What is a MESSAGE QUEUE and Where is it used?
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- เผยแพร่เมื่อ 29 พ.ค. 2024
- Messaging Queues are widely used in asynchronous systems. Message processing in an asynchronous fashion allows the client to relieve itself from waiting for a task to complete and, hence, can do other jobs during that time. It also allows a server to process its jobs in the order it wants to.
Messaging Queues provide useful features such as persistence, routing, and task management. We will be discussing the benefits of a message queue in future videos.
A system having a message queue can move to higher-level requirements while abstracting implementation details of message delivery and event handling to the messaging queue.
The 'queue' is just a name for this data structure. In practice, it could be storing messages using any policy. Some examples of message queues are Kafka and RabbitMQ. They are widely used for various purposes, such as command query request segregation (CQRS) and event sourcing.
00:00 Pizza Shop Example
01:40 Benefits of Asynchronous Processing
02:44 Scaling Shops (Horizontally)
03:10 Fault Tolerance
04:09 Features of a message queue
08:38 Encapsulation
09:38 Thank you!
Code: github.com/coding-parrot/Low-...
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Asynchronous Request-Response:
stackoverflow.com/questions/1...
www.enterpriseintegrationpatte...
Message Queue:
blog.codepath.com/2013/01/06/a...
highscalability.com/blog/2012/...
www.cloudamqp.com/blog/2014-1...
www.rabbitmq.com/getstarted.html
Load Balancing:
• What is CONSISTENT HAS...
You can find me here:
/ gkcs0
www.quora.com/profile/Gaurav-...
github.com/gkcs/
#message-queue #system-design #scalability #server
Notes to self:
* Servers are processing jobs in parallel.
* A server can crash. The jobs running on the crashed server still needs to get processed.
* A notifier constantly polls the status of each server and if a server crashes it takes ALL unfinished jobs (listed in some database) and distributes it to the rest of the servers. Because distribution uses a load balancer (with consistent hashing) duplicate processing will not occur as job_1 which might be processing on server_3 (alive) will land again on server_3, and so on.
* This "notifier with load balancing" is a "Message Queue".
Very good notes 👍
I don't understand why there might be a duplicate ?
the notifier will just query the tasks that handled by the cracked server and distribute them!
@@mahmoudelrabee2456 That is true if we store the server id also. This is explained as the first approach at @4:52
Consistent hashing and load balancer are 2 different things not same
The alternative approach is, instead of assigning individual task to server, you can let servers poll from the queue. In this case, your message queue is decoupled from application servers since message queue doesn't need to know anything about servers.
This guy reminds me of that friend that tries to explain and wrap up the whole semester for you 30 minutes right before the exam, because you didn't attend any lecture since the beginning.
great comment.... the way he is explaining its really wonderful
Lmao
dipak sonawane r
Exactly :)
those people are saints
Great job explaining everything in a way anyone can understand. You are a natural teacher! Please continue teaching and sharing your knowledge!
Thank you!
Former teacher turned Linux engineer here. Very well done explanation of this concept. Easy to follow with great usage of visuals and ongoing metaphor!
Message queue is getting lots of spot light in the industry, please keep making the video on this topic i like you way of teaching. thanks again.
know a days People like Bhaiya and didi on linkdln those who are giving lecture on system design other bla bla.. even don't know how to code, have more subscribers than this genuine talent. Hats of bro.😃
Explained the whole thing in literally the first 40 seconds. Truly amazing work!
This was the best video so far. The way you explained the entire stuff without saying Message Queue the whole time awakened my grey cells. Thanks a lot!
I like the sheer excitement with which the topic is delivered!! Kudos!!
Brother, I've been researching about message queues and I was so confused until I saw your video, thanks alot!
I am a java dev. For learning purpose I am planning to make queue system. But from your video i got idea that JMS is something I should learn now. Thanks Gaurav.
EXCELLENT job in all areas: Simplifying the use cases for explaining easily to non-experts, very VERY close examples to real-world instead of using hypothetical cases, starting from simple (in memory) to more complex approach (with database), and avoiding super technical jargon; yet not shying away from technical details (i.e. load balancing, hashing, etc.)
Well done Gaurav!! I enjoyed this video.
well said.
Thank you! Your tutorials are great! My college did not have System Design and Analysis class, and your videos helped to learn a lot.
