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  • ActiveMQ, timestamp for broker receiving the message to send

    - by StaxMan
    Ok, as per ActiveMQ docs, it appears that Message.getJMSTimestamp() returns time that client claims it sent the message (with its local clock). And that there is supposedly property "JMSActiveMQBrokerInTime" that is added to Message (see http://activemq.apache.org/activemq-message-properties.html). However, trying to access it on an ActiveMQ 4.1.2 installation gives an error. Does anyone know if this is something that was only added in 5.0 or later? Or is there some other explanation as to where it might have disappeared? Message.getPropertyNames() returns empty enumeration, which could indicate that nothing gets through.

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  • EventAggregator + Event Broker

    - by Kumar
    Anyone look at extending/integrating EventBroker in the EventAggregator in CAB/CAG ? Essentially looking at binding events based on string topics for binding publishers/subscribers in addition to the known event types defined in a common library !

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  • Grails external Jms broker (active mq)

    - by TheBigS
    I have what will become an 'external' activemq server I'd like grails to be able to talk to. Right now I am just running it on my dev box. Here is what I have setup right now: 1) Run activemq server 2) Run activemq/examples using ant to produce messages 3) View ActiveMQ admin site: http://localhost:8161/admin/queues.jsp verify that messages are in the queue. 4) Follow Mini Tutorial to create the Service and Controller: http://www.grails.org/ActiveMQ+Plugin 5) Configured my Grails resources.groovy file as follows: beans = { jmsConnectionFactory(SingleConnectionFactory){ targetConnectionFactory = { ActiveMQConnectionFactory cf -> brokerURL = 'tcp://localhost:61616' } } } When I run the grails app I get a BindException saying port 61616 is already in use. How do I configure this to use my server that is already running? I've tried changing 'localhost' to '127.0.0.1' and to my LAN ip, but no luck, it keeps trying to setup its own embedded activemq server. Any ideas?

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  • SQL Server service broker reporting as off when I have written a query to turn it on

    - by dotnetdev
    I have made a small ASP.NET website. It uses sqlcachedependency The SQL Server Service Broker for the current database is not enabled, and as a result query notifications are not supported. Please enable the Service Broker for this database if you wish to use notifications. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.InvalidOperationException: The SQL Server Service Broker for the current database is not enabled, and as a result query notifications are not supported. Please enable the Service Broker for this database if you wish to use notifications. Source Error: Line 12: System.Data.SqlClient.SqlDependency.Start(connString); This is the erroneous line in my global.asax. However, in sql server (2005), I enabled service broker like so (I connect and run the SQL Server service when I debug my site): ALTER DATABASE mynewdatabase SET ENABLE_BROKER with rollback immediate And this was successful. What am I missing? I am trying to use sql caching dependency and have followed all procedures. Thanks

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  • How do I securely buy a domain from a private party?

    - by Matt
    I have a domain I want. I found the owners contact information, and negotiated a price. Is there a domain brokerage service out there that would help me with the exchange. I don't want to send off money, and never hear from him again, and I'm sure it's likewise. I've found a lot of sites that carry collections of domains for sale, but I've already found mine, and contacted the owner. I just want a service to facilitate the hand-off. Has anyone used a service like this that they could recommend?

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  • How can I prevent application domain stealing?

    - by dr jerry
    I'm in the process of making a javascript application and I want to bring that online, lets call it mydesign. I'm living in the Netherlands so mydesign.nl can be mine. Now is mydesign.com available for sale by some domain broker sales bastards. And those bastards don't accept a first bid lower than 1000$ which is a about ten times of the budget I'm willing to pay. So far so good, it's a sick business model but it's there. Now lets imagine that mydesign.nl is a huge success in the Netherlands and I'm makin tons of profits out of advertisements and other things I'm not yet aware of (I know entering the lotery gives a better chance of earning money, but lets just imagine). Is there a way (licence, legal or otherwise) to prevent the sick owners of mydesign.com to download and steal my javascript app and deploy it on their own site and take the profits of my app?

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  • IF I have multiple candidate keys which one is a primary key and justify your choice ??

    - by zahrani
    Given R = { Account , Analyst , Assets, Broker, Client, Commission, Company, Dividend, Exchange, Investment, Office, Profile, Return, Risk_profile, Stock, Volume} and a set of functional dependencies F{fd1, fd2,fd3, fd4, fd5,fd6, fd7, fd8, fd9, fd10, fd11} where: fd1: Client - Office fd2: Stock - Exchange, Dividend fd3: Broker - Profile fd4: Company - Stock fd5: Client - Risk_profile, Analyst fd6: Analyst - Broker fd7: Stock, Broker - Invenstment, Volume fd8: Stock - Company fd9: Investment,Commission - Return fd10: Stock, Broker - Client fd11: Account - Assests these are candidate key(s) : (Account, Commission,Analyst ,Company) (Account, Commission,Analyst ,Stock) (Account ,Commission,Broker ,Company) (Account ,Commission,Broker ,Stock) (Account ,Commission,Client, Company) (Account ,Commission,Client ,Stock) (Q) Select a primary key and justify your choice ? I was select (Account ,Commission,Broker ,Stock) as a primary key ??? I chose that because it has the most direct dependencies compared to other ones. e.g. more attributes are functionally dependent on this primary key. please check if my answer is it true ? or Not I'm waiting your answer asap thank you

