CODEWITHSUNDEEP
scalajava-native-interface
Algeboy
Algeboy

Reputation: 290

scala native vs. JNI

I'm lifting a native API to Scala. There appear to be two paths: use JNI or use Scala Native.

JNI usage creates the methods you want in Java and then shadows them in C where you write C code to access your API. Pro: you can use the native API's data structures directly. Con: your Scala code now also has to provide its own native wrapper library increasing chances of portability complications, and now you wrapped the library twice, once in JNI C to get it into the JVM and then in the Java/Scala module. A lot of work, many places for bugs. I used this path many times, I figured it was the way the world was.

Then along comes Scala native which does the reverse and shadows the C functions in Scala. Pro: you don't write in C so no new native library and no double wrapper. Con: it seems you can only lift Scala native primitives so complex native data structures can't be accessed. That makes the native library useless if it can't use its data structures.

Neither is terribly portable, as expected, but is there some functionality I'm over looking that fixes the cons of one or both of these approaches? Or some other reason to pick on Scala native over JNI?

Upvotes: 4

Views: 942

Answers (1)

Andreas ZUERCHER
Andreas ZUERCHER

Reputation: 902

Scala Native does not "shadow" C functions in JVM-based Scala. Scala Native is the direct equivalent of bare-metal/native C language but with Scala syntax instead of C syntax and Scala semantics (without any JVM-based semantics) instead of C semantics. If you were to chose JNI, then you would conceivably have 2 choices in the scope of your question of which language to utilize to invoke the JNI injections into the JVM from outside the JVM: either C or Scala Native. If you were to choose Scala Native to write UI code on a JVM-based infrastructure (e.g., Android) then you would be effectively choosing JNI as well by having Scala Native invoke JNI (instead of C invoking JNI). (All mentioning of C here applies to C++ as well.) All that said, utilizing Scala Native invoking JNI to perform UI function invocation from outside the JVM is highly unorthodox (and utilized widely only in the Xamarin-based world).

Upvotes: 1

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