.Region but there is no provision as such.
Please Suggest

I setup the aws sqs client this way:
BasicAWSCredentials bAWSc = new BasicAWSCredentials(accessKey, secretKey);
return AmazonSQSClientBuilder.standard().withRegion(region).withCredentials(new AWSStaticCredentialsProvider(bAWSc)).build();

based on what #Francesco put, I created a more intuitive version
BasicAWSCredentials bAWSc = new BasicAWSCredentials(accessKey, secretKey);
final AmazonSQS sqs = AmazonSQSClientBuilder.standard()
.withRegion(Regions.US_EAST_1)
.withCredentials(new AWSStaticCredentialsProvider(bAWSc ))
.build();

Vertx HttpClient getNow not working

I have problem with vertx HttpClient.
Here's code which shows that tests GET using vertx and plain java.
Vertx vertx = Vertx.vertx();
HttpClientOptions options = new HttpClientOptions()
.setTrustAll(true)
.setSsl(false)
.setDefaultPort(80)
.setProtocolVersion(HttpVersion.HTTP_1_1)
.setLogActivity(true);
HttpClient client = vertx.createHttpClient(options);
client.getNow("google.com", "/", response -> {
System.out.println("Received response with status code " + response.statusCode());
});
System.out.println(getHTML("http://google.com"));
Where getHTML() is from here: How do I do a HTTP GET in Java?
This is my output:
<!doctype html><html... etc <- correct output from plain java
Feb 08, 2017 11:31:21 AM io.vertx.core.http.impl.HttpClientRequestImpl
SEVERE: java.net.UnknownHostException: failed to resolve 'google.com'. Exceeded max queries per resolve 3
But vertx can't connect. What's wrong here? I'm not using any proxy.

For reference: a solution, as described in this question and in tsegismont's comment here, is to set the flag vertx.disableDnsResolver to true:
-Dvertx.disableDnsResolver=true
in order to fall back to the JVM DNS resolver as explained here:
sometimes it can be desirable to use the JVM built-in resolver, the JVM system property -Dvertx.disableDnsResolver=true activates this behavior
I observed this DNS resolution issue with a redis client in a kubernetes environment.

I had this issue, what caused it for me was stale DNS servers being picked up by the Java runtime, i.e. servers registered for a network the machine was no longer connected to. The issue is first in the Sun JNDI implementation, it also exists in Netty which uses JNDI to bootstrap its list of name servers on most platforms, then finally shows up in VertX.
I think a good place to fix this would be in the Netty layer where the set of default DNS servers is bootstrapped. I have raised a ticket with the Netty project so we'll see if they agree with me! Here is the Netty ticket
In the mean time a fairly basic workaround is to filter the default DNS servers detected by Netty, based on whether they are reachable or not. Here is a code Sample in Kotlin to apply before constructing the main VertX instance.
// The default set of name servers provided by JNDI can contain stale entries
// This default set is picked up by Netty and in turn by VertX
// To work around this, we filter for only reachable name servers on startup
val nameServers = DefaultDnsServerAddressStreamProvider.defaultAddressList()
val reachableNameServers = nameServers.stream()
.filter {ns -> ns.address.isReachable(NS_REACHABLE_TIMEOUT)}
.map {ns -> ns.address.hostAddress}
.collect(Collectors.toList())
if (reachableNameServers.size == 0)
throw StartupException("There are no reachable name servers available")
val opts = VertxOptions()
opts.addressResolverOptions.servers = reachableNameServers
// The primary Vertx instance
val vertx = Vertx.vertx(opts)
A little more detail in case it is helpful. I have a company machine, which at some point was connected to the company network by a physical cable. Details of the company's internal name servers were set up by DHCP on the physical interface. Using the wireless interface at home, DNS for the wireless interface gets set to my home DNS while the config for the physical interface is not updated. This is fine since that device is not active, ipconfig /all does not show the internal company DNS servers. However, looking in the registry they are still there:
Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces
They get picked up by the JNDI mechanism, which feeds Netty and in turn VertX. Since they are not reachable from my home location, DNS resolution fails. I can imagine this home/office situation is not unique to me! I don't know whether something similar could occur with multiple virtual interfaces on containers or VMs, it could be worth looking at if you are having problems.

