My Java program needs to get a list of the drive letters of connected USB devices, but only those that support USB 3.0 (both the device and the USB port it is plugged into, so that it works with high speed).
Currently I try to use WMI through a PowerShell command my Java programm executes.
I already found this: Powershell: Grab USB Drive letter. But it would also list USB 2.0 devices.
Regarding version detection I found this: How to check the version of the available USB ports? - The PowerShell command I tried is Get-WmiObject Win32_USBHub. This brings up several problems. First: It lists far more stuff than only USB drives (I think also all the USB hubs of my PC). Second: Even though there is a field USBVersion for all items in the list it is always empty.
Update
The essence of my research over the last days is, that there are 2 realms of information I need to connect.
Drives / Logical Drives
Drive Letter
BusType (is equal to "USB" for my matter)
USB devices
Vendor ID and Product ID (VID&PID)
bcdUSB (value within the usb device descriptor, indicating USB Version)
For a given drive letter I need to find the bcdUSB value. But I haven't found a way to get the drive corresponding to a USB device.
What I tried so far
WMI over PowerShell
Relevant commands I found are
Get-Disk // Get BusType
gwmi Win32_LogicalDisk // Get drive letter
// Those make the connection between disk and logical disk
gwmi Win32_LogicalDiskToPartition
gwmi Win32_LogicalDiskToPartition
Even though I get the BusType I couldn't make a connection to bcdUSB
usb4java (Link)
I only get information from the USB device realm here. I can load devices and see ther VID&PID and the bcdUSB value, but no way to map this to drives and drive letters.
lsusb via Cygwin
According to this post the linux command is easier to handle than WMI. So I tried to use it under Windows. But I like usb4java I only got VID&PID + bcdUSB, not the mount point (drive letter).
Searching the Windows Registry
I did a few string searchs in the Windows registry. No success.
Reading Windows Event log
I thought about ovserving Windows events to detect what Drive and what USB device connect at the same time. I didn't even find events when plugging in a USB stick.
Maybe this is what you are looking for:
Find Windows Drive Letter of a removable disk from USB VID/PID
At least someone marked the answer as working... :-)
Since the suggested Link solves this problem for C# not Java and leaves out one step, I'll post my final code here.
Summary
In Java
Use USB4Java to find all connected USB devices with bcdUSB=0x0300
Get Vendor ID and Product ID (VID&PID) for that devices
Via Powershell (with jPowerShell)
Get PnPEntity for given VID&PID
Get related USB Controller
Find associator of that USB Controller that is associated with a disk drive
Get that Disk drive
Get related disk partition
Get related logical disk -> LogicalDisk.DeviceID = Drive Letter
Code
Java class:
class UsbDetector {
private PowerShell shell;
#PostConstruct
private void init() {
shell = com.profesorfalken.jpowershell.PowerShell.openSession();
}
#OnDestroy
private void onShutdownHook() {
shell.close();
}
/**
* Get drive letters of USB 3.0 devices.
*/
public List<String> getDriveLettersForUsb3Devices() throws IOException, UsbException {
List<UsbDevice> devicesUSB3 = getAllUsb3Devices();
ImmutableList.Builder<String> driveLetterList = ImmutableList.builder();
for (UsbDevice device : devicesUSB3) {
String vidAndPid = getVidAndPid(device);
String powerShellScript = buildScript(vidAndPid);
String driveLetter = executeOnPowerShell(powerShellScript);
driveLetterList.add(driveLetter);
}
return driveLetterList.build();
}
private String executeOnPowerShell(String powerShellScript) {
InputStream psScriptStream = new ByteArrayInputStream(powerShellScript.getBytes());
BufferedReader psScriptReader = new BufferedReader(new InputStreamReader(psScriptStream));
PowerShellResponse response = shell.executeScript(psScriptReader);
return response.getCommandOutput();
}
private String buildScript(String vidAndPid) throws IOException {
InputStream psScriptStream =
getClass().getClassLoader().getResourceAsStream("GetUsbDrives.ps1");
String psScript = IOUtil.toString(psScriptStream);
psScript = String.format("$input=\"%s\"", vidAndPid) + "\n" + psScript;
return psScript;
}
/**
* The Vendor ID and Product ID are necessary to find the device via WMI.
