what's the best way to pass data between two ruby programs over the internet? The data is small and needs to be passed frequently. Also, since this happening over the internet, it needs to be secure. I'd appreciate any help, extra points for a pointer to some guides on this topic.
You can use sockets to communicate between two ruby programs ...
https://www6.software.ibm.com/developerworks/education/l-rubysocks/l-rubysocks-a4.pdf
For security use encryption
Related
I need to do something relatively simple, and I don't really want to install a MOM like RabittMQ etc.
There are several programs that "register" with a central
"service" server through TCP. The only function of the server is to
call back all the registered clients when they all in turn say
"DONE". So it is a kind of "join" (edit: Barrier) for distributed client processes.
When all clients say "DONE" (they can be done at totally different times), the central server messages
them all saying "ALL-COMPLETE". The clients "block" until asynchronously called back.
So this is a kind of distributed asynchronous Observer Pattern. The server has to keep track of where the clients are somehow. It is ok for the client to pass its IP address to the server etc. It is constructable with things like Boost::Signal, BOOST::Asio, BOOST::Dataflow etc, but I don't want to reinvent the wheel if something simple already exists. I got very close with ZeroMQ, but non of their patterns support this use-case very well, AFAIK.
Is there a very simple system that does this? Notice that the server can be written in any language. I just need C++ bindings for the clients.
After much searching, I used this library
https://github.com/actor-framework
It turns out that doing this with this framework is relatively straightforward. The only real "impediment" to using it is that the library seems to have gotten an API transition recently and the documentation .pdf file has not completely caught up with the source. No biggie since the example programs and the source (.hpp) files get you over this hump. However, they need to bring the docs in sync with the source. In addition, IMO they need to provide more interesting examples on how to use c++ Actors for extreme performance. For my case it is not needed, but the idea of actors (shared nothing) in this use-case is one of the reasons people use it instead shared memory communication when using threads.
Also, getting used to the syntax that the library enforces (get used to lambdas!) if one is not used to state of the art c++11 programs it can be a bit of a mind-twister at first. Then, the triviality of remembering all the clients that registered with the server was the only other caveat.
STRONGLY RECOMMENDED.
I'd like to start investigating client/server communication. I've started to look at Distributed Objects and a tad at CFNetwork. Let's just say I'm looking for something more my speed (which is slower).
I'd like to be able to send a message from one computer to another, possibly carrying a string or some other type of data. I'm thinking of building a simple student response system where one computer is acting as a server and the clients are connecting and sending data to it.
I'm looking for resources that might help me out as well as suggestions of where to start understanding the concepts involved. I've been teaching myself Objective-C and am a relative newbie to programming, so I know I have holes in my understanding.
"Sockets" is the canonical answer.
If you're interested, here's a great introduction to socket programming (biased toward C, but still very informative):
Beej's Guide to Network Programming
Another way of doing it really simple is by letting the server set up a local http server (inside it self), and then let the clients simply make http requests. By doing that you let the http layer do all the fancy sockets stuff. More simple, and with more overhead, but may be suitable for your case. Also a lot easier to debug, since you can use your browser to test the connection. There are many ways of implementing a HTTP server in cocoa, can't remember which one i've used, but a quick google pointed me at this one for example
before I start I realise there are a few SNMP related questions here already but not many seem to have been answered - that could mean I'm asking in the wrong place but I don't know where else to go at the moment.
I've been reading up as best I can on SNMP for a couple of days but am finding it difficult to get my head around what is meant to be happening. The idea is eventually we will integrate SNMP into our Java application server which will allow the end users to incorporate it into their pre-existing Network Management Systems(NMS).
Unfortunately I'm feeling entirely confused by what is meant to be going on. From what I understood from talking to the end users (which was unfortunately before any research) was that the monitoring allows their existing NMS to give their admin guys a view of the vital statistics in a tree type display, giving them feedback regarding different parts of the system at a high level and allowing them to dig down into specific subsystems.
From reading around we would implement an 'Agent' which has several defined interfaces allowing for GET requests etc to be processed and responded to. That makes sense but I am at a loss to work out what the format of the communication is - there don't seem to be any specific examples of what any of the messages look like, how the information is encoded.
More of my confusion though is regarding Management Information Base(MIB). I had, wrongly, assumed that the interface of the agent would allow for the monitored attributes to be requested and then in turn the values for those attributes requested. Allowing any new Agent to be started and detected without any configuration on the NMS end (with the exception of authentication in v3). This, if I understand correctly, is not the case and the Agent must instead define MIBs which can be used by the NMS to determine those attributes. My confusion is increased when people start referring to thousands of existing MIBs and that they can be reused which I don't understand. Is the intention that a single MIB definition can be used to say describe how a particular attribute of a network device (something simple like internet connected on a router:yes/no) for many different devices? If so I don't believe that our software would allow the monitoring of anything common to any other device/system but should we be looking for already exising MIBs? At the moment I don't really see any good rational for such a system, surely it would be easier for the Agent to export that information - so I'd appreciate it if someone could enlighten me!
