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Java usb4java reading from usb device on windows 10 platform

I am trying to read a message from RFID reader connected via USB to windows 10pro machine with usb4java library.
I have managed to claim the interface, opened pipe and registered listener for the data, however the listener is never triggered. The reader acts as keyboard and whatever it reads ends up in active application, such as IDE i have open, instead of in listener.
UsbInterface usbInterface = activeInteface(device);
// there is only one endpoint in the list
UsbEndpoint endpoint = (UsbEndpoint)usbInterface.getUsbEndpoints().get(0);
UsbPipe pipe = endpoint.getUsbPipe();
try {
usbInterface.claim();
// true
System.out.println("claimed usb interface: " + usbInterface.isClaimed());
pipe.open();
// true
System.out.println("pipe open: " + pipe.isOpen());
pipe.addUsbPipeListener(new MessageListener());
// true
System.out.println("pipe active: " + pipe.isActive());
// keep main thread alive, async call should be done from another thread i guess
Thread.sleep(15000);
}
catch (Exception any) {System.out.println(any);}
}
And the listener:
private static class MessageListener implements UsbPipeListener {
#Override
public void errorEventOccurred(UsbPipeErrorEvent event) {
System.out.println(event.toString() + " , " +event.getUsbException());
}
#Override
public void dataEventOccurred(UsbPipeDataEvent event) {
// this code block never triggers
System.out.println("listener ...);
int actualLength = event.getActualLength();
System.out.println("length: " + actualLength);
byte[] data = event.getData();
System.out.println("data length " + data.length);
}
}
i have also tried synchronous read instead of asynchronous in the block above, like this:
byte[] buffer = new data[8];
// this fails on its own, don't even need to read something with RFID reader
int received = pipe.syncSubmit(buffer);
fails with:
USB error1: Transfer error on interrupt endpoint: Input/Output error
There is some windows specific property that library supports: org.usb4java.javax.useUSBDK = true
but this fails when i try to set it with an exception.
I have 0 experience with USB devices so not sure how to proceed from here. Is there something wrong with the code, do i need USBDK or device does not support libUSB driver ? Sadly this is not my device and i don't have access to documentation of the device so cannot be sure if it is device driver issue.

I know that this is 2 years old, but i've had similar issue and this was one of the first questions that i ran into looking for solution, which took me hours.
So, basically, windows doesn't let to read/write keyboard devices directly, to do so, you have to override it's driver (That's why you're getting Input/Output error, and it's written in the hid4java's FAQ).
First way to override device driver is described in libusb wiki.
As far as i know you would have to install a new driver every time you connect the device to a new USB port, which is why i recommend you to read further.
Second way is what you've already mentioned, which is using UsbDk (Usb Drivers Development Kit for Windows). It makes the device accessible for you by detaching the kernel driver and reattaching it back after you're done playing with it.
In order to use it, you need to do two things:
Set the org.usb4java.javax.useUSBDK = true in you javax.usb.properties file as stated in the manual (this can also be done manually in low-level usb4java, see OPTION_USE_USBDK and setOption(Context, int)).
Download and install UsbDk on your system (simplest way is to download x64 or x86 version msi installer which has GUI and is fully automated), which is sadly not in the manual (maybe it's obvious for some people, but took me amount of time that i am not proud of to realize).
Im guessing that the lack of second step is why OP has been getting an exception.
Hope that this will help someone, knowing all this two days ago would save me a lot of headache.

RFID readers operate in keyboard emulation mode by default.
You can normally get a tool from the manufacturer's website to configure the RFID reader.
This will allow you to change the reader to HID mode.
This should resolve your issues.
Sorry for the late response but I hope it helps others.

