We are developing an app that will have Web service in JAVA and Application in iOS.
Web-service will compute the list on a Particular Algorithm and that list has to be Shown realtime on the Device.
We were thinking of making a Routine Post Calls on every minute and get result from server but I think this would be very Costly and inappropriate way for syncing data with the Web-service's Result.
Can anyone provide Best alternative and Ideal Way for such type of requirement. Which approach should we choose to Provide such Real-time Sync for application.
You can use a WebSocket connection for this. WebSocket establish a full duplex connection between iOS and your server. This allows the server to trigger the client if new data is available.
As you mention it doing a routine post call every minute could work, but it will cost a lot of resources. It's not a good solution.
One solution could be to use websocket. So the server will send notification when data have changed. See here what is websocket http://fr.wikipedia.org/wiki/WebSocket
Use netty-socketio java realtime framework, it supports long-polling and websocket transports. javascript, ios, android client libs also available.
After googling and research, I found Socket.io better option for Our case
Socket.IO is a WebSocket API created by Guillermo Rauch, CTO of LearnBoost and lead scientist of LearnBoost Labs.
Socket.IO will use feature detection to decide if the connection will be established with WebSocket, AJAX long polling, Flash, etc., making creating realtime apps that work everywhere a snap. Socket.IO also provides an API for Node.js which looks very much like the client side API.
I am interested in putting a chatting functionality as part of an application.
What I am interested in:
I would like to keep my application instances acting as peers, i.e.
I would prefer not to write also some server module to handle
message communications
I would like it to be able to use it with exising IM accounts. E.g.
someone can use it using his MSN account or any other client
account he may have, same way he would use MSN Messenger or Tor client etc
I googled and found that there are some Java MSN libraries available and also some other libraries that support IM e.g. SMACK for JABBER etc (not sure what that is) but I am not sure if the latter could be used for option 2 I mention.
My preference on 2 is because I assume that this way a user could do chat no matter where he is while in other solution I assume that some network infrastructure e.g. with routable IPs etc would be required. Am I wrong here?
Does anyone have expererience with Java IM libraries? Are for example any issues e.g. with different MSN versions or something?(Don't know if the protocol has been changing often to matter for me).
What would be the best path/option for my requirements?
I would go with a Jabber based approach. Jabber (also called XMPP) is an open protocol with lots of implementations and supports connecting to other IM services via transports. That way you would not have to deal with changes to the Windows Live protocols. You can rely on the open source community to provide that functionality for you.
Edit: It seems, that Windows Live even allows native XMPP access.
If you like, you can always set up your own Jabber server to provide a tighter integration with existing user accounts. In that case you wouldn't need to write the whole server.
Wikipedia defines XMPP as:
...an open-standard communications protocol for message-oriented middleware based on XML.
xmpp.org defines XMPP as:
The Extensible Messaging and Presence Protocol (XMPP) is an open XML technology for real-time communication, which powers a wide range of applications.
Although I'm sure both these definitions are very accurate, they don't tell me a thing about what I - a Java developer - can actually do with XMPP!
For instance, I've heard XMPP can be used with message-oriented middleare (MOM). How so? Can XMPP somehow integrate with my Apache Camel routes, my ESB or some SOA implementation to deliver a better/faster/more robust business tier? If so, how?!?!
A good, King's-English explanation of XMPP, along with some practical examples (preferable MOM-centric) would be greatly appreciated. Thanks in advance!
XMPP can be used for a wide range of messaging based applications. Basically, it provides core services which can be used to build XML based messaging applications. Its based on a decentralized client-server architecture and utilizes long-lived TCP connections for communicating...
core services include...
channel encryption, authentication, presence, contact lists, one-to-one messaging, multi-party messaging, notifications
service discovery, capabilities advertisement, structured data formats, workflow management, peer-to-peer media sessions
textbook use cases...
instant messaging (using presence, contact lists, one-to-one messaging)
group chat, gaming, systems control, geolocation, middleware/cloud computing, data syndication
bots (weather, database interface, system monitoring)
messaging modes/patterns...
point-to-point messaging is used to send to a specific receiver
multi-user messaging is used to message to a group of receivers
publish/subscribe support is used when there are large volume of events and systems are interested in differing subsets of events. Publishers put events into topics and subscribers indicate which topics they are interested in. This decouples the publisher/subscriber and allows for scalable real-time messaging. For more information, see this article: http://www.isode.com/whitepapers/xmpp-pubsub.html
deployment methods...
