I am a bit confused about the AMQP 1.0 specification.
In versions prior to 1.0 there were a lot of details about the message broker itself. In version 1.0 - as i understand - are no details about the message broker or even the existence of a message broker. Using the exchanges of AMQP prior to 1.0 multiple messaging patterns were possible to configure.
Does AMQP 1.0 still specify multiple patterns?
(I am especially interested in Publish/Subscribe)
Thanks in Advance
AMQP 1.0 doesn't include broker details because it's possible to use AMQP point to point without a broker in AMQP 1.0. You certainly can still use a broker (or more than one) but it's not required like it was prior to 1.0.
Yes, multiple patterns, including pub-sub, are supported. Of course, the terminology and mechanics of how it happens "under the covers" is all different. However, if you use a higher level API to access pub-sub features on AMQP pre-1.0 you can probably just continue to use the same API.
Related
I am studying the possibility to use Kafka with Masstransit on our Information System. Masstransit documentation says Kafka may be used but as a Rider; As the usage of a transport is mandatory we must use another tool (as ActiveMQ, RabbitMQ) in addition of Kafka with Masstransit.
What does transport do that can not be done by Kafka, that prevent exclusive usage of Kafka?
MassTransit is designed with publish-subscribe with competing consumers in mind, which is the default pattern when using a message broker.
Riders were introduced, as mentioned in the docs, as a gateway between event streaming and pub-sub. So, the main purpose of riders is to support the scenario when you need to consume a message from a rider and publish it to the bus. Even producers are optional for riders, and they are implementation-specific. As event streaming infrastructure like Kafka doesn't even support competing consumers, it makes little sense to make something like Kafka transport, as it introduces a heavy impedance mismatch between MassTransit concepts and what Kafka does.
You can still only use Kafka with MassTransit, but you'd need to use the in-memory transport to configure and start the bus.
I am developing a mobile messaging app. I was going through technology needed and found two MQTT & Apache Kafta. To me both seems doing the same thing in the same way (in terms of subscribing & publishing to a topic).
I heard that MQTT is fit for mobiles as it is very light weight ? So basically what is the difference between these two and what are the advantage of each on other?
The main motive behind Kafka is scalability.
MQTT is a protocol with public specification for lightweight client / message broker communications, allowing publish/subscribe exchanges. Multiple implementations of client libraries and brokers (Mosquitto, JoramMQ...) exist and are virtually compatible. MQTT just specifies the transport, and vaguely the application part (i.e. how data is handled and possibly stored, how clients are authorized...). The spec is not clear if data consumed on a topic is only real-time or possibly persistent. The spec doesn't state anything about how the message broker implementing MQTT could/should scale.
On the other hand, Apache Kafka is a message broker based on an internal "commit log": its focus is storing massive amounts of data on disk, and allowing consumption in real-time or later (as long as data is still available on disk). It's designed to be deployable as cluster of multiple nodes, with good scalability properties. Kafka uses its own network protocol.
So you are comparing two different things here: a standard pub/sub protocol (with multiple implementations), and a specific message storing/distributing software, vaguley of the same family with its own protocol.
I'd say that if you need to store massive amount of messages, to ensure batch processing, look more at Kafka. If you have lots of clients/apps exchanging messages in real-time on many independent topics look more at the MQTT (or even AMQP) message broker implementations.
MQTT is a standard protocol (with many implementations). Kafka (which is also a protocol) is normally used by downloading it from the Apache website or e.g. a Confluent Docker image.
It is like comparing apples and oranges, both exist for very different reasons.
Most use cases I see in IoT environments combine both MQTT and Apache Kafka. The edge devices speak MQTT protocol (for the benefits it has in edge environments. These are then forwarded to Apache Kafka to get the events into the rest of the enterprise architecture.
You can do this either via a MQTT Broker like HiveMQ + Apache Kafka or via a MQTT Proxy (so that you don't need the MQTT Broker). Both options have trade-offs, of course.
