I have a C program and that runs a web server. I have a Air Application and I want to communicate with that web server using Air Application. I create a socket object and do the following.
public function httpTest():void
{
sock.addEventListener(Event.CONNECT, onConnect);
sock.addEventListener(ProgressEvent.SOCKET_DATA, onDataRecv);
sock.addEventListener(IOErrorEvent.IO_ERROR, onError);
try
{
trace("Connecting...");
sock.connect("127.0.0.1", 9800);
sock.writeMultiByte("GET /Connection?data=version", "us-ascii");
sock.flush();
}
catch(err:Error)
{
trace(err.message);
}
}
public function onConnect(event:Event):void
{
trace("onConnect +");
}
public function onDataRecv(event:ProgressEvent):void
{
trace("onDataRecv +");
}
public function onError(event:Event):void
{
trace("onError +");
}
socket connects successfully and its connection event is fired. but when I try to request the connection url nothing is received on server side. am I missing something. Thanks
Like just about everything to do with networking in Flex, socket.connect is asynchronous and non-blocking, meaning that just because sock.connect has returned without error it doesn't mean the socket is actually ready for use yet. I suspect that if you put trace(sock.connected) in your original code after your call to writeMultiByte it will print false.
You will need to delay your sock.writeMultiByte call until the connection is ready, which isn't until your onConnect handler fires. Try:
try
{
trace("Connecting...");
sock.connect("127.0.0.1", 9800);
}
catch(err:Error)
{
trace(err.message);
}
...
public function onConnect(event:Event):void
{
trace("onConnect +");
sock.writeMultiByte("GET /Connection?data=version", "us-ascii");
sock.flush();
}
I made a mistake. I did not add HTTP version and string terminator in the Get String. Thats why I did not receive any print on server side. Because the request was invalid. I posted the working code. Thanks for help.
public function httpTest():void
{
sock.addEventListener(Event.CONNECT, onConnect);
sock.addEventListener(ProgressEvent.SOCKET_DATA, onDataRecv);
sock.addEventListener(IOErrorEvent.IO_ERROR, onError);
try
{
trace("Connecting...");
sock.connect("127.0.0.1", 9800);
sock.writeMultiByte("GET /Connection?data=version HTTP/1.0\r\n\r\n", "us-ascii");
sock.flush();
}
catch(err:Error)
{
trace(err.message);
}
}
public function onConnect(event:Event):void
{
trace("onConnect +");
}
public function onDataRecv(event:ProgressEvent):void
{
trace("onDataRecv +");
}
public function onError(event:Event):void
{
trace("onError +");
}
Related
I have a HTTPPUT request that is not being called. I have a similar put request that manages another tab and it works. Both pages are pretty identical. I don't know what I am doing wrong.
I have tried almost everything and don't know what else to try.
controller:
[HttpPut]
[Route("updateAllocations({type})")]
public IHttpActionResult UpdateAllocations(string type, T_LOC entity)
{
System.Diagnostics.Debug.WriteLine("inside");
_allocationsService.UpdateAllocations(type,entity);
return Ok();
}
interface:
using OTPS.Core.Objects;
using System.Collections.Generic;
using OTPS.Core.Models;
namespace OTPS.Core.Interfaces
{
public interface IAllocationsService
{
void UpdateAllocations(string type, T_LOC entity);
}
}
service:
public void UpdateAllocations(string type, T_LOC entity)
{
System.Diagnostics.Debug.WriteLine("inside");
}
CLIENT SIDE:
public updateAllocation(type: string , entity) {
console.log("sdfsdf")
console.log(`${this.baseUrl}/api/allocations/updateAllocations(${type})`)
return this.http.put(`${this.baseUrl}/api/allocations/updateAllocations({type})`, entity, { headers: this.headers, withCredentials: true })
.pipe(catchError((error: Error) => {
console.log("sdfasd111111sdf")
return this.errorService.handleError(error);
}));
}
I am expecting the clinet side to call the put request before making any further logic but the print on server side never gets called..
