Abstract: Methods and systems are provided for upgrading a web application from an existing version to a new version without causing or creating any interruption in service to clients receiving the upgrade. A combination of techniques and strategies are used to fully migrate all connected clients from a first version to a second version of an application while keeping at least two deployment constraints in mind: (1) prevent clients from running with a mixture of resources from two different versions of an application (e.g., Version A and Version B of a given application); and (2) prevent clients from accessing service endpoints from a different version of the application than the client is running (e.g., accessing service endpoints for Version B when running Version A).