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  • A Communication System for XAML Applications

    - by psheriff
    In any application, you want to keep the coupling between any two or more objects as loose as possible. Coupling happens when one class contains a property that is used in another class, or uses another class in one of its methods. If you have this situation, then this is called strong or tight coupling. One popular design pattern to help with keeping objects loosely coupled is called the Mediator design pattern. The basics of this pattern are very simple; avoid one object directly talking to another object, and instead use another class to mediate between the two. As with most of my blog posts, the purpose is to introduce you to a simple approach to using a message broker, not all of the fine details. IPDSAMessageBroker Interface As with most implementations of a design pattern, you typically start with an interface or an abstract base class. In this particular instance, an Interface will work just fine. The interface for our Message Broker class just contains a single method “SendMessage” and one event “MessageReceived”. public delegate void MessageReceivedEventHandler( object sender, PDSAMessageBrokerEventArgs e); public interface IPDSAMessageBroker{  void SendMessage(PDSAMessageBrokerMessage msg);   event MessageReceivedEventHandler MessageReceived;} PDSAMessageBrokerMessage Class As you can see in the interface, the SendMessage method requires a type of PDSAMessageBrokerMessage to be passed to it. This class simply has a MessageName which is a ‘string’ type and a MessageBody property which is of the type ‘object’ so you can pass whatever you want in the body. You might pass a string in the body, or a complete Customer object. The MessageName property will help the receiver of the message know what is in the MessageBody property. public class PDSAMessageBrokerMessage{  public PDSAMessageBrokerMessage()  {  }   public PDSAMessageBrokerMessage(string name, object body)  {    MessageName = name;    MessageBody = body;  }   public string MessageName { get; set; }   public object MessageBody { get; set; }} PDSAMessageBrokerEventArgs Class As our message broker class will be raising an event that others can respond to, it is a good idea to create your own event argument class. This class will inherit from the System.EventArgs class and add a couple of additional properties. The properties are the MessageName and Message. The MessageName property is simply a string value. The Message property is a type of a PDSAMessageBrokerMessage class. public class PDSAMessageBrokerEventArgs : EventArgs{  public PDSAMessageBrokerEventArgs()  {  }   public PDSAMessageBrokerEventArgs(string name,     PDSAMessageBrokerMessage msg)  {    MessageName = name;    Message = msg;  }   public string MessageName { get; set; }   public PDSAMessageBrokerMessage Message { get; set; }} PDSAMessageBroker Class Now that you have an interface class and a class to pass a message through an event, it is time to create your actual PDSAMessageBroker class. This class implements the SendMessage method and will also create the event handler for the delegate created in your Interface. public class PDSAMessageBroker : IPDSAMessageBroker{  public void SendMessage(PDSAMessageBrokerMessage msg)  {    PDSAMessageBrokerEventArgs args;     args = new PDSAMessageBrokerEventArgs(      msg.MessageName, msg);     RaiseMessageReceived(args);  }   public event MessageReceivedEventHandler MessageReceived;   protected void RaiseMessageReceived(    PDSAMessageBrokerEventArgs e)  {    if (null != MessageReceived)      MessageReceived(this, e);  }} The SendMessage method will take a PDSAMessageBrokerMessage object as an argument. It then creates an instance of a PDSAMessageBrokerEventArgs class, passing to the constructor two items: the MessageName from the PDSAMessageBrokerMessage object and also the object itself. It may seem a little redundant to pass in the message name when that same message name is part of the message, but it does make consuming the event and checking for the message name a little cleaner – as you will see in the next section. Create a Global Message Broker In your WPF application, create an instance of this message broker class in the App class located in the App.xaml file. Create a public property in the App class and create a new instance of that class in the OnStartUp event procedure as shown in the following code: public partial class App : Application{  public PDSAMessageBroker MessageBroker { get; set; }   protected override void OnStartup(StartupEventArgs e)  {    base.OnStartup(e);     MessageBroker = new PDSAMessageBroker();  }} Sending and Receiving Messages Let’s assume you have a user control that you load into a control on your main window and you want to send a message from that user control to the main window. You might have the main window display a message box, or put a string into a status bar as shown in Figure 1. Figure 1: The main window can receive and send messages The first thing you do in the main window is to hook up an event procedure to the MessageReceived event of the global message broker. This is done in the constructor of the main window: public MainWindow(){  InitializeComponent();   (Application.Current as App).MessageBroker.     MessageReceived += new MessageReceivedEventHandler(       MessageBroker_MessageReceived);} One piece of code you might not be familiar with is accessing a property defined in the App class of your XAML application. Within the App.Xaml file is a class named App that inherits from the Application object. You access the global instance of this App class by using Application.Current. You cast Application.Current to ‘App’ prior to accessing any of the public properties or methods you defined in the App class. Thus, the code (Application.Current as App).MessageBroker, allows you to get at the MessageBroker property defined in the App class. In the MessageReceived event procedure in the main window (shown below) you can now check to see if the MessageName property of the PDSAMessageBrokerEventArgs is equal to “StatusBar” and if it is, then display the message body into the status bar text block control. void MessageBroker_MessageReceived(object sender,   PDSAMessageBrokerEventArgs e){  switch (e.MessageName)  {    case "StatusBar":      tbStatus.Text = e.Message.MessageBody.ToString();      break;  }} In the Page 1 user control’s Loaded event procedure you will send the message “StatusBar” through the global message broker to any listener using the following code: private void UserControl_Loaded(object sender,  RoutedEventArgs e){  // Send Status Message  (Application.Current as App).MessageBroker.    SendMessage(new PDSAMessageBrokerMessage("StatusBar",      "This is Page 1"));} Since the main window is listening for the message ‘StatusBar’, it will display the value “This is Page 1” in the status bar at the bottom of the main window. Sending a Message to a User Control The previous example sent a message from the user control to the main window. You can also send messages from the main window to any listener as well. Remember that the global message broker is really just a broadcaster to anyone who has hooked into the MessageReceived event. In the constructor of the user control named ucPage1 you can hook into the global message broker’s MessageReceived event. You can then listen for any messages that are sent to this control by using a similar switch-case structure like that in the main window. public ucPage1(){  InitializeComponent();   // Hook to the Global Message Broker  (Application.Current as App).MessageBroker.    MessageReceived += new MessageReceivedEventHandler(      MessageBroker_MessageReceived);} void MessageBroker_MessageReceived(object sender,  PDSAMessageBrokerEventArgs e){  // Look for messages intended for Page 1  switch (e.MessageName)  {    case "ForPage1":      MessageBox.Show(e.Message.MessageBody.ToString());      break;  }} Once the ucPage1 user control has been loaded into the main window you can then send a message using the following code: private void btnSendToPage1_Click(object sender,  RoutedEventArgs e){  PDSAMessageBrokerMessage arg =     new PDSAMessageBrokerMessage();   arg.MessageName = "ForPage1";  arg.MessageBody = "Message For Page 1";   // Send a message to Page 1  (Application.Current as App).MessageBroker.SendMessage(arg);} Since the MessageName matches what is in the ucPage1 MessageReceived event procedure, ucPage1 can do anything in response to that event. It is important to note that when the message gets sent it is sent to all MessageReceived event procedures, not just the one that is looking for a message called “ForPage1”. If the user control ucPage1 is not loaded and this message is broadcast, but no other code is listening for it, then it is simply ignored. Remove Event Handler In each class where you add an event handler to the MessageReceived event you need to make sure to remove those event handlers when you are done. Failure to do so can cause a strong reference to the class and thus not allow that object to be garbage collected. In each of your user control’s make sure in the Unloaded event to remove the event handler. private void UserControl_Unloaded(object sender, RoutedEventArgs e){  if (_MessageBroker != null)    _MessageBroker.MessageReceived -=         _MessageBroker_MessageReceived;} Problems with Message Brokering As with most “global” classes or classes that hook up events to other classes, garbage collection is something you need to consider. Just the simple act of hooking up an event procedure to a global event handler creates a reference between your user control and the message broker in the App class. This means that even when your user control is removed from your UI, the class will still be in memory because of the reference to the message broker. This can cause messages to still being handled even though the UI is not being displayed. It is up to you to make sure you remove those event handlers as discussed in the previous section. If you don’t, then the garbage collector cannot release those objects. Instead of using events to send messages from one object to another you might consider registering your objects with a central message broker. This message broker now becomes a collection class into which you pass an object and what messages that object wishes to receive. You do end up with the same problem however. You have to un-register your objects; otherwise they still stay in memory. To alleviate this problem you can look into using the WeakReference class as a method to store your objects so they can be garbage collected if need be. Discussing Weak References is beyond the scope of this post, but you can look this up on the web. Summary In this blog post you learned how to create a simple message broker system that will allow you to send messages from one object to another without having to reference objects directly. This does reduce the coupling between objects in your application. You do need to remember to get rid of any event handlers prior to your objects going out of scope or you run the risk of having memory leaks and events being called even though you can no longer access the object that is responding to that event. NOTE: You can download the sample code for this article by visiting my website at http://www.pdsa.com/downloads. Select “Tips & Tricks”, then select “A Communication System for XAML Applications” from the drop down list.

