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The jetty @ eclipse project is now in incubation at the eclipse foundation as part of the EclipseRT runtime project. On Tuesday 24th March, the Jetty-7 code base was converted to org.eclipse.jetty package space and checked  into the eclipse jetty svn repository!!!

What is changing?

It is only the core components of Jetty that are moving to eclipse. The project will also remain at codehaus and it will be at codehaus the the jetty@eclipse components are packaged into distributions of an application server, potentionally mixing in other OS projects (eg. cometd.org, Atomikos JTA and activeMQ JMS).   Thus Jetty will be able to be consumed as components from either maven or eclipse repositories, or as a complete product from codehaus downloads.

Some components previously built and released with Jetty are being spun out to their own projects or at least modules with their own release cycles.  The cometd implementation has already moved from the contrib repository to the cometd.org project of the Dojo Foundation.

Jetty will remain apache 2.0 licensed, but the ECL will be added as a dual license so that Jetty may be used and distributed under the terms of either.

Why the change?

The move to eclipse was motivated for a variety of reasons that affect all parties concerned:

Good for Jetty:

New Ideas and Requirements

Change is good! It prevents a project from becoming static and complacent. Exposing jetty to new communities, new requirements and new environments will give us an opportunity to continue to improve jetty or validate that it is still relevant and well targeted.

Improved process

The eclipse foundation offers jetty improved processes for building and distributing components. The improvements are both legal and technical. Legally, The IP status of Jetty will be greatly improved by the rigour of the eclipse contribution processes. Technically, the eclipse packaging processes have highlighted a number of issues:

Community

The move to eclipse will grow the jetty community. The OSGi and eclipse runtime community, already significant jetty users, will be brought into the process of developing and enhancing Jetty. Hopefully new contributions, contributors an corporate sponsorship will result.

Publicity

The move generates publicity for the project, which is good in attracting attention to the latest features and developments.  Publicity also helps the commercial interests that sponsor the development of Jetty and of those who use Jetty.  We would like to use this publicity to increase awareness of the asynchronous HTTP client components with in jetty, so that the jetty project is seen as the source of a HTTP server, HTTP client and Servlet container.

Good for eclipse:

New Ideas and Requirements

The Jetty project and community will bring new ideas and requirements to the eclipse runtime community and through it to the OSGi community. For example, the OSGi HTTP Service has been stuck at servlet 2.2 level for a number of years and the Jetty project is keen to see how we can help move equinox and/or the standard onto a more recent HTTP feature set.

Validate process

The extensive processes of eclipse are tested by the contribution of a large project like Jetty. The issues already found and fixed in Jetty validate these processes, while the pain points of the process (ipzilla) reveal where they may need to be improved.

Community

Jetty will bring hundreds of thousand of new users to the eclipse community, many of whom would have been unaware that eclipse is more than just an IDE and that there is a foundation behind it and that the foundation has an already significant runtime project.

Publicity

Eclipse is much more than the eclipse IDE. The eclipse foundation is an open source community focused on building an open development platform comprised of
extensible frameworks, tools and runtimes for building, deploying and managing software across the lifecycle. By joining the eclipse runtime project, Jetty will help improve awareness of the eclipse offerings above and beyond the IDE.

What next?

March 24-26, Webtide has a booth at EclipseCon in Santa Clara, and is running Birds of a Feather sessions. Have Jetty/servlet, Cometd questions, or just want to actually meet in person? Come on down! 19/03/2009

With the release of the latest cometd-jetty in Jetty 6.1.15, the oft requested feature of reliable message delivery is now supported by the Acknowledged Message Extension in the jetty server and in the dojo and jquery clients.

The initial concept of cometd was to provide "web quality" communications between the server and the browser, ie it was not intended to provide a reliable, transactional and/or atomic delivery of messages. The premise was that if your network failed, then messages can be lost. While this is sufficient for many applications, it is not sufficient for many others. Luckily, the Bayeux protocol implemented by cometd provides for an extension mechanism, which cometd-jetty, cometd-dojox and cometd-jquery have now used to provide an acknowledged message mechanism for reliable message delivery.

Server side

To enable cometd-jetty support for acknowledged messages, the extension must be added to the bayeux instance during initialization:

  bayeux.addExtension(new AcknowledgedMessagesExtension());

The AcknowledgedMessageExtension is a per server extension that monitors handshakes from new clients, looking to see if they also support the acknowledged message extension and then adds the AcknowledgedMessagesClientExtension to each client on handshake.

Once added to a client, the AcknowledgedMessagesClientExtension prevents messages being delivered on any request other than a /meta/connect so to prevent the possibility of out of order delivery. The extension also maintains a list of unacked messages and intercepts the /meta/connect traffic to insert and check ack IDs.

