Hi,
Once you created system user and gave all the necessary permission. The you need to create a mapping to configure a bundle-to-user mapping, for that you can create new config like below:
service Mapping => <bundle Symbolic Name>:<Any-serviceName>=<systemuser>
You can get session from service user like below
session = repository.loginService("readService", null);
where readService is service name
Thanks
Arun
Arun Patidar