HTTP Monitor raises error when starting Tomcat in Netbeans 26

[Knusende-Ro]

Hi folks,
It seems that HTTP Monitor stopped working in Netbeans 26. It used to work previously. In the Apache Tomcat log tab, the following error message is displayed when starting Tomcat from Netbeans, and the HTTP Monitor option active (run or debug):

org.apache.catalina.core.StandardContext.filterStart Exception starting filter [HTTPMonitorFilter] java.lang.NoClassDefFoundError: javax/servlet/Filter

The error does not seem to be project oriented, as it occurs just by starting Tomcat from the Service tab in Netbeans. There don't seem to be any other project problems I'm aware of. Everything compiles, runs and debugs as could be expected.

I would be grateful for any information about how to get this working. It's not a complete show stopper, but the HTTP Monitor is useful sometimes.

Environment:
OS: Debian Bookworm 12.11 with current packages from Bookworm backports, kernel 6.12.22+bpo-amd64
Graphical environment: LXDE
Project location: Share on Samba server (Samba 4.22.1)
Java: OpenJDK Runtime Environment Zulu21.42+19-CA (build 21.0.7+6-LTS)
Apache Tomcat: 11.0.7 installed under user environment
Netbeans 26: Installed with global access under /opt/netbeans

Best regards,

Peter

[Knusende-Ro]

Hi folks,
I have continued to test the failure of the HTTP monitor. It works with NetBeans up to Tomcat 9.0.xxx. From Tomcat 10 and up it doesn't. I have a mix of older projects using javax and newer ones with jakarta, so I switch between Tomcat versions, and naturally got confused.
It's a pity the HTML monitor doesn't work with later versions of Tomcat. It's quite useful sometimes.

Best regards,

Peter

[matthiasblaesing]

The monitor is implemented as a servlet filter and thus tied to Servlet specification. Tomat 9 is based on JavaEE, while Tomecat 10 is based on JakartaEE.

With the JavaEE -> JakartaEE transition the Eclipse Foundation was forced to change the namespaces of the classes and XML schemas. Causing all code to break. This is another problem indroduced by that.

I had a quick look and I think it is doable to build this, so that it works in both worlds (JavaEE and JakartaEE).

[Knusende-Ro]

Hi Matthias,

Thanks for the clarification. I had a hunch that that was the reason.

Wouldn't it be nice to have the HTTP monitor as a plugin, where the user could choose whether to use the javax based, or the jakarta based one? Unfortunately, I'm currently not in the position to help with developing of a jakarta based HTTP monitor. Otherwise I would be glad to help.

Best regards,

Peter

[Knusende-Ro]

Hi Matthias,
That was a quick PR. I will sure appreciate the new jakarta HTTP monitor, when NetBeans 27 is out. In the meantime, I'll try to sort things out using other tools.

Thanks a lot for the effort!

Best regards,

Peter

[Knusende-Ro]

Hi Matthias,

Many thanks for the test build. HTTP monitor works!

Really appreciated.

Best regards,

Peter

[matthiasblaesing]

@Knusende-Ro Thanks for testing. Did you test both tomcat 9+11 or only one of these, if only one, which one?

[Knusende-Ro]

Hi Matthias, I tested only Tomcat 11, as it is what I mainly work with. The applications under Tomcat 9 are slowly being phased out, so the need for the HTTP monitor is not essential. Many thanks for your effort, very appreciated! Best regards, Peter

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On 10.06.2025 22:01, Matthias Bläsing wrote: @Knusende-Ro <https://github.com/Knusende-Ro> Thanks for testing. Did you test both tomcat 9+11 or only one of these, if only one, which one? — Reply to this email directly, view it on GitHub <#8570 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BBY3S5CNMJN2IQYSD7F43W33C42RZAVCNFSM6AAAAAB62H6DZKVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTGNBSGUZTMNI>. You are receiving this because you were mentioned.Message ID: ***@***.***>