fritzprix / yarmi

yet-another RMI Framework for Java

RMI (Remote Method Invocation) framework supporting service discovery out-of-box among devices within same network considering IOT(internet of device) proof-of-concept project

Features

1. Zero configuration for service integration based on RMI and Service Discovery
2. Simple APIs

discover and request service with just a few API calls

2. Support large blob as method parameter or response

yarmi supports blob exchange between client and server by default with BlobSession which exposes familiar read / write APIs

How-To

Using with Maven

1. Add Maven Repository

<repositories>
    <repository>
        <id>yarmi-core</id>
        <name>yarmi</name>
        <releases>
            <enabled>true</enabled>
        </releases>
        <snapshots>
            <enabled>false</enabled>
        </snapshots>
        <url>https://raw.githubusercontent.com/fritzprix/yarmi/releases</url>
    </repository>
</repositories>

2. Add dependency

<dependencies>
        <dependency>
            <groupId>net.doodream</groupId>
            <artifactId>yarmi-core</artifactId>
            <version>0.1.1</version>
        </dependency>
            <dependency>
                <groupId>net.doodream.yarmi</groupId>
                <artifactId>sdp-mdns</artifactId>
                <version>0.1.1</version>
            </dependency>
</dependencies>

Using with Gradle

1. Add Repository

allprojects {
    repositories {
        ...
        maven {
            url 'https://raw.githubusercontent.com/fritzprix/yarmi/releases'
        }
        maven {
            url 'https://raw.githubusercontent.com/fritzprix/yarmi/snapshots'
        }
        ...
    }
}

2. Add Dependency

dependencies {
...
    implementation 'net.doodream:yarmi-core:0.1.1'
    implementation 'net.doodream.yarmi:sdp-mdns:0.1.1'
    implementation 'org.jmdns:jmdns:3.5.1'

...
}

Build Service (Server)

1. Declare controller stubs with RMIExpose annotation

public interface TestController {

    @RMIExpose
    Response<String> echo(String message);
} 

2. Implement Controller

public class TestControllerImpl implements TestController {


    @Override
    public Response<String> echo(String message) {
        return Response.success(message);
    }
}  

3. Declare your service with route configuration

@Service(name = "test-service",
         provider = "com.example",
         params = {
            @AdapterParam(key=TcpServiceAdapter.PARAM_PORT, value = "6644")
         })
public class TestService {

    @Controller(path = "/test", version = 1, module = TestControllerImpl.class)
    TestController controller;
}

4. Start service & advertise it

    final RMIService service = RMIService.create(TestService.class);
    final ServiceRegistry registry = MDnsServiceRegistry.create();
    
    service.listen();
    registry.register(service);
    registry.start();

Build Client

1. Discover service & create client

    // build target service information
    final ServiceDiscovery discovery = MDnsServiceDiscovery.create();
    discovery.start(TestService.class, new ServiceDiscoveryListener() {
        @Override
        public void onDiscoveryStarted() {
            // discovery started
        }

        @Override
        public void onServiceDiscovered(RMIServiceInfo service) {
            // new service discovered
            Object client = RMIClient.create(servce, TestService.class, new Class[] {
                    TestController.class
            });
            // cast client proxy into interface of interest
            TestController controller = (TestController) client;
            // and use it 
            Response<String> response = controller.echo("Hello");
            if(response.isSucessful()) {
                // successfully RMI handled and response received successfully
                System.out.println(response.getBody());
            }
        }

        @Override
        public void onDiscoveryFinished(int i, Throwable throwable) {
            // service discovery finished
        }
    });

License

Apache License, Version 2.0

yarmi's Issues

downgrade to Java 8 -> 7

to support Android device below N

Optimize Request Size

• Replace endpoint field in Request with smaller alternative

HaRMIClient raises exception in invoking call proxy

method invoke with null argument was equivalent to invoke with no argument in Java8 (no problem with no-arg method)
method invoke with null argument for no-arg method raise IllegalArgumentException in Java7

originally method invocation has been directly performed by calling RMIClient::invoke method and it was changed to calling call proxy of RMIClient later. however, the invocation has not reflected the change

service discovery migration (into separate package)

key for method lookup is not unique

unique key is generated by code below (com.doodream.rmovjs.model.Endpoint)

final String methodLookupKey = String.format("%x%x%x", rmiMethod.hashCode(), controller.path().hashCode(), paramUnique.hashCode()).toUpperCase();

which was actually generate same keys for methods whose RMIMethod declared / parameter / enclosing controller are same.

