I have an application that sends email and fax notifications when an item is complete. My implementation is working but it takes several seconds to construct (i.e. connecting to our servers). This ends up freezing the UI for several seconds until the notification services have been fully constructed and used. I’m already pushing the problem as far as it will go by injecting factories and creating my services at the last possible minute.
What options do I have for injecting external services that takes several seconds to construct? I’m thinking of instructing my container that these services are singletons, which would only construct the services once per application start-up.
Simple solution
I would give those services a longer lifetime (singleinstance).
The problem though is that TCP connections are usually disconnected if nothing have happened for a while. Which means that you need to have some kind of keep alive packets to keep them open.
More robust solution
imho the connection setup is not the problem. Contacting a service should not take long. You haven’t specified what the external services are. I’m guessing that they are some kind of web services hosted in IIS. If so, make sure that the application pools aren’t recycled too often. Starting a new application in IIS can take time.
The other thought is if you really need to wait for the service to complete? Why not queue the action (to be handled by the thread pool or in a separate thread) and let the user continue? If required, simply use a messagebox when the service have been called and something failed.