Issue getting JSON-RPC response using Java client

Question

So I am trying to write a Java client that can communicate to the multichain server. The server is running on an Ubuntu VM (VM1) and I am writing my code on another Ubuntu VM (VM2).

Both VMs are on the same network and can communicate with one another. I can run multichain-cli commands from VM2 and get a successful response.

i was following the example from http://www.multichain.com/qa/2331/help-connection-to-mutlichain-using-java-client and I have the following code;

 

public JSONObject invokeRPC(String id, String method, List<Object> params, String chainName){
    HttpClient httpClient = HttpClientBuilder.create().build();
    JSONObject jsonObject = new JSONObject();
    jsonObject.put("id", id);
    jsonObject.put("method", method);
    if(params != null && params.size() != 0){
        jsonObject.put("params", params);
    }
    jsonObject.put("chain_name", chainName);
    JSONObject responseJSONObject = new JSONObject();
    try{
        CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
        credentialsProvider.setCredentials(
                new AuthScope("192.168.1.6", 9732),
                new UsernamePasswordCredentials("multichainrpc", "EZikv3MtoKA2yjrG6T7eTkPZMXntwr9k1ft7ja3jLLaA")
        );
        StringEntity myEntity = new StringEntity(jsonObject.toString());

        HttpPost httpPost = new 

HttpPost("http://192.168.1.6:9732");       //HttpPost("http://multichainrpc:EZikv3MtoKA2yjrG6T7eTkPZMXntwr9k1ft7ja3jLLaA@192.168.1.6:9732");
        httpPost.setEntity(myEntity);

        HttpResponse httpResponse = httpClient.execute(httpPost);
        HttpEntity httpEntity = httpResponse.getEntity();

        System.out.println("------------------");
        System.out.println(httpResponse.getStatusLine());

        if(httpEntity != null){
            System.out.println("Response content length: " + httpEntity.getContentLength());
        }

        responseJSONObject = new JSONObject().getJSONObject(EntityUtils.toString(httpEntity));

    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        httpClient.getConnectionManager().shutdown();
    }

    return responseJSONObject;
}

The code fails at 'HttpResponse httpResponse = httpClient.execute(httpPost);' with the following Exception;

org.apache.http.conn.HttpHostConnectException: Connect to 192.168.1.6:9732 [/192.168.1.6] failed: Connection refused (Connection refused)

at org.apache.http.impl.conn.DefaultHttpClientConnectionOperator.connect(DefaultHttpClientConnectionOperator.java:158)

at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.connect(PoolingHttpClientConnectionManager.java:353)

at org.apache.http.impl.execchain.MainClientExec.establishRoute(MainClientExec.java:380)

at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:236)

at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:184)

at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:88)

at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:110)

at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184)

at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)

at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:107)

at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:55)

at com.recordz.general.connect.Connect.invokeRPC(Connect.java:52)

at com.recordz.general.connect.Connect.main(Connect.java:28)

Caused by: java.net.ConnectException: Connection refused (Connection refused)

at java.net.PlainSocketImpl.socketConnect(Native Method)

at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)

at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)

at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)

at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)

at java.net.Socket.connect(Socket.java:589)

at org.apache.http.conn.socket.PlainConnectionSocketFactory.connectSocket(PlainConnectionSocketFactory.java:74)

at org.apache.http.impl.conn.DefaultHttpClientConnectionOperator.connect(DefaultHttpClientConnectionOperator.java:141)

... 12 more

 

I am not sure why this is happening as both VMs are on the same LAN and can communicate with one another.

Any advice would be much appreciated

Answer 1

So I found the solution.

On the client vm I had to edit the multichain.conf file in the blockchain directory with the rpcallowip entry.

I had previously done this, but on the blockchain vm VM1.