Spark: Job restart and retries

Suppose you have Spark + Standalone cluster manager. You opened spark session with some configs and want to launch SomeSparkJob 40 times in parallel with different arguments.
Questions
How to set reties amount on job failures?
How to restart jobs programmatically on failure? This could be useful if jobs failure due lack of resources. Than I can launch one by one all jobs that require extra resources.
How to restart spark application on job failure? This could be useful if job lack resources even when it's launched simultaneously. Than to change cores, CPU etc configs I need to relaunch application in Standalone cluster manager.
My workarounds
1) I pretty sure the 1st point is possible, since it's possible at spark local mode. I just don't know how to do that in standalone mode.
2-3) It's possible to hand listener on spark context like spark.sparkContext().addSparkListener(new SparkListener() {. But seems SparkListener lacks failure callbacks.
Also there is a bunch of methods with very poor documentation. I've never used them, but perhaps they could help to solve my problem.
spark.sparkContext().dagScheduler().runJob();
spark.sparkContext().runJob()
spark.sparkContext().submitJob()
spark.sparkContext().taskScheduler().submitTasks();
spark.sparkContext().dagScheduler().handleJobCancellation();
spark.sparkContext().statusTracker()

You can use SparkLauncher and control the flow.
import org.apache.spark.launcher.SparkLauncher;
public class MyLauncher {
public static void main(String[] args) throws Exception {
Process spark = new SparkLauncher()
.setAppResource("/my/app.jar")
.setMainClass("my.spark.app.Main")
.setMaster("local")
.setConf(SparkLauncher.DRIVER_MEMORY, "2g")
.launch();
spark.waitFor();
}
}
See API for more details.
Since it creates process you can check the Process status and retry e.g. try following:
public boolean isAlive()
If Process is not live start again, see API for more details.
Hoping this gives high level idea of how we can achieve what you mentioned in your question. There could be more ways to do same thing but thought to share this approach.
Cheers !

check your spark.sql.broadcastTimeout and spark.broadcast.blockSize properties, try to increase them .

Modbus4J Modbus RTU master

Currently I am working with the Schneider Power Logic electrical device. I want to read the data from the device and show the value in my system. So far, I discover J2mod, Jamod and Modbus4Java library. I used all modbus4java to connect and get the device's data.
Actually I still confuse whether I suppose to create Master side or Slave side. Based on my understanding, the device will be Slave and my system will be Master (1st question).
Below is the setting AT MY DEVICE. It indicate that the device in slave mode and its protocol is Modbus RTU. So, I need to create a master apps to communicate with it right which is using the ModbusRTU protocol right ? (2nd question)
Mode: Slave
Protocol: Modbus RTU
Address: 1
Baud Rate: 38400
Parity: None
Below is the code of my apps act as the Master and using the ModbusRTU protocol
public static void main(String[] args) throws ModbusTransportException, ErrorResponseException {
ModbusFactory factory = new ModbusFactory();
SerialParameters params = new SerialParameters();
params.setCommPortId("COM6");
params.setBaudRate(9600);
params.setDataBits(8);
params.setStopBits(1);
params.setParity(0);
ModbusMaster master = factory.createRtuMaster(params);
master.setTimeout(1000);
master.setRetries(0);
long start = System.currentTimeMillis();
try {
master.init();
} catch (Exception e) {
System.out.println( "Modbus Master Init Error: " + e.getMessage());
return;
}
try {
System.out.println("Reg. 1001 Value:" + master.getValue(1, RegisterRange.HOLDING_REGISTER, 3110, DataType.FOUR_BYTE_FLOAT_SWAPPED));
}
finally {
master.destroy();
}
System.out.println("Time elapsed: " + (System.currentTimeMillis() - start) + "ms");
}
This is the code that I get from the sample code provide by the Modbus4Java page. The other thing that concern me is the value of params.setCommPortId("COM6"); What other value than "COM6" that I can put there. Because basically it receive a String value. So am I able to put any String value to it ? And what is the function of this particular setCommPortID. (3rd question)
Looking at the sample code provide by the Modbus4Java page, it does not put the IP address of the device. But in my case, my device got an IP address. And the IP address only use in the Slave apps only. How should my system recognize the IP address of the device ? (4th question).
And after I run this code snippet, I got an error:
Stable Library
Native lib Version = RXTX-2.1-7
Java lib Version = RXTX-2.1-7
Modbus Master Init Error: com.serotonin.io.serial.SerialPortException: gnu.io.NoSuchPortException
Please, please and please help me. I been stuck with this almost a month. Really hope someone out there will be able to help me. Thank you in advance for any kind of help and suggestion.

