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https://github.com/renatoathaydes/protobuf-tcp-rsa-provider

TCP/Protobuffer implementation of Aries RSA DistributionProvider.
https://github.com/renatoathaydes/protobuf-tcp-rsa-provider

apache-aries java osgi-services protobuf3 protobuffer rpc

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TCP/Protobuffer implementation of Aries RSA DistributionProvider.

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README 

        
# ProtoBuffer TCP RSA Provider



This project implements a tiny RPC protocol over TCP connections using

[Protobuffer](https://developers.google.com/protocol-buffers/) as a serialization mechanism.



It also contains a implementation of OSGi RSA (Remote Service Admin) 

`DistributionProvider`, which allows any OSGi service to be exported as a remote service

via the [Apache Aries RSA](http://aries.apache.org/modules/rsa.html) implementation.



## RPC Protocol



The RPC protocol is as simple as it can be and consists of the single 

[rpc.proto](protobuf-tcp-rsa-provider/src/main/proto/rpc.proto) file:



```proto

syntax = "proto3";



package com.athaydes.protobuf.tcp.api;



import "google/protobuf/any.proto";



option java_package = "com.athaydes.protobuf.tcp.api";

option java_outer_classname = "Api";



message MethodInvocation {

    string methodName = 1;

    repeated google.protobuf.Any args = 2;

}



message Exception {

    string type = 1;

    string message = 5;

}



message Result {

    oneof result {

        google.protobuf.Any successResult = 1;

        Exception exception = 2;

    }

}

```



This protocol can represent any method invocation and can be used from any language

that supports Protobuffers.



## Java Server/Client example



The following example shows how to start a remote service server and client in Java:



```java

// This code can be run with JGrab: https://github.com/renatoathaydes/jgrab

// #jgrab com.athaydes.osgi:protobuf-tcp-rsa-provider:0.1.0

// #jgrab org.slf4j:slf4j-simple:1.7.25



import com.athaydes.protobuf.tcp.api.RemoteServices;



import java.io.Closeable;

import java.io.IOException;

import java.util.function.IntToDoubleFunction;



public class HelloWorld {



    public static void main(String[] args) throws IOException {

        // service implementation

        IntToDoubleFunction squareCalculator = (n) -> Math.pow(n, 2);



        // create server

        Closeable server = RemoteServices.provideService(squareCalculator, 8023, IntToDoubleFunction.class);



        // create client

        IntToDoubleFunction client = RemoteServices.createClient(IntToDoubleFunction.class, "localhost", 8023);



        try {

            // invoke the remote service

            double response = client.applyAsDouble(5);

            System.out.println("The square of 5 is " + response);

        } finally {

            server.close();

        }

    }

}

```



Other Java examples can be found in the [samples/java](samples/java) directory.



## Samples in other languages



Check the [samples](samples) directory for examples in other languages.



## OSGi usage



To use this bundle in OSGi, you'll need to install the [Aries RSA](http://aries.apache.org/modules/rsa.html) runtime

bundles.



There is an [Aries RSA Example](https://github.com/renatoathaydes/aries-rsa-example) project that uses

Gradle and the [osgi-run](https://github.com/renatoathaydes/osgi-run) plugin to create a runtime.



The OSGi runtime declarations look like this:



```groovy

dependencies {

    // Aries RSA bundles

    final ariesRsaVersion = '1.11.0'

    osgiRuntime "org.apache.aries.rsa:org.apache.aries.rsa.core:$ariesRsaVersion"

    osgiRuntime "org.apache.aries.rsa:org.apache.aries.rsa.spi:$ariesRsaVersion"



    // set topology-manager's startLevel to 6 to make sure it starts AFTER the RSA Core,

    // otherwise it will not work

    osgiRuntime osgi("org.apache.aries.rsa:org.apache.aries.rsa.topology-manager:$ariesRsaVersion:6".toString())



    osgiRuntime "org.apache.aries.rsa.discovery:org.apache.aries.rsa.discovery.local:$ariesRsaVersion"

    osgiRuntime "com.athaydes.osgi:protobuf-tcp-rsa-provider:1.0-SNAPSHOT"



    // Logging

    osgiRuntime 'org.apache.felix:org.apache.felix.log:1.0.1', {

        transitive = false

    }

    osgiRuntime 'com.athaydes.osgiaas:slf4j-to-osgi-log:1.7.0'

}

```



### Exporting a OSGi service remotely



To export a service remotely, you just need to declare one service property:



```

service.exported.interfaces=*

```



You can also set the port to which the service is bound by declaring the following property

(in this case, setting the port to `5561`):



```

com.athaydes.protobuf.port=5561

```



Hence, using Declarative Services annotations, you would annotate your service with the following:



```java

@Component(immediate = true, property = {

        "service.exported.interfaces=*",

        "com.athaydes.protobuf.port=5561"

})

public class MyService implements SomeService {}

```



### Importing a remote OSGi service



To import a remote OSGi service, you must declare at least the following property:



```xml

com.athaydes.protobuf

```



If you are using [Local Discovery](https://github.com/apache/aries-rsa/tree/master/discovery/local),

you can create a XML descriptor like the following in order to import a remote service:



```xml



    

        

            

                com.athaydes.osgi.api.MessageService

            

        

        tcp://127.0.0.1:5561

        com.athaydes.protobuf

    



```



See the [XML Descriptor](https://github.com/renatoathaydes/aries-rsa-example/blob/master/osgi-client/src/main/resources/OSGI-INF/remote-service/server.xml)

in the [Aries RSA Example](https://github.com/renatoathaydes/aries-rsa-example) for details.