Explaining the concept of the service-activator pattern

Suppose a client needs to request a business service, which is a process that takes a long time. In this case, the client should not wait in a synchronous way until the end of the process. Instead, there must be a way to make an asynchronous service call that does not block the client or user. This service can then be activated at some point in the future. There may be several reasons for the delay of a process. For example, there may be a database query that consumes a lot of time, or an access to a legacy system that is beyond the control of the current application. The pattern of asynchronously performing the required task is known as the service activator.

So, the service activator pattern is always used when the client needs to call a service asynchronously. This means that the client makes the request and does not wait for the response.

We can imagine some alternative solutions to this problem. One method would be to send the request...