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  • Automating Etrade

    - by iAlexTsang
    Hey everyone, I was wondering how would I start programming an interface to trading stocks in Etrade in python. I am attempting to make an automated trading bot, but there is no api publicly available for automated trading with Etrade. Thanks in advance. ^^

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  • SQL Server JOIN with optional NULL values

    - by Paul McLoughlin
    Imagine that we have two tables as follows: Trades ( TradeRef INT NOT NULL, TradeStatus INT NOT NULL, Broker INT NOT NULL, Country VARCHAR(3) NOT NULL ) CTMBroker ( Broker INT NOT NULL, Country VARCHAR(3) NULL ) (These have been simplified for the purpose of this example). Now, if we wish to join these two tables on the Broker column, and if a country exists in the CTMBroker table on the Country, we have the following two choices: SELECT T.TradeRef,T.TradeStatus FROM Trades AS T JOIN CTMBroker AS B ON B.Broker=T.Broker AND ISNULL(B.Country, T.Country) = T.Country or SELECT T.TradeRef,T.TradeStatus FROM Trades AS T JOIN CTMBroker AS B ON B.Broker=T.Broker AND (B.COUNTRY=T.Country OR B.Country IS NULL) These are both logically equivalent, however in this specific circumstance for our database (SQL Server 2008, SP1) two different execution plans are produced for these two queries with the second version significantly outperforming the first version in terms of both time and logical reads. My question really is as follows: as a general rule would (2) be preferred to (1), or does this just happen to be exploiting some particular idiosyncracy of the optimiser in 2008 SP1 (that could therefore change with future versions of SQL Server).

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  • What happens when the server that the Remote Desktop Connection Broker goes down?

    - by Frank Owen
    I would like to setup the Remote Desktop Connection Broker to allow better load balancing of the two terminal servers we have as well as allowing the user to re-establish to the correct server if they get disconnected. My worry is, if I set this up and the server this service is running goes down, does the terminal server stop accepting connections or will they just lose the benefit of having RDCB turned on? I don't want to add another point of failure in this equation unless I have to.

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  • If my Remote Desktop Connection Broker server goes down, can users still access my two Terminal Servers?

    - by Frank Owen
    I would like to setup the Remote Desktop Connection Broker to allow better load balancing of the two terminal servers we have as well as allowing the user to re-establish to the correct server if they get disconnected. My worry is, if I set this up and the server this service is running goes down, does the terminal server stop accepting connections or will they just lose the benefit of having RDCB turned on? I don't want to add another point of failure in this equation unless I have to.

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  • ActiveMQ - "Cannot send, channel has already failed" every 2 seconds?

