I thought I understood this technology, but maybe I don't. What's the difference between the two? Why would you choose one over the other?
Usecase: ~Realtime updates.
I'm the author of Faye. Conceptually, Faye and Redis pub/sub do very similar things, indeed the latest release of Faye can use Redis as a back-end. As Tom says, Redis is appropriate for inter-process messaging within your server cluster since the Redis client will get access to your whole Redis database.
Faye is more appropriate if you want to provide a publicly accessible pub/sub service over the web, for example to power the UI for your website. It only does pub/sub, not any other storage like Redis provides, and works over HTTP and WebSocket rather than over a raw TCP socket. It also allows for user-defined client- and server-side extensions to expand the messaging protocol it uses.
Redis publish/subscribe is a very simple system for internal use in a server cluster - it requires an open connection to redis (unauthenticated and giving complete access to everything in redis).
Obviously this is the most efficient way to handle scenarios where this is appropriate, but if you need authentication, reliable delivery, or http connections you will need to add a more complete messaging system on top of redis. Faye is one of the options in this space.
Related
I have explored the web on MULE and got to understand that for Apps to communicate among themselves - even if they are deployed in the same Mule instance - they will have to use either TCP, HTTP or JMS transports.
VM isn't supported.
However I find this a bit contradictory to ESB principles. We should ideally be able to define EndPoints in and ESB and connect to that using any Transport? I may be wrong.
Also since all the apps are sharing the same JVM one would expect to be able to communicate via the in-memory VM queue rather than relying on a transactionless HTTP protocol, or TCP where number of connections one can make is dependent on server resources. Even for JMS we need to define and manage another queue and for heavy usage that may have impact on performances. Though I agree if we have distributed and clustered systems may be HTTP or JMS will be only options.
Is there any plan to incorporate VM as a inter-app communication protocol or is there any other way one Flow can communicate with another Flow Endpoint but in different app?
EDIT : - Answer from Mulesoft
http://forum.mulesoft.org/mulesoft/topics/concept_of_endpoint_and_inter_app_communication
Yes, we are thinking about inter-app communication for a future release.
Still is not clear when we are going to do it but we have a couple of ideas on how we want this feature to behave. We may create a server level configuration in which you can define resources to use in all your apps. There you would be able to define a VM connector and use it to send messages between apps in the same server.
As I said, this is just an idea.
Regarding the usage of VM as inter-app communication, only MuleSoft can answer if VM will have a future feature or not.
I don't think it's contradictory to the ESB principle. The "container" feature is pretty well defined in David A Chappell's "Enterprise Service Bus book" chapter 6. The container should try it's best to keep the applications isolated.
This will provide some benefits like "independently deployable integration services" (same chapter), easier clusterization, and other goodies.
You should approach same VM inter-app communications as if they where between apps placed in different servers.
Seems that Mule added in 3.5 version, a feature to enable communication between apps deployed in the same server. But sharing a VM connector is only available in the Enterprise edition.
Info:
http://www.mulesoft.org/documentation/display/current/Shared+Resources#SharedResources-DefiningDomains
Example:
http://blogs.mulesoft.org/optimize-resource-utilization-mule-shared-resources/
Are Activemq, Redis and Apache camel a right combination?
Am planning for a high performant enterprise level integration solution accross multiple applications
My objective is to make the solution
a. independent of the consumers performance
b. able to trouble shoot in case of any issue
c. highly available with failover support
d. Hanlde 10k msgs per second
Here I'm planning to have
a. network of activemq brokers running in all app servers and storing the consumed messages in redis data store
b. from redis data store, application can retrieve the messages through camel end points
(camel end point is chosen to process the messages before reaching the app).
Also can ActiveMQ be removed with only Redis + Apache camel, as I see from the discussions forms that Redis does most of the ActiveMQ stuff
Could any one advise on this technology stack.
ActiveMQ and Camel works great together and scales very well - should be no problem to handle the load given proper hardware.
Are you thinking about something like this?
Message producer App -> ActiveMQ -> Camel -> Redis
Message Consumer App <- Camel [some endpoint] <- Redis
Puting ActiveMQ in between is usually a very good way to achieve HA, load balancing and making the solution elastic. Depending on your specific setup with machines etc. ActiveMQ can help in many ways to solve HA issues.
