2.x/examples/osgi-helloworld-webapp does not work with Jetty 12 but with Jetty 10

[gpfeifer]

2.x/examples/osgi-helloworld-webapp does not work with Jetty 12 but with Jetty 10

[jansupol]

Jetty 12 is aligned with Jakarta EE 10, whereas Jetty 9 is aligned with Jakarta EE 8.
Jersey 3.1.x is aligned with Jakarta EE 10, whereas Jersey 2.x is aligned with Jakarta EE 8.
Hence, Jersey 2.x supports Jetty 9, Jersey 3.0.x Jetty 11, and Jersey 3.1.5+ Jetty 12.

[gpfeifer]

IMPORTANT: You need to add this to MANIFEST

  Jetty-Environment: ee8

[gpfeifer]

@jansupol We wrote a comment at the same time :-)

I'm using Jetty 12 with EE8

[jansupol]

@gpfeifer Can you point us to a documentation regarding this MANIFEST tag?

[gpfeifer]

There is no documentation as far as I know. As I wrote in jetty/jetty.project#11315 it took me some hours to find out that this entry is needed. I found this entry in: https://github.com/jetty/jetty.project/tree/jetty-12.0.x/jetty-ee8/jetty-ee8-osgi

[gpfeifer]

I created a PR (#5524). The PR contains a minimalistic example of a working osgi-helloworld-jetty-12-webapp. Unfortunately a automated JUnit test is missing.

[joakime]

Jetty 12 is aligned with Jakarta EE 10, whereas Jetty 9 is aligned with Jakarta EE 8.
Jersey 3.1.x is aligned with Jakarta EE 10, whereas Jersey 2.x is aligned with Jakarta EE 8.
Hence, Jersey 2.x supports Jetty 9, Jersey 3.0.x Jetty 11, and Jersey 3.1.5+ Jetty 12.

This is the chart you need ...

Jetty version	Environment	EE Level	Servlet ver	Servlet namespace
12	ee10	Jakarta EE10	Servlet 6.0	jakarta.servlet
12	ee9	Jakarta EE9	Servlet 5.0	jakarta.servlet
12	ee8	Jakarta EE8	Servlet 4.0	javax.servlet
11	n/a	Jakarta EE9	Servlet 5.0	jakarta.servlet
10	n/a	Jakarta EE8	Servlet 4.0	javax.servlet
9	n/a	Java EE7	Servlet 3.1	javax.servlet

Note: Jetty 12 server has no servlet dependencies anymore.
The various environments in Jetty 12 have the servlet layers (along with other APIs that are also in that EE level)
When EE11 releases, it'll still be Jetty 12, but just a new environment definition called "ee11".

[joakime]

Using your definitions of Jersey versions to EE levels, the extended chart would look like ...

Jetty version	Environment	EE Level	Servlet ver	Servlet namespace	Jersey Version
12	ee10	Jakarta EE10	Servlet 6.0	jakarta.servlet	Jersey 3.1.5+
12	ee9	Jakarta EE9	Servlet 5.0	jakarta.servlet	Jersey 3.0.x
12	ee8	Jakarta EE8	Servlet 4.0	javax.servlet	Jersey 2.x
11	n/a	Jakarta EE9	Servlet 5.0	jakarta.servlet	Jersey 3.0.x
10	n/a	Jakarta EE8	Servlet 4.0	javax.servlet	Jersey 2.x
9	n/a	Java EE7	Servlet 3.1	javax.servlet	Not supported

But that doesn't make sense, as we know you support Jetty 9.

Looking at your codebase.

• https://github.com/eclipse-ee4j/jersey/tree/3.1
• https://github.com/eclipse-ee4j/jersey/tree/3.0
• https://github.com/eclipse-ee4j/jersey/tree/2.0

Ah, Jersey 2.x codebase doesn't support EE8, it supports EE7 (based on it's use of Servlet 2.4/2.5), that's the mistake!
The corrected chart would be ...

Jetty version	Environment	EE Level	Servlet ver	Servlet namespace	Jersey Version
12	ee10	Jakarta EE10	Servlet 6.0	jakarta.servlet	Jersey 3.1.x+
12	ee9	Jakarta EE9	Servlet 5.0	jakarta.servlet	Jersey 3.0.x
12	ee8	Jakarta EE8	Servlet 4.0	javax.servlet	Not supported
11	n/a	Jakarta EE9	Servlet 5.0	jakarta.servlet	Jersey 3.0.x
10	n/a	Jakarta EE8	Servlet 4.0	javax.servlet	Not supported
9	n/a	Java EE7	Servlet 3.1	javax.servlet	Jersey 2.x

[joakime]

Technically speaking, Jersey 2.x supports Eclipse Jetty 7, as that's the version that introduced support for Servlet 2.4 (Jetty 8 was Servlet 3.0)

[gpfeifer]

@joakime The codebase I'm working on is running in production and is using Jetty 10 and Jersey 2.x. I'm migrating this codebase to Jetty 12. The Jersey example (2.x/examples/osgi-helloworld-webapp) works with Jetty 10 and Jersey 2.x. But is does not work with Jetty 12 ee8. My example (osgi-helloworld-webapp-jetty-12) works with Jetty 12 (ee8) and Jersey 2.x. I will use the approach used in osgi-helloworld-webapp-jetty-12 in my codebase. Is there anything against it?

[gpfeifer]

@joakime Or in other words: I don't get it.

Jetty 10 works with Jersey 2.x in production.
Why is Jetty 10 not supported by Jetty 2.x?

Jetty 12 e88 seems to work with Jetty 2.x, but I'm not finished with my migration.
Why is Jetty 12 e88 not supported by Jetty 2.x?

[joakime]

@gpfeifer some history ...

• Servlet 1.0 thru Servlet 3.1 were backward compatible. (meaning if you wrote for and older version and deployed on a newer version, no big deal, it'll work)
• Servlet 4.0 added a few things to the APIs, but isn't 100% backward compatible with Servlet 3.1 or older (mostly due to behavior changes).
• Servlet 5.0 is not backward compatible with any versions before it (due to namespace changes)
• Servlet 6.0 removed classes and methods, changed important APIs, and changed behaviors. (this means if you wrote for Servlet 5.0 and deployed here, you'll likely have issues)
• Servlet 6.1 has a few changes to support new browser changes. (going from 6.0 to 6.1 should be trivial)

The fact that it seems to work for you is just luck, and is not to be relied on, as the most trivial change can suddenly cause issues for you. (eg: using Java 11 or older then moving to Java 17 and using those old versions of the Servlet spec, suddenly some of your responses are different.)
Jersey has newer versions to support (some of) the servlet specs listed above, in turn those containers (like Jetty) support the improvements in the Servlet spec too.

In Jetty 12, ee8, we try to maintain bug for bug compatibility with how things worked back then, but it's not perfect, and only strives for the bugs that existed back in EE8 days, not earlier.
Some things we cannot work around, like the changes in the JVM impacting behavior of your webapp.