Push telephone calls to a browser
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Pointcast. PUSH will kill the browser. Never worked out that way. That doesn't mean that PUSH is dead. Comet is the next generation of Push technology, and Alessandro Alinone of Lightstreamer wrote an interesting article on Next Generation Push: a viable technology for web-based FX market data delivery.
The article discusses what this is all about, and choices available in push:
Conclusion
There is no doubt that pushing live FX market data via the Internet can benefit all FX market participants (i.e. both sell-side and buy-side). Specific real-time dashboards for both the trading and sales roles can be developed, requiring on the client side nothing more than a very common Web browser and an Internet connection (not necessarily broadband). The result is an improvement in information pervasiveness and a simplification in the client-side system administration.
Alex MacCaw has released a plugin for Ruby on Rails that "aims to revolutionize your Rails app by letting the server initiate a connection and push data to the client. In other words your app can have a real time connection to the server with the advantage of instant updates."
The plugin Juggernautinitiates a flash xmlsocket between server and browser allowing real time communication between the two. The open socket connection allows the server to 'push' base64 encoded javascript to the browser which is subsequently decoded and evaluated.
I see this as Comet for Rails, as it is about the interaction model not technology (e.g. if Flash or not). Alex may disagree :)
Frequently Asked Questions
What flash version does Juggernaut use?
Flash socket uses version 6 which is supported by more than 95% of users.
Does it work in all browsers?
It works in all the major ones: Firefox 1+, IE 6+ and Safari 2+.
What are the advantages/disadvantages of using a flash socket over other methods?
It's better than comet because:
- It's much less of a hack
- It doesn't crash your browser (Comet can do this after a while)
- 95% of browsers support it (flash 6).
- It's much easier to implement
- It can use a different port - unlike comet - so you don't need any custom dispatch servlets for forwarding messages through rails to the push server - it can connect directly.
It's better than polling because:
- Much cleaner
- Doesn't use as many server resources
Related javascript Projects
script.aculo.us provides you with easy-to-use, cross-browser user interface JavaScript libraries to make your web sites and web applications fly.
jQuery UI is a set of themable widgets and interactions, built on top of the jQuery JavaScript Library, that you can use to build highly interactive web applications.
Just by adding this small JavaScript module to the end of your web pages, you get your form's submissions intercepted and, instead of sending request to the server in the usual way, they are done asynchronously and in an AJAX-style smooth way.
As long as it is a client-side library it will work with any server technology: ASP.NET, PHP, JSP, Classic ASP... and even with local HTM files.
I've included extensibility so that you can add easily your own progress indicators (several included) and show error messages the way you prefer (by default it shows an alert).
It's transparent to your server code and could be used to add AJAX capabilities to some applications without writting a single line of code.
Documentation is included.
Features summary
• No-code AJAXification of web apps
• Supports any server technology, including ASP.NET, JSP, PHP, ASP 3.0...
• In ASP.NET it supports all kinds of postbacks: direct and by code.
• Works in any modern browser that supports AJAX.
• Supports cross-posting of forms, that is, you can send the information to any web page in the same domain. If all your web pages have AJAXInterceptor included (for example, you include it in your master page or template) you can hace
• Respects your custom onsumit event handlers.
• Supports browser history so that your users can hit the previous button and get the last rendered page.
• Two versions of the module:
- AJAXInterceptor.js: full commented one. Useful for debugging purposes.
- AJAXINterceptor_r.js: reduced-size version. It downloads faster as it only is 2.6 kB in size. It's better to use this on production apps.
• Automatically show/hide custom progress indicators.
• Support for cancelling operations.
• Support for custom message displaying.
• Supports any form in your page
Obviously this is not substitute at all of full-fledged APIs like Microsoft's ASP.NET AJAX, PHPLiveX or AJAX.NET, but will let you add AJAX support to your apps in a few seconds and without writing any code. Just give it a try!
In the ZIP you will find teh module, a working sample with ASP.NET and a PDF with the help documentation.
This project is just for fun :-)
I will be very glad if you drop me a line in case you use AJAXInterceptor in any real-world application or if you enhance it with new features.
Visit my .NET blog (Spanish) at http://www.jasoft.organd my e-mail marketing blog (English) at http://www.theemailingexperience.com
Lily is an open source, browser-based, visual programming environment written in JavaScript. Lily enables users to build programs graphically by connecting functional modules to fetch and direct the flow of data, play sound or video, add animation or interactivity, and display results. Lily programs can be shared with other Lily users, installed as Firefox add-ons or run as standalone apps using XULrunner.
mapper.js 1.2 allows you to add automatic area highlighting to image maps on your webpages (inc. export to SVG). It works in all the major browsers - Mozilla Firefox 1.5+, Opera 9+, Safari and IE6+. On older browsers, it can use "jsgraphics" from Walter Zorn (if installed), else it'll degrade and your visitors won't notice a thing.