Develop Reference

Error running RMI application in Visual Studio Code [duplicate]

I'm programming a simple rmi application, and I have a problem.
If I run the registry in the same directory, it works; but if I change the directory from which I run the registry, it does not.
The registry would work generically from another host, but only the change of directory stop his functionality.
I'm working on this problem by 3 days without solution, I change also every possible configuration of the codebase parameter but nothing.
I describe the situation and code with the directory:
fileserver.java :
`package testrmi2;
import java.rmi.*;
public interface fileserver extends Remote {
public void scrivifile(String nomefile, String arg) throws RemoteException;
}
`
fileserverimpl.java:
package testrmi2;
import java.io.*;
import java.rmi.*;
import java.rmi.server.*;
public class fileserverimpl extends UnicastRemoteObject implements fileserver{
public fileserverimpl() throws RemoteException {
super();
}
public void scrivifile(String nomefile, String arg) throws RemoteException {
try {
FileWriter myfile = new FileWriter(nomefile);
myfile.write(arg);
myfile.close(); }
catch (Exception e) {System.out.println(e);}
}
public static void main (String arg[]) {
try {
fileserverimpl s = new fileserverimpl();
if (System.getSecurityManager() == null) {
System.setSecurityManager(new RMISecurityManager());
}
String codebase = System.getProperty("classpath");
System.out.println("Trying to access code base: " + codebase+"\n\nuse is "+System.getProperty("useCodebaseOnly"));
Naming.rebind("//127.0.0.1:2005/fileserverimpl", s);
System.out.println("Server attivato.");
} catch (Exception e) {System.out.println("errore inizializzazione server\n\n"+e.getMessage()+"\n\n\n");
}}}
client.java:
package testrmi2;
import java.rmi.*;
import java.io.*;
public class client {
public static void main (String arg[]) {
fileserver myserver;
String nomefile=" ";
String testo=" ";
System.out.println("Scrivi il nome del file");
nomefile=ReadString();
System.out.println("Scrivi il testo");
testo=ReadString();
try {
myserver = (fileserver) Naming.lookup("//127.0.0.1:2005/fileserverimpl");
myserver.scrivifile(nomefile, testo);
} catch (Exception e) {System.out.println(e);}
}
public static String ReadString() {
BufferedReader stdIn =new BufferedReader(new InputStreamReader(System.in));
String s=" ";
try{
s=stdIn.readLine();
}
catch(IOException e) {System.out.println(e.getMessage()); }
return s;
}
}
and the policy file is:
grant {
// Allow everything for now
permission java.security.AllPermission;
};
all this files are on the directory:
/Users/franco/Desktop/prova
to compiling it I goes in the /Users/franco/Desktop/prova directory and do in terminal :
javac -cp . -d . *.java
rmic rmic testrmi2.fileserverimpl
jar cvf testrmi2.jar testrmi2/fileserver.class testrmi2/fileserverimpl_Stub.class
after I run registry in another terminal with the following commands but in another directory:
export classpath=""
rmiregistry 2005 &
Finally I would to run the filesereveimpl.class goes with terminal in the /Users/franco/Desktop/prova directory and write :
java -classpath /Users/franco/Desktop/prova/ -Djava.rmi.server.codebase=file:/Users/franco/Desktop/prova/testrmi2.jar -Djava.security.policy=testrmi2/policy testrmi2.fileserverimpl &
But the results are:
Trying to access code base: null
use is null
errore inizializzazione server
RemoteException occurred in server thread; nested exception is:
java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.lang.ClassNotFoundException: testrmi2.fileserverimpl_Stub
I also try to public he jar on a local webserver xampp and try to run with the following:
java -classpath . -Djava.rmi.server.codebase=http://127.0.0.1/testrmi2/ -Djava.security.policy=testrmi2/policy testrmi2.fileserverimpl &
or with :
java -classpath . -Djava.rmi.server.codebase=http://127.0.0.1/testrmi2.jar -Djava.security.policy=testrmi2/policy testrmi2.fileserverimpl &
but I have the same results.