    - by quanta
    ActiveMQ 5.7.0 In the activemq.log, I'm seeing this exception every 2 seconds: 2013-11-05 13:00:52,374 | DEBUG | Transport Connection to: tcp://127.0.0.1:37501 failed: org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://127.0.0.1:37501 | org.apache.activemq.broker.TransportConnection.Transport | Async Exception Handler org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://127.0.0.1:37501 at org.apache.activemq.transport.AbstractInactivityMonitor.doOnewaySend(AbstractInactivityMonitor.java:282) at org.apache.activemq.transport.AbstractInactivityMonitor.oneway(AbstractInactivityMonitor.java:271) at org.apache.activemq.transport.TransportFilter.oneway(TransportFilter.java:85) at org.apache.activemq.transport.WireFormatNegotiator.oneway(WireFormatNegotiator.java:104) at org.apache.activemq.transport.MutexTransport.oneway(MutexTransport.java:68) at org.apache.activemq.broker.TransportConnection.dispatch(TransportConnection.java:1312) at org.apache.activemq.broker.TransportConnection.processDispatch(TransportConnection.java:838) at org.apache.activemq.broker.TransportConnection.iterate(TransportConnection.java:873) at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:129) at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:47) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) Due to this keyword InactivityIOException, the first thing comes to my mind is InactivityMonitor, but the strange thing is MaxInactivityDuration=30000: 2013-11-05 13:11:02,672 | DEBUG | Sending: WireFormatInfo { version=9, properties={MaxFrameSize=9223372036854775807, CacheSize=1024, CacheEnabled=true, SizePrefixDisabled=false, MaxInactivityDurationInitalDelay=10000, TcpNoDelayEnabled=true, MaxInactivityDuration=30000, TightEncodingEnabled=true, StackTraceEnabled=true}, magic=[A,c,t,i,v,e,M,Q]} | org.apache.activemq.transport.WireFormatNegotiator | ActiveMQ BrokerService[localhost] Task-2 Moreover, I also didn't see something like this: No message received since last read check for ... or: Channel was inactive for too (30000) long Do a netstat, I see these connections in TIME_WAIT state: tcp 0 0 127.0.0.1:38545 127.0.0.1:61616 TIME_WAIT - tcp 0 0 127.0.0.1:38544 127.0.0.1:61616 TIME_WAIT - tcp 0 0 127.0.0.1:38522 127.0.0.1:61616 TIME_WAIT - Here're the output when running tcpdump: Internet Protocol Version 4, Src: 127.0.0.1 (127.0.0.1), Dst: 127.0.0.1 (127.0.0.1) Version: 4 Header length: 20 bytes Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00: Not-ECT (Not ECN-Capable Transport)) 0000 00.. = Differentiated Services Codepoint: Default (0x00) .... ..00 = Explicit Congestion Notification: Not-ECT (Not ECN-Capable Transport) (0x00) Total Length: 296 Identification: 0x7b6a (31594) Flags: 0x02 (Don't Fragment) 0... .... = Reserved bit: Not set .1.. .... = Don't fragment: Set ..0. .... = More fragments: Not set Fragment offset: 0 Time to live: 64 Protocol: TCP (6) Header checksum: 0xc063 [correct] [Good: True] [Bad: False] Source: 127.0.0.1 (127.0.0.1) Destination: 127.0.0.1 (127.0.0.1) Transmission Control Protocol, Src Port: 61616 (61616), Dst Port: 54669 (54669), Seq: 1, Ack: 2, Len: 244 Source port: 61616 (61616) Destination port: 54669 (54669) [Stream index: 11] Sequence number: 1 (relative sequence number) [Next sequence number: 245 (relative sequence number)] Acknowledgement number: 2 (relative ack number) Header length: 32 bytes Flags: 0x018 (PSH, ACK) 000. .... .... = Reserved: Not set ...0 .... .... = Nonce: Not set .... 0... .... = Congestion Window Reduced (CWR): Not set .... .0.. .... = ECN-Echo: Not set .... ..0. .... = Urgent: Not set .... ...1 .... = Acknowledgement: Set .... .... 1... = Push: Set .... .... .0.. = Reset: Not set .... .... ..0. = Syn: Not set .... .... ...0 = Fin: Not set Window size value: 256 [Calculated window size: 32768] [Window size scaling factor: 128] Checksum: 0xff1c [validation disabled] [Good Checksum: False] [Bad Checksum: False] Options: (12 bytes) No-Operation (NOP) No-Operation (NOP) Timestamps: TSval 2304161892, TSecr 2304161891 Kind: Timestamp (8) Length: 10 Timestamp value: 2304161892 Timestamp echo reply: 2304161891 [SEQ/ACK analysis] [Bytes in flight: 244] Constrained Application Protocol, TID: 240, Length: 244 00.. .... = Version: 0 ..00 .... = Type: Confirmable (0) .... 