What are good ways to get something like D-Bus to work across multiple Linux machines, possibly through firewalls?

Question

The D-Bus specification says that

D-Bus is.. a simple way for applications to talk to one another... Currently the communicating applications are on one computer...

I would like something like D-Bus but to work across multiple Linux machines, and there may be firewalls involved. For example, if my mail server decides it receives an important message, I would like it to post an event to the bus that my computer at home can see and perhaps respond by launching a linpopup window.

The events I'm interested in are relatively infrequent, so a low-performance technique is OK. But I would prefer not to reinvent any wheels. I would also prefer that as much as possible is written in shell scripts or other high-level languages and as little as possible in C (but I am willing to call C APIs if that is what it takes).

The way I interpret the official D-Bus web pages, they say it would be nice to get D-Bus to talk to multiple computers, but it doesn't work.

Edit: What's attractive to me about D-Bus is the model of publish and subscribe:

• A machine that observes an interesting event publishes that event to "the system".

• A machine that is curious about particular events subscribes just to those events. When an event happens, "the system" lets the machine know.

In D-Bus, "the system" is a single machine. I want something similar for multiple machines. This rules out direct solutions like TCP or SMTP communicating between machines. But I am happy to have a central server which receives all publication and subscription requests. I'm beginning to think it would be easier to build my own than to understand the Advanced Message Queueing Protocol (AMQCP), which is too darn advanced for the likes of me.

Performance is no object. Simplicity is definitely an object.

Once more: What software should I look at?

Answer 1

Maybe I'm missing the point (entirely possible!), but why not just use SMTP and send e-mail messages? Or TCP packets, and have a listener program on the other side?

Answer 2

I know of no ready-made solutions like this.

My suggestion is that you write scripts that use curl or wget to send HTTP POST requests to a very simple web application, containing your info. And another machine polls the same web in intervals and GETs the info.

Comet can improve the polling nastiness, but will probably require more effort.

Answer 3

The "new thing" for managing messages and communication between apps, apparently is Rabbit.

Is an implementation of AMQP, that establishes messaing, routing and security...

check this:

http://www.rabbitmq.com

http://en.wikipedia.org/wiki/Advanced_Message_Queuing_Protocol

Answer 4

You should search for messaging solutions but those depend on what language you intend to work in. Java has had this feature for a while, called JMS (Java Message Service). However other implementations exist.

• ZeroMQ has API bindings for: C, C++, Python, .NET/Mono and more
• OpenAMQ has API binding for: Python, Java, Ruby and C

I have no experience with the different frameworks so I can't tell you what to use, but you could give these a shot.

Answer 5

If you are interested in trying a lower layer protocol, you could try SOAP. Its not as efficient as binary protocols, and you would have to do the higher level queueing yourself, but it can operate through web proxies and via SMTP servers. There is a decent PERL implementation that I have experimented with before.

For more info:

http://www.w3schools.com/soap/default.asp

Answer 6

A TCP/IP based message queue (MQ) / message oriented middle ware (MOM) solution should meet your needs. Most mature offerings provide native-language bindings for a variety of languages. I've had good luck with ActiveMQ, it has a CLI interface that might suffice for simple scripting tasks.

A bit of background can be found here: http://en.wikipedia.org/wiki/Message-oriented_middleware

Good luck,

Shannon