1. A method of updating data in a distributed system, the method comprising: at a server, in a run-time environment, receiving a request from a client system to read application data stored in the server; responsive to said receiving, populating a first data structure with the requested application data, the first data structure defined by a uniform data structure scheme; responsive to said populating a first data structure, generating a first unique identifier by performing a hash function calculation on the application data populated in the first data structure; transmitting the requested application data and the first unique identifier to the client system; receiving, from the client system, the first unique identifier and changes to the requested application data performed on the client system through a web service application, wherein the changes include extending the requested application data to include customer-specific data; populating a second data structure with the requested application data, the second data structure defined by the uniform data structure scheme; responsive to said populating a second data structure, generating a second unique identifier by performing the hash function calculation on the requested application data populated in the second data structure; comparing the first unique identifier and the second unique identifier, wherein if the first unique identifier and the second unique identifier are identical, replacing the requested application data with the changed application data, and wherein if the first unique identifier and the second unique identifier are not identical, discarding the changed application data.