blobsessin closed with remaining unread data

Data missed at the end of the stream happens quite often in multi threading situation

• PipedInput/Outputstream is used for delivering the incoming data from the network (socket) to the another read end point.
• each writer & reader is performed at different thread
• read() returns -1 when the writer thread is dead
• reader finishes the read loop

If alternative (spf4j) is used the issue has been resolved.

concurrent request timeouts when single request blocks

Concurrent method call should be serialized

• method invocation and return should be atomic considering concurrent scenario

Logo Proposal for Yarmi

Hi, I'm a graphic designer and I like to collaborate with open source projects. Do you know that the graphic image of a project is very important? thinking about it I would like to design a logo for your Project Yarmi.

I will be pleased to collaborate with you.

JUnit testing is failing on Travis CI

maven test is failing on Travis CI environment, which is not reproduced on my own machine.

java.lang.NullPointerException
at com.doodream.rmovjs.test.ServiceNoReplyTest.startServer(ServiceNoReplyTest.java:28)
[INFO] Running com.doodream.rmovjs.test.EchoBackTest
[ERROR] Tests run: 2, Failures: 0, Errors: 2, Skipped: 0, Time elapsed: 0 s <<< FAILURE! - in com.doodream.rmovjs.test.EchoBackTest
[ERROR] com.doodream.rmovjs.test.EchoBackTest Time elapsed: 0 s <<< ERROR!
java.lang.NullPointerException
at com.doodream.rmovjs.test.EchoBackTest.startServer(EchoBackTest.java:35)
[ERROR] com.doodream.rmovjs.test.EchoBackTest Time elapsed: 0 s <<< ERROR!
java.lang.NullPointerException
at com.doodream.rmovjs.test.EchoBackTest.stopServer(EchoBackTest.java:43)

add high availability support (HaRMIClient)

provides RMI proxy which delegates multiple service proxy in order to

• support high availability
• optionally provides load balancing feature

SimpleServiceDiscovery doesn't work across the hosts

SimpleServiceDiscovery & SimpleServiceAdvertiser is tested on single host so far, there was no problem. but testing between two host it doesn't work. tried to modify udp related code as below but still doesn't work

creating packet

return new DatagramPacket(infoByteString, infoByteString.length, Inet4Address.getByName("255.255.255.255"), BROADCAST_PORT);

sending it

        DatagramSocket socket = new DatagramSocket();
        socket.setBroadcast(true);
        socket.send(datagramPacket);
        socket.close();

receiver

       DatagramSocket serviceBroadcastSocket = new DatagramSocket(SimpleServiceAdvertiser.BROADCAST_PORT);
       serviceBroadcastSocket.setBroadcast(true);

receiving

        byte[] buffer = new byte[64 * 1024];
        Arrays.fill(buffer, (byte) 0);
        DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
        serviceBroadcastSocket.receive(packet);

and tcpdump shows broadcast packet dest address of 255.255.255.255

add health check for service

• check service availability with defined policy
• provides service recovery

Generic containers (Response) have been not properly deserialized

Gson handles json object whose type is ambiguous in runtime by generating generic key value map.

slim down dependencies

remove libraries widely adopted in developing application to prevent unnecessary dependency conflict.

list

• gson
• guava
• rxjava

add support messaging protocol more appropriate for binary data

json is inefficient for binary data exchange due to

• base64 encoding / decoding overhead
• byte length of base64 encoded byte array is much larger than byte array

Add support for large blob exchange between client and server

Opt #1. socket
Opt #2. byte array

• there should be mod in de-ser interface to support both cases in above

RMIClient::create causes exception on Android K

W/System.err: Caused by: java.lang.NoSuchMethodError: No virtual method getParameterCount()I in class Ljava/lang/reflect/Constructor; or its super classes (declaration of 'java.lang.reflect.Constructor' appears in /system/framework/core-libart.jar)
W/System.err: at com.doodream.rmovjs.net.tcp.TcpServiceAdapter$3.test(TcpServiceAdapter.java:45)
W/System.err: at com.doodream.rmovjs.net.tcp.TcpServiceAdapter$3.test(TcpServiceAdapter.java:42)

Handling recursive type parameter in serialization

class serialization performed with Class.getName() -> Class.forName()
in this way, there are some cases out of handle

• return type or any parameter using type parameter in recursive like Response<List>