0000 = Option Count: 0 Code: Unknown (0) Transaction ID: 240 Payload Content-Type: text/plain (default), Length: 240, offset: 4 Line-based text data: text/plain [truncated] \001ActiveMQ\000\000\000\t\001\000\000\000<DE>\000\000\000\t\000\fMaxFrameSize\006\177<FF><FF><FF><FF> <FF><FF><FF>\000\tCacheSize\005\000\000\004\000\000\fCacheEnabled\001\001\000\022SizePrefixDisabled\001\000\000 MaxInactivityDurationInitalDelay\006\ It is very likely a tcp port check. This is what I see when trying telnet from another host: 2013-11-05 16:12:41,071 | DEBUG | Transport Connection to: tcp://10.8.20.9:46775 failed: java.io.EOFException | org.apache.activemq.broker.TransportConnection.Transport | ActiveMQ Transport: tcp:///10.8.20.9:46775@61616 java.io.EOFException at java.io.DataInputStream.readInt(DataInputStream.java:375) at org.apache.activemq.openwire.OpenWireFormat.unmarshal(OpenWireFormat.java:275) at org.apache.activemq.transport.tcp.TcpTransport.readCommand(TcpTransport.java:229) at org.apache.activemq.transport.tcp.TcpTransport.doRun(TcpTransport.java:221) at org.apache.activemq.transport.tcp.TcpTransport.run(TcpTransport.java:204) at java.lang.Thread.run(Thread.java:662) 2013-11-05 16:12:41,071 | DEBUG | Transport Connection to: tcp://10.8.20.9:46775 failed: org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection.Transport | Async Exception Handler org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://10.8.20.9:46775 at org.apache.activemq.transport.AbstractInactivityMonitor.doOnewaySend(AbstractInactivityMonitor.java:282) at org.apache.activemq.transport.AbstractInactivityMonitor.oneway(AbstractInactivityMonitor.java:271) at org.apache.activemq.transport.TransportFilter.oneway(TransportFilter.java:85) at org.apache.activemq.transport.WireFormatNegotiator.oneway(WireFormatNegotiator.java:104) at org.apache.activemq.transport.MutexTransport.oneway(MutexTransport.java:68) at org.apache.activemq.broker.TransportConnection.dispatch(TransportConnection.java:1312) at org.apache.activemq.broker.TransportConnection.processDispatch(TransportConnection.java:838) at org.apache.activemq.broker.TransportConnection.iterate(TransportConnection.java:873) at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:129) at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:47) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) 2013-11-05 16:12:41,071 | DEBUG | Unregistering MBean org.apache.activemq:BrokerName=localhost,Type=Connection,ConnectorName=ope nwire,ViewType=address,Name=tcp_//10.8.20.9_46775 | org.apache.activemq.broker.jmx.ManagementContext | ActiveMQ Transport: tcp:/ //10.8.20.9:46775@61616 2013-11-05 16:12:41,073 | DEBUG | Stopping connection: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,073 | DEBUG | Stopping transport tcp:///10.8.20.9:46775@61616 | org.apache.activemq.transport.tcp.TcpTranspo rt | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,073 | DEBUG | Initialized TaskRunnerFactory[ActiveMQ Task] using ExecutorService: java.util.concurrent.Threa dPoolExecutor@23cc2a28 | org.apache.activemq.thread.TaskRunnerFactory | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Closed socket Socket[addr=/10.8.20.9,port=46775,localport=61616] | org.apache.activemq.transpo rt.tcp.TcpTransport | ActiveMQ Task-1 2013-11-05 16:12:41,074 | DEBUG | Forcing shutdown of ExecutorService: java.util.concurrent.ThreadPoolExecutor@23cc2a28 | org.apache.activemq.util.ThreadPoolUtils | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Stopped transport: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Connection Stopped: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,902 | DEBUG | Sending: WireFormatInfo { version=9, properties={MaxFrameSize=9223372036854775807, CacheSize=1024, CacheEnabled=true, SizePrefixDisabled=false, MaxInactivityDurationInitalDelay=10000, TcpNoDelayEnabled=true, MaxInactivityDuration=30000, TightEncodingEnabled=true, StackTraceEnabled=true}, magic=[A,c,t,i,v,e,M,Q]} | org.apache.activemq.transport.WireFormatNegotiator | ActiveMQ BrokerService[localhost] Task-5 So the question is: how can I find out the process that is trying to connect to my ActiveMQ (from localhost) every 2 seconds?