See this example of how to combine MQTT with Apache Kafka. Or go directly to the Github code: "Deep Learning UDF for KSQL for Streaming Anomaly Detection of MQTT IoT Sensor Data".
I also created a live demo about how to integrate Apache Kafka and MQTT.
A little background.
Very big monolithic Django application. All components use the same database. We need to separate services so we can independently upgrade some parts of the system without affecting the rest.
We use RabbitMQ as a broker to Celery.
Right now we have two options:
HTTP Services using a REST interface.
JSONRPC over AMQP to a event loop service
My team is leaning towards HTTP because that's what they are familiar with but I think the advantages of using RPC over AMQP far outweigh it.
AMQP provides us with the capabilities to easily add in load balancing, and high availability, with guaranteed message deliveries.
Whereas with HTTP we have to create client HTTP wrappers to work with the REST interfaces, we have to put in a load balancer and set up that infrastructure in order to have HA etc.
With AMQP I can just spawn another instance of the service, it will connect to the same queue as the other instances and bam, HA and load balancing.
Am I missing something with my thoughts on AMQP?
At first,
REST, RPC - architecture patterns, AMQP - wire-level and HTTP - application protocol which run on top of TCP/IP
AMQP is a specific protocol when HTTP - general-purpose protocol, thus, HTTP has damn high overhead comparing to AMQP
AMQP nature is asynchronous where HTTP nature is synchronous
both REST and RPC use data serialization, which format is up to you and it depends of infrastructure. If you are using python everywhere I think you can use python native serialization - pickle which should be faster than JSON or any other formats.
both HTTP+REST and AMQP+RPC can run in heterogeneous and/or distributed environment
So if you are choosing what to use: HTTP+REST or AMQP+RPC, the answer is really subject of infrastructure complexity and resource usage. Without any specific requirements both solution will work fine, but i would rather make some abstraction to be able switch between them transparently.
You told that your team familiar with HTTP but not with AMQP. If development time is an important time you got an answer.
If you want to build HA infrastructure with minimal complexity I guess AMQP protocol is what you want.
I had an experience with both of them and advantages of RESTful services are:
they well-mapped on web interface
people are familiar with them
easy to debug (due to general purpose of HTTP)
easy provide API to third-party services.
Advantages of AMQP-based solution:
damn fast
flexible
cost-effective (in resources usage meaning)
Note, that you can provide RESTful API to third-party services on top of your AMQP-based API while REST is not a protocol but rather paradigm, but you should think about it building your AQMP RPC api. I have done it in this way to provide API to external third-party services and provide access to API on those part of infrastructure which run on old codebase or where it is not possible to add AMQP support.
If I am right your question is about how to better organize communication between different parts of your software, not how to provide an API to end-users.
If you have a high-load project RabbitMQ is damn good piece of software and you can easily add any number of workers which run on different machines. Also it has mirroring and clustering out of the box. And one more thing, RabbitMQ is build on top of Erlang OTP, which is high-reliable,stable platform ... (bla-bla-bla), it is good not only for marketing but for engineers too. I had an issue with RabbitMQ only once when nginx logs took all disc space on the same partition where RabbitMQ run.
UPD (May 2018):
Saurabh Bhoomkar posted a link to the MQ vs. HTTP article written by Arnold Shoon on June 7th, 2012, here's a copy of it:
I was going through my old files and came across my notes on MQ and thought I’d share some reasons to use MQ vs. HTTP:
If your consumer processes at a fixed rate (i.e. can’t handle floods to the HTTP server [bursts]) then using MQ provides the flexibility for the service to buffer the other requests vs. bogging it down.
Time independent processing and messaging exchange patterns — if the thread is performing a fire-and-forget, then MQ is better suited for that pattern vs. HTTP.
