message-queue | 易学教程

Busy Application leads to false “Not responding” state on Windows 7 - WM_UPDATE

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问题 During long term operations our C++ Win32 application shows a modal status dialog with a process bar, which is updated irregular every few seconds or so. Starting with Windows 7 we realized that Windows quite soon shows a message " seems to hang..." and/or appends "Not responding" to our window title bar. We figured out that the process dialog must handle messages to avoid this. More specifically it seems that Windows 7 is constantly sending WM_UPDATE messages to check if our program is alive

How to peek into a Linux (POSIX) message queue without removing an item?

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问题 I need to peek into a message queue without removing them. I will go ahead and remove the message queue item only if it complies to certain criteria. How to do this? Following are the APIs I know — but none seems support peeking. mq_close() — close a message queue mq_getattr() — get the current attributes of a message queue mq_notify() — notify the calling process when the queue becomes nonempty mq_open() — open or create a message queue mq_receive() — receive a message from a queue mq_send()

Message Queue Error: cannot find a formatter capable of reading message

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问题 I'm writing messages to a Message Queue in C# as follows: queue.Send(new Message("message")); I'm trying to read the messages as follows: Messages messages = queue.GetAllMessages(); foreach(Message m in messages) { String message = m.Body; //do something with string } However I'm getting an error message which says: "Cannot find a formatter capable of reading this message." What am I doing wrong? 回答1: I solved the problem by adding a formatter to each message. Adding a formatter to the queue

Rabbitmq Ack or Nack, leaving messages on the queue

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问题 I have been playing around with RabbitMq.net and the message acknowledgements. If the consumer is able to process the message you can send back an ack in the form of channel.BasicAck(ea.DeliveryTag, false); which will take it off the queue. But what about if the message was unable to be processed ? maybe a temporary outage and you don't want the message taken off the queue just put to the back and carry on with the next message? I have tried using channel.BasicNack(ea.DeliveryTag, false, true

Why choosing JMS for asynchronous solution ? Why is it better than a simple entity bean?

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问题 In most projects I have participated, the choice of an asynchronous solution has been a source of much discussion ... Each time a single entity bean was enough to manage a queue: we just store a message (ticket) in a table and a processing cron unstacks the queue. This simple solution has the advantage of being very simple, it's based on the transactional context of the database and we can manage the state of the received message during its execution. I therefore ask the following questions:

What is the best way to format messages for queueing?

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I've been reading up on message queueing lately, and I'd like to implement a simple, extendable, system for my app. While there's a lot of good information on the subject of setting up a MQ system out there, I can't find a lot about the actual implementation. I'm looking for patterns and best practices on how to properly format messages for a queue, and ways to execute the jobs in PHP. Should I use JSON, serialized objects, text, URLs or XML? What information should I send? Is a worker with a switch($job['command']) {} (or something like that) the way to go, or are there any established

Kafka - How to commit offset after every message using High-Level consumer?

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问题 I'm using Kafka's high-level consumer. Because I'm using Kafka as a 'queue of transactions' for my application, I need to make absolutely sure I don't miss or re-read any messages. I have 2 questions regarding this: How do I commit the offset to zookeeper? I will turn off auto-commit and commit offset after every message successfully consumed. I can't seem to find actual code examples of how to do this using high-level consumer. Can anyone help me with this? On the other hand, I've heard

JMS - Going from one to multiple consumers

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问题 I have a JMS client which is producing messages and sending over a JMS queue to its unique consumer. What I want is more than one consumer getting those messages. The first thing that comes to my mind is converting the queue to a topic, so current and new consumers can subscribe and get the same message delivered to all of them. This will obviously involve modifying the current clients code in both producer and consumer side of things. I would like to also look at other options like creating

Why do we need message brokers like RabbitMQ over a database like PostgreSQL?

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问题 I am new to message brokers like RabbitMQ which we can use to create tasks / message queues for a scheduling system like Celery. Now, here is the question: I can create a table in PostgreSQL which can be appended with new tasks and consumed by the consumer program like Celery. Why on earth would I want to setup a whole new tech for this like RabbitMQ? Now, I believe scaling cannot be the answer since our database like PostgreSQL can work in a distributed environment. I googled for what

Message Queue vs. Web Services? [closed]

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问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 6 years ago . Under what conditions would one favor apps talking via a message queue instead of via web services (I just mean XML or JSON or YAML or whatever over HTTP here, not any particular type)? I have to talk between two apps on a local network. One will be a web app and have to