I'm new-ish to networking, and I'm swimming (drowning) in semantics.
I have a VM which runs a Java application. Ideally, it would be fed inputs from the host through a RabbitMQ queue. The Java application would then place the results on another RabbitMQ queue on a different port where it will be used by the host application. After researching it for a bit, it seems like RabbitMQ only exists in the localhost space with listeners on different ports, am I correct in this?
Do I need 2 RabbitMQ servers running in tandem, then, (one on the VM and other on Host) each listening to the same port? Or do I just need one RabbitMQ server running while both applications are pointed to the same IP Address/Port?
Also, I have also read that you cannot connect as 'guest/guest' unless it is on localhost, which I understand, but how is RabbitMQ supposed to be configured/reachable to anything besides localhost?
I've been researching for several hours, but the documentation does not point to a direct answer/how-to guide. Perhaps it is my lack of network experience. If anyone could elaborate on these questions or point me to some articles/helpful guides, I would be much obliged.
P.S. -- I don't even know what code to display to give context. Let me know and I'll edit the code into the post.
RabbitMQ listens to TCP port 5672 on all network interfaces out-of-the-box. This includes the "loopback" interface (to allow fast connections to self) and interfaces visible to other remote hosts (including VMs).
For your use case, you probably need a single RabbitMQ instance for both directions. The application on the host will publish messages to one queue and the Java application in the VM will consume messages from that queue and push the result to a second queue. This second queue can be consumed by the application on the host.
For the user, you need to create a new user with the appropriate rights. This is documented in the access control article. To create the user, you can do it from the management web UI (after you enabled the management plugin) or using the rabbitmqctl command line tool.
The last part is networking between the host and the VM. It really depends on the technology you use. It may work out-of-the-box or you may have to configure how VMs are connected to the network. Refer to the documentation of your hypervisor.
Related
I'm trying to create an app with notification service whenever a call is made on API.
Is it possible for me to create a logger on port:8080 and when app is run on the server it listens to api running on another server.
Both applications are run on local machine for testing purposes using Docker.
So far I've been reading https://www.baeldung.com/spring-boot-logging in order to implement it but I'm having problems with understanding the path mapping.
Any ideas?
First let's name the two applications:
API - the API service that you want to monitor
Monitor - which wants to see what calls are made to (1)
There are several ways to achieve this.
a) Open up a socket on Monitor for inbound traffic. Communicate the IP address and socket port manually to the API server, have it open up the connection to the Monitor and send some packet of data down this "pipe". This is the lowest level approach simple, but very fragile as you have to coordinate the starting of the services, and decide on a "protocol" for how the applications exchange data.
b) REST: Create a RESTful controller on the Monitor app that accepts a POST. Communicate the IP address and port manually to the API server. Initiate a POST request to the Monitor app when needed. This is more robust but still suffers from needing careful starting of the servers
c) Message Queue. install a message queue system like RabbitMQ or ActiveMQ (available in Docker containers). API server publishes a message to a Queue. Monitor subscribes to the Queue. Must more robust, still requires each application to be advised of the address of the MQ server, but now you can stop/start the two applications in any order
d) The java logging article is good started into java logging. Most use cases log to a local file on the local server. There are some implementations of backend logging that send logs to remote places (I don't think that article covers them), and there are ways of adding your own custom receiver of this log traffic. In this option, on the API side, it would use ordinary logging code with no knowledge of the downstream consumption of the logging. Your monitor app would need to integrate tightly into a particular logging system with this approach.
I've a question which may seem strange, but I'm working in a environment which has very restricted options.
Basically, I've a job which runs on a SAP Netweaver server, which is clustered.
This job runs socket server code, which allows an ancient system to communicate with it.
My question is this:
Depending on which side of the cluster the job runs on (and I can't influence this), the sock server will either run on a .127 IP or a .129 IP.
Since the connecting system needs a fixed IP to connect to, It gives me a problem.
So, can I open the socket on the .127 IP each time, regardless of which of the two IP the Job happens to be running on, or does it have to be opened on the same IP that the code is actually running on ?
Well, if you can't influence the server, you can introduce a component between the ancient system and the cluster that will redirect the request to one of the IPs in the cluster (.127 / .129 in your example).
|-> [IP .127]
[ancient system] --> [load balancing/proxy component] |
|-> [IP .129]
An actual implementation can vary, basically it boils down to hardware based solution or software based solution.