*/
private String getVidAndPid(UsbDevice device) {
short vendorId = device.getUsbDeviceDescriptor().idVendor();
short productId = device.getUsbDeviceDescriptor().idProduct();
String vendorIdHexString = String.format("%04x", vendorId).toUpperCase();
String productIdHexString = String.format("%04x", productId).toUpperCase();
String vidAndPid = String.format("VID_%s&PID_%s", vendorIdHexString, productIdHexString);
return vidAndPid;
}
/**
* From all Usb devices find those with USB 3.0. The value bcdUsb is a hexadecimal coded number
* telling us the USB version.
*/
private List<UsbDevice> getAllUsb3Devices() throws UsbException {
List<UsbDevice> devicesUSB3 = Lists.newArrayList();
UsbServices services = new org.usb4java.javax.Services();
UsbHub hub = services.getRootUsbHub();
List<UsbDevice> devices = getAllUsbDevices(hub);
for (UsbDevice device : devices) {
UsbDeviceDescriptor descriptor = device.getUsbDeviceDescriptor();
short bcdUsb = descriptor.bcdUSB();
String bcdDecoded = DescriptorUtils.decodeBCD(bcdUsb);
if (Objects.equal(bcdDecoded, "3.00")) {
devicesUSB3.add(device);
}
}
return devicesUSB3;
}
/**
* UsbHubs can either mount UsbDevices or further UsbHubs. This method searches through the tree
* of UsbHubs for UsbDevices and returns them as list.
*/
private List<UsbDevice> getAllUsbDevices(UsbHub hub) {
List<UsbDevice> devices = Lists.newArrayList();
List<UsbDevice> attachedDevices = hub.getAttachedUsbDevices();
for (UsbDevice device : attachedDevices) {
if (device instanceof UsbHub) {
List<UsbDevice> subdevices = getAllUsbDevices((UsbHub) device);
devices.addAll(subdevices);
} else {
devices.add(device);
}
}
return devices;
}
}
PowerShell script:
# $input = "VID_XXXX&PID_XXXX (this line is added in Java Code)
# For given VID and PID of a USB device we search for
# the corresponding logical disk to get the drive letter.
# The chain of objects is:
# PnPEntity (PnP = Plug and Play)
# -> USBController
# -> Some associator of USBController that has a related disk drive
# -> diskDrive
# -> diskPartition
# -> logicalDisk
# Find PnPEntity for given VID and PID
$usbPnPEntity = (gwmi Win32_PnPEntity | where DeviceID -match $input)
# Get USB Controller related to PnP Entity
$usbController = $usbPnPEntity.getRelated("Win32_USBController")
$usbControllerID = $usbController.DeviceID
# Find objects associated with the USB Controller
$query = "ASSOCIATORS OF {Win32_USBController.DeviceID='$usbControllerID'}"
$associators = ([wmisearcher]$query).get()
# Search through associators
foreach ($associator in $associators) {
# Find associator that is related to a disk Drive
$assoDeviceID = $associator.DeviceID
$diskDrive = (gwmi win32_diskdrive | where PNPDeviceID -eq $assoDeviceID)
if($diskDrive){
# Get logical Disk related to the disk drive
$logicalDisk = $diskDrive.getRelated("Win32_DiskPartition").getRelated("Win32_LogicalDisk")
# Print device ID which is the drive letter (e.g. "C:")
$logicalDisk.DeviceID
break
}
}
Maven dependencies:
<dependency>
<groupId>org.usb4java</groupId>
<artifactId>usb4java-javax</artifactId>
<version>1.3.0</version>
</dependency>
<dependency>
<groupId>com.profesorfalken</groupId>
<artifactId>jPowerShell</artifactId>
<version>3.1.1</version>
</dependency>
I am trying to develop and application to read and write to RF tags. Reading is flawless, but I'm having issues with writing. Specifically the error "GetStatus Write RFID_API_UNKNOWN_ERROR data(x)- Field can Only Take Word values"
I have tried reverse-engineering the Zebra RFID API Mobile by obtaining the .apk and decoding it, but the code is obfuscated and I am not able to decypher why that application's Write works and mine doesn't.
