On 11/30/06, Pete Robbins <[EMAIL PROTECTED]> wrote:
On 30/11/06, Pete Robbins <[EMAIL PROTECTED]> wrote:
>
>
>
> On 30/11/06, Simon Laws <[EMAIL PROTECTED]> wrote:
> >
> > On 11/30/06, Pete Robbins <[EMAIL PROTECTED]> wrote:
> > >
> > > On 30/11/06, Pete Robbins <[EMAIL PROTECTED]> wrote:
> > > >
> > > >
> > > >
> > > > On 30/11/06, Jean-Sebastien Delfino < [EMAIL PROTECTED]>
wrote:
> > > > >
> > > > > Pete Robbins wrote:
> > > > > > Our current method of packaging and loading an extension is
> > fairly
> > > > > > simple:
> > > > > > we load all schema and libraries in the extensions path. This
> > has a
> > > > > > number
> > > > > > of problems.
> > > > > >
> > > > > > 1. An extension may consist of more than one library e.g.
> > > > > > libmy_extension.so
> > > > > > and libmy_extension_utils.so. Our current loading scheme will
> > > attempt
> > > > > to
> > > > > > load both of these and may fail on the one that doesn't
provide
> > the
> > > > > > extension initialize method. On MacOS the output of our build
> > > produces
> > > > > a
> > > > > > libx.dylib and a series of symlinks to this called
libx.0.dylib,
> > > > > > libx.0.0.dylib etc.. ur runtime loads ALL of these which
doesn't
> > > cause
> > > > > > problems as they are all the sam library and just repeatedly
> > > register
> > > > > to
> > > > > > handle the same requests. Very inefficient though!
> > > > > >
> > > > > > 2. Control of whether or not to load an extension library is
> > > currently
> > > > > by
> > > > > > renaming the library so the runtime doesn't find it. An
example
> > is
> > > > > > that we
> > > > > > ship our python extension as libtuscany_sca_python.so.diabled.
> > This
> > > is
> > > > >
> > > > > > horrible and error prone.
> > > > > >
> > > > > > We could improve this by having a system configuration file
that
> > > lists
> > > > > > the
> > > > > > required extensions but the I like the self contained package
> > > approach
> > > > > > that
> > > > > > we have now. I'd like to implement an improved scheme for
> > packaging
> > > an
> > > > > > extension by introducing a per extension configuration file.
> > > Something
> > > > > > like:
> > > > > >
> > > > > >
> > > > > > tuscany_sca_ws_binding.extension
> > > > > >
> > > > > >
> > > > > > <scacpp:extension name="ws binding" enabled="true">
> > > > > > <library name="tuscany_sca_ws_reference"/>
> > > > > > <library name="tuscany_sca_ws_service"/>
> > > > > > </scacppp:extension>
> > > > > >
> > > > > > So the package would look like:
> > > > > >
> > > > > > extensions/
> > > > > > ws/
> > > > > > tusany_sca_ws_binding.extension
> > > > > > lib/
> > > > > > xsd/
> > > > > > other_folder/
> > > > > > ...
> > > > > >
> > > > > > The .extension configuration file is saying to load the
library
> > > which
> > > > > is
> > > > > > located somewhere in the package... the runtime will find
it...
> > no
> > > > > > need to
> > > > > > specify a path.
> > > > > >
> > > > > > Taking this further the configuration file could list the
schema
> > to
> > > be
> > > > > > loaded. Currently the runtime will just load any it finds but
> > these
> > > > > > may not
> > > > > > be needed by the runtime e.g. the schema may be for some
> > extension
> > > > > > implementation specific purpose.
> > > > > >
> > > > > > I think it would also be good for the extension
initialization()
> > > > > > method to
> > > > > > take as a parameter the root of the extension e.g.
> > > > > > extension("/tuscany/extensions/ws"). This would allow the
> > extension
> > > > > > package
> > > > > > to contain any configuration information that it needs.
> > > > > >
> > > > > > I'd like to start by at least introducing the .extension file
> > for
> > > each
> > > > > > extension and loading only the specified library(ies) if the
> > > extension
> > > > > is
> > > > > > enabled.
> > > > > >
> > > > > > Any thoughts?
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > > > > Two thoughts:
> > > > > - convention over configuration
> > > > > - the runtime should be consumable without having to go tweak
XML
> > > > > configuration files
> > > > >
> > > > > If I remember correctly, renaming the dlls to .disabled was a
last
> >
> > > > > minute change to work around DLL loading errors with our M2
> > release on
> > > > > Windows.
