I'm using the below code to receive the messages using serial port event handler. But it dosent receives any.I am not getting errors. The code breaks in "string msg = comport.Readline()" Am i doing something wrong ?
public partial class SerialPortScanner : Form
{
private SerialPort comPort = new SerialPort();
public SerialPortScanner()
{
InitializeComponent();
comPort.Open();
comPort.DataReceived += new SerialDataReceivedEventHandler(comPort_DataReceived);
}
void comPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
if (comPort.IsOpen == true)
{
string msg = comPort.ReadLine();
MessageBox.Show(msg);
}
}
}
The DataReceived event is raised on a secondary thread when data is received from the SerialPort object. Because this event is raised on a secondary thread, and not the main thread, attempting to modify some elements in the main thread, such as UI elements, could raise a threading exception.
Source : Check this
ReadLine depends on having a NewLine character. You might have better luck with the Read method. See also the BytesToRead property.
Related
I am opening a socket in jmeter (using groovy in JSR223 Sampler), and storing the message in a jmeter variable. This is the below code:
SocketAddress inetSocketAddress = new InetSocketAddress(InetAddress.getByName("localhost"),4801);
def server = new ServerSocket()
server.bind(inetSocketAddress)
while(!vars.get("caseId"))) {
server.accept { socket ->
log.info('Someone is connected')
socket.withStreams { input, output ->
InputStreamReader isReader = new InputStreamReader(input);
BufferedReader reader = new BufferedReader(isReader);
StringBuffer sb = new StringBuffer();
String str;
while((str = reader.readLine())!= null){
sb.append(str);
}
String finalStr = sb.toString()
String caseId = finalStr.split("<caseId>")[1].split("</caseId>")[0]
vars.put("caseId", caseId)
}
log.info("Connection processed")
}
}
if(vars.get("caseId"))
{
try
{
server.close();
vars.put("socketClose",true);
}
catch(Exception e)
{
log.info("Error in closing the socket: " + e.getMessage());
}
}
Now, there is some time delay between the first loop is executed and the message being recieved from the port. It doesnt receive the message immediately, and hence while loop is executed again. And then message is received and it sets caseId. It goes on to close the socket, because caseId is set. And that is throwing the error, because socket is still waiting for the message. So is there a way, to wait until socket has recieved all the messages, so i could properly close it?
Or just force close the socket, and Jmeter wont throw any exception?
Or when i execute next component, say IF controller in Jmeter, it waits until variable socketClose is set true? In that way, instead of while loops inside JSR223 sampler, i could use multiple If Controllers in Jmeter thread.
This is how ServerSocket.close() function works
public void close()
throws IOException
Closes this socket. Any thread currently blocked in accept() will throw a SocketException.
I don't think there is a way "to wait until socket has recieved all the messages" because Socket is dump as a rock and it can either listen for connections or shut down.
Maybe you might be interested in setSoTimeout() function?
Also this line:
vars.put("socketClose",true)
is very suspicious, I think you need to change it either to:
vars.put("socketClose", "true")
or to
vars.putObject("socketClose",true)
as JMeterVariables.put() function can accept only a String, see Top 8 JMeter Java Classes You Should Be Using with Groovy article for more details.
I have a StreamSocket in UWP and I send my messages like this using a DataWriter object using the StoreAsync() method:
public static async Task<bool> SendNetworkMessage(NetworkMember member, NetworkMessage message)
{
DataWriter writer = member.DataWriter;
//Check that writer is not null
if (writer != null)
{
try
{
//Serialize Message
string stringToSend = SerializeObject<NetworkMessage>(message);
//Send Message Length
writer.WriteUInt32(writer.MeasureString(stringToSend));
//Send Message
writer.WriteString(stringToSend);
await writer.StoreAsync();
return true;
}
catch (Exception e)
{
Debug.WriteLine("DataWriter failed because of " + e.Message);
Debug.WriteLine("");
Disconnect(member);
OnMemberDisconnectedEvent(member);
return false;
}
}
else { return false; }
}
All is well, the only problem is that I don't know if a connection went down.
