Add project files.

ManagementApp/Models/ModelBase.cs

@@ -0,0 +1,17 @@
+namespace ManagementApp.Models
+{
+    public abstract class ModelBase: IPaging
+    {
+        public abstract Task<MessageHeader> AddAsync();
+
+        public abstract Task<MessageHeader> UpdateAsync();
+
+        public abstract Task<MessageHeader> DeleteAsync();
+        public bool IsFirstQuery { set; get; }
+        public int PageSize { get; set; }
+        public int PageNumber { get; set; }
+        public int MaxRow { get; set; }
+
+
+    }
+}