Long-lived processes are better suited for MQ as you can send a request and have a seperate thread listening for responses (note WS-Addressing allows HTTP to process in this manner but requires both endpoints to support that capability).
Loose coupling where one process can continue to do work even if the other process is not available vs. HTTP having to retry.
Request prioritization where more important messages can jump to the front of the queue.
XA transactions – MQ is fully XA compliant – HTTP is not.
Fault tolerance – MQ messages survive server or network failures – HTTP does not.
MQ provides for ‘assured’ delivery of messages once and only once, http does not.
MQ provides the ability to do message segmentation and message grouping for large messages – HTTP does not have that ability as it treats each transaction seperately.
MQ provides a pub/sub interface where-as HTTP is point-to-point.
UPD (Dec 2018):
As noticed by #Kevin in comments below, it's questionable that RabbitMQ scales better then RESTful servies. My original answer was based on simply adding more workers, which is just a part of scaling and as long as single AMQP broker capacity not exceeded, it is true, though after that it requires more advanced techniques like Highly Available (Mirrored) Queues which makes both HTTP and AMQP-based services have some non-trivial complexity to scale at infrastructure level.
After careful thinking I also removed that maintaining AMQP broker (RabbitMQ) is simpler than any HTTP server: original answer was written in Jun 2013 and a lot of changed since that time, but the main change was that I get more insight in both of approaches, so the best I can say now that "your mileage may vary".
Also note, that comparing both HTTP and AMQP is apple to oranges to some extent, so please, do not interpret this answer as the ultimate guidance to base your decision on but rather take it as one of sources or as a reference for your further researches to find out what exact solution will match your particular case.
The irony of the solution OP had to accept is, AMQP or other MQ solutions are often used to insulate callers from the inherent unreliability of HTTP-only services -- to provide some level of timeout & retry logic and message persistence so the caller doesn't have to implement its own HTTP insulation code. A very thin HTTP gateway or adapter layer over a reliable AMQP core, with option to go straight to AMQP using a more reliable client protocol like JSONRPC would often be the best solution for this scenario.
Your thoughts on AMQP are spot on!
Furthermore, since you are transitioning from a monolithic to a more distributed architecture, then adopting AMQP for communication between the services is more ideal for your use case. Here is why…
Communication via a REST interface and by extension HTTP is synchronous in nature — this synchronous nature of HTTP makes it a not-so-great option as the pattern of communication in a distributed architecture like the one you talk about. Why?
Imagine you have two services, service A and service B in that your Django application that communicate via REST API calls. This API calls usually play out this way: service A makes an http request to service B, waits idly for the response, and only proceeds to the next task after getting a response from service B. In essence, service A is blocked until it receives a response from service B.
This is problematic because one of the goals with microservices is to build small autonomous services that would always be available even if one or more services are down– No single point of failure. The fact that service A connects directly to service B and in fact, waits for some response, introduces a level of coupling that detracts from the intended autonomy of each service.
AMQP on the other hand is asynchronous in nature — this asynchronous nature of AMQP makes it great for use in your scenario and other like it.
If you go down the AMQP route, instead of service A making requests to service B directly, you can introduce an AMQP based MQ between these two services. Service A will add requests to the Message Queue. Service B then picks up the request and processes it at its own pace.
This approach decouples the two services and, by extension, makes them autonomous. This is true because:
If service B fails unexpectedly, service A will keep accepting requests and adding them to the queue as though nothing happened. The requests would always be in the queue for service B to process them when it’s back online.
If service A experiences a spike in traffic, service B won’t even notice because it only picks up requests from the Message Queues at its own pace
This approach also has the added benefit of being easy to scale— you can add more queues or create copies of service B to process more requests.
Lastly, service A does not have to wait for a response from service B, the end users don’t also have to wait for long— this leads to improved performance and, by extension, a better user experience.
Just in case you are considering moving from HTTP to AMQP in your distributed architecture and you are just not sure how to go about it, you can checkout this 7 parts beginner guide on message queues and microservices. It shows you how to use a message queue in a distributed architecture by walking you through a demo project.
