I'm new to Heroku, and I was thinking about building a java RESTful web service that spins up TCP/UDP servers/clients to handle streams of data based on the RESTful calls. Aka, the RESTful calls are the triggers of TCP/UDP server creation for streaming data. Is that possible?
Heroku can only handle traffic over HTTP. I'm not completely clear on your use case, but if you want the servers that you spin up to handle incoming UDP traffic then you won't be able to do it on Heroku.
This answer comes long after the question was asked, but I can confirm that today you can host a UDP server on Heroku, having just built a little proof of concept Node WebRTC app.
Related
I am not as familiar with web services and I'm having a hard time finding information about a question regarding the way clients interact with a RESTful web service.
I've implemented a REST web interface to interact with clients using Java and the Jersey JAX-RS library, however I need to limit the number of connected clients to 6. If I have 6 clients connected and a 7th tries to connect, I need to know if one of the other 6 has disconnected at some point so I can give the new client a connection. Is there a simple way to tell on the server side if a client is still connected? Do clients maintain connection in a REST web service after they complete a request to the server? Normally the clients I'm dealing with make HTTP POST and GET requests to the server at least one a second.
The only thing I can think of would be to ping each connected client and wait for a response in the event of another client trying to connect. If one ping times out then I could replace that client with the new one. But I'm not really sure how that would impact server performance. If anyone has any input on a way too accomplish this, I would greatly appreciate it. Thanks!
What are the possible ways in which Java Swing Application which is running on client side can communicate with server?
I've read that JSP can be used in web pages to communicate between server and client.But, is it possible to use JSP with Swing application? if so, how? It would be helpful, if it is demonstrated with simple login form. Thanks.
Any client-side application, whether it be a java swing app or otherwise, can certainly communicate with any server (assuming no network limiting architecture -- firewalls and whatnot). Your options are numerous
Raw sockets
Any one of the myriad of network protocols.
HTTP/HTTPS
FTP
SCP
et. al.
It depends on what protocol, services and applications are available on the server to connect with.
HTTP/HTTPS is very common. You'll need to manually create HTTP requests and send them to the server (assuming the server is a web server).
I'm trying to build a Java web app that will let me browse a remote file system behind my NAT router. The client can talk outbound HTTP only.
I've got my Java client on the remote machine talking to my Tomcat server, which is then serving the data back up as web pages. Something like this:
File Server (java client) -> Web Server <- Browser
What I can't figure out is how to have the Tomcat server talk back to the remote Java client.
What I want to happen is:
User clicks on a folder in their browser.
Browser ajaxes to the server.
The Tomcat server contacts the remote java client.
The remote java client responds with the directory listing.
The Tomcat server sends back the new data formatted as HTML to the user.
I've looked at Comet and Tomcat 7's asynchronous stuff but I'm struggling!
If you need full-duplex communication over HTTP, than I strongly recommend using Atmosphere and Web Sockets. It simplifies server push a lot, and it's container agnostic (the framework).
You can use Async Http Client library for your remote java client in that case.
If you want to implement a PUSH behavior, then Commet is the way to go.
If there are few clients, perhaps you could solve your requirements by allowing the client to continuosly PULL changes from the server each few seconds.
I would like to have the clients query each other through the server without delay ( = no polling interval ).
Example: Server S, clients A and B
Client A wants to request Client B.
Client A will make a request to the server S, no problem there.
Then Server S needs to be able to request Client B but how to do that without polling?
All the node.js/APE (for PHP) technos are designed for the web, however I don't use a web server for that. Does Java has something close to a push technology/framework that is not web?
I would really prefer a solution that doesn't require each client to use their own reserved port (I don't want to end up with 1 WebService per client for example)
Note: all the clients are on the same machine.
A couple of options...
Plain socket communication. java.net.Socket, java.net.ServerSocket. Maximum flexibility but requires knowledge of low level TCP/IP API/concepts.
The good old RMI. Java based RPC layer on top of TCP/IP. Works good when client and server are both in Java and generally in same subnet. May give problems when client and/or server are natted.
Spring Remoting, it's actually pretty decent.
Bi-Directional Web Services. i.e. clients host their own WSes which the Server calls when it needs to do a callback.
JMS as someone already mentioned.
Distributed Data Structures, Check out http://www.hazelcast.com/
Lots of options to chose from, no need for webserver.
If you really don't want to use a web server then I would check out JMS. That being said, all the cool kids are using web servers these days since the protocols are so ubiquitous.
Your use case requires a messaging protocol. We don't really know the scope of your problem but you already said you want a server to exchange requests between clients, so I would go with an existing solution rather than a roll your own approach.
JMS has been mentioned and is certainly a viable Java based solution, another would be XMPP which is a real time communication protocol commonly used for instant messaging.
It is an open standard that has both server and client support in every major language and platform. This would allow you to have standalone apps, web based ones and apps for mobile devices all being able to communicate with each other. The only potential gotcha for your use case is that it is text based. Since you haven't said what requests you want to pass back and forth, I don't know if this will fit your bill or not.
You can use Smack for client side development in Java and any OS server you want.
I have to design a client/server system emulated on a website running Ruby on Rails that should work like this:
a page is requested by a web browser and once it's opened the server can push messages to it
I know this is not possible "naturally" but I was thinking of a sort of "java applet" that is running on that page, listening on a port for messages to be sent by the hosting server. This should be done opening a sort of a socket that listens on some port where the server can connect to send its messages.
Can this be done? Do I have to develop a java server thread or can I simply address the client applet via it's ip address and port and use any web service connection from the server?
thanks,
Luca
Comet is definately what you want. Depending on your needs, you can host your own comet server, or use a SaaS solution, such as WebSync On-Demand (disclaimer: I work there). Using the SaaS stuff, you get server-push capabilities without having to actually run your own comet server.
The easiest way to do that is to use Javascript to emulate the push mechanism. Polling in regular intervals using AJAX is sufficient in most cases. Have also a look at Comet.
An alternative to using a java applet may be to use a combination of javascript and an approach known as Comet. In a nutshell, Comet is a way to enable server push over HTTP. I'm not really a ruby on rails guy, but a quick google search for ruby on rails and comet nets a fair amount of useful information.
have you looked at juggernaut
If you want go the applet route, you need to make the connection from applet to the same server where the web page is served. The applet can't listen. Once the TCP connection is established, it's a 2-way channel, you can pull or push as long as your protocol allows it. This is how it's done with most Applet-based chat clients.
More and more people are simply using long polling in Javascript. It's pretty involved to get a reliable long polling system running, I would suggest you to use a framework. For example,
http://cometdproject.dojotoolkit.org/