[CAUSEWAY-661] BackgroundService and BackgroundTaskService as a way of creating mementos to execute jobs asynchronously

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: objectstore-jdo-1.3.0, core-1.3.0
• Fix Version/s: objectstore-jdo-1.4.0, core-1.4.0
• Component/s: Core, Persistence JDO
• Assignee: Daniel Keir Haywood
• Reporter: Daniel Keir Haywood
• Created: 28/Jan/14 07:08
• Updated: 11/Mar/14 07:39
• Resolved: 31/Jan/14 10:58

Description

BackgroundService is the service that creates the mementos, with a default implementation in isis-core.

usage:

public void submitInvoices() {
for(Customer customer: customerRepository.findCustomersToInvoice())

{ backgroundService.execute(customer).submitInvoice(); }

}

@javax.inject.Inject
private BackgroundService backgroundService;

Here the service creates a javassist proxy through which it can figure out the arguments. The MementoService and BookmarkService can be used to create the memento string (XML).

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BackgroundTaskService is the service that persists the mementos, with a default implementation in objectstore-jdo. Each persisted BackgroundTask should be associated with the transactionId of the Interaction (see ISIS-660).

~~~~
also:

• require separate "contributions" service to add in the BackgroundTask collection to the Interaction.

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NB: the docs should indicate that an alternative implementation for BackgroundTaskService could be webhooks. Per Maurizio's comment:

a web hook is basically an HTTP callback
An example of web hook is available on the Google infrastructure, where task longer than 30 sec. are not allowed.
This is similar to your idea of background service:

public void calculateInvoices() {
for(Customer customer: customerRepository.findCustomersToInvoice())

{ Queue queue = QueueFactory.getDefaultQueue(); queue.add(withUrl("/worker").param("id", customer.getId())); }

}

Tasks added to the queue will execute by calling the request handler at the URL /worker with the parameter id at a given task rate.

https://developers.google.com/appengine/docs/java/taskqueue/overview-push