Recently started looking into these AMQP (RabbitMQ, ActiveMQ) and ZeroMQ technologies, being interested in distributed systems/computation. Been Googling and StackOverflow'ing around, couldn't find a definite comparison between the two.
The farthest I got is that the two aren't really comparable, but I want to know the differences. It seems to me ZeroMQ is more decentralized (no message broker playing middle-man handling messages/guarenteering delivery) and as such is faster, but is not meant to be a fully fledged system but something to be handled more programmatically, something like Actors.
AMQP on the other hand seems to be a more fully fledged system, with a central message broker ensuring reliable delivery, but slower than ZeroMQ because of this. However, the central broker creates a single point of failure.
Perhaps a metaphor would be client/server vs. P2P?
Are my findings true? Also, what would be the advantages, disadvantages, or use cases of using one over the other? A comparison of the uses of *MQ vs. something like Akka Actors would be nice as well.
EDIT Did a bit more looking around.. ZeroMQ seems to be the new contender to AMQP, seems to be much faster, only issue would be adoption/implementations?
Here's a fairly detailed comparison of AMQP and 0MQ: http://www.zeromq.org/docs:welcome-from-amqp
Note that 0MQ is also a protocol (ZMTP) with several implementations, and a community.
AMQP is a protocol. ZeroMQ is a messaging library.
AMQP offers flow control and reliable delivery. It defines standard but extensible meta-data for messages (e.g. reply-to, time-to-live, plus any application defined headers). ZeroMQ simply provides message delimitation (i.e. breaking a byte stream up into atomic units), and assumes the properties of the underlying protocol (e.g. TCP) are sufficient or that the application will build extra functionality for flow control, reliability or whatever on top of ZeroMQ.
Although earlier versions of AMQP were defined along client/server lines and therefore required a broker, that is no longer true of AMQP 1.0 which at its core is a symmetric, peer-to-peer protocol. Rules for intermediaries (such as brokers) are layered on top of that. The link from Alexis comparing brokered and brokerless gives a good description of the benefits such intermediaries can offer. AMQP defines the rules for interoperability between different components - clients, 'smart clients', brokers, bridges, routers etc -
such that a system can be composed by selecting the parts that are useful.
In ZeroMQ there are NO MESSAGE QUEUES at all, thus the name. It merely provides a way to use messaging semantics over otherwise ordinary sockets.
AMQP is standard protocol for message queueing which is meant to be used with a message-broker handling all message sends and receives. It has a lot of features which are available because it funnels all message traffic through a broker. This may sound slow, but it is actually quite fast when used inside a data centre where host to host latencies are tiny.
I'm not really sure how to respond to your question, which is comparing a lot of different things... but see this which may help you begin to dig into these issues: http://www.rabbitmq.com/blog/2010/09/22/broker-vs-brokerless/
AMQP (Advanced Message Queuing Protocol) is a standard binary wire level protocol that enables conforming client applications to communicate with conforming messaging middleware brokers. AMQP allows cross platform services/systems between different enterprises or within the enterprise to easily exchange messages between each other regardless of the message broker vendor and platform. There are many brokers that have implemented the AMQP protocol like RabbitMQ, Apache QPid, Apache Apollo etc.
ZeroMQ is a high-performance asynchronous messaging library aimed at use in scalable distributed or concurrent applications. It provides a message queue, but unlike message-oriented middleware, a ØMQ system can run without a dedicated message broker.
Broker-less is a misnomer as compared to message brokers like ActiveMQ, QPid, Kafka for simple wiring.