Here is the sample code which works for me.
public class TemplVerticle extends HttpVerticle {
public static void main(String[] args) {
Vertx vertx = Vertx.vertx();
// Create the web client and enable SSL/TLS with a trust store
WebClient client = WebClient.create(vertx,
new WebClientOptions()
.setSsl(true)
.setTrustAll(true)
.setDefaultPort(443)
.setKeepAlive(true)
.setDefaultHost("www.w3schools.com")
);
client.get("www.w3schools.com")
.as(BodyCodec.string())
.send(ar -> {
if (ar.succeeded()) {
HttpResponse<String> response = ar.result();
System.out.println("Got HTTP response body");
System.out.println(response.body().toString());
} else {
ar.cause().printStackTrace();
}
});
}
}

Try using web client instead of httpclient, here you have an example (with rx):
private val client: WebClient = WebClient.create(vertx, WebClientOptions()
.setSsl(true)
.setTrustAll(true)
.setDefaultPort(443)
.setKeepAlive(true)
)
open fun <T> get(uri: String, marshaller: Class<T>): Single<T> {
return client.getAbs(host + uri).rxSend()
.map { extractJson(it, uri, marshaller) }
}
Another option is to use getAbs.

Java websocket with proxy

I have been trying all day and night for couple of days trying to make websocket to work using proxy in Java. I tried different library like
https://github.com/TooTallNate/Java-WebSocket
https://github.com/AsyncHttpClient/async-http-client
But sadly these library doesn't support proxy with credentials. If you guys have known any other library that supports proxy then I would be appreciated.
Thanks in advance

Try nv-websocket-client library. It supports authentication at a proxy server. Note that, however, the current implementation supports Basic Authentication only.
// 1. Create a WebSocketFactory instance.
WebSocketFactory factory = new WebSocketFactory();
// 2. Set up information about a proxy server.
// Credentials can be set here.
ProxySettings settings = factory.getProxySettings();
settings.setServer("http://proxy.example.com");
settings.setCredentials("id", "password");
// 3. Connect to a WebSocket endpoint via the proxy.
WebSocket ws = factory.createSocket("ws://websocket.example.com");
// 4. Add a listener to receive WebSocket events.
ws.addListener(new WebSocketAdapter() {
#Override
public void onTextMessage(WebSocket ws, String message) {
// Received a text message.
......
}
});
// 5. Perform a WebSocket opening handshake.
ws.connect();
// 6. Send frames.
// 6-1. Text
ws.sendText("Hello.");
// 6-2. Binary
byte[] binary = ......;
ws.sendBinary(binary);
// 6-3. Ping
ws.sendPing("Are you there?");
// 6-4. Pong (unsolicited pong; RFC 6455, 5.5.3. Pong)
ws.sendPong("I'm OK.");
// 6-5. Fragmented Frames
ws.sendText("How ", false)
.sendContinuation("are ")
.sendContinuation("you?", true);
// 6-6. Periodical Ping
ws.setPingInterval(60 * 1000);
// 6-7. Periodical Pong (unsolicited pong; RFC 6455, 5.5.3. Pong)
ws.setPongInterval(60 * 1000);
// 6-8. Close (if you want to send one manually).
ws.sendClose(WebSocketCloseCode.NORMAL, "Bye.");
// 7. Disconnect
ws.disconnect();
Blog
WebSocket client library (Java SE 1.5+, Android)
http://darutk-oboegaki.blogspot.jp/2015/05/websocket-client-library-java-se-15.html
GitHub
https://github.com/TakahikoKawasaki/nv-websocket-client
JavaDoc
http://takahikokawasaki.github.io/nv-websocket-client/
Maven
<dependency>
<groupId>com.neovisionaries</groupId>
<artifactId>nv-websocket-client</artifactId>
<version>1.3</version>
</dependency>
The size of nv-websocket-client-1.3.jar is 62,854 bytes and it does not require any external dependencies.

You can try Tyrus (reference implementation of WebSocket API in Java EE); client side does not require any Java EE server to be running and if you are using Java 7, the client could be minimized to ~500kb.
Client behing proxy and Dependencies should provide enough info to try.