Make sure that you subscribe to the service method inside component:
this.myService.updateAllocation(type, entity).subscribe( response => {
// do something here with response
});
You must call subscribe() or nothing happens. Just calling
Service method does not initiate the PUT/DELETE/POST/GET request.
Always subscribe!
An HttpClient method does not begin its HTTP request until you call
subscribe() on the observable returned by that method. This is true
for all HttpClient methods.
I have a streaming service that indefinitely streams from the server to a client until the client cancels.
On the server side, I have a thread that populates an ehcache with data sourced from a database.
Ehcache provides callbacks on cache events, i.e, when an item is added, when an item is removed, etc. I only care about notifying clients when an element is put into the cache, so when a client connects to my gRPC service, I register a notifyElementPut() callback with the cache, that has a reference to the connected clients StreamObserver:
public class GrpcAwareCacheEventListener extends CacheEventListenerAdapter {
private StreamObserver<FooUpdateResponse> responseObserver;
public GrpcAwareCacheEventListener(
StreamObserver<FooUpdateResponse> responseObserver) {
this.responseObserver = responseObserver;
}
#Override
public void notifyElementPut(Ehcache cache, Element element) throws CacheException {
Foo foo = (Foo) element.getObjectValue();
if (foo != null) {
responseObserver.onNext(
FooResponse.newBuilder().setFoo(foo).build());
}
}
}
My streaming foo service is as follows:
public void streamFooUpdates(Empty request,
StreamObserver<FooResponse> responseObserver) {
final CacheEventListener eventListener = new GrpcAwareCacheEventListener(responseObserver);
fooCache.getCacheEventNotificationService().registerListener(eventListener);
Context.current().withCancellation().addListener(new CancellationListener() {
public void cancelled(Context context) {
log.info("inside context cancelled callback");
fooCache.getCacheEventNotificationService().unregisterListener(eventListener);
}
}, ForkJoinPool.commonPool());
}
This all works fine, the client is notified of all foo updates as long as he is connected.
However, after the client disconnects or explicitly cancels the call, I expect that the server's Context's cancellation listener would fire, unregistering the callback with the cache.
This is not the case, regardless of whether the client shutdowns the channel, or explicitly cancels the call. (I expect the server side cancelled context to fire for both of these events). I'm wondering if my cancel semantics on the client side are incorrect, here is the my client code, taken from a test case:
Channel channel = ManagedChannelBuilder.forAddress("localhost", 25001)
.usePlaintext().build();
FooServiceGrpc.FooService stub = FooServiceGrpc
.newStub(channel);
ClientCallStreamObserver<FooResponse> cancellableObserver = new ClientCallStreamObserver<FooResponse>(){
public void onNext(FooResponse response) {
log.info("received foo: {}", response.getFoo());
}
public void onError(Throwable throwable) {
}
public void onCompleted() {
}
public boolean isReady() {
return false;
}
public void setOnReadyHandler(Runnable runnable) {
}
public void disableAutoInboundFlowControl() {
}
public void request(int i) {
}
public void setMessageCompression(boolean b) {
}
public void cancel(#Nullable String s, #Nullable Throwable throwable) {
}
};
stub.streamFooUpdates(Empty.newBuilder().build(), cancellableObserver);
Thread.sleep(10000); // sleep 10 seconds while messages are received.
cancellableObserver.cancel("cancelling from test", null); //explicit cancel
((ManagedChannel) chan).shutdown().awaitTermination(5, TimeUnit.SECONDS); //shutdown as well, for good measure.
Thread.sleep(7000); //channel should be shutdown by now.
}
I'm wondering why the server is not firing the "Context cancelled" callback.
Thanks!
You are not cancelling the client call correctly. The StreamObserver on the second argument of stub.streamFooUpdates() is your callback. You shouldn't call anything on that StreamObserver.
There are two ways to cancel the call from the client-side.