It is useful and can be applied to hotspots to reduce network hops and hence latency, as we add reliability, store and forward feature and high availability requirements, you probably need a distributed broker service along with a queue for sharing data to support a loose coupling - decoupled in time - this topology and architecture can be implemented using ZeroMQ, you have to consider your use cases and see, if asynchronous messaging is required and if so, where ZeroMQ would fit, it has a good role in solution it appears and a reasonable knowledge of TCP/IP and socket programming would help you appreciate all others like ZeroMQ, AMQP, etc.
I'm working on a messaging/notification system for our products. Basic requirements are:
Fire and forget
Persistent set of messages, possibly updating, to stay there until the sender says to remove them
The libraries will be written in C#. Spring.NET just released a milestone build with lots of nice messaging abstraction, which is great - I plan on using it extensively. My basic question comes down to the question of message brokers. My architecture will look something like app -> message broker queue -> server app that listens, dispatches all messages to where they need to go, and handles the life cycle of those long-lived messages -> message broker queue or topic -> listening apps.
Finally, the question: Which message broker should I use? I am biased towards ActiveMQ - We used it on our last project and loved it. I can't really think of a single strike against it, except that it's Java, and will require java to be installed on a server somewhere, and that might be a hard sell to some of the people that will be using this service. The other option I've been looking at is MSMQ. I am biased against it for some unknown reason, and it also doesn't seem to have great multicast support.
Has anyone used MSMQ for something like this? Any pros or cons, stuff that might sway the vote one way or the other?
One last thing, we are using .NET 2.0.
I'm kinda biased as I work on ActiveMQ but pretty much all of benefits listed for MSMQ above also apply to ActiveMQ really.
Some more benefits of ActiveMQ include
great support for cross language client access and multi protocol support
excellent support for enterprise integration patterns
a ton of advanced features like exclusive queues and message groups
The main downside you mention is that the ActiveMQ broker is written in Java; but you can run it on IKVM as a .net assembly if you really want - or run it as a windows service, or compile it to a DLL/EXE via GCJ. MSMQ may or may not be written in .NET - but it doesn't really matter much how its implemented right?
Irrespective of whether you choose MSMQ or ActiveMQ I'd recommend at least considering using the NMS API which as you say is integrated great into Spring.NET. There is an MSMQ implementation of this API as well as implementations for TibCo, ActiveMQ and STOMP which will support any other JMS provider via StompConnect.
So by choosing NMS as your API you will avoid lockin to any proprietary technology - and you can then easily switch messaging providers at any point in time; rather than locking your code all into a proprietary API
Pros for MSMQ.
It is built into Windows
It supports transactions, it also supports queues with no transactions
It is really easy to setup
AD Integration
It is fast, but you would need to compare ActiveMQ and MSMQ for your traffic to know which is faster.
.NET supports it nativity
Supports fire and forget
You can peek at the queue, if you have readers that just look. not sure if you can edit a message in the queue.
Cons:
4MB message size limit
2GB Queue size limit
Queue items are held on disk
Not a mainstream MS product, docs are a bit iffy, or were it has been a few years since I used it.
Here is a good blog for MSMQ
Take a look at zeromq. It's one of the fastest message queues around.
I suggest you have a look at TIBCO Enterprise Messaging Service - EMS, which is a high performance messaging product that supports multicasting, routing, supports JMS specification and provides enterprise wide features including your requirements suchas fire-forget and message persistence using file/database using shared state.
As a reference, FEDEX runs on TIBCO EMS
as its messaging infrastructure.
http://www.tibco.com/software/messaging/enterprise_messaging_service/default.jsp
There are lot other references if i provide, you'd really be surprised.
There are so many options in that arena...
Free: MantaRay a peer to peer fully JMS compliant system. The interesting part of Mantaray is that you only need to define where the message goes and MantaRay routes it anyways that will get your message to it's detination - so it is more resistant to failures of individual nodes in your messaging fabric.
Paid: At my day job I administer an IBM WebSphere MQ messaging system with several hundred nodes and have found it to be very good. We also recently purchased Tibco EMS and it seems that it will be pretty nice to use as well.