I see the error in the https://www.ptsmobile.com/rfd8500/rfd8500-rfid-developer-guide.pdf at page 185, but I have no idea what's causing it.
I've tried forcefully changing the writeData to Hex, before I realized that the API does that on its own, I've tried changing the Length of the writeData as well, but it just gets a null value. I'm so lost.
public boolean WriteTag(String sourceEPC, long Password, MEMORY_BANK memory_bank, String targetData, int offset) {
Log.d(TAG, "WriteTag " + targetData);
try {
TagData tagData = null;
String tagId = sourceEPC;
TagAccess tagAccess = new TagAccess();
tagAccess.getClass();
TagAccess.WriteAccessParams writeAccessParams = tagAccess.new WriteAccessParams();
String writeData = targetData; //write data in string
writeAccessParams.setAccessPassword(Password);
writeAccessParams.setMemoryBank(MEMORY_BANK.MEMORY_BANK_USER);
writeAccessParams.setOffset(offset); // start writing from word offset 0
writeAccessParams.setWriteData(writeData);
// set retries in case of partial write happens
writeAccessParams.setWriteRetries(3);
// data length in words
System.out.println("length: " + writeData.length()/4);
System.out.println("length: " + writeData.length());
writeAccessParams.setWriteDataLength(writeData.length()/4);
// 5th parameter bPrefilter flag is true which means API will apply pre filter internally
// 6th parameter should be true in case of changing EPC ID it self i.e. source and target both is EPC
boolean useTIDfilter = memory_bank == MEMORY_BANK.MEMORY_BANK_EPC;
reader.Actions.TagAccess.writeWait(tagId, writeAccessParams, null, tagData, true, useTIDfilter);
} catch (InvalidUsageException e) {
System.out.println("INVALID USAGE EXCEPTION: " + e.getInfo());
e.printStackTrace();
return false;
} catch (OperationFailureException e) {
//System.out.println("OPERATION FAILURE EXCEPTION");
System.out.println("OPERATION FAILURE EXCEPTION: " + e.getResults().toString());
e.printStackTrace();
return false;
}
return true;
}
With
Password being 00
sourceEPC being the Tag ID obtained after reading
Memory Bank being MEMORY_BANK.MEMORY_BANK_USER
target data being "8426017056458"
offset being 0
It just keeps giving me "GetStatus Write RFID_API_UNKNOWN_ERROR data(x)- Field can Only Take Word values" and I have no idea why this is the case, nor I know what a "Word value" is, and i've searched for it. This is all under the "OperationFailureException", as well. Any help would be appreciated, as there's almost no resources online for this kind of thing.
Even this question is a bit older, I had the same problem so as far as I know this should be the answer.
Your target data "8426017056458" length is 13 and at writeAccessParams.setWriteDataLength(writeData.length()/4)
you are devide it with four. Now if you are trying to write the target data it is longer than the determined WriteDataLength. And this throws the Error.
One 'word' is 4 Hex => 16 Bits long. So your Data have to be filled up first and convert it to Hex.
so I built a pi zero keyboard emulator as mentioned here:
https://www.rmedgar.com/blog/using-rpi-zero-as-keyboard-setup-and-device-definition
I make it type text that it reads from a local text-file (everything developed in java - for reasons :) ).
My problem now is that the configured keysets on the various computers my pi zero is attached to differ very much (german, english, french, ...). Depending on the computer this leads to several typing mistakes (e.g., z instead of y).