> > > > >
> > > > > I agree that we should do better than renaming to .disabled, but
> > I'd
> > > > > like to understand better the actual issues that we faced before
> > > > > inventing yet another XML based runtime configuration language
:)
> > > > >
> > > > > I'm aware of the following issues:
> > > > > 1. We need the runtime to load extension libs only, not other
libs
> > > under
> > > > >
> > > > > the extension directory which are not actual extensions
> > > > > 2. Same for XSDs, we need to load XSDs that contribute to SCDL,
> > and
> > > > > leave other XSDs under the extension directory alone
> > > > > 3. Extensions that cannot be loaded because some of their
> > dependencies
> > > > > are not there should no break the runtime
> > > > > 4. The system admin / installer should be able to disable
> > extensions
> > > > > that won't load because their dependencies are not there (I'm
not
> > yet
> > > > > convinced that this is still an issue if we manage to solve
issue
> > #3)
> > > > >
> > > > > Did we run into any other big issues?
> > > >
> > > >
> > > > No, that's about it.
> > > >
> > > > 2. XSD loading can be done by convention (schemas for the runtime
> > are
> > > > always in a folder called 'xsd'
> > > > 1. Could be solved in a similar way by only loading libraries in a
> > > folder
> > > > called ???
> > > > 3. Can be solved by just ignoring the load errors/issuing a
warning
> > > rather
> > > > than giving up
> > > > 4. Can be solved by solution to 3.
> > > >
> > > >
> > > >
> > >
> > > I recall now why 3. was a big problem. Windows sometimes throws up
an
> > > error
> > > dialog when the load fails so it was not just a case of the runtime
> > > handling
> > > the load failure so we had to "disable" the extension.
> > >
> > > Cheers,
> > >
> > > --
> > > Pete
> > >
> > >
> > >
> > > --
> > > Pete
> > >
> > > Pete, just summarizing so that I understand. It seems there are two
> > parts
> > to this.
> >
> > A/ Building and installing an extension in order that it can be
consumed
> > by
> > the runtime. Building and installing extensions is potentially a
> > separate
> > activity from building and installing the runtime itself. Looking at
the
> > M2
> > download they all come together at the moment.
>
>
> Yes. It just happens that we are the only providers of extensions at the
> moment.
>
> B/ Optionally consuming/enabling an extension in the runtime, once the
> > extension has been installed, in such a way that the runtime is able
to
> > find
> > and load it.
>
>
> Yes.
>
> If I understand the previous posts (and the current code) A/ is achieved
> > by
> > building the extension in the deployed folder layout
> > extension type/
> > bin
> > lib
> > xsd
>
>
> The current runtime does not mandate any layout. It will seek and
> destroy.. I mean seek and load any library it finds and any .xsd it
finds.
> That layout is just how we package extensions in ou build at the moment.
>
>
> and Pete you are proposing that this is adjusted so that there are
> > directories that hold just the stuff that the contains the extension
> > rather
> > than the things it depends on.
> > extension type/
> > bin
> > extensionbin?
> > lib
> > xsd
> > extensionxsd?
> >
> > You are also proposing that B/ is achieved by ensuring that this
> > directory
> > structure be placed in a location that the the runtime can search for
> > active
> > extensions (as it does at the moment in the deploy directory)
>
>
> it currently loads any extensions from under the
> <sca_install_dir>/extensions folder
>
> and that the
> > runtime ignores any badly configured extensions if possible. Removing
an
> > extension's directory from the deploy
>
>
> extensions not deploy
>
> directory structure has the effect of
> > disabling it so I guess this is the fallback if the runtime can't
> > continue.
>
>
> That is true in today's implementation.
>
> Anything more complex and, as Jean-Sebastien suggests, you start getting
> > into the full blown package and dependency management problem that
many
> > other systems try to solve in different ways, e.g. rpm or pear.
>
>
> Agreed... I'll give up on that plan ;-)
>
>
> What we need is to enable the runtime to identify which extension
> libraries to load and which schema to load. My suggestion is:
>
> my_extension/
> bin/
> extension/
> library_that_will_be_loaded_by_the_runtime.so
> lib/
> lib_my_extension.so
> include/
> ... some headers maybe
> xsd/
> my_binding.xsd
> any_other_folder/
> any_stuff_I_like.xsd
>
> So the runtime will load any xsd that is in a folder named xsd and
attempt
> to load any library in a folder called extension. It would not attempt
to
> load the any_stuff_I_like.xsd or the lib_my_extension.so
>
>
> Cheers,
>
> --
> Pete
>
--
Pete
Sounds like the right idea to me. What goes in the bin dir?. Should the
lib be...
lib/
lib_my_extension.lib
Maybe you could stick with bin,include, lib,xsd and then have your "other"
directory have everything else in it that the extension might rely on.
Depends what you now anticipate being in bin and lib over and above the
actual library exposing the extension.
Will you continue to mandate a specific place where extensions are
installed, i.e. from you post <sca_install_dir>/extensions folder? So that
you can move an extension out of there if you don't want it to load.
Simon
