Along with numerous fixes and improvements, this release has some exciting new features.
Java 8 Support
Jetty 9.2.0 has been updated to run well with Java 8, including updating dependencies such as ASM. While Jetty does not yet take advantage of any Java 8 language features, the server does run on the JVM 8, so that improvements in the JIT and garbage collector are available to Jetty users.
We have already announced the quickstart mechanism that resulted from our collaboration with Google AppEngine. The quick start mechanism allows the start up time of web applications to be reduced to a few hundred milliseconds. For cloud system like AppEngine, this reduced start time can save vital resources as it allows web applications to be started on demand within the acceptable response time of a single request.
The 9.2 release has switched to using the Apache version of Jasper for JSP and JSTL. Early releases of Jetty used these implementations, but switched to Glassfish when it became the reference implementation. However the Apache version is now more rigorously maintained and hence we have switched back. Currently we are using a slightly modified version of 8.0.3, however our modifications have been contributed back to apache and have been accepted for their 8.0.9 release, so we will soon switch to using a standard jar from Apache.
Async I/O Proxying
The ProxyServlet class implements a flexible reverse proxy by leveraging Jetty 9’s asynchronous HttpClient. Before Jetty 9.2.0 the ProxyServlet implementation was reading data from the downstream client and writing data to the downstream client using the blocking APIs of, respectively, the request ServletInputStream and the response ServletOutputStream.
From Jetty 9.2.0 a new implementation has been introduced, AsyncProxyServlet, that leverages the asynchronous I/O features of Servlet 3.1 to read from and write to the downstream client, therefore making possible to be 100% fully asynchronous. This means better scalability and less resources used by the server to proxy the requests/responses.
Users that are bound to use Servlet 3.0 can continue to use ProxyServlet; you can leverage AsyncProxyServlet’s scalability by updating your web application to use Servlet 3.1, and by deploying it in Jetty 9.2.0 or greater.
By using AsyncProyServlet, the FastCGI proxying has become even more efficient and allows Jetty to run with a minimum of memory (just 20 MiB of occupied heap) and minimum of threads.
With Jetty 9.2.0 you can deploy your PHP applications leveraging Jetty’s scalability and SPDY support (along with Jetty’s SPDY Push) to make your web sites quick and responsive.
Jetty 9.2.0 provides an implementation of ALPN, the Application Layer Protocol Negotiation specification.
ALPN is the successor to NPN (the Next Protocol Negotiation) and is implemented for both JDK 7 and JDK 8. ALPN will be used by SPDY and HTTP 2.0 to negotiate the application protocol of a TLS connection.
Users using NPN and JDK 7 may continue to do so, or update to ALPN. Users of JDK 8 will only be able to use ALPN.
Multiple Jetty base directories
The Jetty 9.0 series introduced the $jetty.base and $jetty.home mechanism, which allows local configuration modifications to all be put into a base directory which is kept separate from the home directory, which can be kept as an unmodified jetty distribution. This allows simple upgrades between jetty versions without the need to refactor your configuration. Jetty 9.2 has now extended this mechanism to allow multiple directories. You can now have layers of configuration, your your enterprise, your cluster, your node and your webapp, or however you wish to layer your configuration.