The actual communication to the storage array is handled by SRA. SRA is vendor specific component. It's up to the storage vendor how to implement the communication between SRA and their storage array, SRM has nothing to do with that.
SRM 8.2 communicates with the SRA using a simple command entry point - in SRM Windows it's a perl script (command.pl) and in SRM Virtual Appliance it's just "command" that transfers the data to the SRA packaged as a Docker container.
For more details I would recommend to check the attached SRA specs:
1) Sra20Spec.pdf - this is the main SRA spec document describing all the SRA commands format of requests/responses etc.
2) Sra20ContainerizedSRAs.pdf - this is an appendix specially that explains the containerized SRAs for VA