Weblog for the AMIS Technology corner
Posts tagged event
First steps with jWebSocket – open source Java framework for WebSockets – installation and running samples
Jan 12th
This month, In have been delving into Push architectures for the Web, looking into WebSockets among several other things. WebSockets, a fairly new standard (!) evolved along with HTML 5, specifies a communication protocol that provides an alternative to classic HTTP communication. WebSocket based interaction has lower overhead and – more importantly – is bi-directional which means that push from server to client is really supported (and not just emulated through poll, long poll or streaming responses as is currently the case in comet push style frameworks).
All modern browsers provide support for the WebSocket specification – meaning they can communicate based on the WebSocket protocol (ws:// and wss:// in addition to http:// and https://) and they implement the WebSocket client side (JavaScript) APIs. These API are well defined – http://dev.w3.org/html5/websockets/ – and seem to be truly standard across all browsers.
The WebSocket server side is at this moment not very well defined. Other than the fact that the communication over ws:// and wss:// should be handled by a server, not much has been decided about the server side of WebSockets. Currently, WebSockets is not supported in classic JEE servers although such support seems imminent with JEE 7 through the Servlet 3.1 specification (JSR 340, http://jcp.org/en/jsr/summary?id=340; also read http://antwerkz.com/websockets-and-java-ee/ on how WebSockets my be included in the Servlet API). Initial support for WebSockets has been shown in Jetty and GlassFish, with other JEE containers undoubtedly following suit in next 18 months or so. In the meanwhile, several stand alone WebSocket servers have been released, including Kaazing (a commercial offering which I mentioned in two earlier articles: http://technology.amis.nl/blog/14755/get-going-with-kaazing-websocket-gateway-html5-edition-installing-locally-and-running-demos and http://technology.amis.nl/blog/14777/push-based-synchronized-slideshow-web-application-implemented-using-websockets-and-kaazing-websocket-gateway) and jWebSocket (an open source offering – http://jwebsocket.org/), that I will introduce in this article.
These WebSocket servers are capable of handling WebSocket interaction with a variety of clients – well, the server should not have to care about the type of client but only about the communication. How the WebSocket server should relay WebSocket messages received from a client to a back end service is not well defined, at least not in a standardized way. Vice versa: how back end services can deliver their push messages and events – chat message, JMS message, mail reception, RSS entry, Tweet, database update, business event … – to the WebSocket server for onward routing to interested clients is not covered by an existing standard either. Even integration of WebSocket interaction into regular JEE Web Applications is very much in question. Kaazing spokesmen even suggested that perhaps WebSocket communication provides the foundation for a whole new type of application in which traditional JEE application servers are no longer needed (see: http://www.businesswire.com/news/home/20111019005426/en).
Well, before going to deep into these discussions, let’s take a look at how we can get the jWebSocket server going to at least run a few demo application on our local machine (or at least my local environment).
(Slides for) Push to the limit – rich and pro-active user interfaces with ADF (Oracle Open World 2011)
Oct 6th
Below you will find the slides for my Oracle Open World 2011 presentation Push to the limit – rich and pro-active user interfaces with ADF on ADF’s active data service and other facilities to do client to server push as well as JMS to Client push and Database to Client push. The presentation also discusses some useful tricks (the nudge pattern for example) as well the overall challenges with push across various tiers in an enterprise application architecture. The BAM Data Control makes an appearance, and some future developments are taken into account (WebSockets, HTML 5 etc.)
View more presentations from Lucas Jellema
Castle in the clouds – Building the Connexys SaaS application with Fusion Middleware
Mar 24th
SaaS applications serve users in many organizations from a single application instance running in a cloud. Common SaaS requirements include: customization including hiding and adding fields, managing boilerplate text & influencing the look & feel and a Service API for retrieving and manipulating data as well as allowing registration of listeners – applications outside the cloud that are notified by the SaaS application of events. Deep link navigation into the SaaS application allows visual integration with local applications.
Connexys provides a SaaS application (150+ customers) to support human resource and recruitment processes. The Connexys NextGen application is developed on Fusion Middleware using ADF. The application has an impressive number of specific SaaS enhancements (some inspired by Salesforce.com) that make it a compelling & competitive SaaS offering.
Below you will find the slides from the OBUG 2010 presentation that Arne van der Ing and I submitted and prepared for yesterday’s conference.
Come to our Forms2Future event (or “Oracle Classic and what next” event) on April 13th to here more about Connexys and other stories about moving to the future from current Oracle classical environments. See http://www.amis.nl/modernisering for more information.
ADF 11g: how events in one region cause other regions to refresh
Aug 28th
One of the challenges in building Portal pages is to have events from one Portlet have the desired effect on other Portlets. For example when I select a location on a Map in one Portlet, other Portlets may need to be synchronized to show the weather, the best restaurants and the driving instructions for actually going there. The JSR-168 specification does not address this issue; the upcoming JSR-286 ("Portal 2.0") specs do. Working with ADF 11g, we have some fairly new mechanisms at our disposal, such as Task Flows and Regions, that allow us to construct pages (and applications) that are somewhat reminiscent of Portlets – or at least some of the interesting sides of Portlets in terms of creating relatively simple pieces of (stand-alone) functionality that can be wired together in a larger mashup – where ideally the mashup framework can provide event propagation between the stand alone pieces. In this article, I want to investigate how for example an event occuring in region A – based on a bounded taskflow – can be passed on to region B that is based on another bounded taskflow.
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