Do I have to list the dangers of util bundles in this forum?
It is easy to make a jar that drags in a lot of unwanted components.
It is always so painful to install a jar just to find out it needs the
util bundle that needs ...
Of course many of the problems are alleviated if the code is included
in the target JAR and not imported.
Kind regards,
Peter Kriens
RSH> Felix Meschberger wrote:
>> Hi all,
>>
>> Over the last few days, I started thinking about whether it would be
>> worth it to have some kind of Felix Util Bundle. This bundle would
>> take all sorts of utility classes, which may be used by different
>> bundles. In this sense this would be kind of a library bundle. The
>> reason for this is, that there is some functionality, which is used
>> over and over and which tends to be reimplemented repeatedly, for
>> example:
>>
>>
>> Logging
>>
>> Logging is defined in the LogService Specification, but it might not
>> always be around or only be registered after first use. The simple
>> workaround is to create a helper class, which uses the LogService if
>> available or write to stdout/stderr otherwise. The Felix Util bundle
>> could provide such a helper class to prevent reinventing the wheel or
>> copying source code over and over ...
>>
>>
>> Read-Only Case-Insensitive String-Key Dictionary
>>
>> Another common definition found all over the OSGi specs is the
>> Dictionary which has String keys, which are treated ignoring case and
>> in some situations are read-only (see Config Admin and Service
>> Compontents). The Felix Util bundle could provide such a Dictionary.
>>
>>
>> Requirement/Capability Abstractions
>>
>> Both the bundlerepository bundle and in the framework use
>> Requirement/Capability abstractions of the [Dynamic]Import-Package and
>> Export-Package headers. In a (currently internal) project I use the
>> same abstraction to build a Bundle Repository Server. In providing
>> these abstractions in the Felix Util bundle, the common functionality
>> may be reutilized.
>>
>>
>> I see two use cases for this Felix Util bundle: In the standard case
>> of using the Felix framework, the bundle would be placed on the class
>> path with the o.a.f.framework jar and the packages be defined as
>> framework system packages. If using a different OSGi framework such as
>> Equinox or Knopflerfish the Felix Util bundle may simply be deployed
>> as another bundle.
>>
>>
>> What do you think of such a util bundle ? If there is any interest I
>> could also provide some initial implementation.
RSH> This idea came up a while back on the Oscar mailing list too, but never
RSH> quite made it to fruition.
RSH> The three examples you give are reasonable and all exist in some fashion
RSH> in the framework already, so they could likely be refactored slightly to
RSH> make them stand-alone in cases where they are not.
RSH> The only one that is currently problematic is the capability/requirement
RSH> stuff since it is still undergoing changes in the framework. There could
RSH> also be some debate here as to whether this should be defined here or in
RSH> OBR itself.
RSH> Of course, with the maven-bundle-plugin, we can eliminate some worries
RSH> about placement of this stuff, since we can just suck it in where it is
RSH> needed to make various distributions for different purposes.
->> richard
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