So I now built some "translation tables" that map characters to the keycodes fitting to the computer. Such a table looks like this:
public scancodes_en_us() {
//We have (Character, (scancode, modifier))
table.put("a",Pair.create("4","0"));
table.put("b",Pair.create("5","0"));
table.put("c",Pair.create("6","0"));
table.put("d",Pair.create("7","0"));
table.put("e",Pair.create("8","0"));
table.put("f",Pair.create("9","0"));
table.put("g",Pair.create("10","0"));
table.put("h",Pair.create("11","0"));
table.put("i",Pair.create("12","0"));
table.put("j",Pair.create("13","0"));
table.put("k",Pair.create("14","0"));
table.put("l",Pair.create("15","0"));
table.put("m",Pair.create("16","0"));
table.put("n",Pair.create("17","0"));
table.put("o",Pair.create("18","0"));
table.put("p",Pair.create("19","0"));
table.put("q",Pair.create("20","0"));
table.put("r",Pair.create("21","0"));
table.put("s",Pair.create("22","0"));
table.put("t",Pair.create("23","0"));
table.put("u",Pair.create("24","0"));
table.put("v",Pair.create("25","0"));
table.put("w",Pair.create("26","0"));
table.put("x",Pair.create("27","0"));
table.put("y",Pair.create("28","0"));
table.put("z",Pair.create("29","0"));
table.put("A",Pair.create("4","2"));
table.put("B",Pair.create("5","2"));
table.put("C",Pair.create("6","2"));
table.put("D",Pair.create("7","2"));
table.put("E",Pair.create("8","2"));
table.put("F",Pair.create("9","2"));
table.put("G",Pair.create("10","2"));
table.put("H",Pair.create("11","2"));
table.put("I",Pair.create("12","2"));
table.put("J",Pair.create("13","2"));
table.put("K",Pair.create("14","2"));
table.put("L",Pair.create("15","2"));
table.put("M",Pair.create("16","2"));
table.put("N",Pair.create("17","2"));
table.put("O",Pair.create("18","2"));
table.put("P",Pair.create("19","2"));
table.put("Q",Pair.create("20","2"));
table.put("R",Pair.create("21","2"));
table.put("S",Pair.create("22","2"));
table.put("V",Pair.create("25","2"));
table.put("W",Pair.create("26","2"));
table.put("X",Pair.create("27","2"));
table.put("Y",Pair.create("28","2"));
table.put("Z",Pair.create("29","2"));
table.put("1",Pair.create("30","0"));
table.put("2",Pair.create("31","0"));
table.put("5",Pair.create("34","0"));
table.put("6",Pair.create("35","0"));
table.put("7",Pair.create("36","0"));
table.put("8",Pair.create("37","0"));
table.put("9",Pair.create("38","0"));
table.put("0",Pair.create("39","0"));
table.put("!",Pair.create("30","2"));
table.put("#",Pair.create("31","2"));
table.put("#",Pair.create("32","2"));
table.put("$",Pair.create("33","2"));
table.put("%",Pair.create("34","2"));
table.put("^",Pair.create("35","2"));
table.put("&",Pair.create("36","2"));
table.put("*",Pair.create("37","2"));
table.put("(",Pair.create("38","2"));
table.put(")",Pair.create("39","2"));
table.put(" ",Pair.create("44","0"));
table.put("-",Pair.create("45","0"));
table.put("=",Pair.create("46","0"));
table.put("[",Pair.create("47","0"));
table.put("]",Pair.create("48","0"));
table.put("\\",Pair.create("49","0"));
table.put(";",Pair.create("51","0"));
table.put("'",Pair.create("52","0"));
table.put("`",Pair.create("53","0"));
table.put(",",Pair.create("54","0"));
table.put(".",Pair.create("55","0"));
table.put("/",Pair.create("56","0"));
table.put("_",Pair.create("45","2"));
table.put("+",Pair.create("46","2"));
table.put("{",Pair.create("47","2"));
table.put("}",Pair.create("48","2"));
table.put("|",Pair.create("49","2"));
table.put(":",Pair.create("51","2"));
table.put("\"",Pair.create("52","2"));
table.put("~",Pair.create("53","2"));
table.put("<",Pair.create("54","2"));
table.put(">",Pair.create("55","2"));
table.put("?",Pair.create("56","2"));
Having such a table for many different keyboard layouts is a pain. Is there some more clever version to map a character to the scancode for a specific keyboard layout?
