I have an application that uses Java on the backend end, Angular on the frontend, and I'm trying to use STOMP messaging between the two to exchange state data.
What I would like to do is have my services, on startup, publish their states and have that data stay in the queue for any client that later connects to the server.
(edit)
For clarification, I don't mean I want to messages to survive a server reboot. What I want is for certain message queues to retain all messages until the server reboots.
How do I tell Spring Boot's STOMP implementation to not delete the contents of a /queue?
You can configure ActiveMQ Artemis as an "external broker" and use a "non-destructive" queue. When a STOMP client receives and acknowledges a message from a non-destructive queue the broker will not remove it. You can define a special "initialization" queue which all clients connect to initially to receive the state data which you care about and then they can connect to whatever other queues they need to complete their normal work.
In this kind of use-case the queue is typically configured as non-destructive and as a "last value" queue. This way each client can use its own "last value" and can keep their state data up-to-date without the complication of stale state data on the queue.
I realize your question was asking about how to do this with Spring's built-in broker, but all my research indicates that Spring's simple in-memory broker neither supports last-value queue semantics nor non-destructive queue semantics nor even persistent messages. From what I understand Spring's broker is only meant for the most basic use-cases which is why then enable integration with 3rd party brokers which can support more advanced use-cases (e.g. like yours).