Re: Rethinking the Servlet API packaging
Hello Emanual,
I agree the servlet-api should live/be built by their own packages.
>From a development point of view they are part of Java EE/Jakarta EE and
tomcat consumes them.
Having multiple versions of the API in Debian also makes.
Regards,
Eugen
On 06.08.2018 13:47, Emmanuel Bourg wrote:
> Hi all,
>
> I'm starting to plan the packaging of Tomcat 9 which should be the
> version of Tomcat shipped with Buster. Before doing that I'd like to
> rethink how the Servlet/JSP API are packaged in Debian. Historically the
> tomcat packages have been the source of the libservlet<n>-java packages:
> * src:tomcat6 had libservlet2.5-java containing the Servlet 2.5,
> JSP 2.1 and EL 2.1 APIs
> * src:tomcat7 has libservlet3.0-java containing the Servlet 3.0,
> JSP 2.2 and EL 2.2 APIs
> * src:tomcat8 has libservlet3.1-java containing the Servlet 3.1,
> JSP 2.3, EL 3.0 and WebSocket 1.1 APIs (the WebSocket API is wrongly
> numbered 1.0 in our package)
>
> Before tomcat6 there was a standalone src:javax-servletapi2.2 package
> building libservlet2.2-java with the Servlet 2.2 and JSP 1.1 APIs. It
> came from the Apache Jakarta project, when Tomcat wasn't yet a top level
> Apache project. At this time the Servlet API was a separate dependency
> of Tomcat.
>
> So far the libservlet<n>-java packages always included several APIs
> (Servlet, JSP, EL and now WebSocket) at different versions and that was
> fine. With Tomcat 9 this model derails a bit because while the Servlet
> API is upgraded to the version 4.0, the version of the JSP, EL and
> WebSocket APIs don't change. So if the src:tomcat9 package was to build
> libservlet4.0-java, it would conflict with libservlet3.1-java, or depend
> on libservlet3.1-java which would prevent the removal of src:tomcat8.
>
> Another notable annoyance with the Servlet API packages is the recurrent
> burden of the transitions to a higher version. There are about ~100
> packages that build depend on the Servlet API. For each transition,
> that's roughly once per release cycle, we have to update the
> dependencies and quite often also add stub methods to fix the source
> compatibility [1][2]. It would be much easier to keep several versions
> of the Servlet API in the archive and avoid this extra work, something
> we are reluctant to do because it drags the full source of ancient
> Tomcat releases in Debian. We kept the src:tomcat7 package for
> libservlet3.0-java, but that's still a bit odd and a source of confusion
> (a tomcat package that doesn't actually build Tomcat always raises
> questions).
>
> So I'd like to take the opportunity of the Tomcat 9 packaging to suggest
> the following changes:
> * The src:tomcat(n>=9) packages no longer build libservlet<m>-java.
> * The Servlet, JSP, EL and WebSocket APIs are packaged separately,
> using the JavaEE (now Eclipse EE4J/JakartaEE) repositories on GitHub.
> These API packages are kept in the archive as long as necessary. Being
> pure API with no actual implementation, they aren't security sensitive
> and don't create a maintenance burden.
> * When src:tomcat(n<9) is removed, introduce standalone API packages.
>
> In details, that would give:
>
> 1. Create a new src:servlet-4.0-api package building libservlet4.0-java
> with the Servlet API *only*, no JSP/EL/WebSocket API, not even as a
> dependency.
>
> 2. libservlet3.1-java gets split into 4 packages, one per API:
> libservlet3.1-java, libjsp2.3-java, libel3.0-java and
> libwebsocket1.1-java. libservlet3.1-java would depend on the three
> other packages to preserve the compatibility and avoid updating
> all the packages depending on the JSP/EL APIs.
>
> 3. libservlet3.0-java is similarly split into: libservlet3.0-java,
> libjsp2.2-java, libel2.2-java
>
> 4. Create new source packages to take over the API packages from
> src:tomcat7 and src:tomcat8:
> * servlet-3.0-api and servlet-3.1-api
> (built from https://github.com/javaee/servlet-spec)
> * jsp-2.2-api and jsp-2.3-api
> (built from https://github.com/javaee/javaee-jsp-api)
> * el-2.2-api and el-3.0-api
> (built from https://github.com/javaee/el-spec)
> * websocket-1.1-api
> (built from https://github.com/javaee/websocket-spec)
>
> 5. remove src:tomcat7, and later src:tomcat8 once src:tomcat9
> is available
>
> What do you think?
>
> Emmanuel Bourg
>
> [1]
> https://salsa.debian.org/java-team/libxmlrpc3-java/blob/master/debian/patches/02-servlet-api-compatibility.patch
> [2]
> https://salsa.debian.org/java-team/tiles/blob/master/debian/patches/01-servlet-3.1-compatibility.patch
>
>
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