Try to set the classpath var before to execute the rmregistry:
export classpath="/Users/franco/Desktop/prova/"
rmiregistry 2005 &

There are three cases.
You got that exception in the server when exporting/constructing the remote object. Solution: run rmic to generate the stub.
You got it in the server when binding/rebinding. Solution: make the stub class available to the Registry's CLASSPATH, or run the Registry in the server JVM via LocateRegistry.createRegistry().
You got it in the client, in lookup(). Solution: make the stub class available to the client's CLASSPATH.
These also apply to the remote interface itself, and any application classes it depends on, and so on recursively until closure.
Solution for stubs to all three: take the measures outlined in the Javadoc preamble to UnicastRemoteObject, so you don't need a stub at all.

Can't start localstack on Gitlab runner with LocalstackTestRunner

I have an issue of running Java integration tests with LocalstackTestRunner on Gitlab agent.
I've taken example from official localstack site:
import cloud.localstack.LocalstackTestRunner;
import cloud.localstack.TestUtils;
import cloud.localstack.docker.annotation.LocalstackDockerProperties;
#RunWith(LocalstackTestRunner.class)
#LocalstackDockerProperties(services = { "s3", "sqs", "kinesis:77077" })
public class MyCloudAppTest {
#Test
public void testLocalS3API() {
AmazonS3 s3 = TestUtils.getClientS3();
List<Bucket> buckets = s3.listBuckets();
}
}
and run it with help of gradle as gradle clean test.
If I run it locally on my Mac Book - all is ok but if it's run on Gitlab agent - there is an issue:
com.amazonaws.SdkClientException: Unable to execute HTTP request: Connect to localhost.localstack.cloud:4566 [localhost.localstack.cloud/127.0.0.1] failed: Connection refused (Connection refused)
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.handleRetryableException(AmazonHttpClient.java:1207)
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeHelper(AmazonHttpClient.java:1153)
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.doExecute(AmazonHttpClient.java:802)
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeWithTimer(AmazonHttpClient.java:770)
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.execute(AmazonHttpClient.java:744)
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.access$500(AmazonHttpClient.java:704)
at com.amazonaws.http.AmazonHttpClient$RequestExecutionBuilderImpl.execute(AmazonHttpClient.java:686)
My gitlab ci job looks likes as follows:
Localstack_test:
stage: test
services:
- docker:dind
when: always
script:
- ./gradlew clean test --stacktrace
It happens that S3 client can't connect to localhost.localstack.cloud:4566 because docker container created by LocalstackTestRunner is started within parent docker:dind container and AmazonS3 client can't access it. I've tried with other AWS services - result is the same - AWS client can't access localstack endpoint.
I've found some workaround as follows:
add localstack as service in gitlab-ci
add alias to it
expose env variable HOSTNAME_EXTERNAL=alias
Make an implementation of IHostNameResolver to return my alias as HOSTNAME_EXTERNAL specified in gitlab-ci.
Something like that:
Gitlab-ci:
Localstack_test:
stage: test
services:
- docker:dind
- name: localstack/localstack
alias: localstack-it
variables:
HOSTNAME_EXTERNAL: "localstack-it"
when: always
script:
- ./gradlew clean test --stacktrace |& tee -a ./gradle.log
Java IT test:
#RunWith(LocalstackTestRunner.class)
#LocalstackDockerProperties(
services = { "s3", "sqs", "kinesis:77077" },
hostNameResolver = SystemEnvHostNameResolver.class
)
public class MyCloudAppTest {
#Test
public void testLocalS3API() {
AmazonS3 s3 = TestUtils.getClientS3();
List<Bucket> buckets = s3.listBuckets();
}
}
public class SystemEnvHostNameResolver implements IHostNameResolver {
private static final String HOSTNAME_EXTERNAL = "HOSTNAME_EXTERNAL";
#Override
public String getHostName() {
String external = System.getenv(HOSTNAME_EXTERNAL);
return !Strings.isNullOrEmpty(external) ?
external :
new LocalHostNameResolver().getHostName();
}
}
It works but as a result 2 localstack Docker containers are run and internal docker container is still not available. Maybe does somebody know better solution?
STR:
gradle-6.7
cloud.localstack:localstack-utils:0.2.5

