Is there any good library which supports WebSockets and is compatible with GWT? Ideally, the library would support WebSockets as well as a fallback for browsers which don't support WebSocket, e.g. a comet-like approach or polling.
I'm currently using GWT-Comet to push data from my server to my GWT web application. However, this library is a bit broken in some aspects and it seems it's not maintained actively anymore. Thus, I'm searching for an alternative.
I found Atmosphere, which suits the needs stated in the question pretty good. It supports GWT, and also Websockets. Also, it supports many different application Servers, like Tomcat and Jetty.
Related
i'm just a beginner in cometd , and i'm interested and wanted to learn what cometd is and what for it is used i googled it out and found some resource.Under the following link
1.http://docs.cometd.org/reference/installation.html#d0e346.
I tried out with the given demo but i could not able to get the expected output from it. can anybody post some resource url's so that i can learn ?
Disclaimer: I'm the CometD project leader.
CometD is a set of library to write web applications that perform messaging over the web.
Whenever you need to write applications where clients need to react to server-side events, then CometD is a very good choice. Think chat applications, online games, monitoring consoles, collaboration tools, stock trading, etc.
See more at the preface.
CometD ships a JavaScript client library, a Java client library and a Java server library.
This allows you to write applications in the browser with fine-grained logic and control on the server.
The server library, being in Java, leverages the high scalability of the JVM and the powerful asynchronous I/O API that the JVM and the Servlet specification provide.
CometD is transport agnostic: you write your applications using high level APIs, and CometD takes care of delivering the messages over the wire using the best transport available: WebSocket or HTTP, also providing a transparent fallback in case WebSocket does not work.
CometD provides a clustering solution called Oort that allows you to scale horizontally your web applications.
CometD comes with a ton of features and an extended documentation along with tutorials and demos you can use as a starting point for your project.
Join CometD to start hacking on your CometD-based web applications.
The CometD tutorials are currently written for CometD 2.x, but a port to CometD 3.x (the current version of CometD) is currently underway, so that requires a bit of patience.
But you can start right away by following the primer and deploying the demos.
I hope you can get started with CometD with the above references.
Drop an email on the mailing lists for any help you may need.
I'm about to build a web application in Play Framework and I'll need to have bidirectional communication between the server and the browser.
For modern browsers I can use web sockets, but for older browsers I will need to use long polling. Is there a library that will abstract away this choice and choose whichever one is supported by the browser? Similar to SignalR in .net.
It seems like the Atmoshphere library is absolutely what I was looking for. https://github.com/Atmosphere/atmosphere
Two good options nowdays:
SignalJ based on SignalR https://github.com/chanan/SignalJ using Akka and integrated in Play and with good integration with SignalJ web servers (based on .net)
Atmoshphere library https://github.com/Atmosphere/atmosphere that also supports Play integration and multitude of frameworks
What is the 'best' server-side technology on Linux to use with Google Web Toolkit & why? I'd like opinions about:
JSF and other Java based server technologies
Rails
Django
PHP
GWT is a client side technology used to convert Java to JavaScript.
If you want to use GWT as a client code for a client-server application you should use a Java based server to avoid problems.
You can use the GWT-RPC with any language or you can even use your own JSON wrapping, but the easier solution is to use a Java server.
My recommendation would be GAE, TomCat or Jetty. Both Tomcat and Jetty are really easy to configure in Linux and TomCat integrates nicely with Eclipse.
The server technology has very little to do with it; use whatever you're most comfortable with.
If you want to take advantage of GWT-RPC to pass Java objects between browser and server, you'll obviously need a server written in Java, but any Java server container will work more or less the same.
If you don't care about GWT-RPC, your server can be in any language, Python/Django, .NET/ASP, PHP, Rails, anything. At that point you're just going to be hosting JavaScript files, even static hosting should work for you.
You could even write a GWT app that doesn't connect to a server at all, where the user downloads the JS directly, perhaps packaged as a Chrome extension.
The path of least resistance will be a Java servlet container like Apache Tomcat or Jetty. The GWT servlets are deployed in the servlet container, and call into your own code for the purpose of persistence and other server-side application logic. All of the presentation logic should reside in the client-side GWT code.