I'm the maintainer for j2mod, so my answer is going to suggest you look at the test programs which are included with j2mod. You can find j2mod on SourceForge at this URL --
https://sourceforge.net/projects/j2mod/
I'm pretty good about answering questions there, but I also follow stackoverflow, so I can explain more here as well. There are a LOT of questions in here, so I apologize in advance if I've missed anything.
The Schneider device is the slave, or "server" and your application is the master or "client". Modbus is a master/slave protocol, with the master initiating all requests. Your application will be the master and responsible for making all requests of your device.
The exact communications will be provided by the device documentation. In this instance, you indicate that the device uses 38400 baud, and so forth. Those are the parameters you will use to update SerialParameters with the RXTX library (which just so happens to also be used by j2mod).
The value passed to setCommPortId() is the Windows COM port identifier - you should be able to pass any value which is associated with an actual COM port -- "COM1", "COM2", etc. Note that some USB converters change their COM port each time they are used, so you may be chasing port names.
You mentioned that your device also has an IP address. You cannot use the RTU classes and methods to access a Modbus/TCP device. The same is true for jamod and j2mod - most Modbus libraries have different classes for RTU and TCP transports (as well as ASCII and UDP, for libraries which support those other transports).

ELM327 returns `?` when trying to use it with ODB Java API

I'm trying to use ODB Java API (this library) to get the data from ELM327 via Bluetooth from my car, but in returns ? on every request, and library raises MisunderstoodException
Here is my code:
socket = device.createInsecureRfcommSocketToServiceRecord(uuid);
socket.connect();
final CustomRPMCommand engineRpmCommand = new CustomRPMCommand();
final SpeedObdCommand speedObdCommand = new SpeedObdCommand();
while (!Thread.currentThread().isInterrupted()) {
engineRpmCommand.run(socket.getInputStream(), socket.getOutputStream());
speedObdCommand.run(socket.getInputStream(), socket.getOutputStream());
runOnUiThread(new Runnable() {
#Override
public void run() {
speedometerGauge.setSpeed(engineRpmCommand.getRPM(), true);
rpmGauge.setSpeed(speedObdCommand.getMetricSpeed(), true);
}
});
}
What's wrong?

I also used the same library for the first steps into trying out OBD, so I can say at least at the time I used it, it worked fine.
From my experience however, getting ? back can sometimes happen with cheap Bluetooth devices (maybe even with expensive ones? never had one). I guess this happens, if some bits are lost during the transmission, because then command will be misunderstood.
What I did to circumvent this problem is setting up a process where I sent all AT commands up to 10 times until I get the desired response of OK (except for ATZ, which will respond with ELM327). As for value requests like RPM etc. I usually just throw away the erroneous values.
That's the short answer, but since such problems with the devices can annoy a lot, I will guide you into debugging the whole process...
Setting up a terminal on windows
First of all to test the functionality of the ELM device, you can send commands to the serial interface directly. On windows, this is possible using for example TeraTerm and then setting up new Bluetooth connection on your windows as a COM device (search for Bluetooth in start -> search box and then choose Change Bluetooth settings or similar). From there, go to COM connections and then add a new one Outgoing for the Bluetooth OBDII device. Wait a bit for windows to calculate the new COM port number, you will need it.
If you cannot find OBDII in the dropdown box, you have to bond your PC with your Bluetooth device first. This can be done via devices and printers, there you should see the OBDII device, so you only have to connect it (PIN usually is 1234).
If you're on Linux, it might be somewhat easier, but I haven't done it :)
Sending some commands via terminal
Once you have your Bluetooth connection and TeraTerm installed, you can start TeraTerm and connect to the adapter. Choose Serial and then the port you just set up. Ensure, that no other device is connected to the OBD adapter (also not your phone). Only one device can be connected at a time.
If connection was successful, you should be able to type letters. Usually, in default settings you should be able to see the letters you type (Echo mode on), but since this is not certain, just type ATZ and hit <Enter>. The ELM should respond with "ELM327" in the same line now (which for me usually results in odd display if echo mode was on, but you should get any response).
From terminal I usually send these commands in order:
ATZ
E1
L1
010c
This will trigger:
Reset of the OBD device
Make sure that echo is on, so I see what I am typing
Make sure Line feed is on, so we get responses in the next line
Request RPM from the vehicle
Between each command I'll check what is the reply of the device. For all AT commands (1., 2. and 3.) it must be OK. If I get back ?, which can happen, I will repeat the command another time. You will see that in such a case the device indeed did not follow the instructions, e.g. did not set line feed on if it was off. So we really have to send it again.
In programming mode on the other hand, we will set e0 and l0 (echo mode off and line feed off), because we do not want to get sent back what we already sent out.