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  • how can I send messages to/from a Websphere Message Broker from an embedded C client (no JVM)?

    - by queBurro
    What are my options for pubsubing (or point to point but pubsub is better) messages to and from an IBM message broker from an embedded headless C/C++ linux client that doesn't have a JVM? Ideally we want large file transfer (2GB once per day off of the client) encryption (SSL) reliable ('assured' delivery / QoS2, maybe QoS1 would do) The client in question currently only has exes and some bash scripts, I've been playing with MQTTv3 and RSMB, but for that I'd have to chomp the large files up (and reassemble back home) and I don't want to get into that if there's a transport that will do this for me? I've looked at MQTTv5 (but our client's got no JVM); JMS (no JVM) and XMS? which again looks like it gives me a C API but then needs the JVM to be installed on the client (or am I wrong?) any clues or hints would be appreciated, cheers

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  • Which JMS broker implementations allowing resending messages saved in dead message queue?

    - by marabol
    I wonder, if there JMS broker, that allows administrators to resend (via GUI or any tool) messages, saved in a ded message queue or dead letter queue, after solving the causing problem (e.g. database is down, not enough space...). WebSphere provide a feature to resend messages saved in dead letter queue: 1 Glassfish 2.1.1 using Sun Java System Message Queue 4.4 has no feature to do this, I think so. What are the options on other JMS brokers? Or is the best way, not to use the DMQ/DLQ feature, if you are depend on a message? Thanks a lot

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  • Queue remote calls to a Python Twisted perspective broker?

    - by agartland
    The strength of Twisted (for python) is its asynchronous framework (I think). I've written an image processing server that takes requests via Perspective Broker. It works great as long as I feed it less than a couple hundred images at a time. However, sometimes it gets spiked with hundreds of images at virtually the same time. Because it tries to process them all concurrently the server crashes. As a solution I'd like to queue up the remote_calls on the server so that it only processes ~100 images at a time. It seems like this might be something that Twisted already does, but I can't seem to find it. Any ideas on how to start implementing this? A point in the right direction? Thanks!

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  • Python MQTT: TypeError: coercing to Unicode: need string or buffer, bool found

    - by user2923860
    When my python code tries to connect to the MQTT broker it gives me this Type Error: Update- I added the Complete Error Traceback (most recent call last): File "test.py", line 20, in <module> mqttc.connect(broker, 1883, 60, True) File "/usr/local/lib/python2.7/dist-packages/mosquitto.py", line 563, in connect return self.reconnect() File "/usr/local/lib/python2.7/dist-packages/mosquitto.py", line 632, in reconnect self._sock = socket.create_connection((self._host, self._port), source_address=(self._bind_address, 0)) File "/usr/lib/python2.7/socket.py", line 561, in create_connection sock.bind(source_address) File "/usr/lib/python2.7/socket.py", line 224, in meth return getattr(self._sock,name)(*args) TypeError: coercing to Unicode: need string or buffer, bool found The code of the python file is: #! /usr/bin/python import mosquitto broker = "localhost" #define what happens after connection def on_connect(rc): print "Connected" #On recipt of a message do action def on_message(msg): n = msg.payload t = msg.topic if t == "/test/topic": if n == "test": print "test message received" # create broker mqttc = mosquitto.Mosquitto("python_sub") #define callbacks mqttc.on_message = on_message mqttc.on_connect = on_connect #connect mqttc.connect(broker, 1883, 60, True) #Subscribe to topic mqttc.subscribe("/test/topic", 2) #keep connected while mqttc.loop() == 0: pass I have no idea why its giving me this it work 2 days ago.

