This article specifically discusses calling external C ABI libraries via the FFM API.
GraalVM is for compiling JVM bytecode to native, architecture-specific binaries.
FFM is like "[DllImport]" in .NET, or "extern" definitions in other languages.
The article shows how to auto-generate JVM bindings from C headers, and then allocate managed memory + interact with externally linked libs via the FFM API passing along said managed memory.
BTW: We (the GraalVM team) maintain a full-blown LLVM bitcode runtime that can be embedded in Spring or any other JVM application and compiled to native: https://github.com/oracle/graal/tree/master/sulong
One of the neatest things I've been able to do is compile a .dll library "plugin" for an application which loads plug-ins by invoking a special exported symbol name like "int plugin_main()" using GraalVM and @CEntryPoint
The entrypoint function starts a Graal isolate via annotation params and no native code was needed
GraalVM is for compiling JVM bytecode to native, architecture-specific binaries.
FFM is like "[DllImport]" in .NET, or "extern" definitions in other languages.
The article shows how to auto-generate JVM bindings from C headers, and then allocate managed memory + interact with externally linked libs via the FFM API passing along said managed memory.