How to get output of docker executed command in docker-java library

I am trying to pull an alpine image using docker-java library. Image got pulled successfully but I am not seeing any docker output on console. How to enable logging in docker-java library.
public class DockerPull {
public static void main(String[] args) throws InterruptedException {
DockerClientConfig standard = DefaultDockerClientConfig.createDefaultConfigBuilder().build();
DockerClient dockerClient = DockerClientBuilder.getInstance(standard).build();
dockerClient.pullImageCmd("alpine:latest").exec(new PullImageResultCallback()).awaitCompletion(3600, TimeUnit.SECONDS);
}
}
Output:
Process finished with exit code 0

Java-grpc and tikv-java: NoSuchFieldError: CONTEXT_SPAN_KEY

I am using java-grpc together with tikv-java (separately they work OK). But together I am struggling with the following error:
Exception in thread "main" java.lang.NoSuchFieldError: CONTEXT_SPAN_KEY
at io.grpc.internal.CensusTracingModule$TracingClientInterceptor.interceptCall(CensusTracingModule.java:327)
at io.grpc.ClientInterceptors$InterceptorChannel.newCall(ClientInterceptors.java:104)
at io.grpc.internal.ManagedChannelImpl.newCall(ManagedChannelImpl.java:551)
at io.grpc.stub.ClientCalls.blockingUnaryCall(ClientCalls.java:113)
at com.pv.app.GetInsertServiceGrpc$GetInsertServiceBlockingStub.insert(GetInsertServiceGrpc.java:195)
at com.pv.app.Client.main(Client.java:55)
My code-client:
package com.pv.app;
import io.grpc.*;
public class Client {
public static void main(String[] args) throws Exception {
// Channel is the abstraction to connect to a service endpoint
// Let's use plaintext communication because we don't have certs
final ManagedChannel channel =
ManagedChannelBuilder.forTarget("0.0.0.0:8080").usePlaintext().build();
GetInsertServiceGrpc.GetInsertServiceBlockingStub stub =
GetInsertServiceGrpc.newBlockingStub(channel);
GetInsertServiceOuterClass.HelloMessage request =
GetInsertServiceOuterClass.HelloMessage.newBuilder().setName("hello").build();
System.out.println(request);
System.out.println("b4 req");
// Finally, make the call using the stub
stub.insert(request);
channel.shutdownNow();
}
}
My code-server:
package com.pv.app;
import io.grpc.Server;
import io.grpc.ServerBuilder;
/** Hello world! */
public class App {
public static void main(String[] args) throws Exception {
System.out.println("Hello-start");
Server server = ServerBuilder.forPort(8080).addService(new GetInsertServiceImpl()).build();
// Start the server
server.start();
// Server threads are running in the background.
System.out.println("Server started");
// Don't exit the main thread. Wait until server is terminated.
server.awaitTermination();
}
}
My code-implementation:
package com.pv.app;
import org.tikv.common.TiConfiguration;
import org.tikv.common.TiSession;
import org.tikv.raw.RawKVClient;
public class GetInsertServiceImpl
extends GetInsertServiceGrpc.GetInsertServiceImplBase {
#Override
public void insert(
GetInsertServiceOuterClass.HelloMessage request,
io.grpc.stub.StreamObserver<com.google.protobuf.Empty> responseObserver) {
// HelloRequest has toString auto-generated.
System.out.println("insert");
System.out.println(request);
TiConfiguration conf = TiConfiguration.createRawDefault("pd0:2379");
System.out.println(1);
System.out.println("2");
System.out.println(conf);
TiSession session = TiSession.create(conf);
System.out.println("3");
RawKVClient client = session.createRawClient();
System.out.println("4");
// When you are done, you must call onCompleted.
responseObserver.onCompleted();
}
}
My proto:
syntax = "proto3";
import "google/protobuf/empty.proto";
option java_package = "com.pv.app";
// Request payload
message HelloMessage {
string name = 1;
}
// Defining a Service, a Service can have multiple RPC operations
service GetInsertService {
// Define a RPC operation
rpc insert (HelloMessage) returns (google.protobuf.Empty) {
};
}
What I do to deploy:
In downloaded repo client-java I do mvn clean install -Dmaven.test.skip=true
In my project folder
mvn install:install-file \
-Dfile=../client-java/target/tikv-client-java-2.0-SNAPSHOT.jar \
-DgroupId=org.tikv \
-DartifactId=tikv-client-java \
-Dversion=2.0-SNAPSHOT \
-Dpackaging=jar
In my project pom.xml
<dependency>
<groupId>org.tikv</groupId>
<artifactId>tikv-client-java</artifactId>
<version>2.0-SNAPSHOT</version>
</dependency>
Running java 8:
mvn -DskipTests package exec:java -Dexec.mainClass=com.pv.app.App
mvn -DskipTests package exec:java -Dexec.mainClass=com.pv.app.Client
Does anyone have a suggestion how to fix?
Full code is available here
I did my searching, tried to exclude grpc and opencensus, switch versions - did not help.

