How do I change the name of an existing channel. My client has informed me that they are changing the channel but keeping the CONNAME the same. I am not able to use the ALTER function. Should I DELETE and re-DEFINE the channel?
IBM MQ does not have a RENAME action, so you would need to DEFINE a new channel and once you are no longer using the old channel DELETE it.
To make it easier you can use the LIKE verb to copy most (if not all) of the parameters of the old channel to the new channel, for example:
DEFINE CHL(NEW.CHL) CHLTYPE(SDR) LIKE(OLD.CHL)
In the above case the NEW.CHL will have the same values as OLD.CHL for things like XMITQ, CONNAME, etc.
Related
I am using github.com/nsqio/go-nsq Go package to work with NSQ, and I've met following problem. When producer writes a message - it creates a topic, but not a channel, and it seems that NSQ server just discards a messages when there are no channels. I don't want to lose messages, also I don't want to rely on consumer and producer startup order. So a possible solution is to create a channel on producer side, so when it writes it will not discard messages. How can I create and destroy a consumer without consuming a message, just for sake of channel creation?
sequence of
nsq.NewConsumer()
consumer.AddConcurrentHandlers()
consumer.ConnectToNSQLookupd()
can consume
removing AddConcurrentHandlers leads to error
From protocol spec I cannot see how is it supposed to do, other that sending SUB followed by CLS, but because those are two commands and non "atomic" kind of op - something theoretically may happen in between..
So probably I am trying to do that wrong? RABBITMQ for example can pre-create it, is here something like that?
Whenever there is a channel with the name that matches a certain regex, we want to add a certain group of members to these channel automatically. For example, if a new slack channel with the name that matches the regex INC-.* is created, slack group #incidentmembers will be added to that new slack channel automatically
Is there a way to configure this in Slack?
There's no native way to do this in Slack, but you could build something using the public APIs. Specifically you would
Listen to the channel_created event which fires when a public channel is created, which you can then regex as you see fit.
Grab the membership of the relevant User Group using usergroups.users.list (if the membership is static you could probably skip this)
Use conversations.invite to add the users to the channel
One limitation of this approach is that you won't get channel_created events for private channels. There's no way around this I'm afraid.
I'm trying to send and receive messages to channels/topics whose destination names are in a database, so they can be added/modified/deleted at runtime, but I'm surprised I have found little on the web. I'm using Spring Cloud Streams to allow to change the underlying broker.
To send messages to dynamically bound destinations I'm going with BinderAwareChannelResolver.resolveDestination(target).send(message), but I haven't found something that works like it to receive messages.
My questions are:
1. Is there something similar?
2. how can the message be processed periodically as #StreamListener does?
3. And not as important, but can you create a subscriber automatically in case there is none?
Thanks for any help!
This is a bit out of scope of the original design of the framework. But I would further question your architecture. . . If you truly desire to subscribe to unlimited amount of destinations I wonder why? What is the underlying business requirement?
Keep in mind that even if we were to do it somehow that would require creation of a message listener container dynamically for each new destination which would raise more questions, such as, how long would such container have to live since eventually you would run out of resources.
If, however, you simply asking about possibility of mapping multiple destinations to a single channel so all messages go to the same message handler (e.g., StreamListener), then you can simply use input destination property and define multiple destination delimited by comas.
As explained by this post, when the client first connects with the server, a “main socket/process” gets created and holds its assigns. Later, when the client joins specific channels/topics, each channel’s socket/process copies those assigns and can add to them as it will.
I now have a use case where, upon the user joining their own individual channel (i.e. user:#{user_id}), I retrieve some information about the user from the DB, which should then be globally available to all channels this user later joins. However I haven’t been able to find a way to put those information into socket.assigns so that they can be available everywhere. If I try to assign them, they will only be available in the socket.assigns of this particular user:#{user_id} channel.
Is there a way to do it? Should I just instead simply try to fetch all those information in one go when the user first connects, instead of when they join the individual user channel?
Different channels mean different sockets.
The easiest solution would be to maintain the permanent state (Agent, ETS, DETS, mnesia, ...), holding a map user_id => user_info and query this state whenever you need this info.
I am trying to write a consumer for an existing queue.
RabbbitMQ is running in a separate instance and queue named "org-queue" is already created and binded to an exchange. org-queue is a durable queue and it has some additional properties as well.
Now I need to receive messages from this queue.
I have use the below code to get instance of the queue
conn = Bunny.new
conn.start
ch = conn.create_channel
q = ch.queue("org-queue")
It throws me an error stating different durable property. It seems by default the Bunny uses durable = false. So I've added durable true as parameter. Now it states the difference between other parameters. Do I need to specify all the parameters, to connect to it? As rabbitMQ is maintained by different environment, it is hard for me to get all the properties.
Is there a way to get list of queues and listening to the required queue in client instead of connecting to a queue by all parameters.
Have you tried the :passive=true parameter on queue()? A real example is the rabbitmq plugin of logstash. :passive means to only check queue existence rather than to declare it when consuming messages from it.
Based on the documentation here http://reference.rubybunny.info/Bunny/Queue.html and
http://reference.rubybunny.info/Bunny/Channel.html
Using the ch.queues() method you could get a hash of all the queues on that channel. Then once you find the instance of the queue you are wanting to connect to you could use the q.options() method to find out what options are on that rabbitmq queue.
Seems like a round about way to do it but might work. I haven't tested this as I don't have a rabbitmq server up at the moment.
Maybe there is way to get it with rabbitmqctl or the admin tool (I have forgotten the name), so the info about queue. Even if so, I would not bother.
There are two possible solutions that come to my mind.
First solution:
In general if you want to declare an already existing queue, it has to be with ALL correct parameters. So what I'm doing is having a helper function for declaring a specific queue (I'm using c++ client, so the API may be different but I'm sure concept is the same). For example, if I have 10 subscribers that are consuming queue1, and each of them needs to declare the queue in the same way, I will simply write a util that declares this queue and that's that.
Before the second solution a little something: Maybe here is the case in which we come to a misconception that happens too often :)
You don't really need a specific queue to get the messages from that queue. What you need is a queue and the correct binding. When sending a message, you are not really sending to the queue, but to the exchange, sometimes with routing key, sometimes without one - let's say with. On the receiving end you need a queue to consume a message, so naturally you declare one, and bind it to an exchange with a routing key. You don't need even need the name of the queue explicitly, server will provide a generic one for you, so that you can use it when binding.
Second solution:
relies on the fact that
It is perfectly legal to bind multiple queues with the same binding
key
(found here https://www.rabbitmq.com/tutorials/tutorial-four-java.html)
So each of your subscribers can delcare a queue in whatever way they want, as long as they do the binding correctly. Of course these would be different queues with different names.
I would not recommend this. This implies that every message goes to two queues for example and most likely a message (I am assuming the use case here needs to be processed only once by one subscriber).