yarmi is yet anotehr RMI based on JSON. it's simple yet powerful when developing server & client based distributed application within a network of small scale

Features

1. 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

2. Provide service discovery out-of-the-box

yarmi contains simple service discovery feature and also support another type of service discovery (e.g. DNS-SD) as module

3. Support various transport

yarmi also provides abstraction over transport layer so it can over any kinds of transport like tcp / ip or bluetooth rfcomm.

4. Zero-cost migration to (from) RESTful application

Provides conceptual similarity to popular RESTful application framework (like service / controller mapping). and that means not only the migration from / to RESTful implementation is easy but also implementing proxy for any RESTful service in heterogeneous network scenario (like typical IoT application) is also well supported

How-To

Using 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>com.doodream</groupId>
            <artifactId>yarmi-core</artifactId>
            <version>0.0.2</version>
        </dependency>
</dependencies>

Build Service (Server)

1. Declare controller stub in a very similar way doing with Spring REST Controller

public interface UserIDPController {

    @Get("/{id}")
    Response<User> getUser(@Path(name = "id") Long userId);

    @Get("/list")
    Response<User> getUsers();

    @Post("/new")
    Response<User> createUser(@Body(name = "user") User user);
    
    @Post("/new/thumbnail")
    Response<Long> postThumbnail(@Body(name = "th_nail") BlobSession blob, Long userId);

} 

2. Implement Controller Stub

public class UserIDControllerImpl implements UserIDPController {

    private HashMap<Long, User> userTable = new HashMap<>();

    @Override
    public Response<User> getUser(Long userId) {
        User user = userTable.get(userId);
        if(user == null) {
            return null;
        }
        return Response.success(user, User.class);
    }

    @Override
    public Response<User> getUsers() {
        return null;
    }

    @Override
    public Response<User> createUser(User user) {
        int id = user.hashCode();
        userTable.put((long) id, user);
        user.id = (long) id;
        return Response.success(user, User.class);
    }
    
    @Override
    public Response<Long> postThumbnail(BlobSession blob, Long userId) {
        // example save blob as file
        byte[] rb = new byte[1024];
        int rsz;
        try {
            Session session = blob.open();
            FileOutputStream fos = new FileOutputStream("thumbnail_" + userId);
            while((rsz = session.read(rb,0, rb.length)) > 0) {
                fos.write(rb, 0, rsz);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            fos.close();
        }
        return Response.success(userId);    
    }
}  

3. Declare your service with route configuration

@Service(name = "test-service",
        params = {"6644"})
public class TestService {

    @Controller(path = "/user", version = 1, module = UserIDControllerImpl.class)
    UserIDPController userIDPService;
}

4. Start service & advertise it

public static class SimpleServer {
    
    public static void main (String[] args) {
        RMIService service = RMIService.create(TestService.class, new SimpleServiceAdvertiser());
        service.listen(true);
        // listen will block, you can change the blocking behaviour with the argument
    }
}

Build Client

1. Discover service & create client

public static class SimpleClient {
    
    public static void main (String[] args) {
            // build target service information
            
            SimpleServiceDiscovery discovery = new SimpleServiceDiscovery();
            discovery.startDiscovery(TestService.class, new ServiceDiscoveryListener() {
                @Override
                public void onDiscovered(RMIServiceProxy proxy)  {
                    discoveredService.add(proxy);
                }
    
                @Override
                public void onDiscoveryStarted() { 
                    discoveredService = new LinkedList<>();
                }
    
                @Override
                public void onDiscoveryFinished() {
                    // pick RMIServiceProxy and create client
                    if(discoveredService == null) {
                        return;
                    }
                    if(discoveredService.size() > 0) {
                        RMIServiceProxy serviceProxy = discoveredService.get(0);
                        if(!serviceProxy.provide(UserIDPController.class)) {
                            // check given controller is provided from the service
                            return;
                        }
                        try {
                                UserIDPController userCtr = RMIClient.create(serviceProxy, TestService.class, UserIDPController.class);
                                // will be create client-side proxy 
                                // and use it just like simple method call
                                
                                User user = new User();
                                user.setName("David");
        
                                Response<User> response = userCtr.createUser(user);
                                assert response.isSuccessful();
                                user = response.getBody();
                                
                                response = userCtr.getUser(user.getId());
                                assert response.isSuccessful();
                                response.getBody();
                                
                                // example : upload file as thumbnail images
                                FileInputStream fis = new FileInputStream("./thumbnail.jpg");
                                byte[] buffer = new byte[2048];
                                BlobSession session = new BlobSession(ses -> {
                                    int rsz;
                                    try {
                                        while((rsz = fis.read(buffer)) > 0) {
                                            ses.write(buffer, rsz);
                                        }
                                        ses.close();
                                    } catch (IOException e) {
                                        e.printStackTrace();
                                    }
                                });
                                Response<Long> thumbResponse = controller.postThumbnail(session, 1L);
                                assert thumbResponse.isSuccessful();
                                
                            } catch (IllegalAccessException | InstantiationException | IOException e) {
                                e.printStackTrace();
                            }    
                        }
                        
                    }
            });
            
    }
}

License

Apache License, Version 2.0