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From Ivan <xhh...@gmail.com>
Subject Re: Implementing rfc66 in Geronimo
Date Mon, 18 Jan 2010 07:06:19 GMT
2010/1/18 David Jencks <david_jencks@yahoo.com>

>
> On Jan 17, 2010, at 9:01 PM, Ivan wrote:
>
>
>
> 2010/1/18 Jarek Gawor <jgawor@gmail.com>
>
>> On Thu, Jan 14, 2010 at 9:47 PM, Ivan <xhhsld@gmail.com> wrote:
>> > I am thinking that while implementing the WAB extender, how does it use
>> > current deployer ? There might be something need to consider :
>> > 1. Current Geronimo deployer is designed for two steps deployment, which
>> > means that it needs to install package to the OSGI environment twice,
>> how to
>> > handler it in the extender ?
>>
>> Right now I think the idea is to modify our deployment process to 1)
>> work directly with a Bundle object and 2) not to create any additional
>> or temporary bundles during deployment and just create a configuration
>> object that the extender can load/start/stop.
>>
>>     For WAB, it might be OK, but for common Java EE applications, it is
> difficult.
>     Since only one time installation, the extender would need handle
> something itself, such as loading dependency artifacts.
>
>
> I know of 3 approaches to loading dependency artifacts:
> 1. our geronimo-plugin.xml dependency list which explicitly specifies
> maven-url dependencies for some bundles (our plugins).  This is normally
> derived from maven dependency info while building the plugin
> 2. karaf feature.xml dependencies.  I haven't looked at this very hard but
> think it's pretty much equivalent to (1).
> 3. aries application bundle + OBR.  I don't understand any details about
> this but think that it basically involves the bundles specifying
> import-packages and using the OBR to resolve these into dependency bundles
> which are then installed.  The part that seems missing to me in this
> approach is how to populate the OBR.
>
> I am hoping that we can come up with a unified solution that basically
> involves using the maven-like dependency information such as in our
> geronimo-plugin.xml or karaf feature.xml aggregated together to populate one
> or possibly more than one OBR.  I think Jarek suggested this idea.
>
>
>
>
>> > 2. Where and when we store the configuration datas ? Not sure in the
>> spec,
>> > there is any description about the contain's behavior, or it would
>> analysis
>> > the WAB each time while starting it ?
>>
>> We could store that information in the bundle private storage area. If
>> the information is already there and the bundle hasn't been updated we
>> could reuse the information and skip the deployment.
>
>
>    The reason that I asked this is based on the one time installation, as
> those configurations ( config.ser/geronimo-plugin.xml) are not ready. So the
> WAB starting codes might be different between the deployment phase and
> restart phase.
>
>
> I'm not sure I understand... are you saying that we would only generate the
> config.ser file if it was not present, otherwise we would skip this
> deployment step?
>

   No, I did not mean this. While deploying the WAB to Geronimo, the
extender is triggered by the installation event, which means that the bundle
is in the process of installing to the OSGI container. So at this time slot,
writing config.ser/geronimo-plugin.xml to the bundle package did not affect
the installed bundle itself, in other words, the bundle should be in the
"read-only" status (Am I making any mistake here ?). Then, our existing
start logic would not find the new added configuration files.


