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MUSIC will be maintained as a shared service exporting REST end-points that can be used across ONAP components. ONAP components can directly use the REST API provided by MUSIC (like ONAP HAS does now) for state-management.
- If an ONAP component maintains state in a SQL database (and want to continue doing so), then they it simply need needs to replace their existing jdbc driver with mdbc driver.
- The HAL daemon is expected to run as a companion daemon to the ONAP component at each site, ideally in the same failure domain the ONAP component (i.e, they fail together). Hence, it should be a process in the same VM or container of the ONAP component. While HAL currently exports a REST API we are working on a java library that components can simply link to their code.
ONAP components need to provide HAL with (1) failover scripts that HAL will call when an ONAP component on a site is taking over requests corresponding to the failed component. This could involve actions such as updating MSB or DMaap that are very component-specific. (2) site-selection/request-redistribution scripts that HAL will use to decide which site (and the ONAP component) must take-over which request on failure. For example a simple policy could be: "the least busy site must take over all requests that were assigned to the failed ONAP component".
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