XMPP user - connects as a normal user and responds to requests addressed to the user
XMPP Server plugins - deployed as part of the server plugin architecture
XMPP Components - service external to an XMPP server that connects and behaves like a plugin
Java Integration
Smack API - A pure Java library, it can be embedded into your applications to create anything from a full XMPP client to simple XMPP integrations such as sending notification messages and presence-enabling devices.
Camel XMPP - A Camel component that allows integration with Smack API in Camel routes
To your specific question "can it be used in SOA/middleware?"....
yes, it can be used to wire together applications via XML messaging and XMPP APIs
whether its the best technology choice depends heavily upon requirements
one good use case, interactive system monitoring/management...here are some other examples
Also, XMPP integration with Camel is trivial. See this camel-xmpp unit test for a basic example of interfacing with a Google Talk server. Also, Camel's framework allows you to build an application and easily swap out different messaging technologies (JMS, STOMP, mina, etc).
I can start combining information from al kinds of sources found on the internet using Google (keywords: XMPP Java MoM examples), rewrite (or even copy) the definition of XMPP, but of course I will not do so. There is just too much. I also do not have examples available for you.
Below I will list the links I found most interesting, so you can start reading and get more knowledge on the subject.
1) http://www.xmpp.org/
This is probably the best starting point. Browse through the menu left to right and top to bottom. That is what I did. The site lists servers, clients and libraries, so you should be able to find the desired examples this way.
2) http://www.ibm.com/developerworks/webservices/library/x-xmppintro/index.html
Clear article, which also mentions MoM. No Java examples, but Ruby.
3) http://fyi.oreilly.com/2009/05/what-can-you-do-with-xmpp.html
Maybe you should just get the book? No examples in the article.
4) http://kirkwylie.blogspot.com/2008/07/real-mom-is-hard-lets-use-xmpp.html
Interesting article where the last line basically says: Why use XMPP if you can use AMQP or JMS?
I hope this helps you I finding what you need.
XMPP is an open and extensible standard for real time communications.
XMPP comes with a core that is defined in its rfc, which describes the basic protocol for doing instant messaging and exchanging presence information. However where XMPP really shines is in its extensibility: XMPP defines the building blocks (presence, message and iq stanzas) to create protocols of communication. These typically come as extensions. A list of currently available standard extensions can be found here. The most important of these are typically available for all the popular XMPP servers.
It is exactly this extensibility that makes XMPP appropriate as message-oriented middleware.
Let me take as an example Publish-Subscribe which is a typical pattern for middleware and becomes a necessity as soon as you depart from the scenario with a few entities where simple messaging is adequate. PubSub is used in situations where entities, or producers, produce information that is to be consumed by other entities, the consumers. Typically, the information is written to nodes, to which consumers are subscribed. Being subscribed they receive notifications when an item is added/updated/deleted. An incredible amount of use-cases can be elegantly covered by PubSub, from queuing long-running jobs and having workers handle them, to micro-blogging. XMPP has a very robust and widely available extension to handle PubSub in a standard way, described in XEP-0060 and providing out of the box a workflow for handling publishing, subscriptions, notifications and security. Having a look at the use-cases in the XEP will give you an idea for the simplicity of the whole thing.
Now, while most use-cases are covered by using (or abusing) existing standard extensions, eventually you might need the little extra custom protocol that is not covered elsewhere. Using your language of choice you can write an XMPP component defining your own protocol. You then connect the component to the XMPP server you are running and by using simple namespacing let the server know what kind of messages you can handle and let the server advertise your protocol capabilities to clients connecting to it. There is no end to how simple or complex you can make this. Lack of better example but maybe good enough for illustration, here is a component I wrote that leverages XMPP to do real-time collaborative editing in the Plone CMS (similar to Google docs). While the details can get complicated I think having a look at the "Protocol Specication" on that page will give you an idea.
Finally, concerning Java specific libraries as #boday mentions, there are libraries around that make it easy to start with as well as Apache Camel integration (although it only does simple messaging as far as I can see). Keep in mind though that the investment in understanding how XMPP works and being able to go beyond using existing libraries is really worth it and can lead to extremely powerful and yet simple integration.
Let me just give you a good overview of what XMPP is ?
XMPP ( Extensible Messaging and Presence Protocol )
It is a Real time communication protocol.
The first IM service based on XMPP was Jabber.org
One XMPP binding is BOSH. Others include TCP and WebSocket.
BOSH is "Bidirectional-streams Over Synchronous HTTP", a technology for two-way communication over the Hypertext Transfer Protocol (HTTP).