Dojox Client

The clients side for dojo is provided by dojox/cometd/ack.js which was released in dojo 1.3.0b2 (but can also be applied to dojo 1.2.x). To enable client side the dojo requires mechanism is used:

  dojo.require("dojox.cometd.ack");

This is sufficient to enable the extension, however it may then be programmatically disable/enabled before initialization by setting the ackEnabled boolean field:

  dojox.cometd.ackEnabled = (dojo.query("#ackInit").attr("checked") == "true");
  dojox.cometd.init(cometdUrl);

JQuery Client

The client side for jquery is enabled by including the jquery.cometd-ack.js file (bundled with jetty 6.1.15):

  <script type="text/javascript" src="../../jquery/jquery.cometd.js"></script>

Details

In order to enable message acknowledgement, both client and server must indicate that they support message acknowledgement. This is negotiated during handshake. On handshake, the client sends "ext":{"ack": "true"} to indicate that it supports message acknowledgement. If the server also supports message acknowledgment, it likewise replies with "ext":{"ack": "true"}.

The extension does not insert ack IDs to every message, as this would impose a significant burden on the server for messages sent to multiple clients (which would need to be reserialized to json for each client). Instead the ack id is inserted in the ext field of the /meta/connect messages that are associated with message delivery. Each /meta/connect request contains the ack ID of the last received ack response: "ext":{"ack": 42}. Similarly, each ack response contains an ext ack ID that uniquely identifies the batch of responses sent.

If a /meta/connect message is received with an ackId lower that any unacknowledged messages held by the extension, then these messages are requeued prior to any more recently queued messages and the /meta/connect response sent with a new ack ID.

Demo

There is an example of acknowledged messages in the dojox chat demo that comes bundled with cometd-jetty.

To run the demo, download the Jetty implementation of cometd, then:

  cd contrib/cometd/demo
  mvn jetty:run

Point your browser to http://localhost:8080/examples/chat/ and make sure to check "Enable reliable messaging?".

Use two different browsers instances to initial a chat session, then briefly disconnect one browser from the network (work offline option will do this). While one browser is disconnected, type some chat in the other browser and this will be received when the disconnected browser is reconnected to the network.

Note that if the disconnected browser is disconnected for in excess of maxInterval (default 10s), then the client will be timed out and the unacknowledged queue discarded.

The results are in for the Febuary 2009 Netcraft Survey and the news is great for Jetty! In January the sites reported using Jetty was at 258k and this month it is at over 289k! That is an increase of over 31k sites in just a month. Sure results vary from month to month as different hosting solutions change back and forth between competing technologies, but it is always nice to see a solid increase for Jetty.
For comparison, Netcraft now lists Jetty at about 70 percent of Tomcat, and 120% of Resin. Sometimes we get asked if jetty is used in production deployment…um. YES!
Anyway, wonderful news for Jetty especially on the cusp of the migration of Jetty7 to the Eclipse Foundation which I’ll give an update on the status for in a subsequent blog entry soon.

We have always known Jetty is used far and wide. This is the first instance I know of where a governmental watchdog has shut down a project using Jetty on competitive grounds. Not Jetty’s fault, of course, just an industry concentration consideration. As kindly noted, Jetty was the basis of Project Kangaroo for video on demand in the UK, and Webtide have been proud to provide back end support. Unfortunately, the UK’s Competition Commission decided that “this joint venture
would be too much of a threat to competition in this developing market and has to be stopped.” We can hope for the viewing public, that everyone gets to have great video on demand served by Jetty in the future, as hopefully the broadcasters who had joined forces will still continue individually. 🙂

Interesting development – Fujitsu announced recently that they will be offering a service to deploy Android onto all different types of hardware.

This potentially opens up interesting opportunities for smart software on a whole range of devices, not just mobile handsets. As Jetty is already running on Android, we could see Jetty on all kinds of devices! Of course, Jetty has already been ported to run under J2ME-based devices in the past, but Android provides a more familiar development environment for users accustomed to J2SE. With Jetty onboard, devices could be dynamically updated with new functionality over HTTP simply by downloading a new war file (well, a war file with classes compiled for the Android dalvik vm of course).

The Jetty-on-Android project – called i-jetty – already provides this dynamic download feature, along with a couple of webapps as demonstrations.

Although, to make this really fly, Google would need to make some modifications to their classloading security mechanism to really support servlet-style classloader hierarchies. This feature has been requested many times on the android groups, such as here and here. Lets hope this feature moves up the priority list soon!

Mingfai Ma has created a grails cometd plugin that combines grails 1.1, jetty-6.1 and cometd 6.1.12 to provide spring based grails application environment.
Because of the great integration between groovy and java, the java server side Bayeux API may be used to subscribe to channels and have messages delivered to groovy handlers.
For more details see http://www.grails.org/Cometd+Plugin

Jetty’s use is obviously extremely widespread. Several projects, including Equinox (OSGi) and the IDE at the Eclipse Foundation actually already include versions of Jetty. And now, Jetty as a project has proposed to join that foundation here. Please do take a look at that proposal, and join the linked newsgroup with your comments. No one currently using Jetty loses any rights, as the existing license still applies and will continue to do so for future releases. Looking forward!

We are also glad to see the early reactions are hugely positive, and in agreement that this will help spread Jetty and help Jetty’s existing users. For example, Infoworld and EclipseSource

We encourage you to visit the proposal, and its linked newsgroup to talk about the move and share any suggestions/encouragement/criticisms you may have.