>
thanks!
> david jencks
>
>
>>
>
>> > 3 . About the double start, while restarting Geronimo, it should be
>> possible
>> > to use location or artifact, but since WAB could be installed by any
>> other
>> > applications, so location/artifact might not enough.
>>
>> I'm not worried about this now but potentially yes. Maybe this won't
>> even be an issue.
>
>
>> Jarek
>>
>> >
>> > 2010/1/14 Rick McGuire <rickmcg@gmail.com>
>> >>
>> >> Rex Wang wrote:
>> >>>
>> >>>
>> >>> 2010/1/14 Jarek Gawor <jgawor@gmail.com <mailto:jgawor@gmail.com>>
>> >>>
>> >>>    Hey all,
>> >>>
>> >>>    I've been looking into implementing rfc66 support in Geronimo a
>> little
>> >>>    bit more. Here are some things that we need to do and my
>> >>>    thoughts/impressions about them:
>> >>>
>> >>>    1. WAR to WAB converter. Installs webbundle: url handler that
>> converts
>> >>>    standard WAR files into Web Application Bundles (WAB). The
>> converter
>> >>>    code was contributed by IBM to Apache Aries but so far it has not
>> been
>> >>>    moved to trunk yet. This code will probably need some updates but
I
>> >>>    think we could just mostly use it as it is in Geronimo.
>> >>>
>> >>>    2. WAB extender. Watches for WABs to be started in the framework
>> and
>> >>>    performs the necessary steps to deploy the applications.
>> >>>     a. In Geronimo we will need a custom extender that effectively
>> >>>    invokes Tomcat/JettyWebModuleBuilders to deploy the application.
>> There
>> >>>    might be an extender implementation donated to Aries at some point
>> but
>> >>>    I don't think we will be able to use since it most likely will use
>> the
>> >>>    Tomcat or Jetty API directly to deploy the application. In Geronimo
>> we
>> >>>    build the GBeans which then use Tomcat/Jetty API to set everything
>> up.
>> >>>     b. The biggest issue that I see with Geronimo WAB extender is
>> >>>    updating the WebModuleBuilders (or actually the whole deployment
>> >>>    process) to work with Bundle objects. Right now the deployment
>> process
>> >>>    for the most part assumes it is working with JarFiles.
>> >>>
>> >>> So, what is the standard method to install/deploy a WAB into Geronimo
>> >>> 3.0? From the osgi perspective, that should be the same with
>> installing a
>> >>> normal bundle to framework, and then the extender will track this and
>> help
>> >>> deploy it to geronimo by instantiating some gbeans. Should we support
>> the
>> >>> geronimo deployment process such as deploy a WAB with a external plan?
>> >>
>> >> One key point with WABs is to remember that a WAB is an OSGi
>> programming
>> >> construct and even though it is running under Geronimo, it should
>> function
>> >> under OSGi rules.  One key point here is any application may install
>> and
>> >> start a WAB bundle using a BundleContext without ever knowing anything
>> about
>> >> the hosting Geronimo server.  That's the key purpose of the
>> extender...it
>> >> processes any bundle that has the manifest entries that identify this
>> as a
>> >> WAB and take the steps necessary to deploy this.  The bundle in
>> question
>> >> might not have gone through the Geronimo deployment process first.
>> >>>
>> >>>     c. Rick has some initial extender code in the sandbox that we
>> should
>> >>>    be able to reuse (or at least parts of it) in Geronimo.
>> >>>     d. Things to keep in mind:
>> >>>       1. The specification talks about support for lazy bundles. More
>> >>>    specifically, that a request on static resource of a lazy activated
>> >>>    bundle should not cause the bundle to become fully activated.  This
>> >>>    might be tricky to implement in Geronimo and would require changes
>> to
>> >>>    existing code. However, support for lazy bundles seems to be
>> optional
>> >>>    in the specification.
>> >>>       2. The specification says that “it should be possible for a
Web
>> >>>    application bundle to remain installed when its Web Container is
>> >>>    dynamically replaced”. Which I think it means what happens if
>> somebody
>> >>>    deploys WAB, then stops Tomcat container and starts Jetty container
>> >>>    all at runtime. Does the application continue to work? Should
>> Geronimo
>> >>>    support this case? It is an optional feature.
>> >>>
>> >>> Does that indicate each WAB will contain several plans for different
>> >>> containers? That might require a way to distinguish the plans.
>> >>>
>> >>>       3. The extender might need to track somehow which WABs were
>> >>>    already deployed to prevent double start problems. Once some WAB
is
>> >>>    deployed and the Geronimo server is restarted, Geronimo will
>> attempt
>> >>>    to start the generated configuration/plugin for the WAB. Starting
>> of
>> >>>    the plugin will also start the actual WAB and then the extender
>> will
>> >>>    see the starting bundle and attempt to deploy the WAB again.
>> >>>
>> >>> Yes, I think the other RFC66 implementation also need to take care of
>> it.
>> >>>
>> >>> Thanks
>> >>> -Rex
>> >>>
>> >>>
>> >>>    3. Annotation and resource discovery.
>> >>>     a. The specification does not describe an exact way of discovering
>> >>>    annotations or resources in a WAB. For example, if WAB imports some
>> >>>    package from another bundle, are all classes in that package
>> scanned
>> >>>    for annotations? What about resources in META-INF directory? Are
>> the
>> >>>    bundles wired to the WAB checked for META-INF resources?  These are
>> >>>    some unanswered questions that we need to keep track of.
>> >>>     b. In certain cases (e.g. servlets 3.0, EJBs, etc.) we will need
>> to
>> >>>    discover all accessible classes in bundle class space that have a
>> >>>    given annotation. For that we will need annotation discovery code
>> that
>> >>>    might need to know how to scan bundles based on Bundle-Classpath
>> and
>> >>>    possibly on Import-Packages, DynamicImport-Package, Require-Bundle,
>> >>>    etc. depending on what the specification will say. The annotation
>> >>>    scanning code might get even more difficult if it needs to support
>> >>>    lazy bundles.
>> >>>     c. Tag library scanning might require similar code as used in
>> >>>    annotation discovery since the tld files can be included in any
>> >>>    directory in a JAR under the META-INF directory. This also depends
>> on
>> >>>    what the final specification will say.
>> >>>
>> >>>    4. JSP Runtime Compilation. Not sure yet what that will require
>> >>>    (if anything).
>> >>>
>> >>>    5. JNDI (RFC 142) integration. Get services from service registry
>> >>>    using JNDI lookup using osgi:service/<interface> name (and
>> therefore
>> >>>    OSGi services could be injected via standard @Resource annotation).
>> >>>    Support for RFC 142 is recommended but not required by RFC 66. This
>> is
>> >>>    an optional item but useful to have. There is RFC 142
>> implementation
>> >>>    in Apache Aries that seems pretty complete so it just needs to be
>> >>>    integrated in Geronimo.
>> >>>
>> >>>    I think updating the WebModuleBuilders (2.b) will take the most
>> time
>> >>>    and effort. The annotation and resource discovery (3.b and 3.c)
>> >>>    shouldn't be a lot of work but it's still not very well defined in
>> the
>> >>>    specification and that is something we need to keep track of. The
>> good
>> >>>    news is that we can work on all (except maybe the JSP compilation)
>> of
>> >>>    these items at the same time without stepping on each other's feet.
>> >>>    Also, if the specification decides to require support for lazy
>> bundles
>> >>>    that will cause some fairly major changes in Geronimo. For now, I
>> >>>    think we should assume that lazy bundles are optional and assume
>> >>>    fairly simple rules for annotation and resource discovery code
>> (i.e.
>> >>>    scan jars files or directories specified on the Bundle-ClassPath
>> >>>    only).
>> >>>
>> >>>    Comments?
>> >>>
>> >>>    Jarek
>> >>>
>> >>>
>> >>>
>> >>>
>> >>> --
>> >>> Lei Wang (Rex)
>> >>> rwonly AT apache.org <http://apache.org>
>> >>
>> >
>> >
>> >
>> > --
>> > Ivan
>> >
>>
>
>
>
> --
> Ivan
>
>
>


-- 
Ivan

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