BOSH emulates many of the transport primitives that are familiar from the Transmission Control Protocol (TCP). For applications that
require both "push" and "pull" communications, BOSH is significantly
more bandwidth-efficient and responsive than most other bidirectional
HTTP-based transport protocols and the techniques known as AJAX.
BOSH achieves this efficiency and low latency by long polling.
How does XMPP works?
XMPP achieves low latency by implementing Long polling.
What is Normal Polling and Long Polling ?
NORMAL POLLING:
Consider the old chat apps that used normal polling. Here the top of the graph indicates client side. Bottom indicates server side. Let the timeout be 5 min.
Client asks the server : " Is there any new message for me ?"
Server Responds : "No ! "
After 5 min
Client asks the server : " Is there any new message for me ?"
Server Responds : "No !"
After 1 min
Client Receives a message
After 4 min
Client asks the server : " Is there any new message for me ?"
Server Responds : "Yes! " + message.
LONG POLLING
The top part of the graph is client . Bottom part is server.
Client asks the server : " Is there any new message for me ?"
Server Answers : "No ! But you may soon receive a new message, so let me just hold your client state for 5 min in the server."
After 5 min
Server Responds : "No !"
Client asks the server : " Is there any new message for me ?"
Server Answers : "No ! But you may soon receive a new message, so let me just hold your client state for 5 min in the server."
After 1 min
Client Receives a message
Server Responds : "Yes! " + message.
You can see clearly, how instantaneously the communication happens.
You can read more about XMPP HERE
In case, if you are curious to set up your own XMPP server, read this.
XMPP is fundamentally a protocol for chat room clients to talk to a chat server. Camel does allow you to integrate with XMPP so that you can consume messages from or produce to such a mechanism http://camel.apache.org/xmpp.html
When you start talking business tier, ESB, SOA etc. and MOMs you're probably looking for a messaging mechanism that supports point to point and publish subscribe messaging. You're probably also thinking about things such as guaranteed messaging, high availability, and fine-grained security. You won't get these from a mechanism that reads and writes text messages into a chat server. A messaging platform such as ActiveMQ is likely to be a far better fit.
There are very few instances where I would contemplate using XMPP with integration mechanisms, maybe as a notification mechanism to a dev chat room, or as a duct-tape mechanism for controlling servers that monitor a chat server for instructions.
I've just received a request for an online backgammon game engine. It shouldn't be to hard to make as after all is essentially a chat program that moves pieces instead of showing text messages. I am basically a PHP developer but as I need event driven stuff (no pooling) I assume I could combine a java built core application and a Flash interface. Any suggestions to where should I look for some practical examples and maybe some advices?
Thanks
You can also build up the the Flash GUI with Adobe's Flex SDK. There are plenty of tutorials in the web for game developing with Flash/Flex. This, for example, is a useful site I found: Flash Game Development with Flex and ActionScript
For the Java backend you could use BlazeDS which provides highly scalable remote access and messaging.
BlazeDS uses two primary exchange
patterns between server and client. In
the first pattern, the
request-response pattern, the client
sends a request to the server to be
processed. ... The second pattern is
the publish-subscribe pattern where
the server routes published messages
to the set of clients that have
subscribed to receive them.
Another possible answer may be using red5 or ElectroServer. Client is in Flash and Server plugins are Java.
I'm looking for a library that will allow me to deliver simple text events from the server to the clients via sockets. Something simple and lightweight. I can write it myself, but decided to check if such thing exists first. The idea is that there's an application that generates events (such as order rejected or an internal error occurred) and acts as a server. Those events must be delivered to all connected clients in real-time. And a client is just a tray-icon app that pop ups the said event's text. Some simple UDP client/server. Does anyone know if there's a library out there for Java?
Thanks!
There are many possible solutions, but if you want simple I suggest you try Hazelcast
It is as simple as using java.util.{Queue, Set, List, Map}. Just add the hazelcast.jar into your classpath and start coding.
This could be easily accomplished with XMPP pubsub. You can use Smack to connect to the server of your choice that supports pubsub (OpenFire, ejabberd, ...) so your application that creates the events is the publisher and the clients are all subscribers. It will require a 3rd party server to be used (many are open source), but it is just a single library for all client access. I have experience with OpenFire and it can be set up in about 15 minutes.
Many will not consider this light weight, but rolling your own pubsub solution is really not necessary.
You should check out JBoss Netty and/or Apache MINA, which are both frameworks for building network protocols. It's debatable whether you consider them simple, although you can certainly build lightweight implementations with them.