Hardware
Some network equipment, like load balancers provide this feature, so talk to your network department about this, they'll provide a couple of options.
Software
You can install solutions like "ha-proxy" that will solve this at the level of software
I have a application which listens for commands over IP.
The program works fine locally but when I try to send the application commands with a remote address it won't connect.
Is there anyway to get around the router blocking the inbound network traffic?
I'm using JAVA
Thanks.
If this is a pair of hosts you control, you can open the incoming port. You might also
succeed using a tunneling program such as Hamachi to effectively set up a VPN linking
the hosts.
If you're talking about a pair of unrelated computers (for example trying to set up
a connection for a game) there's no general solution that doesn't involve installing
and trusting additional software. The usual solution is to use a public server and
relay the traffic between the end points.
I'm trying to get a BACNet scanner up on an Seimens server running the Apogee system with a BACNet interface. I've tried using BACNet4j put i get a port bind error on the LocalDevice object for test/Scan.java.
Does anyone know of any other libraries I could use or a reference to instructions for setting up a BACNet plugin to a building management system?
I have had the same problem before, i.e. the BACnet client needs to both send and receive from UDP port 47808. Since the BACnet server already uses that port to listen (and reply) my solution was to use a virtual IP (a bridge) so that my client runs on the same Ethernet card but with a different IP address. A bit convoluted, I know, but it works.
Whether or not the Apogee system supports virtual (or simply additional) network drivers is another question altogether. On my Linux and Windows machines I can run as many servers and clients as I need (I actually don't know what is the limit, I have run up to 5 servers and 3 clients without any problems).
Concerning the port bind error, you may have to configure your firewall because:
BACnet/IP is using UDP
the default port number is 47808 (0xBAC0)
Your issue might be the use of a (BACnet port #) socket that is already in-use; you have to ensure that it's not in exclusive-use - before binding to the socket, but also (slightly more) important, also ensure it's marked for reuse.
But unless you're listening for Who-Is broadcasts, I'd recommend listening for the (unicast) responses upon a different port #, e.g. 0xBAC1/47809, but still send upon the standard port # 0xBAC0/47808.
I created a game and I want to put it on online. I want to buy a website (I'll probably use goddaddy to buy a domain name and use them as the web host) to use as the server to handle game play. Because I would need a separate server for each game, I would need each game's server to exists on different ports. So this leads to my question, is is possible to access these ports on my future web server? (I wrote the program in Java, so I would assume that I would access the ports from the server side by choosing a port for a ServerSocket, and from the client side by using the IP address from the website and the chosen port for a Socket)
(note: also, I am aware that it may be easier to simply use one port and run the servers on different threads instead, but I am just curious to have my question answered)
thanks a lot,
Ian
Technically it is possible to use different ports, but I don't think that a webhoster like goddaddy will let you run a java process that binds to a special port.
If you mean that you are going to create your own TCP server you obviously can create as many instances of your server and configure them to listen to different ports. But it is year 2011 now. This solution was OK in early 90s.
I'd suggest you to use Restful API that works over HTTP. In this case you can forward calls to server side of each application using URL, e.g.
http://www.lan.com/foo/login?user=u123&password=123456 - log in into application foo
http://www.lan.com/bar/login?user=u123&password=123456 - log in into application bar
In this case you need only one server (the web server) that is listening to socket (port 80).
Your server side implementation could be done using various web techonlogis (php, java, asp.net etc) on your choice.
Yes, that should work. The security manager permits connections to a different port on the same IP address that the applet was loaded from.
You can run a Java server on whatever port you want. Each server will accept incoming requests on one port.
The correct way is simply run on one port and each connection will instantiate a new servlet instance (which happens to run in its own thread) that can then service that request. You usually don't need to run separate ports or worry about concurrency, especially if all the stuff that's shared between connections (e.g. multiple players in one game) is handled through database read/writes.
Your host (GoDaddy) will have to allow you use of those ports, but if they are providing proper hosting (not virtual hosting) and given you your own IP there's no reason why you shouldn't be able to.
Your solution may work theoritically, and I like AlexR's solution. But providers like godaddy doesnt let you run a java server, on ANY port. You will need to find out somebody who does. What I found is the cost goes up from $5/mo to about $20/mo, but you get a much better (read faster) machine. Good wishes, - MS.