Hi Gaurav, This is the one of the best real life example (with pizza shop) showing the need of asynchronous request/response system. Thanks for the great video. Really loved it.
Thanks!
Bro, keep bringing up more videos like this. We are all such a big fan of yours. ALL the best! 👍
PS: Amazon has SQS ;)
Are we just going to ignore the fact that 9 / 11 were pointing at the same server and THAT was the server that crashed! :P Your lectures are fun man!
Illuminati confirmed! Well done.
Amazing explanation Gaurav. The best way to explain any concept is with practical examples, and you did the same.
There are very less resource available for system design in youtube so please complete series . I like the way you teach. Thanks for making videos for us. God bless you
Thanks Sameer :)
"Very less", Very few. Indian English is hilarious though.
Your channel is amazing. Your explanations are some of the best I’ve ever heard/seen. Good job man.
Again, thanks so much for taking the time to make this video. I've learned a lot from you. Keep it up!
great clear presentation!
one tip: use higher contrast ink and board.
So that means more lighting to make the board more lighter/white
and/or using dark ink like black or brown so we can see it more clearly.
great content. subscribed. keep up the good work!
The concept has been explained very clearly. It would be great if you would come with practical implementation using NodeJS with any MQ
"Now I know everything about how to run a restaurant; I will be starting my own restaurant very soon."
Thanks to the legend Gaurav.
As a European developer that has seen too much low-quality programming disasters from projects outsourced to low-wage Asian country developers, I must say that it's refreshing to see an Indian engineer that has actually studied for this stuff and knows what he's talking about, using the correct terminology... I'm subscribing; you're creating great content.
Low-quality programmers are everywhere not just in Asia.
Great Explanations of Sytem Design. Made fall in love with each concept.
When to use a Topic vs a Que would have been a nice addition.
Explained the concept really well , easy to understand
kya to samjaya hai Gaurav, maza aa gaya.. Such precise explanation is so rare on online tutorials.
Great video! This video explains the system design of a pizza shop very well. However, it spends a lot of time explaining load balancers and the notifier and very few minutes are dedicated to discussing message queues. I am more interested in the actual use of message queues in real-world systems like pizza shop here.
this is the first time I found the wrong explanation.
1. Once you have notified and it found that server 3 is dead then it can give that specific task to "assigner" node which basically divides the task and share between other nearest server to that location (it is important).
2. Each shop has to maintain his own task queue and "assigner node" would add those task in that queue based on priority ( but this will be least among its own task, as it requires to completes own task first then other. )
3. there is no use of centralized queue, until n unless you provide a feature to the pizza shop and based on user location pizza shop automatically (user did not select the shop which is always the case in dominoes at least) assign this task to the nearest shop.
4. Load balancer (if you were talking about the actual load balancer between servers) is no use for the assignment, as its responsibility to just equally divides the task across multiple servers within the same region for which this load balancer responsible for.
You explained it so well, thank you
Thanks for the valuable video! It really helps me to understand what the message queue is :)
Thanks a lot for the content. Even I discussed the same heartbeat like mechanism (Got the idea from the video :P) in an interview. It was really helpful!
The only youtuber that keeps his video at 9:59
Hahaha
HAHAHAHAHAHAHA
haha :?
back in the golden days of youtube everybody made videos to make videos, not to make money
Amazing work Gaurav, Keep inspiring!
In a typical System design interview: Dabbe banao dabbe.. :D
Nice explanation. You are actually doing excellent work. Thank you.
Gaurav, this is really a nice and knowledgeable tutorial you have made, in very sort time you have explained this topic very clearly. Can you try to make it as a practical ( how to implement RabbitMQ)
Excellent and lite tutorial on messaging and load balancing
If you could cover on the concepts of real time operating systems- which includes tasks, task states, ,message queues and mailboxes etc..., It will be definetely helpful for me and for those who are interested in embedded computing and RTOS...
You don't necessarily need to assign a task to a specific server. A server that is ready can go and pull the pizza order from the queue and process it.
It is much faster
But what if a task was pulled , was in progress and then the server crashes , how do we make sure that this task, is again pulled by any up & running servers ?
@@kanishkamakhija9046 Notifier(which does the heartbeat check) could detect whether a server has crashed and mark the corresponding tasks to be unassigned.
Alternatively, a timeout could be added to each assigned task and if the in process task times out we remark it as unassigned and pick some alive server to handle it.
