I have two Java Programs each running in its own JVM instance ? Can they communicate with each other using any IPC technique like Shared Memory or Pipes ? Is there a way to do it ?
Yes; D-BUS and Pipes are both easy to use, and cross-platform. D-BUS is useful for general message-passing IPC, and pipes for sending bulk data.
You can also open a TCP or UDP socket on localhost, if you need to support multiple clients connecting to a central server.
I also found an implementation of UNIX sockets in Java, though it requires the JNI.
http://java.sun.com/javase/technologies/core/basic/rmi/index.jsp
Java Remote Method Invocation (Java RMI) enables the programmer to create distributed Java technology-based to Java technology-based applications, in which the methods of remote Java objects can be invoked from other Java virtual machines*, possibly on different hosts. RMI uses object serialization to marshal and unmarshal parameters and does not truncate types, supporting true object-oriented polymorphism.
Sure. Have a look at RMI or a Shared Memory concept like Java Spaces.
Use MemoryMappedByteBuffer in Java NIO for sharing memory between processes.
There is a fairly new initiative for language-agnostic IPC of columnar (i.e. array-based) data from Apache called Plasma.
As of yet (Sept '17) there are no JVM bindings, but as the project is backed by the likes of Spark, I think it won't be long before we see an implementation.
My understanding however is that there is not a general IPC system, as it is geared toward sharing arrays of primitives like double,long, for scientific computing, rather than classes/objects; though I could be wrong here.
On the plus side, it's also language-agnostic, so you could use it to communicate with another (non-JVM) runtime. However, the OP did ask for Java IPC so this could be irrelevant.
Related
Is it possible to implement a RabbitMQ RPC between Java (acting as a client) and a .NET application (server/worker) using the RabbitMQ .NET library?
It seems like it should be possible, as RabbitMQ broker handles the queues and the socket connections are established between party and the RabbitMQ broker.
Are there any practical considerations in doing so?
The short answer is yes. In fact, my company uses RabbitMQ for that very reason - it offers a platform-neutral (as close as possible anyway) way to communicate between different applications. So in theory, I could have Java applications running on Linux and .NET applications running on Windows, and everything works together just fine.
You will need to come up with a common serialization format for your messages; I recommend using JSON as there are JSON libraries in every major programming language.
If you have any trouble with the RabbitMQ .NET library, feel free to post more questions :-)
I am attempting to build a client/server game architecture and would like to begin testing the game using my local Mac as the server. I have found several articles on Bonjour, but that is for local network traffic only. My goal is to make this application work over the Internet, connecting to a hosted application on a static address to facilitate turn data. However, I'm at a loss as to which Cocoa APIs to use for this purpose. Should I use NSConnection, NSStream subclasses, or good 'ol C sockets and whatnot. The game state is already built in Objective-C and is ready to be set in motion once I have the server facilities ready. Any insight?
NSConnection, NSStrean and C sockets are build for different needs. You need to specify the needs of your game and the kind of service in order to get more help. If you want to develop a client-server application that relies on the Internet and not on the local network, Bonjour will not be able to help.
C sockets, and Cocoa APIs that wrap around them are intended to operate on an open network stream between the client and the server. The advantage of having an open stream is that you can have the server send data to the client without the client having requested for it. NSURLConnection in Cocoa works differently. With it, you can perform HTTP requests and receive formatted responses from a server.
If your application is based on HTTP requests, I recommend you take a look an NSURLConnection, or AFNetworking, as a 3rd party alternative. If your application relies on open streams, I recommend you take a look at CFNetwork from Apple (C wrapper around BSD sockets that originates from the days Macs had Carbon, with great performance, stability and versatility) and GCDAsyncSocket, a 3rd party library wrapped around BSD Sockets, supports Crand Central Dispatch, is Objective-C ready, and does the job wonderfully.
I hope I helped.
I suggest you to use sockets, since they're not hard to use and are a standard way. I've even written an asynchronous wrapper class around BSD sockets: https://github.com/H2CO3/TCPHelper
This is for simple, one-to-one TCP protocol connections, supporting both IPv4 and IPv6. You can send and receive raw NSData and possibly build a protocol around it.
Foundation classes such as NSURLConnection are not particularily for this purpose; rather than to interact with standard HTTP servers (I suppose you don't want to implement a full HTTP server for a game).
NSNetServices may suit you just like CFNetwork, but the latter is a bit harder to use. If you'd like to use Foundation classes, I'd recommend NSNetServices.
Hope it helps.
There are many different ways to accomplish this. It really depends on how you'll be passing the data and what it will be used for.
First, I would setup a hostname that you can use for development purposes with your game. You can use anything like http://dyn.com/dns/ to setup this for your Mac. Then you can enable a compiler setting to switch out the development / production URL's.
Next, I would recommend using TCP sockets for your game (using CocoaAsyncSocket - https://github.com/robbiehanson/CocoaAsyncSocket). This method should work fine your your use case. Since you are doing turn-based data (and since all of that data is vital) I would not recommend using UDP sockets (but those would work if you were solely passing position, video, or audio data where a dropped packet might not matter).