The problem is caused by conflicting io.opencensus versions. I was able to fix it by shading it in the tikv/client-java project.
In the tikv/client-java, pom.xml, maven-shade-plugin configuration:
<relocations>
...
<relocation>
<pattern>io.opencensus</pattern>
<shadedPattern>shade.io.opencensus</shadedPattern>
</relocation>
<relocations>
UPDATE
I have just realized that there were changes to the pom.xml merged to the master yesterday, so you may want to update it if you haven't yet.
UPDATE 2
I have just checked your project with the recent version of the tikv/client-java. The NoSuchFieldError: CONTEXT_SPAN_KEY is gone. There are other errors (java.net.UnknownHostException) but they are rather not related.

Java JAR problem

My Java is very rusty and I'm having a bit of a headache here.
Here's my server.java:
import java.io.IOException;
import net.tootallnate.websocket.WebSocket;
import net.tootallnate.websocket.WebSocketServer;
public class server extends WebSocketServer
{
public server(int port)
{
super(port, Draft.AUTO);
}
public void onClientOpen(WebSocket conn)
{
System.out.println("onopen");
/*try
{
this.sendToAll(conn+" entered the room!");
}
catch(IOException ex)
{
ex.printStackTrace();
}*/
}
public void onClientClose(WebSocket conn)
{
System.out.println("onclose");
}
public void onClientMessage(WebSocket conn,String message)
{
System.out.println("onmessage"+message);
}
public static void main(String[] args)
{
int port = 8000;
try
{
port=Integer.parseInt(args[0]);
}
catch(Exception ex)
{
}
server s = new server(port);
s.start();
System.out.println("ChatServer started on port: "+s.getPort());
}
}
I need to include a jar file: ./Java-WebSocket/dist/WebSocket.jar (available from http://github.com/TooTallNate/Java-WebSocket/)
It compiles OK:
prompt> javac -classpath ./Java-WebSocket/dist/WebSocket.jar server.java
However, when I go to run:
prompt> java -classpath ./Java-WebSocket/dist/WebSocket.jar server
Exception in thread "main" java.lang.NoClassDefFoundError: server
Caused by: java.lang.ClassNotFoundException: server
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
Could not find the main class: server. Program will exit.
I hope someone can help.
Thanks in advance,

java -classpath .:./Java-WebSocket/dist/WebSocket.jar server
^^
Or on Windows:
java -classpath .;./Java-WebSocket/dist/WebSocket.jar server
^^
The classpath defaults to the current directory. You need to point to your classes as well as the library.

Isn't server placed into a package ? If it is, specify the full class name.
e.g. prompt> java -classpath ./Java-WebSocket/dist/WebSocket.jar app.core.server
I would also uppercase the class name, though.

Have you tried using the full class name (your.package.server)?