I also saw another approach where you can maintain a separate queue that holds in-progress tasks. If the server crashes, any other server can pick up tasks from the corresponding queue.
You are the best teacher. Thank you very much.
Very good job. I had so many confusion you just cleared
Your charisma and you way of teaching gain me to be your subscriber :)
Thats an excellent explanation Gaurav.. Thank you.
Man, You are awesome.. the way you explain is truly great.😂
Gaurav, fantastic job with explaining the key tenants of high-level system design; how about bringing in some tooling and technology stack to support each of the architectures.
Appreciate your work!! thanks for sharing.
Please confirm if my video understanding related to queues are correct :
When S3 crashed, we wanted to re-distribute the order no 9 and 11 to other pizza stores (s0 to s2).But server did not have record or order no's which were assigned to Pizza store S3.
Initially we thought of using 'Load Balancer' for this purpose.
(This is clear to me, so moving to queue now)
After that we improved our solution by using 'Message queues'. If we use 'Message queues' then we need to have one 'Queue' for each Pizza Store (Both at client and server side applications). Each pizza store will listen to its own 'Message queue'. Whenever a new Pizza is added to a 'Queue' (belonging to S3). when this Message is received by Pizza store S3 and acknowledged and then S3 starts processing it. If S3 is 'SUCCESSFULLY' able to complete it then message will be removed from the Queue at server side.
If S3 crashes then heart beats are not received and all messages stored in the Queue [belonging to Store S3] will be added to other store's Queues.
If S3 throws error/Exception (Enough Cheese not available for Pizza) during processing then message is still on server queue [Not a valid use case for current discussion]
Hey Gaurav, Thank you so much for the great explanation. Your videos are awesome. Keep up the great work.👍
Thanks!
Very clear explanation. Thank you
so smart the way he is explaining. keep it up man
Brilliant:-) good job. Really appreciable. Kindly make complete series on system design and soon start video series on python programming:-):-)
Everyday you learn something new!
I always thought PS3 stood for PlaStation 3, but here I learn that it stands for PizzaShop 3.
Thanks for the great explanation man!!
Damn man you are an amazing teacher. Subscribed!
@Gaurav Sen Very informative video! I request you to make a video or videos about every component of any system design. Different problems employ different components. If we first study all the different components and their properties then at least we can stay thinking in right direction. Thanks for your video series!
Gaurav! Its good conceptually. Thanks
Short.. To the point.. Brilliant 👍
banks, thats a fairly common use case that uses messaging services/queues extensively.
batch processing transactions, after the card scheme authorises your tx and the request is send to the issuing bank, the entire xml message is stacked up on a messaging queue that is being constantly listened to by the issuing bank messaging service
Dude, you should get a Ph.D. for this... made it easy to understand. Thanks for sharing.
Really nice explanation, impressive.
for each system design if a detailed explaination is there, then, it will be helpful for all becoz i think i can learn system designs from you
thank you for your extraordinary work
Thanks David :)
amazing series!
"Filling up the coke can" 2:20 haha. Love your videos bro.
his expressions are hilarious !
Nicely and simply explained
Excellent explanation.
Thanks
We would like to have videos on object-oriented design patterns too like observer pattern etc.
Please keep making videos. :D
OOP is overrated and people are finally moving towards functional programming with NodeJS and React as some common examples
Nice narration..!! My pizza just got delivered under 30min
Great video. Would like a part 2
Maybe one on Apache Kafka and it's features :)
this is awesome explanation
I've learnt a heck of a lot about how pizza shops work
Very giid analogies and articulation of topics..gr8 wrk.
Please create a video over HermesJMS. This video was really helpful in getting the basics of MQ
Amazing explanation! Thanks!
You're welcome!
great explantaion!
not trying anything but a lot of indians are really smart. keep it up bro.
Hi Gaurav, In the video where we discussed about duplicating order no. '3' between S3 and S2, the S2 is still up and running right? So will there be a case where load from S2 should be distributed to other servers? Will we be doing load balancing even if the Server is active?
Pretty well explained.
Excellent stuff - Cheers !!
Good Teaching!!! Keep it up with great work
thanks for the informative presentation
Glad it was helpful!
Super!!! Thank you Bro...
Really good video. Khub valo laglo dekhe.