Now I want to check my connection using a DispatcherTimer like this:
private static async void NetworkTimer_Tick(object sender, object e)
{
foreach (NetworkMember member in networkMemberCollection)
{
if (member.Connected == true && member.Disconnecting == false)
{
await SendNetworkMessage(member, new PingMessage());
}
}}
However, this is causing timing issues which is causing ObjectDisposedExceptions on the DataWriter. It seems that the DispatcherTimer thread cannot use the StreamSocket when I send a message from a different thread. My question is: How can I make sure the Ping is sent each time but that SendNetworkMessage operations are done in order instead of overlapping?
Thanks
It seems that the DispatcherTimer thread cannot use the StreamSocket when I send a message from a different thread.
How can I make sure the Ping is sent each time but that SendNetworkMessage operations are done in order instead of overlapping?
It's possible, and I think your code using foreach and await operation can ensure the work of sending message in order.
the only problem is that I don't know if a connection went down.
If you want to know if the connection went down, you can refer to Handling WinRT StreamSocket disconnects (both server and client side).
I am wondering how to shutdown JeroMQ properly, so far I know three methods that all have their pro and cons and I have no clue which one is the best.
The situation:
Thread A: owns context, shall provide start/stop methods
Thread B: actual listener thread
My current method:
Thread A
static ZContext CONTEXT = new ZContext();
Thread thread;
public void start() {
thread = new Thread(new B()).start();
}
public void stop() {
thread.stopping = true;
thread.join();
}
Thread B
boolean stopping = false;
ZMQ.Socket socket;
public void run() {
socket = CONTEXT.createSocket(ROUTER);
... // socket setup
socket.setReceiveTimeout(10);
while (!stopping) {
socket.recv();
}
if (NUM_SOCKETS >= 1) {
CONTEXT.destroySocket(socket);
} else {
CONTEXT.destroy();
}
}
This works just great. 10ms to shutdown is no problem for me, but I will unnecessarily increase the CPU load when there are no messages received. At the moment I prefer this one.
The second method shares the socket between the two threads:
Thread A
static ZContext CONTEXT = new ZContext();
ZMQ.Socket socket;
Thread thread;
public void start() {
socket = CONTEXT.createSocket(ROUTER);
... // socket setup
thread = new Thread(new B(socket)).start();
}
public void stop() {
thread.stopping = true;
CONTEXT.destroySocket(socket);
}
Thread B
boolean stopping = false;
ZMQ.Socket socket;
public void run() {
try {
while (!stopping) {
socket.recv();
}
} catch (ClosedSelection) {
// socket closed by A
socket = null;
}
if (socket != null) {
// close socket myself
if (NUM_SOCKETS >= 1) {
CONTEXT.destroySocket(socket);
} else {
CONTEXT.destroy();
}
}
}
Works like a charm, too, but even if recv is already blocking the exception does not get thrown sometimes. If I wait one millisecond after I started thread A the exception is always thrown. I don't know if this is a bug or just an effect of my misuse, as I share the socket.
"revite" asked this question before (https://github.com/zeromq/jeromq/issues/116) and got an answer which is the third solution:
https://github.com/zeromq/jeromq/blob/master/src/test/java/guide/interrupt.java
Summary:
They call ctx.term() and interrupt the thread blocking in socket.recv().
This works fine, but I do not want to terminate my whole context, but just this single socket. I would have to use one context per socket, so I were not able to use inproc.
Summary
At the moment I have no clue how to get thread B out of its blocking state other than using timeouts, share the socket or terminate the whole context.
What is the correct way of doing this?
It is often mentioned that you can just destroy the zmq context and anything sharing that context will exit, however this creates a nightmare because your exiting code has to do its best in avoiding a minefield of accidentally calling into dead socket objects.
Attempting to close the socket doesn't work either because they are not thread safe and you'll end up with crashes.
ANSWER: The best way is to do as the ZeroMQ guide suggests for any use via multiple threads; use zmq sockets and not thread mutexes/locks/etc. Set up an additional listener socket that you'll connect&send something to on shutdown, and your run() should used a JeroMQ Poller to check which of your two sockets receive anything - if the additional socket receives something then exit.