If not - is there some kind of archive where I can find such a character to scancode mapping for many different keyboard layouts?
Thank you very much
Look at how localization works, they all share the same approach: Create a special version for each localization as a property file, then have an abstract class to load the property based on locale.
You will develop a loader class like this:
public scancodes(Locale locale) {
// load locale property file or download if missing
// read the property and store to the table
ResourceBundle scanCodes = ResourceBundle.getBundle("codes",locale);
}
And your codes_locale looks like:
codes_de.properties
a=4,0
b=5,0
By doing this, you separate the locale specific character with your logic code, and you don't need to bundle all keyboards in side your app. You can download them as needed.
You can access a tutorial here
If I understood what you are trying to do correctly then you don't have to map anything at all, just use a pre-made format (like unicode which works for all languages I know of), just send a char code and translate it to it's matching char.
Example file reader - char interpreter:
JFileChooser fc = new JFileChooser();
fc.setFileSelectionMode(JFileChooser.FILES_ONLY);
fc.showOpenDialog(null);
File textFile = fc.getSelectedFile();
if(textFile.getName().endsWith(".txt")) {
System.out.println(textFile.getAbsolutePath());
FileInputStream input = new FileInputStream(textFile);
BufferedReader reader = new BufferedReader(new InputStreamReader(input, "UNICODE"));
char[] buffer = new char[input.available() / 2 - 1];
System.out.println("Bytes left: " + input.available());
int read = reader.read(buffer);
System.out.println("Read " + read + " characters");
for(int i = 0; i < read; i++) {
System.out.print("The letter is: " + buffer[i]);
System.out.println(", The key code is: " + (int) buffer[i]);
}
}
you can later use the key code to emulate a key press on your computer
For scan-code mappings you can visit following sites:
Keyboard scancodes
Scan Codes Demystified
My solution is to determine the list of keycode on runtime, it'll save you a lot of caffeine and headache
package test;
import java.util.HashMap;
import java.util.Map;
import javax.swing.KeyStroke;
public class Keycode {
/**
* List of chars, can be stored in file
* #return
*/
public String getCharsets() {
return "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSVWXYZ12567890!##$%^&*() -=[]\\;'`,./_+{}|:\\~<>?";
}
/**
* Determines the keycode on runtime
* #return
*/
public Map<Character, Integer> getScancode() {
Map<Character, Integer> table = new HashMap<>();
String charsets = this.getCharsets();
for( int index = 0 ; index < charsets.length() ; index++ ) {
Character currentChar = charsets.charAt(index);
KeyStroke keyStroke = KeyStroke.getKeyStroke(currentChar.charValue(), 0);
// only for example i've used Map, but you should populate it by your table
// table.put("a",Pair.create("4","0"));
table.put(currentChar, keyStroke.getKeyCode());
}
return table;
}
public static void main(String[] args) {
System.out.println(new Keycode().getScancode());
}
}
Ok I'll try and keep this short.
First let me explain exactly what I am trying to get. If you open Windows Explorer and go to a network drive there is a DFS tab there(must have DFS enabled VIA the servers on the network so it may not be there).
In that tab there is a list called the "Referral List"... I want what is in that box. I believe this is the DFS or UNC, you can correct me it will help me.
What I have is the \domainname.com\something$\BUS\blah\myDriveHome but this is tied to something else in that box that contains the actual server that that share is setting on and that share is what I need to run a compliance check.
I cannot use an exe that is not package with Windows 7 not any other exe as we cannot distribute exes.
So what have I done... a VERY thorough search for things like DFS/UNC paths from the command line, powershell, and registry and no go. Command line "net use" only return the linked path and not the server so that is useless.
I only ever post a question when I hit a wall that is taking up to much programming time.
If anyone has an info it would be grateful.
