Create WEB API and deploy it on your server

If you need a secure service to process business transactions from your website. If you need to send your website data to others, such as a traffic report or other monitoring service then you need a service to automate this process.
If you want your chat application or service that allows people to communicate or exchange data in real time.
if you need a dashboard application that polls one or more services for data and presents it in a logical presentation.
if you need to expose a workflow implemented using Windows Workflow Foundation as a WCF service.It may be a SOAP or REST service.