Old question, but just in case...
I'd recommend checking out ZThread source. You should be able to create an instance of IAttachedRunnable that you can pass to the fork method, and the run method of your instance will be passed a PAIR socket and execute in another thread, while the fork will return the connected PAIR socket to use for communicating with the PAIR socket that your IAttachedRunnable got.
Check out the jeromq source here, even when you're doing a "blocking" recv, you're still burning CPU the entire time (the thread never sleeps). If you're worried about that, have the second thread sleep between polling and let the parent thread interrupt. Something like (just the relevant portions):
Thread A
public void stop() {
thread.interrupt();
thread.join();
}
Thread B
while (!Thread.interrupted()) {
socket.recv(); // do whatever
try {
Thread.sleep(10); //milliseconds
} catch (InterruptedException e) {
break;
}
}
Also, with regard to your second solution, in general you should not share sockets between threads - the zeromq guide is pretty clear on this - "Don't share ØMQ sockets between threads. ØMQ sockets are not threadsafe." Remember that a major use for ZMQ is IPC - threads communicating through connected sockets, not sharing the same end of one socket. No need for things like shared boolean stop variables.
Ciao, I have tested in several ways, but I'm still unable to test and verify the Event expiration mechanism in Drools Fusion, so I'm looking for some little guidance, please?
I've read the manual and I'm interested in this feature:
In other words, one an event is inserted into the working memory, it is possible for the engine to find out when an event can no longer match other facts and automatically retract it, releasing its associated resources.
I'm using the Drools IDE in Eclipse, 5.4.0.Final and I modified the template code created by the "New Drools Project" wizard to test and verify for Event expiration.
The code below. The way I understood to make the "lifecycle" to work correctly is that:
You must setup the KBase in STREAM mode - check
You must Insert the Events in temporal order - check
You must define temporal constraints between Events - check in my case is last Message()
However, when I inspect the EventFactHandle at the end, none of the Event() has expired.
Thanks for your help.
Java:
public class DroolsTest {
public static final void main(String[] args) {
try {
KnowledgeBase kbase = readKnowledgeBase();
// I do want the pseudo clock
KnowledgeSessionConfiguration conf = KnowledgeBaseFactory.newKnowledgeSessionConfiguration();
conf.setOption(ClockTypeOption.get("pseudo"));
StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession(conf, null);
SessionPseudoClock clock = ksession.getSessionClock();
KnowledgeRuntimeLogger logger = KnowledgeRuntimeLoggerFactory.newFileLogger(ksession, "test");
// Insert of 2 Event:
Message message = new Message();
message.setMessage("Message 1");
message.setStatus(Message.HELLO);
ksession.insert(message);
ksession.fireAllRules();
clock.advanceTime(1, TimeUnit.DAYS);
Message message2 = new Message();
message2.setMessage("Message 2");
message2.setStatus(Message.HELLO);
ksession.insert(message2);
ksession.fireAllRules();
clock.advanceTime(1, TimeUnit.DAYS);
ksession.fireAllRules();
// Now I do check what I have in the working memory and if EventFactHandle if it's expired or not:
for (FactHandle f : ksession.getFactHandles()) {
if (f instanceof EventFactHandle) {
System.out.println(((EventFactHandle)f)+" "+((EventFactHandle)f).isExpired());
} else {
System.out.println("not an Event: "+f);
}
}
logger.close();
} catch (Throwable t) {
t.printStackTrace();
}
}
private static KnowledgeBase readKnowledgeBase() throws Exception {
KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();
kbuilder.add(ResourceFactory.newClassPathResource("Sample.drl"), ResourceType.DRL);
KnowledgeBuilderErrors errors = kbuilder.getErrors();
if (errors.size() > 0) {
for (KnowledgeBuilderError error: errors) {
System.err.println(error);
}
throw new IllegalArgumentException("Could not parse knowledge.");
}
KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();
kbase.addKnowledgePackages(kbuilder.getKnowledgePackages());
// following 2 lines is the template code modified for STREAM configuration
KnowledgeBaseConfiguration config = KnowledgeBaseFactory.newKnowledgeBaseConfiguration();
config.setOption( EventProcessingOption.STREAM );
return kbase;
}
/*
* This is OK from template, as from the doc:
* By default, the timestamp for a given event is read from the Session Clock and assigned to the event at the time the event is inserted into the working memory.