I'm writing software for a new hardware device which I want any kind of new third-party application to be able to access if they want to.
The software will be a native process (C++) that should be pollable by 3rd party games and applications that want to support the hardware device. Those 3rd party apps should also be able to receive events from the native process, on a subscribe basis. So aside from the native process, I'll also supply "connector" libraries to the 3rd party developers, for all platforms/languages that they might choose (Java, C++, Python etc.) to embed in their apps so they can easily connect to the device with hardly any extra code needing to be written by them. I want to target all desktop/laptop OS platforms, and have a pretty good idea of what functions I want to expose, but ideally I don't want to be too stuck (i.e. I want it to be elegantly scalable from both client and server perspectives).
I'm looking for reliability going forward, performance, maintainability going forward, and cross-platform/language flexibility going forward, and ease of development, in that order.
What should I use?
CORBA, MessagePack-RPC, Thrift, or something else entirely?
(I've omitted ICE because of it's licensing)
Thrift or Message Pack is the best option going forward. Both are sleek, light weight and do not add much latencies to your process. They have support for most of the common languages, and are in Active Development. At the current stage I would prefer thrift personally but message pack does seem to promise a lot of features.
Thought thrift might not be as windows friendly as we want but people are using it on windows.
This is a starter guide for thrift on windows.
http://wiki.apache.org/thrift/ThriftInstallationWin32
Only installing and getting the Thrift compiler can be troublesome on windows. Using the generated files depend on the language you choose and lot of the languages have good support to run the files by importing thrift libraries. (Java it is very easy, MAVEN artifact)
There is a discussion on the RPC frameworks available at RPC frameworks available?
CORBA according to me is old cumbersome and very heavyweight.
If ancient and heavyweight don't put you off, obsolete definitely should. Regardless, I can tell you what we've been using Google Protocol Buffers at work recently, and they're pretty easy to use.
From the developer's perspective, all you need to do is have a build of GPB (which really isn't that difficult), and then it will generate source files for you. The end result is a cross-platform binary message transport message passing interface (think XML and limited RMI, not MPI-like functionality).
We use it on Windows to talk to an Arm-based Linux system (TS-7200's from embedded arm) running the same software. to my knowledge, it is compatible with many languages.
CORBA is the only free "RPC" thing that would work for my system right now, even though it scales very badly. Thrift isn't Windows-friendly yet. Neither is MessagePack-RPC yet available in all languages and OSs, even though it's still in development. If CORBA was elegantly scalable it probably wouldn't have become obsolete at all.
Protocol Buffers and messaging would work, I'd have to develop a both a client and service implementation for every platform/language. It would also be very scalable. I've decided on this.
I'm currently using Apache Thrift for a Hospital Manager project. It is better than CORBA in many areas, not to mention it is lightweight and much easier to implement and understand. The learning curve for Thrift is definitely subtle compared to CORBA, but the documentation for Thrift is the worst thing.
I'm using a Ruby Thrift server to which Obj-C and Java clients connect. The Thrift parser or "compiler" does a pretty good job generating source files for the languages you want, although it is far too verbose. I would definitely look into implementing Thrift, or Google ProtoBuffs if I was starting a new project, since CORBA is really outdated, and might not implement new technologies in the future, not to mention that there are many vulnerabilities and exploits targeting CORBA that will not get patched since it's not in development anymore, presenting some serious security holes on your new project.
Thrift supports many programming languages: C++, Java, Python, PHP, Ruby, Erlang, Perl, Haskell, C#, Objective-C, JavaScript, Node.js, Smalltalk, OCaml and Delphi as of this writing. Supporting multiple languages is key, I think, for the purpose of your project.
Was wondering what kind of software and hardware component cant fail in a rmi program?
so for example in a client server model when a client invokes an object in the server?
thanks
Here's a quick list of RMI related failures:
Networking related failures. This list is rather large. If this is Java and windows, watch out for DNS related problems. I've seen some rather nasty challenges on large corporate LANs.
Version control between client and server
I've seen scaling problems with Java RMI and the default ServerSocket handler.
In general, I'm not a big fan of Java RMI. While it takes care of some problems, its implementation in traditional enterprise networks have caused me more problems than it saves. There usually are other choices out there.
While reading about OpenSSL I've stumbled upon sentence: "It would be nice if security was as
simple as linking in a different socket library when building a program".
What is this mentioned socket library? What is it used for (i.e. in Java or C#)?
A socket is the endpoint of an Internet connection. A socket library is a library that implements sockets so that you can use them in your program for Internet communication.
What the text suggests is that it would be nice if you could replace your regular socket library (which would be for example a DLL on Windows) with a different version, which would automatically add SSL functionality for secure, encrypted connections - but adding SSL functionality is not as simple as that.
In Java or C#, you wouldn't use such a library directly. Java for example has classes in its standard API for working with Internet connections. You'd use that API in your Java program, and the JVM will use the socket library that the operating system provides to do the actual communication.