URL Protocols in Native Image can be divided into three classes:
- supported and enabled by default
- supported and disabled by default
- HTTPS support
These are protocols that are enabled by default and added to every generated native image.
Currently, file
and resource
are the only supported URL protocols, enabled by default.
These are protocols that are supported but not enabled by default when building a native image.
They must be enabled during the native image building by adding --enable-url-protocols=<protocols>
to the native-image
command.
The option accepts a list of comma-separated protocols.
The rationale behind enabling protocols on-demand is that you can start with a minimal image and add features as you need them.
This way your image will only include the features you use, which helps keep the overall size small.
Currently http
and https
are the only URL protocols that are supported and can be enabled on demand.
They can be enabled using the --enable-http
and --enable-https
options.
Support for the https
URL protocol relies on the Java Cryptography Architecture (JCA) framework.
Thus when https
is enabled, --enable-all-security-services
is set by default.
This adds to the generated image the code required by the JCA, including statically linking native libraries that the JCA may depend on.
See the documentation on security services for more details.
No other URL protocols are currently tested.
They can still be enabled using --enable-url-protocols=<protocols>
, however they might not work as expected.