I think it would help if I was able to setup a simple SNMP agent and some sort of client, I could begin to see the process and eventually inspect the communication between the two but am finding it difficult to find anywhere that provides any information on doing such a thing. Nagios has been recommended to us as a test 'client'/NMS but their 'get started quick' section recommends downloading a 600Mb virtual machine - surely there is a quicker way to get started?
Any help or suggestions will be appreciated, I have been through the Wiki page but it doesn't seem to go into much detail about the MIBs and the having not had to deal with anything like the referenced RFCs before, while they may contain all of the information they seem completely impenetrable to me at the moment. Or if there are any books that can be recommended for an overview and implementation of v3?
Thanks for reading and even more thanks if you think you can help!
It seems to me that you read all SNMP information piece by piece in an disorganized way. This is highly not recommended and of course lead you to confusion.
What about forgetting what you have learnt so far and dive into a good book such as Essential SNMP?
http://shop.oreilly.com/product/9780596008406.do
Click the Google Preview icon to preview it please.
You could not depend on a network forum to tell you the ABCs, as that's impractical I find out.
The communications interface is SNMP. That's the protocol used for transmission (usually on top of UDP). The thing that services information requests is an SNMP Agent. The thing that sends information requests is an SNMP Manager.
The definition of what information should be made available by the Agent, and requested by the Manager, goes in a MIB. A MIB is the "glue", a directory of what sort of things any particular system can/should offer. It maps numeric codes to names and types that allow us to make sense of the data, much like how a phone directory maps phone numbers to people's names and addresses.
Generally you would create and ship and use your own MIBs that can describe aspects specific to your own product, but you are supposed to service some standard information requests as well, which are defined in existing MIBs. Yes there are thousands of other pre-existing MIBs and the likelihood that you need more than one or two of these is remote. They are typically published versions of MIBs for existing products.
The conventional way to "toy around" is to install Net-SNMP (a software suite that includes an agent implementation and allows you to "bolt on" your own logic and your own MIBs fairly easily) then examine the results using a packet capturer like Wireshark.
For a fuller implementation in production you may stick with Net-SNMP, or write your own Agent software, or do what I did and create a hybrid of the two that's a little more flexible and performant but uses Net-SNMP's backend for handling all the low-level SNMP stuff.
Your first step, though, is to read a book or some other teaching material that can clear all your misconceptions, because guesswork won't cut it.
I had success using the samples from this page. Both the shell and Perl NetSNMP code was very straightforward to implement and query.
I would like to set up a network with some computers I have, where they can connect to one main source, then receive and send messages back to it. I have never done any network programming before, so I'm just wondering what are the best tutorials using Ruby that I could use.
Thanks in advance.
There are about a billion ways you could do this. Could you post more about what the problem is you're trying to solve, or what the content/purpose/size/format/etc. of the messages is to be? Are you building something "for real" or just trying to learn network programming?
Also, do you already have the lower layer stuff figured out? You have networking infrastructure setup, IP addresses assigned, etc? If not, you'll need to get through that. Once you have that, you could start with a tutorial on basic socket programming in Ruby, but - depending on the answers to the questions above - you might not want to "roll your own" solution at that level. The answer might be to use an XMPP (Jabber) server, and use an XMPP client library, or you might want to deploy something like ActiveMQ, HornetQ, etc. and use a library for interfacing with that. Or maybe you want to use HTTP and pass messages around in JSON, or XML or $WHATEVER. In short, there are a LOT of options in this area.
I'm interested in how you would approach implementing a BitTorrent-like social network. It might have a central server, but it must be able to run in a peer-to-peer manner, without communication to it:
If a whole region's network is disconnected from the internet, it should be able to pass updates from users inside the region to each other
However, if some computer gets the posts from the central server, it should be able to pass them around.
There is some reasonable level of identification; some computers might be dissipating incomplete/incorrect posts or performing DOS attacks. It should be able to describe some information as coming from more trusted computers and some from less trusted.
It should be able to theoretically use any computer as a server, however, optimizing dynamically the network so that typically only fast computers with ample internet work as seeders.
The network should be able to scale to hundreds of millions of users; however, each particular person is interested in less than a thousand feeds.
It should include some Tor-like privacy features.
Purely theoretical question, though inspired by recent events :) I do hope somebody implements it.
Interesting question. With the use of already existing tor, p2p, darknet features and by using some public/private key infrastructure, you possibly could come up with some great things. It would be nice to see something like this in action. However I see a major problem. Not by some people using it for file sharing, BUT by flooding the network with useless information. I therefore would suggest using a twitter like approach where you can ban and subscribe to certain people and start with a very reduced set of functions at the beginning.
Incidentally we programmers could make a good start to accomplish that goal by NOT saving and analyzing to much information about the users and use safe ways for storing and accessing user related data!
Interesting, the rendezvous protocol does something similar to this (it grabs "buddies" in the local network)
Bittorrent is a mean of transfering static information, its not intended to have everyone become producers of new content. Also, bittorrent requires that the producer is a dedicated server until all of the clients are able to grab the information.
Diaspora claims to be such one thing.