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  • Slow login to load-balanced Terminal Server 2008 behind Gateway Server

    - by Frans
    I have a small load-balanced (using Session Broker) Terminal Server 2008 farm behind a Gateway Server which is accessed from the Internet. The problem I have is that there is a delay of 20-30 seconds if the session broker switches the user to another server during login. I think this is related to the fact that I am forcing the security layer to be RDP rather than SSL. The background The Gateway server has a public routeable IP addres and DNS name so it can be accessed from the Internet and all users come in via this route (the system is used to provide access to hosted applications to external customers). The actual terminal servers only have internal IP addresses. This works really well, except that with a Vista or Windows 7 client, the Remote Desktop client will negotiate with the server to use SSL for the security layer. This then exposes the auto-generated certificate that TS1 or TS2 has - but since they are internal, auto-generated certificates, the client will get a stern warning that the certificate is not valid. I can't give the servers a properly authorised certificate as the servers do not have public routeable IP address or DNS name. Instead, I am using Group Policy to force the connections to be over RDP instead of SSL. \Computer Configuration\Policies\Administrative Templates\Windows Components\Terminal Services\Terminal Server\Security\Require use of specific security layer for remote (RDP) connections The Windows 7 user now gets a much less stern warning that "the server's identity cannot be confirmed" which I can live with. I don't have enough control over the end-user's machines to ask them to install a new root certificate either. TS1 and TS2 are also load-balanced using the Session Broker, which is installed on the Gateway Server. I am using round-robin DNS, so the user's initial connection will go via Gateway1 to either TS1 or TS2. TS1/TS2 will then talk to the session broker and may pass the user to the other server. I.e. the user may get connected to TS2, but after talking to the session broker the user may be passed to TS1, which is where they will run their session. When this switching of servers happens, in my setup, the screen sits with the word "Welcome" for 20-30 seconds after which it flickers, Welcome is shown again and then flashing through nthe normal login screens (i.e. "wait for user profile manager" etc). Having done some research, I think what is happening is that the user is being fully logged on to TS2 (while "Welcome" is shown) before being passed to TS1, where they are then logged in again. It is interesting that normally when you see the ""Welcome" word, the little circle to left rotates. However, it does not rotate during this delay - the screen just looks frozen. This blog post leads me to think that this is because CredSSP is not being used, probably because I am disallowing SSL and forcing RDP. What I have tried I enabled SSL again which removes the "Welcome" delay. However, it seems to introduc a new delay much earlier in the process. Specifically, when the RDP client is saying "initialising connection" - this is now much slower. Quite apart from the fact that my certificate problem precludes me using that solution without considerable difficulty. I tried disabling the load balancing (just remove the servers from the session broker farm) and the connections do not have any delay. The problem is also intermittent in the sense that it only happens when the user gets bumped from one server to another. I tested this by trying to connect directly to TS1 (via the Gateway, of course) and then checking which server I actually got connected to. Just to be sure, I also by-passed the round-robin DNS to see if it had any impact and it doesn't. The setup is essentially in line with MS recommendations here: TS Session Broker Load Balancing Step-by-Step Guide I tried changing to using a dedicated redirector. Basically, rather than using a round-robin DNS, I pointed my DNS to the Gateway server and configured it to be a dedicated redirector (disallow logons, add it to the farm). Same problem, alas. Any ideas or suggestions gratefully received.

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  • Can't run init script on boot after another init script

    - by Colin McQueen
    I have three init scripts and the Broker init script runs fine, but when I try to run the Consumer init script and then the Data Collector init script, the only process that is running is the Broker. I added the symbolic links to the run levels using update-rc.d for each script and I also changed the number prefixes in the symbolic links to try and run the scripts in the proper order but that did not work. I am able to run the scripts from the terminal and they work fine but they need to all be started on boot. Any ideas as to why my other scripts are not running? Also inside my Consumer and Data Collector I am running: su user1 -c 'java -jar foo.jar' to start the services. Also the Consumer Java class sits and waits for a message from the queue, so the Java code does not stop until I specify the stop argument for the init script. The Broker has to start first, then the Consumer, then the Data Collector. Adding the symbolic links for the runlevels: sudo update-rc.d Broker defaults 10 90 sudo update-rc.d Consumer defaults 15 85 sudo update-rc.d DataCollector defaults 20 80

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  • Real-world SignalR example, ditching ghetto long polling

