subscriber

问题 I have written a ROS subscriber to one of the image topics and I have set my buffer to 1 using: subscriber =rospy.Subscriber("/camera/rgb/image_mono/compressed",CompressedImage, callback, queue_size=1) However my subscriber still lags behind. Any idea what might be causing this? Am I setting the queue size correctly? 回答1: The queue is for queueing incoming messages. This means, if your callback takes longer to proccess than new messages arrive, only queue size is kept, the others are not

问题 I m implementing Pub/Sub model using JMS. I send a message from Pub to all Subscribers. I want that subscribers should get filtered messages based on some string in actual message body. For example a subscriber subscribe to a topic 'sports' and should receive only those posts which has keyword 'cricket' in it in the message text body. p.s. I dont want to use message selectors. How can I implement this. Thanks and Regards. 回答1: Take a look at apache camel. It provides a means of routing and

问题 I m implementing Pub/Sub model using JMS. I send a message from Pub to all Subscribers. I want that subscribers should get filtered messages based on some string in actual message body. For example a subscriber subscribe to a topic 'sports' and should receive only those posts which has keyword 'cricket' in it in the message text body. p.s. I dont want to use message selectors. How can I implement this. Thanks and Regards. 回答1: Take a look at apache camel. It provides a means of routing and

问题 Trying to register a Doctrine EventSubscriber but nothing is ever actually fired. I have, on the Entity, in question, set the @ORM\HasLifeCycleCallbacks annotation. Here's the Subscriber: <?php namespace App\Subscriber; use App\Entity\User; use Doctrine\Common\EventSubscriber; use Doctrine\ORM\Event\LifecycleEventArgs; use Doctrine\ORM\Event\PreUpdateEventArgs; use Doctrine\ORM\Events; use Symfony\Component\Security\Core\Encoder\UserPasswordEncoderInterface; class

问题 Is the communication bi-directional in NServiceBus? a subscriber can also publish/send message? 回答1: NServiceBus does indeed support bi-directional communication, a subscriber can publish messages as well. Configure it as a publisher as per-usual, write handlers for events coming from other publishers, configure the messages in the UnicastBusConfig, and you're done. 来源： https://stackoverflow.com/questions/2437423/can-a-subscriber-also-publish-send-message-in-nservicebus

问题 I have two publisher and subscriber application. App1 -> publish -> Student (1,ABC), Student(2,EFG). After it I run second application. both application subscribe and publish on same domain App2 able subscribe Student (1,ABC), Student(2,EFG) which is published by App1 then I Published data. App2-> publish -> Teacher(1,AAA),Teacher(2,BBB) Now I got Student (1,ABC), Student(2,EFG),Teacher(1,AAA),Teacher(2,BBB) from App2 when I close app2 and reopen again I am unable to subscribe this data How

问题 I have two publisher and subscriber application. App1 -> publish -> Student (1,ABC), Student(2,EFG). After it I run second application. both application subscribe and publish on same domain App2 able subscribe Student (1,ABC), Student(2,EFG) which is published by App1 then I Published data. App2-> publish -> Teacher(1,AAA),Teacher(2,BBB) Now I got Student (1,ABC), Student(2,EFG),Teacher(1,AAA),Teacher(2,BBB) from App2 when I close app2 and reopen again I am unable to subscribe this data How

问题 I created a TOPIC in google pubsub, and created a SUBSCRIPTION inside the TOPIC, with the following settings then I wrote a puller in go, using its Receive to pull and acknowledge published messages package main import ( ... ) func main() { ctx := context.Background() client, err := pubsub.NewClient(ctx, config.C.Project) if err != nil { // do things with err } sub := client.Subscription(config.C.PubsubSubscription) err := sub.Receive(ctx, func(ctx context.Context, msg *pubsub.Message) { msg

问题 Suppose I created a JMS Topic (PropertiesTopic) with one subscriber (PropertiesSubscriber). PropertiesSubscriber is running in a load balanced application server cluster as shown in the picture below. alt text http://www.freeimagehosting.net/uploads/be28c03781.png When a message is delivered to PropertiesTopic, do all the instances of PropertiesSubscriber running on different app servers get that message or does the message get delivered to only one PropertiesSubscriber instance running on an

问题 can someone explain me why code like this: networApi.getList() .subscribeOn(Schedulers.newThread()) .observeOn(AndroidSchedulers.mainThread()) .doOnError(throwable -> { throwable.getMessage(); }) .doOnNext(list -> { coursesView.populateRecyclerView(list); courseList = (List<Course>) courses; }).subscribe(); If there is no internet goes into doOnError but throws it further so the app goes down, but code like this: networkApi.getList() .subscribeOn(Schedulers.newThread()) .observeOn