Flex+JPA/Hibernate+BlazeDS+MySQL how to debug this monster?

Ok so I'm making a "simple" web app using the technologies from the topic, recently I found http://www.adobe.com/devnet/flex/articles/flex_hibernate.html so I'm following it and I try to apply it to my app, the only difference being I'm working on a Mac and I'm using MAMP for the database (so no command line for me).
The thing is I'm having some trouble with retrieving/connecting to the database.
I have the remoting-config.xml, persistance.xml, a News.java class (my Entity), a NewsService.java class, a News.as class - all just like in the tutorial. I have of course this line in one of my .mxmls:
<mx:RemoteObject id="loaderService" destination="newsService" result="handleLoadResult(event)" fault="handleFault(event)" showBusyCursor="true" />
And my remoting-config.xml looks like this (well part of it):
<destination id="newsService">
<properties><source>com.gamelist.news.NewsService</source></properties>
</destination>
NewsService has a method:
public List<News> getLatestNews() {
EntityManagerFactory emf = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT);
EntityManager em = emf.createEntityManager();
Query findLatestQuery = em.createNamedQuery("news.findLatest");
List<News> news = findLatestQuery.getResultList();
return news;
}
And the named query is in the News class:
#Entity
#Table(name="GLT_NEWS")
#NamedQueries({
#NamedQuery(name="news.findLatest", query="from GLT_NEWS order by new_date_added limit 5 ")
})
The handledLoadResult looks like this:
private function handleLoadResult(ev:ResultEvent):void {
newsList = ev.result as ArrayCollection;
newsRecords = newsList.length;
}
Where:
[Bindable]
private var newsList:ArrayCollection = new ArrayCollection();
But when I try to trigger:
loaderService.getLatestNews();
nothing happens, newsList is empty.
Few things I need to point out:
1) as I said I didn't install mysql manually, but I'm using MAMP (yes, the server's running), could this cause some trouble?
2) I already have a "gladm" database and I have a "GLT_NEWS" table with all the fields, is this bad?
Basically the question is how am I suppose to debug this thing so I can find the mistake I'm making? I know that loadData() is executed (did a trace()), but I have no idea what happens with loaderService.getLatestNews()...
#EDIT: ok so I see I'm getting an error in the "fault handler" which says
"Error: Client.Error.MessageSend - Channel.Connect.Failed error NetConnection.Call.Failed: HTTP: Status 404: url: 'http://localhost:8080/WebContent/messagebroker/amf' - "
#EDIT2: Ok i solved the problem, as it turns out my ContextRoot was incorrect, the funny thing is I couldn't edit it by going to Project properties->Flex Server as it was uneditable! I had to find the .flexProject file and edit it (obviously my Flex Navigator didn't show it and by accident I noticed it was being filtered).

To answer your question as to, in general, debug this monster...here is what I do.
Set break points in my Java code
Start up the Java application server with the appropriate debug JVM properties set (e.g. -Xdebug -Xrunjdwp:transport=dt_socket,address=8000,server=y,suspend=n)
From Eclipse, I attach a remote debugger to the app server on the default port 8000. The Java Debugger will open up when a break point is hit.
Set breakpoints in my Flex application (or one of its modules).
From Eclipse (with Flash Builder) I launch a debug configuration for my Flex app. The Flex Debugger will open up when a break point is hit.
At this point I have two debuggers open and everything work great. Two other things I do:
a) extend the transaction system timeout, so it doesn't get trigger while I am sitting there think for a few minutes
b) use Charles Proxy (in reverse proxy mode) inbetween the client and server to watch the AMF traffic and view payloads, etc.
Hope this helps.

your error means you are not calling the server on the right way. Something is wrong there, the url the web.config file or other BlazeDS config files.