Hey Gaurav, appreciate your awesome work. my point is as you gave example if a pizza shop is down. what i think there will be no server on shop side and a shop has a client id only
servers must be at remote location.
orders object must have a client id.
there must be process on server side that check heartbeat of client with an associated client id. if that client id down ( clients spawn a heartbeat thread to server and server checks heartbeat from client) then it will do the rest of things your explained done by your notifier component to assign the orders ( to client having nearest to client which is down)
Thanks Vishal! Have a look at the full playlist. I do speak of it as you mentioned
Please make one video on Kafka. Appreciate your work.
Check learning journal challenge for Kafka video.
Nicely done Gaurav!! Once again... :)
Hi Gaurav , can we have server id as one of the columns in the table and use that also while querying the DB , so that it picks only the undone orders by that server(dead server) only, and rest can be taken care by the load balancers which is distributing the load ?
We could, but wouldn't that complicate things? For example: A job is initially assigned to S0, then reassigned to S1 after S0 crashes. Now S1 crashes. The way to keep track of S1's jobs would be to update the server id on the DB. It's an extra update operation.
Now let's say a new requirement comes of evenly distributed load. In this case, when a new server comes up, it will take jobs from others. The db will again have to be updated.
Consistent Hashing seems like a cleaner solution :)
Nice explanation Gaurav, I was stuck on this only.
Yes, may be it requires querying DB more often to update the server ids. Its better to follow the principle of load balancing which implements the uniqueness.
Thanks. :)
But, if we are not maintaining system id along with each order, then whenever a server dies, we have to again see for all the orders, their nearest server. But, if we have server ids along with them then we would only have to assign the orders which are initially handled by the server that died.
If a new server is added, then we have to anyway check all the entries, then its fine but when a server dies wouldn't maintaining server id's would reduce our work. Anyways great video..!! thanks.
@@shiwanggupta8608 I agree, also let's say you are very large chain, and have thousands of orders in process at any given time, going though all of them seems a waste of time, when you can differentiate by just the server id.
Hi Gaurav, loved your explanation. But I think, here you've mixed up related but different concepts.
You are actually creating a storm topology with input from a kafka queue. The order queue is a message queue (say kafka). Storm topology is polling messages from the order queue & is assigning the tasks to one of the worker nodes (pizza shops) & is internally keeping track of task status using a task queue & using hearbeats (by using a zookeeper) to check whether nodes (pizza shops) are alive or not & if not assign the unfinished tasks on that worker node to a different worker node.
Yes. What about the reallocation of tasks though?
Great explanation
Hey Guarav, I am curious. If S3 (server 3) went down, can't traffic 9 and traffic 11 be identified as the ones that need rerouting if the database table had a column specifying which server it was routed to? That way we can query in the DB for requests that were lost by losing S3 instead of querying for all requests that have not finished yet.
IMHO, the main reason is we don't need to store server to tasks "permanently", the info is not useful comparing to task state/description, .etc, or in short, it's unrelated to the task itself.
If we really want to identify server tasks, we could introduce another DB to store a map from server to in progress tasks, but it's an overkill and more complicated than using a timeout on each task in the queue.
@@bozhang8910 don't you want to see the report who failed frequently and tracking who's serving which item which can help to identify the poor performing outlets.. in case of other use cases where the customer does not need to know which server it delivers the request then your justification is good but incase of pizza deliver i dont think so
@@bozhang8910 You don't need another database, just another column. And there are other reasons to do this. Consider three pizza shops, p1, p2, and p3 where p1 and p2 are very close to each other and p3 is on another continent. If p1 goes down, sending its jobs to p3 would be a disaster, so if the table has a column for the server and a column for its nearest neighbor, the queue can dispatch in a way that doesn't involve transoceanic pizza delivery. A real life example would be CDNs for which the entire point is to find a replica of an asset which is closest to the client for performance reasons. Others would be geographic (like maps) or internationalized/localized services where the location can be inferred from the language.
I like the way you explain it
Well explained!
Cool!
Thanks for sharing.
This is very clear and understandable. Subscribing..
This tutoria is GREAT
Great Analogy!
This video ia really good, thank you
It's an amazing talk.
Here's a follow-up question.
What if the message queue goes down to be a single failure? Should we have the message queue with hot backup such as Active-Passive mode?
That is where the persistence of data comes into play. In order to keep reliability of the messages high, most message queues offer the ability to persist all messages to disk until they have been received and completed by the consumer(s). Even if the applications or the message queue itself happens to crash, the messages are safe and will be accessible to consumers as soon as the system is operational.