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.
Related
Need to develop a rest API which can read published messages from kafka cluster to a dataware house application.
Materials available over internet say use POST/GET commands , but i don't think this is for production use rather useful for testing purposes.
How to implement it in scala/ Java Programming?
Materials available over internet say use POST/GET commands , but i don't think this is for production use rather useful for testing purposes
Please link to where you read this... All production web-services operate over (more than) these two HTTP methods, hundreds of thousands times a day...
If you want to really use Kafka for throughput, though, you wouldn't "hide it" behind a REST interface, though. You would distribute SSL certs plus usernames+passwords, to remote clients, for example.
Need to develop a rest API which can read publish messages from kafka
REST is not meant to keep an open connection, primarily because it is stateless (it shouldn't maintain where you are reading from in Kafka)... It would make more sense to forward a websocket from a Kafka consumer, which is different from a REST API.
how to implement it in scala/ Java Programming
The Confluent REST Proxy is already written in Java, and it is open-source (and used in Production at several companies, I believe). If you need inspiration, then you can start there. Otherwise, you can find examples of Spring and Vert.x, for example, with their Kafka integrations in their respective documentations, but you'll be re-implementing a lot of the existing functionality.
There is a chat project I plan to develop and currently stuck while deciding, which XMPP server and client to use.
Front-end will be implemented using Ionic 3+ framework (fixed requirement).
Main features:
private chat capability (1 on 1)
group chat capability (and ability to add users to existing chat)
online status visibility
offline message delivery (online user sends a message to offline user, and the offline user gets it after going online, etc)
full-time server-side chat history storage
I need to select:
a client library which is convenient to implement with Ionic 3+
a server which enables all the above requirements
Also, the chat messages should cross the network with at least some kind of encryption.
Currently, I have been playing with these server options:
eJabberd - most people recommend this option, but for me, a person, who is newbie at XMPP stuff, it looks like there will be quite a lot of hassle with configuration
openFire - easy to setup and use, but it uses Java VM, and some people argue, that it has problems with performance and memory management.
I also stumbled upon AstraChat - a commercial product, that looks similar to what I need - however, with fixed implementation of it's own public apps - no way to use it's code base.
As of front-end - I have only tried running the Ionic 1 tutorial locally using Strophe.js as the client in the front-end. Since I am developing the app with Ionic 3+ (TypeSript), it would be awesome to use some newer and TS compatible library - however, it is just a wish, not a requirement. :)
Maybe there are some better and more convenient non-XMPP implementations for this concept. Any thoughts are welcome!
eJabbered is very complex decision for your application.
openFire is also very complex and requires JVM
For your apllication I advise Prosody. It is simple and lightweight desicion.
https://en.wikipedia.org/wiki/Comparison_of_XMPP_server_software
But please think twice about using chat on XMPP protocol. This protocol is very difficult to learn and it has a variety of extensions(e. g. XEP) and you will be confused about documentation.
Alternative https://github.com/actorapp/actor-platform
but documentation is obsolete.
I have to build a component that runs in a jvm, uses MongoDB as database and doesn't need a UI. It will be integrated into other products. I'm planning to build this using scala and related tools.
My first thoughts are to just let it expose REST API and let other products integrate using the API. While this is acceptable for some products, it isn't for others due to performance reasons. So I have to enable other components to communicate to this using either http or ipc or message queues. How can achieve this without much duplication of business logic.
Would Play framework be the right choice for this even though there is no UI involved and there is a need to accept messages via http or ipc or message queues?
Using Play for that is ok but there are frameworks better fit for what you are planning to do, as you already said, play has a lot of support for frontend features you don't need.
It will not so much affect the runtime speed as the time you will need for programming, compiling, building and deployment.
There are some framworks that might fit you needs better:
Scalatra Nice, easy to use, integrates good with JavaEE-Stack http://www.scalatra.org/
Finatra Cool if you have the twitter stack running. Metrics and other stuff almost for free http://finatra.info/
Skinny Framework : Looks nice, never tried myself
Spray : Cool features to come, a little elitist
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.
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