    - by Jeff
    One of the highlights of BUILD last week was the announcement that SignalR, a framework for real-time client to server (or cloud, if you will) communication, would be a real supported thing now with the weight of Microsoft behind it. Love the open source flava! If you aren’t familiar with SignalR, watch this BUILD session with PM Damian Edwards and dev David Fowler. Go ahead, I’ll wait. You’ll be in a happy place within the first ten minutes. If you skip to the end, you’ll see that they plan to ship this as a real first version by the end of the year. Insert slow clap here. Writing a few lines of code to move around a box from one browser to the next is a way cool demo, but how about something real-world? When learning new things, I find it difficult to be abstract, and I like real stuff. So I thought about what was in my tool box and the decided to port my crappy long-polling “there are new posts” feature of POP Forums to use SignalR. A few versions back, I added a feature where a button would light up while you were pecking out a reply if someone else made a post in the interim. It kind of saves you from that awkward moment where someone else posts some snark before you. While I was proud of the feature, I hated the implementation. When you clicked the reply button, it started polling an MVC URL asking if the last post you had matched the last one the server, and it did it every second and a half until you either replied or the server told you there was a new post, at which point it would display that button. The code was not glam: // in the reply setup PopForums.replyInterval = setInterval("PopForums.pollForNewPosts(" + topicID + ")", 1500); // called from the reply setup and the handler that fetches more posts PopForums.pollForNewPosts = function (topicID) { $.ajax({ url: PopForums.areaPath + "/Forum/IsLastPostInTopic/" + topicID, type: "GET", dataType: "text", data: "lastPostID=" + PopForums.currentTopicState.lastVisiblePost, success: function (result) { var lastPostLoaded = result.toLowerCase() == "true"; if (lastPostLoaded) { $("#MorePostsBeforeReplyButton").css("visibility", "hidden"); } else { $("#MorePostsBeforeReplyButton").css("visibility", "visible"); clearInterval(PopForums.replyInterval); } }, error: function () { } }); }; What’s going on here is the creation of an interval timer to keep calling the server and bugging it about new posts, and setting the visibility of a button appropriately. It looks like this if you’re monitoring requests in FireBug: Gross. The SignalR approach was to call a message broker when a reply was made, and have that broker call back to the listening clients, via a SingalR hub, to let them know about the new post. It seemed weird at first, but the server-side hub’s only method is to add the caller to a group, so new post notifications only go to callers viewing the topic where a new post was made. Beyond that, it’s important to remember that the hub is also the means to calling methods at the client end. Starting at the server side, here’s the hub: using Microsoft.AspNet.SignalR.Hubs; namespace PopForums.Messaging { public class Topics : Hub { public void ListenTo(int topicID) { Groups.Add(Context.ConnectionId, topicID.ToString()); } } } Have I mentioned how awesomely not complicated this is? The hub acts as the channel between the server and the client, and you’ll see how JavaScript calls the above method in a moment. Next, the broker class and its associated interface: using Microsoft.AspNet.SignalR; using Topic = PopForums.Models.Topic; namespace PopForums.Messaging { public interface IBroker { void NotifyNewPosts(Topic topic, int lasPostID); } public class Broker : IBroker { public void NotifyNewPosts(Topic topic, int lasPostID) { var context = GlobalHost.ConnectionManager.GetHubContext<Topics>(); context.Clients.Group(topic.TopicID.ToString()).notifyNewPosts(lasPostID); } } } The NotifyNewPosts method uses the static GlobalHost.ConnectionManager.GetHubContext<Topics>() method to get a reference to the hub, and then makes a call to clients in the group matched by the topic ID. It’s calling the notifyNewPosts method on the client. The TopicService class, which handles the reply data from the MVC controller, has an instance of the broker new’d up by dependency injection, so it took literally one line of code in the reply action method to get things moving. _broker.NotifyNewPosts(topic, post.PostID); The JavaScript side of things wasn’t much harder. When you click the reply button (or quote button), the reply window opens up and fires up a connection to the hub: var hub = $.connection.topics; hub.client.notifyNewPosts = function (lastPostID) { PopForums.setReplyMorePosts(lastPostID); }; $.connection.hub.start().done(function () { hub.server.listenTo(topicID); }); The important part to look at here is the creation of the notifyNewPosts function. That’s the method that is called from the server in the Broker class above. Conversely, once the connection is done, the script calls the listenTo method on the server, letting it know that this particular connection is listening for new posts on this specific topic ID. This whole experiment enables a lot of ideas that would make the forum more Facebook-like, letting you know when stuff is going on around you.

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  • Python Multiprocessing with Queue vs ZeroMQ IPC

    - by Imraan
    I am busy writing a Python application using ZeroMQ and implementing a variation of the Majordomo pattern as described in the ZGuide. I have a broker as an intermediary between a set of workers and clients. I want to do some extensive logging for every request that comes in, but I do not want the broker to waste time doing that. The broker should pass that logging request to something else. I have thought of two ways :- Create workers that are only for logging and use the ZeroMQ IPC transport Use Multiprocessing with a Queue I am not sure which one is better or faster for that matter. The first option does allow me to use the current worker base classes that I already use for normal workers, but the second option seems quicker to implement. I would like some advice or comments on the above or possibly a different solution.

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  • C# - Which is more efficient and thread safe? static or instant classes?

    - by Soni Ali
    Consider the following two scenarios: //Data Contract public class MyValue { } Scenario 1: Using a static helper class. public class Broker { private string[] _userRoles; public Broker(string[] userRoles) { this._userRoles = userRoles; } public MyValue[] GetValues() { return BrokerHelper.GetValues(this._userRoles); } } static class BrokerHelper { static Dictionary<string, MyValue> _values = new Dictionary<string, MyValue>(); public static MyValue[] GetValues(string[] rolesAllowed) { return FilterForRoles(_values, rolesAllowed); } } Scenario 2: Using an instance class. public class Broker { private BrokerService _service; public Broker(params string[] userRoles) { this._service = new BrokerService(userRoles); } public MyValue[] GetValues() { return _service.GetValues(); } } class BrokerService { private Dictionary<string, MyValue> _values; private string[] _userRoles; public BrokerService(string[] userRoles) { this._userRoles = userRoles; this._values = new Dictionary<string, MyValue>(); } public MyValue[] GetValues() { return FilterForRoles(_values, _userRoles); } } Which of the [Broker] scenarios will scale best if used in a web environment with about 100 different roles and over a thousand users. NOTE: Feel free to sugest any alternative approach.

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