Thanks
I was able to steal the C# code in this answer here and make some modifications so it works with .Net 2.0, and use it within PowerShell:
$dfsCode = #'
using System;
using System.Runtime.InteropServices;
public static class Dfs
{
private enum NetDfsInfoLevel
{
DfsInfo1 = 1,
DfsInfo2 = 2,
DfsInfo3 = 3,
DfsInfo4 = 4,
DfsInfo5 = 5,
DfsInfo6 = 6,
DfsInfo7 = 7,
DfsInfo8 = 8,
DfsInfo9 = 9,
DfsInfo50 = 50,
DfsInfo100 = 100,
DfsInfo150 = 150,
}
[DllImport("netapi32.dll", SetLastError = true)]
private static extern int NetApiBufferFree(IntPtr buffer);
[DllImport("Netapi32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
private static extern int NetDfsGetInfo(
[MarshalAs(UnmanagedType.LPWStr)] string DfsEntryPath, // DFS entry path for the volume
[MarshalAs(UnmanagedType.LPWStr)] string ServerName, // This parameter is currently ignored and should be NULL
[MarshalAs(UnmanagedType.LPWStr)] string ShareName, // This parameter is currently ignored and should be NULL.
NetDfsInfoLevel Level, // Level of information requested
out IntPtr Buffer // API allocates and returns buffer with requested info
);
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
private struct DFS_INFO_3
{
[MarshalAs(UnmanagedType.LPWStr)]
public string EntryPath;
[MarshalAs(UnmanagedType.LPWStr)]
public string Comment;
public int State;
public int NumberOfStorages;
public IntPtr Storage;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
private struct DFS_STORAGE_INFO
{
public int State;
[MarshalAs(UnmanagedType.LPWStr)]
public string ServerName;
[MarshalAs(UnmanagedType.LPWStr)]
public string ShareName;
}
private static T GetStruct<T>(IntPtr buffer, int offset)where T:struct
{
T r = new T();
r = (T) Marshal.PtrToStructure((IntPtr)((long)buffer + offset * Marshal.SizeOf(r)), typeof(T));
return r;
}
public static string GetDfsInfo(string server)
{
string rval = null;
IntPtr b;
int r = NetDfsGetInfo(server, null, null, NetDfsInfoLevel.DfsInfo3, out b);
if(r != 0)
{
NetApiBufferFree(b);
// return passed string if not DFS
return rval;
}
DFS_INFO_3 sRes = GetStruct<DFS_INFO_3>(b,0);
if(sRes.NumberOfStorages > 0)
{
DFS_STORAGE_INFO sResInfo = GetStruct<DFS_STORAGE_INFO>(sRes.Storage,0);
rval = string.Concat(#"\\", sResInfo.ServerName, #"\", sResInfo.ShareName, #"\");
}
NetApiBufferFree(b);
return rval;
}
}
'#
Add-Type -TypeDefinition $dfsCode
[Dfs]::GetDfsInfo('\\ad.domain.com\Share')
This code will work with PowerShell 2.0 which is included with Windows 7.
I went another direction with the use of PSEXEC and DFSUtil to find the DFS info VIA the remote PC. Returns a lot of info but I filtered it in PowerShell after reading the file and matching the UNC. I would post the how to but I had to do some major adapting on my end with the info that is on a few other sites for DFSUtil and what to look for and PSExec. I will note this for PSEXEC:
cmd.exe /s /c C:\Temp\psexec.exe 2> $null
That "2> $null" will save you some headaches and your script crashing if the return is in the error channel. You will need to run it in the PS console though without that to catch the error, but when you have a script like mine performing 50+ system checks you don't want the whole thing to halt for just one error.
I'm experimenting with java flavored zmq to test the benefits of using PGM over TCP in my project. So I changed the weather example, from the zmq guide, to use the epgm transport.
Everything compiles and runs, but nothing is being sent or received. If I change the transport back to TCP, the server receives the messages sent from the client and I get the console output I'm expecting.