Option 1: Pass a ClientResponseObserver as the second argument, implement beforeStart(), which gives you a ClientCallStreamObserver, on which you can call cancel().
Option 2: Run stub.streamFooUpdates() inside a CancellableContext, and cancel the Context to cancel the call. Note that a CancellableContext must be always be cancelled, that's what the finally block is for.
CancellableContext withCancellation = Context.current().withCancellation();
try {
withCancellation.run(() -> {
stub.streamFooUpdates(...);
Thread.sleep(10000);
withCancellation.cancel(null);
});
} finally {
withCancellation.cancel(null);
}
SignalR does not have the ability to have client methods which returns a value. So I am trying to create a helper class to make this possible.
So this is what I am trying to do:
Server side: Call client method and provide unique request id Client(clientId).GetValue(requestId)
Server side: Save requestId and wait for answer using ManualResetEvent
Client side: Inside void GetValue(Guid requestId) call server method hubProxy.Invoke("GetValueFinished", requestId, 10)
Server side: find waiting method by requestId => set return value => set signal
Server side: Method not longer waiting vor ManualResetEvent and returns retrieved value.
I am able to get it work unfortunately. Here is my code:
public static class MethodHandler
{
private static ConcurrentDictionary<Guid, ReturnWaiter> runningMethodWaiters = new ConcurrentDictionary<Guid,ReturnWaiter>();
public static TResult GetValue<TResult>(Action<Guid> requestValue)
{
Guid key = Guid.NewGuid();
ReturnWaiter returnWaiter = new ReturnWaiter(key);
runningMethodWaiters.TryAdd(key, returnWaiter);
requestValue.Invoke(key);
returnWaiter.Signal.WaitOne();
return (TResult)returnWaiter.Value;
}
public static void GetValueResult(Guid key, object value)
{
ReturnWaiter waiter;
if (runningMethodWaiters.TryRemove(key, out waiter))
{
waiter.Value = value;
}
}
}
internal class ReturnWaiter
{
private ManualResetEvent _signal = new ManualResetEvent(false);
public ManualResetEvent Signal { get { return _signal; } }
public Guid Key {get; private set;}
public ReturnWaiter(Guid key)
{
Key = key;
}
private object _value;
public object Value
{
get { return _value; }
set
{
_value = value;
Signal.Set();
}
}
}
Using this MethodHandler class I need to have two method server side:
public int GetValue(string clientId)
{
return MethodHandler.GetValue<int>(key => Clients(clientId).Client.GetValue(key));
}
public void GetValueResult(Guid key, object value)
{
MethodHandler.GetValueResult(key, value);
}
Client side implementation is like this:
// Method registration
_hubProxy.On("GetValue", new Action<Guid>(GetValue));
public void GetValue(Guid requestId)
{
int result = 10;
_hubConnection.Invoke("GetValueResult", requestId, result);
}
PROBLEM:
if I call server side GetValue("clientid"). The client method will not be invoked. If I comment out returnWaiter.Signal.WaitOne();, client side GetValue is called and server side GetValueResult is called. But of course this time the method has already returned.
I thought is has to do with the ManualResetEvent but even using while(!returnWaiter.HasValue) Thread.Sleep(100); will not fix this issue.
Any ideas how to fix this issue?
Thanks in advance!
First, I think that, rather than asking for help in how to make it synchronous, it would be best if you just told us what it is you're trying to do so we could suggest a proper approach to do it.
You don't show your MethodHandler::Retrieve method, but I can guess pretty much what it looks like and it's not even the real problem. I have to tell you in the nicest possible way that this is a really bad idea. It will simply never scale. This would only work with a single SignalR server instance because you're relying on machine specific resources (e.g. kernel objects behind the ManualResetEvent) to provide the blocking. Maybe you don't need to scale beyond one server to meet your requirements, but this still a terrible waste of resources even on a single server.
