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https://issues.apache.org/jira/browse/DERBY-3405?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12569020#action_12569020
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Daniel John Debrunner commented on DERBY-3405:
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> I now think that maybe it is better at least in the short term to create a
> common reference data bundle that contains all the reference data (including
> StoredFormatIds).
Why is a bundle needed. These classes are only needed at compile time, not a
runtime. Does OSGi require a bundle even for compiling?
> org.apache.derby.iapi.services.info.JVMInfo contains a reference to
> org.apache.derby.iapi.reference.JDBC30Translation.SQL_TYPES_BOOLEAN.
That should be replaced with java.sql.Types.BOOLEAN. Both JDBC20Translation and
JDBC30Translation can be removed since Derby's lowest support is JDBC 3/JSR 169
which define all the constants required.
> GeneratedByteCode and GeneratedClass contain reference to Context - but it
> would be better if they had no knowledge of context. Perhaps context should
> be just an object.
Note sure what this really means, Context is a concept that goes across Derby's
code, thus it should be valid for code to use Context where required. Replacing
a specific type with Object just to avoid importing another module's api class
seems to be a bad direction. If the module implementation depends on another
module then it should be free to use its api classes.
> Examine the possibility of implementing Derby modules as OSGI bundles
> ---------------------------------------------------------------------
>
> Key: DERBY-3405
> URL: https://issues.apache.org/jira/browse/DERBY-3405
> Project: Derby
> Issue Type: New Feature
> Reporter: Dibyendu Majumdar
> Assignee: Dibyendu Majumdar
>
> At present, Derby as a whole is offered as an OSGI bundle.
> Internally, Derby does not use OSGI for managing modules. Modules and
> services (which are collections of modules) are managed using the Monitor
> component, which is a custom IoC container, designed specifically for Derby.
> Some of the features of the Monitor component, mirror facilities offered by
> OSGI. The obvious ones are:
> a) Loading modules based upon environment. The features offered by the
> Monitor subsystem were described by Dan like this:
> The monitor ... selects the module implementation that is suitable for the
> given environment by:
> - seeing what the current JDK level is and if a module implementation
> supports it
> - seeing what classes a module implementation requires and if they exist
> - if the module implements ModuleSupportable and if so asking the module if
> it can support the current environment.
> As an example, modules.properties today contains three JDBC implementations,
> JSR169, JDBC 3 and JDBC 4, having multiple exist is not an issue, the monitor
> selects the correct one.
> The ability to load bundles based on environment compatibility is one of OSGI
> features.
> b) Resolving module interdependencies.
> c) Managing life-cycle of services and modules.
> A migration from the Monitor component to an OSGI based packaging is not
> going to be an easy transition. At this stage, therefore, this is more of an
> experiment.
> The benefits of using OSGI are:
> a) It supports dependencies based upon versions of bundles.
> b) It will make it easier to add/remove components, specially at run-time.
> However, the use case for this needs defining.
> c) It may open up Derby to other possibilities ...
> The disadvantages are:
> a) Introduces a dependency on OSGI - whereas Derby at present has its own IoC
> implementation.
> b) Will mean a major change to how Derby is bundled and therefore potentially
> impact users.
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