Installation

The file metaffi.api.jar is deployed in the MetaFFI installation directory.

MetaFFIRuntime Class

MetaFFIRuntime provides a simple FFI framework to connect JVM-based languages with other languages. Pass the runtime plugin name to the constructor (e.g. "go", "python3"), and call loadRuntimePlugin to load the runtime.

Once the runtime is loaded, use loadModule to load a module and receive an instance of MetaFFIModule.

Methods

MetaFFIRuntime(String runtimePlugin)

Constructor specifying the requested runtime plugin to use.

Parameters:

  • runtimePlugin — The name of the runtime plugin (e.g. "go", "python3")

void loadRuntimePlugin()

Loads the runtime of the plugin.

void releaseRuntimePlugin()

Releases the loaded runtime. After calling this function, any loaded entity must not be used.

MetaFFIModule loadModule(String modulePath)

Loads a foreign module from the given modulePath. Returns a MetaFFIModule object representing the foreign module.

The modulePath may contain multiple modules separated by semicolons (for cases like dependencies). Each runtime plugin specifies in its documentation what it expects.

Parameters:

  • modulePath — Path to the module(s) to load

Returns: Instance of MetaFFIModule

static Caller makeMetaffiCallable(Method m)

Wraps the given Java Method and returns a cross-language Caller. The returned Caller instance can be passed to other languages.

Parameters:

  • m — A Java Method

Returns: Caller instance wrapping the given method

MetaFFIModule Class

Provides the load method, which loads a foreign entity and returns it as a Caller object.

The class should not be created directly — use MetaFFIRuntime.loadModule instead.

Methods

MetaFFIModule(MetaFFIRuntime runtime, String modulePath)

Constructor for the MetaFFIModule class.

Parameters:

  • runtime — A MetaFFIRuntime object specifying the runtime plugin
  • modulePath — Path to the module file

Caller load(String entityPath, MetaFFITypeWithAlias[] parametersTypes, MetaFFITypeWithAlias[] retvalsTypes)

Caller load(String entityPath, MetaFFIType[] parametersTypes, MetaFFIType[] retvalsTypes)

Loads a foreign entity from the module and returns a Caller that invokes it.

If the entity is an instance method or field, the first parameter is the object instance (see Entity Path for the instance_required tag).

Parameters:

  • entityPath — Entity path string locating the entity within the module
  • parametersTypes — Array of MetaFFITypeWithAlias (or MetaFFIType) specifying parameter types, or null
  • retvalsTypes — Array of MetaFFITypeWithAlias (or MetaFFIType) specifying return types, or null

Returns: A Caller object with method Object[] call(Object... parameters) that accepts the parameters defined in parametersTypes. Throws MetaFFIException on error.

MetaFFI Types in JVM

MetaFFI Type JVM Type
metaffi_float64_type double
metaffi_float32_type float
metaffi_int8_type byte
metaffi_int16_type short
metaffi_int32_type int
metaffi_int64_type long
metaffi_uint8_type byte
metaffi_uint16_type short
metaffi_uint32_type int
metaffi_uint64_type long
metaffi_bool_type boolean
metaffi_char8_type byte
metaffi_char16_type Character
metaffi_char32_type int
metaffi_string8_type String
metaffi_string16_type String
metaffi_string32_type String
metaffi_handle_type MetaFFIHandle
metaffi_any_type Object
metaffi_null_type null
metaffi_callable_type Method (via makeMetaffiCallable)
metaffi_float64_array_type double[]
metaffi_float32_array_type float[]
metaffi_int8_array_type byte[]
metaffi_int16_array_type short[]
metaffi_int32_array_type int[]
metaffi_int64_array_type long[]
metaffi_uint8_array_type byte[]
metaffi_uint16_array_type short[]
metaffi_uint32_array_type int[]
metaffi_uint64_array_type long[]
metaffi_bool_array_type boolean[]
metaffi_char8_array_type byte[]
metaffi_string8_array_type String[]
metaffi_string16_array_type String[]
metaffi_string32_array_type String[]
metaffi_any_array_type Object[]
metaffi_handle_array_type MetaFFIHandle[]