You're actually on the right track with the client calling back with the requestId as a correlating identifier. Why can't you use that correlation to resume logical execution of whatever process you are in the middle of on the server side? That way no resources are held around while waiting for the message to be delivered to the client, processed and then the follow up message, GetValueResult in your sample, to be sent back a the server instance.
Problem solved:
The problem only occured in Hub.OnConnected and Hub.OnDisconnected. I don't have an exact explanation why, but probably these methods must be able to finish before it will handle your method call to the client.
So I changed code:
public override Task OnConnected()
{
// NOT WORKING
Debug.Print(MethodHandler.GetValue<int>(key => Clients(Context.ConnectionId).Client.GetValue(key)));
// WORKING
new Thread(() => Debug.Print(MethodHandler.GetValue<int>(key => Clients(Context.ConnectionId).Client.GetValue(key)))).Start();
return base.OnConnected();
}
I seem to be having a problem calling:
Clients.Others.SomeJavascriptFunction;
When I use
GlobalHost.ConnectionManager.GetHubContext("MyHub");
I seem to be only able to get this to work within a Hub.
Can anybody shed some light on this.
Regards
Mike
Update
After David's comment
I found that I could do the following:
public class MyHub1 : Hub
{
public static HubConnectionContext MyProperty { get; set; }
public void Start()
{
MyProperty = Clients;
}
}
Then call Start in my js
$.connection.hub.start().done(function () {
sig.server.start();
});
Which then allows me to call my function from my api controller
[HttpPost]
public SaveResult SaveChanges(JObject saveBundle) {
var changes = _contextProvider.SaveChanges(saveBundle);
var stuff = MyHub1.MyProperty;
stuff.Others.refreshToDos();
return changes;
}
Maybe a complete hack but seems to work.
Can anyone see any problems with this?
Others only makes sense when you have a connection id to exclude. Others is shorthand for Clients.AllExcept(Context.ConnectionId). When you're outside the hub there's no current connection id so you can't use Others.
You need to pass the connection id from the client to the API to want to use to do AllExcept.
I am evaluating SignalR (which happens to be used with Knockoutjs) to see if we can use it to notify clients of concurrency issues. Basically user "a" saves a record and users "b,c,d,e,f,g" are notified. I basically have an example working that notifies all clients. So I think I am almost there.
I came across this link and it lead me on the current path that I am on. I have also been looking at the documentation on Github.
Basically I want to exclude the a single client from the Clients.method() call. I dont see a way to loop through the clients and check the ClientId. The only other I can see to accomplish this is to maybe look at using the groups to keep track of it, but that seemed a little cumbersome, but I was having issues with that as well.
public class TicketHub : Hub
{
static int TotalTickets = 10;
public void GetTicketCount()
{
AddToGroup("ticketClients");
Clients.setTicketCount(TotalTickets);
}
public void BuyTicket()
{
if (TotalTickets > 0)
TotalTickets -= 1;
RemoveFromGroup("ticketClients");
// This will call the method ONLY on the calling client
// Caller.updateTicketCountWithNotification(TotalTickets);
// This will call the method on ALL clients in the group
Clients["ticketClients"].updateTicketCountNotify(TotalTickets);
AddToGroup("ticketClients");
Caller.updateTicketCountDontNotify(TotalTickets);
}
}
javascript code:
<script type="text/javascript">
$(document).ready(function () {
var test = $.connection.test;
$("#btnTest").click(function () {
test.testMethod();
});
test.show = function (text, guid) {
if (guid != test.guid) //notify all clients except the caller
alert(text);
};
$.connection.hub.start(function () { test.start(); });
});
</script>
Class :
public class Test : Hub
{
public void Start()
{
Caller.guid = Guid.NewGuid();
}
public void TestMethod()
{
Clients.show("test", Caller.guid);
}
}
If you want to exclude the caller from the call to the client side method you can use:
Clients.Others.clientSideMethod();
There is also Clients.AllExcept(...) that allows excluding certain people.