Knowledge Management Web service
There is already a KM web service available in the tool. It is in the extaccess table, and should be accessible over SOAP/REST by a user with the appropriate permissions. You can make GET requests to search the articles and/or make POST/PUT/DELETE requests to create/update the articles.
^ That would be for integrating with an external system. If you're wanting to search and use KM articles within Service Manager, functionality already exists for that as well - you do not need to build anything. If you're using SmartAnalytics, there is a Use Solution button in the right-hand pane of the web client. If you are not using SA, then find the Use Solution displayoption and track down why it's not showing in your environment.