As an upgradable application, its data structure is also required to be upgradable. However, due to data ownership and asset security requirements, data contracts cannot be upgraded. The method we adopt here is expansion. If new fields are required in a new business, the new fieldswill be stored in a brand new data contract. Meanwhile, the address and field name in this new data contract will be added into the routing table. Business logic can be read and written through the new field’s address obtained from the routing table.