Removing ActiveMQ can a good option if your apps use some other protocol than JMS/ActiveMQ messaging, i.e. HTTP, raw tcp or similar. Can you elaborate on how the apps will communicate with Camel? ActiveMQ, by default, supports transactions, guaranteed delivery and you can live with a limited number of threads on the server, even for your heavy traffic. For other protocols, this might be a bit trickier to achieve. Without a HA layer (cluster) in ActiveMQ you need to setup Redis to handle HA in all aspects, which might be just as easy, but Redis is a bit memory hungry, so be aware of that.
So I've read some articles about scaling Socket.IO. For various reasons I don't want to use built-in Socket.IO scaling mechanism (mostly it seems to be inefficient, since it publishes a lot more stuff to Redis then required from my point of view).
So I've came up with this simple idea:
Each Socket.IO server creates Redis pub/sub/store clients, connects to Redis and subscribes to a channel. Now, when I want to broadcast data I just publish it to Redis and all other Socket.IO servers get it and push it to users.
There is a problem, though (which I think is also a problem for Socket.IO built-in mechanism). Let's say I want to know the number of all connected users. There are at least two ways of doing that:
Server A publishes give_me_clients to Redis. Then each Socket.IO server counts connections and publishes number_of_clients. Server A grabs this data, combines it and sends it to the client.
Each server updates number_of_clients_for::ID_HERE in Redis whenever user connects/disconnects to the server. Then Server A just fetches data and combines it. Might be more efficient.
There are problems with these solutions though:
Server A is not aware of other servers. Therefore he does not know when he should stop listening to number_of_clients. One could fix it with making Server A aware of other servers: whenever a server connects to Redis he publishes new_server (Server A grabs the data and stores it in memory). But what to do, when Redis - Socket.IO connection breaks? Is there a way for Redis to notify clients that one of the client disconnected?
Actually the same as above. When a Socket.IO server crashes how to clear number_of_clients data?
So the real question is: can Redis notify (publish to chanel) clients that the connection with one of them has just ended??
After a lot of testing it seems, that Redis does not have such functionality. Also I've found out, that scaling Socket.IO is really a pain.
So I've switched from Socket.IO to WS (see this link). It is low level (but perfect for my use) and it only supports WebSockets (in all major versions). But then again I only want to support WebSockets and FlashSocket (which I have to imlement manually, but that's fine).
The advantage is that I can easily create cluster with such servers. HAProxy works with such servers almost out of the box (some minor tuning). Servers can easily communicate on a local net (with UDP or central TCP server if the cluster is big).
The disadvantage is that one have to manually implement some cool features like heartbeats, broadcasting, rooms, etc. Also you want have long-polling fallback, but that's fine in my case. Scaling is still more important, imho.
I'm considering Redis for a section of the architecture of a new project. It will consist of a lot of clients (node.js connections) SUBSCRIBING to particular keys with one process PUBLISHING to those keys as needed.
I'm curious about the limits of the PUBLISH/SUBSCRIBE commands and how to mitigate those. An obvious limit is the amount of file descriptors open on the machine with Redis so at some point I'll need to implement Master-Slave or Consistent Hashing to multiple Redis instances.
Does anyone have any solutions about how to scale this architecture with Redis' PubSub?
Redis PubSub scales really easily since the Master/Slave replication automatically publishes to all slaves.
The easiest way is to load balance the connections to node.js with for instance HAProxy, run a Redis slave on each webserver that syncs with a single master that publishes the messages.
I can't give you exact numbers since that greatly depends on the underlying system, but this should scale extremely well. And you don't need to manage the clients and which server they connect to manually. You obviously need some way to handle session state, so you might need to do that anyway, but that's a lot easier to do in the load balancer than in your application.
I am having a hard time understanding the ZeroMQ messaging system, so before I dive in, I wanted to see if anyone knew if what I want to do is even possible.
I want to setup a pubsub server with ZeroMQ that will publish certain streams of data and to subscribe to some of those streams, a user must authenticate to see if they have access to those streams. Everything I have seen has the subscribing taking place with the zmq.SUBSCRIBE, command.
Can this be modified to authenticate? Does it support it out of the box?
No, there is no such functionality out of the box. ZeroMQ operates on lower level and it is likely that auth-features will never be in the core.
Since pubsub is implemented on top of IP-multicast, I can suggest to write an auth-server that will control a network router and forbid all multicast traffic to the client by IP/port until this client will not be authorized. You're free to choose auth method in this case, of course.
If you can sacrifice ZeroMQ’s stability and performance to the development cost, just take ActiveMQ. It has authentication features.