Questions about cross-language data exchange and Android support

[WhiredPlanck]

There is a C++ native library I used for my Android app and it's able to provide data in Cap'n Proto. Naturally I want to utilize the ability to speed up the data exchanging, especially get data from C++ to Java/Kotlin, because common JNI object converting is really slow (ranges in ~40,000 µs to ~120,000 µs). So is there anyway to properly deal with this, like some Gradle plugins or any else example?

[dwrensha]

Yes, you should be able to compile your .capnp schemas with capnpc-java and then use the capnproto-java runtime library. The Addressbook example shows one way to set up a pom.xml to achieve this:

capnproto-java/examples/pom.xml

Lines 52 to 71 in ed9a67c

	<execution>
	<id>generate-sources</id>
	<phase>generate-sources</phase>
	<configuration>
	<target>
	<mkdir dir="src/main/generated"/>
	<exec executable="capnp" failonerror="true">
	<arg value="compile"/>
	<arg value="-I"/>
	<arg value="../compiler/src/main/schema/"/>
	<arg value="--src-prefix=src/main/schema/"/>
	<arg value="-o../capnpc-java:src/main/generated"/>
	<arg value="src/main/schema/addressbook.capnp"/>
	</exec>
	</target>
	</configuration>
	<goals>
	<goal>run</goal>
	</goals>
	</execution>

There is also this maven plugin (but I've never used it): https://github.com/expretio/capnp-maven-plugin

One annoying bit about all this is that capnpc-java is still written in C++: #111

[WhiredPlanck]

@dwrensha No bad. I'll give it a try.