May I also recommend that you take a good look at the Scala programming language? It integrates very neatly with Java, and is therefore a perfect language in which to write your server-side logic.
In terms of client-server communication, I recommend gwt-dispatch to you. It has a good following, and streamlines the handling of requests and responses on both the client side and the server side.
I've started my degree project, a mobile application suitable for iPhone, Android and (in the near future) Symbian. The server architecture is the following:
web site (for "standard" users);
web service (for mobile connections), based on TomCat and Axis2;
mySQL DB to storage users data.
Surfing across the web, I've read a lot of discussion about the interaction between the iPhone and Web Services, and I've to say that I've not a clear idea of what I can do and what not.
Let's start from the protocol used to retrieve data from the DB: the Android-side application uses SOAP protocol, can I do the same with iPhone? Are there some limitations or problems?
I have also read about the using of REST instead of SOAP, could it be possible with the server architecture described above? Which are the main advantages/disadvantages?
Sorry if these questions sound "n00b", but it's my first real experience with iPhone and the lot of informations found on the web messed up my mind and I'm scared to be confused. Forgive me for any error.
SOAP is simply too heavy for mobile communications. Why do all the work to wrap requests in an additional XML layer you'll have to parse? You send more data than you need to, and impose greater CPU burden on client and server.
Use REST. If you are doing a cross-platform project JSON makes a great payload container, otherwise plists work well for sending data from the server.
You can definitely do SOAP on the iPhone. Here is a nice tutorial on the subject. After all, SOAP is a HTTP based protocol and you have all the libraries you need to do HTTP on the iPhone.
Having said that, RESTful APIs are simpler than SOAP, so you might want to consider them. They're also HTTP based so you won't have any problems on doing that on iPhone. On the server side, if you use Java, you will have to use JAX-RS to implement that part.
Hope it helps.
Google Buffers
If your looking for a language and platform agnostic solution have a look at Google Buffers. You can easily serialise objects for transmission over the wire.
This question should get you started in Objective-C.
JSON
I have also used JSON within iPhone Apps with great success. Again, relatively language and platform agnostic but much simpler than Google Buffers.
SOAP with Fast Infoset is suited for small devices:
JAX-WS 2.0 and its reference implementation support both Fast Infoset and MTOM/XOP. This article includes information about Web Service Performance for Fast Infoset vs. MTOM/XOP:
http://www.devx.com/xml/Article/35385/1954
Fast Infoset is optimized for small
devices that have bandwidth
constraints, and is supported by many
vendors such as Microsoft .NET and
.NET CF, Sun GlassFish, BEA WebLogic,
IBM SDK for Java 6.0 and others.
http://en.wikipedia.org/wiki/Fast_Infoset
I want to call some RESTful web services from a J2ME client running on a MIDP enabled mobile device. I read the MIDP api for HTTPConnections and thought this is just crying out for a simple wrapper to hide all those unpleasant byte arrays and such like. Before I write my own I wondered whether there was a good open source library already available.
-FE-
You might want to check out this little gem, Mobile Ajax for Java ME:
https://meapplicationdevelopers.java.net/mobileajax.html
One part is (from the site):
Asynchronous I/O for Java ME
This library provides the equivalent
of XmlHttpRequest for Java ME with
some additional functionality useful
for invoking RESTful web services.
It is layered on top of the
com.sun.me.web.path library. Features
include -
* Asynchronous versions of HTTP Get and Post
* HTTP Basic Authentication
* Multipart MIME (sender only)
* Progress listeners
LWUIT 1.5 now includes classes for accessing REST, using OAuth2, JSON, etc.
I don't know of any such library, but found some succinct examples of accessing various RESTful web services
We ended up writing our own simple wrapper api for a variety of reasons not the least of which was the fact that the Sony Ericsson K750 that we were developing for had a weird bug (that SE refused to fix) where if you tried to get/use a connection when the device was off network, more than about 20 times, the internal connection pool would get hosed and never recover unless you restarted the app.