C# Push Notification Service

I have a need for push notification service to be integrated with my software solutions. The service will need to connect to ASP.NET, WPF, Win Forms and must be written in c# class. In the past I have used record locking to prevent end users from editing the same record. This has caused me too many issues with people wanting to view records at the same time. I want to fix this permanently. The service must be able to connect from remote locations using a port. So lets say using sockets would be a good solution. I need a way to track the sockets and access them through the application. The last thing is to have some variable (key, file name, application being used, application user id) that can be set. This will allow me to see how many people have a certain record up in a certain application and a way to get a list of them to notify. Then when that record changes I know what users and what computers the data needs to refresh on. So that when a user changes the information and saves, I will have a method on the other clients that will be called via an event and the screen will refresh with the current data. This way customers do not end up with old data and overlay changes that have been made to the record. They can view and update information. The only person that will be affected is the person that might be in the middle of changing a record and has not saved will lose their changes. I am ok with that because I will send a notification message to the user that the record has changed before I actually refresh the data. Most applications do not address this at all and would just take the last information that was saved. This needs to be like a commercial application and the code is expected to be the best practice and an elegant solution. It will be packaged with 20 other applications so it must be the best solution possible. I do not want to use SignalR or anything like that I need a custom solution that is not dependent on other people or companies. If you have any other questions please let me know and good luck bidding.