*/
public static class Message {
public static final int HELLO = 0;
public static final int GOODBYE = 1;
private String message;
private int status;
public String getMessage() {
return this.message;
}
public void setMessage(String message) {
this.message = message;
}
public int getStatus() {
return this.status;
}
public void setStatus(int status) {
this.status = status;
}
}
}
Drools:
package com.sample
import com.sample.DroolsTest.Message;
declare Message
#role(event)
end
declare window LastMessageWindow
Message() over window:length(1)
end
rule "Hello World"
when
accumulate( $m : Message(status==Message.HELLO) from window LastMessageWindow,
$messages : collectList( $m ) )
then
System.out.println( ((Message)$messages.get(0)).getMessage() );
end
Please note: even if I add expiration of 1second to the Message event, by
#expires(1s)
I still don't get the expected result that the very first Message event inserted, I would have expected is now expired? Thanks for your help.
Found solution! Obviously it was me being stupid and not realizing I was using Drools 5.4.0.Final while still referring to old documentation of 5.2.0.Final. In the updated documentation for Drools Fusion 5.4.0.Final, this box is added for 2.6.2. Sliding Length Windows:
Please note that length based windows do not define temporal constraints for event expiration from the session, and the engine will not consider them. If events have no other rules defining temporal constraints and no explicit expiration policy, the engine will keep them in the session indefinitely.
Therefore the 3rd requirement I originally enlisted of "You must define temporal constraints between Events" is obviously NOT met because I now understand Sliding Length Window in Drools 5.4.0.Final:
Message() over window:length(1)
are indeed NOT a definition of a temporal constraints for event expiration from the session.
Updating this answer hopefully somebody will find it helpful. Also, just so for your know, me being stupid actually for relying on googling in order to reach the doc, and sometimes you don't get redirected to the current release documentation, so it seems...
I'm having an issue using sockets in flash builder 4. The code below sends a set of bytes to a receiving c# sockerServer. If I dismiss the error I get in flash builder manually, the bytes are sent fine and all comes across as it should on 127.0.0.1:10. Now if I could just get the same results without an error being displayed in Flex.
So, I have two questions:
1) Why does it return an error when I try to close the socket? See closeConnection() below for context. I tried flushing it just before which didn't help.
2) Why is nothing sent when I use socket.flush()?
package
{
import flash.events.IOErrorEvent;
import flash.net.Socket;
import flash.utils.ByteArray;
public class socketClient
{
private var socket:Socket;
public function openConnection(address:String, port:int):void
{
if (socket != null && socket.connected)
socket.close();
socket = new Socket();
try {
socket.connect( address, port );
}
catch( e:Error ) { }
}
public function sendProtocol(p:socketProtocol):void {
//p.serialize() gets me a bunch of bytes in a ByteArray
var buffer:ByteArray = p.serialize();
socket.writeBytes(buffer, 0, buffer.length);
//Nothing happens when I flush
socket.flush();
}
public function closeConnection():void {
//As soon as I get to socket.close(), I get this
//"Unhandled IOErrorEvent:. text=Error #2031: Socket Error."
socket.close();
}
}
}
I use the class like this:
var socket:socketClient = new socketClient();
//works fine, I see the connection on the server
socket.openConnection("127.0.0.1", 10);
//no errors, but nothing sent
socket.sendProtocol(protocol);
//returns the error. (if manually dismissed, data is sent)
socket.closeConnection();
I finally solved it after hammering this one since I posted the question.
I had to add a
socket.addEventListener(flash.events.Event.CLOSE, closeHandler)
and do the socket.close() from there.