So, what are the requirements for using PGM? I changed the string, that I'm passing to the bind and connect methods, to follow the zmq api for zmq_pgm: "transport://interface;multicast address:port". That didn't work. I get and invalid argument error whenever I attempt to use this format. So, I simplified it by dropping the interface and semicolon which "works", but I'm not getting any results.
I haven't been able to find a jzmq example that uses pgm/epgm and the api documentation for the java binding does not define the appropriate string format for an endpoint passed to bind or connect. So what am I missing here? Do I have to use different hosts for the client and the server?
One thing of note is that I'm running my code on a VirtualBox VM (Ubuntu 14.04/OSX Mavericks host). I'm not sure if that has anything to do with the issue I'm currently facing.
Server:
public class wuserver {
public static void main (String[] args) throws Exception {
// Prepare our context and publisher
ZMQ.Context context = ZMQ.context(1);
ZMQ.Socket publisher = context.socket(ZMQ.PUB);
publisher.bind("epgm://xx.x.x.xx:5556");
publisher.bind("ipc://weather");
// Initialize random number generator
Random srandom = new Random(System.currentTimeMillis());
while (!Thread.currentThread ().isInterrupted ()) {
// Get values that will fool the boss
int zipcode, temperature, relhumidity;
zipcode = 10000 + srandom.nextInt(10000) ;
temperature = srandom.nextInt(215) - 80 + 1;
relhumidity = srandom.nextInt(50) + 10 + 1;
// Send message to all subscribers
String update = String.format("%05d %d %d", zipcode, temperature, relhumidity);
publisher.send(update, 0);
}
publisher.close ();
context.term ();
}
}
Client:
public class wuclient {
public static void main (String[] args) {
ZMQ.Context context = ZMQ.context(1);
// Socket to talk to server
System.out.println("Collecting updates from weather server");
ZMQ.Socket subscriber = context.socket(ZMQ.SUB);
//subscriber.connect("tcp://localhost:5556");
subscriber.connect("epgm://xx.x.x.xx:5556");
// Subscribe to zipcode, default is NYC, 10001
String filter = (args.length > 0) ? args[0] : "10001 ";
subscriber.subscribe(filter.getBytes());
// Process 100 updates
int update_nbr;
long total_temp = 0;
for (update_nbr = 0; update_nbr < 100; update_nbr++) {
// Use trim to remove the tailing '0' character
String string = subscriber.recvStr(0).trim();
StringTokenizer sscanf = new StringTokenizer(string, " ");
int zipcode = Integer.valueOf(sscanf.nextToken());
int temperature = Integer.valueOf(sscanf.nextToken());
int relhumidity = Integer.valueOf(sscanf.nextToken());
total_temp += temperature;
}
System.out.println("Average temperature for zipcode '"
+ filter + "' was " + (int) (total_temp / update_nbr));
subscriber.close();
context.term();
}
}
There are a couple possibilities:
You need to make sure ZMQ is compiled with the --with-pgm option: see here - but this doesn't appear to be your issue if you're not seeing "protocol not supported"
Using raw pgm requires root privileges because it requires the ability to create raw sockets... but epgm doesn't require that, so it shouldn't be your issue either (I only bring it up because you use the term "pgm/epgm", and you should be aware that they are not equally available in all situations)
What actually appears to be the problem in your case is that pgm/epgm requires support along the network path. In theory, it requires support out to your router, so your application can send a single message and have your router send out multiple messages to each client, but if your server is aware enough, it can probably send out multiple messages immediately and bypass this router support. The problem is, as you correctly guessed, trying to do this all on one host is not supported.
So, you need different hosts for client and server.
Another bit to be aware of is that some virtualization environments--RHEV/Ovirt and libvirt/KVM with the mac_filter option enabled come to mind-- that, by default, neuter one's abilities via (eb|ip)tables to utilize mcast between guests. With libvirt, of course, the solution is to simply set the option to '0' and restart libvirtd. RHEV/Ovirt require a custom plugin.
At any rate, I would suggest putting a sniffer on the network devices on each system you are using and watching to be sure traffic that is exiting the one host is actually visible on the other.