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https://github.com/ikvmnet/ikvm-maven

Support for adding dependencies on Maven artifacts to .NET projects, using IKVM.
https://github.com/ikvmnet/ikvm-maven

Last synced: 6 days ago
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Support for adding dependencies on Maven artifacts to .NET projects, using IKVM.

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README 

        
# IKVM.Maven.Sdk - IKVM support for Maven dependencies



`IKVM.Maven.Sdk` is a set of MSBuild extensions for referencing Maven artifacts within .NET SDK projects.



To use, install the `IKVM.Maven.Sdk` package from NuGet, and add a `` element to your SDK-style project. Various Maven options are supported through item-metadata.



The simplest use case is to specify the group ID and artifact ID coordinates on the item specification, and use `Version` for the metadata.



```



    



```



Optionally, use an arbitrary value for the item specification, and explicitely specify information through metadata:



```



    

        org.foo.bar

        foo-lib

        

        1.2.3

        

        

    



```



## Underspecified Dependencies



It is fairly common for Java developers to underspecify dependencies within Maven. For instance, if their library is often used

as a dependency of another aggregate package, or another library, at runtime, they can be reasonably certain classes they rely on will exist.

Also, if they do not exist, but the specific code path that requires dependent classes is never hit, users won't experience any issue.



However, since IKVM is statically compiling assemblies, we need to be able to properly track dependencies between

each assembly we might be building. We can't fully build Library A if it depends on missing classes from Library B.

As such, IKVM.Maven.Sdk requires that Maven dependencies be fully specified.



But, we aren't the authors of Maven artifacts. Nor can we provide local overrides for missing Maven dependencies, as the

Maven artifacts need to be available to any user who might indirectly add a reference through a NuGet package. Therefor,

if you encounter an underspecified or missing dependency in Maven, the proper place to fix it is in Maven. Report the missing

dependency to the authors of the Maven library you are attempting to use.



## Transitive Dependencies



The `` item group operates similar to a `dependency` in Maven. All transitive dependencies are

collected and resolved, and then the final output is produced. However, unlike `PackageReference`s, `MavenReference`s

are collected by the final output project, and reassessed. That is, each dependent Project within your .NET

SDK-style solution contributes its `MavenReference`s to project(s) which include it, and each project makes its own

dependency graph. Projects do not contribute their final built assemblies up. They only contribute their dependencies.

Allowing each project in a complicated solution to make its own local conflict resolution attempt.



`PackageReference`s are supported in the same way. Projects which include `MavenReference`s do not pack the generated IKVM

assemblies into their NuGet packages. Instead, they pack a partial POM file which only declares their dependencies. At 

build-time on the consumer's machine the final dependency graph is collected and generation happens. No generated

assemblies are published to NuGet. This prevents possible conflicts between NuGet packages and incompatible base Java

dependencies. For instance, if a package on nuget.org contained an actual copy of `commons-logging.dll`, there would be

no guarentee that this assembly was generated with the correct options to support a different package on nuget.org that

also depended on commons-logging. Since the final build machine is responsible for gathering and generating the

dependencies, these conflicts become simple Maven conflicts: multiple packages dependending on differnet versions of

the same thing, and Maven being unable to come up with a solution. Basically, not our problem.



`MavenReference`s fully support TFMs. A `` element can be conditional based on TFM. As the partial

packaged POM-file is indexed by TFM in the generated .nupkg.



## Assembly Generation



Assembly generation options are limited. Users are not allowed to customize the assembly name, version, or other

optimization information that IKVM's compiler uses to produce the output. This is to ensure that NuGet packages that

depend on generated assemblies do so under a certain set of assumptions that can continue to be met. As non-Java

assemblies published in NuGet packages are compiled against on certain assembly names and version, allowing different

people to rename or change assemblies away from their default would break the expectation that two NuGet packages that

depend on the same Maven artifact resolve to the same assembly name.