Example
ClientContext oClientContext = new ClientContext("http://MyServer/sites/MySiteCollection/MyWebSite");
Web oWebsite = clientContext.Web;
Principal oUser = oWebsite.SiteUsers.GetByLoginName(@"DOMAIN\alias");
RoleDefinition oRoleDefinition = oWebsite.RoleDefinitions.GetByName("Create and Manage Alerts");
RoleDefinitionBindingCollection collRoleDefinitionBinding = new RoleDefinitionBindingCollection(clientContext);
collRoleDefinitionBinding.Add(oRoleDefinition);
RoleAssignment oRoleAssignment = oWebsite.RoleAssignments.Add(oUser, collRoleDefinitionBinding);
clientContext.Load(oUser,
user => user.Title);
clientContext.Load(oRoleDefinition,
role => role.Name);
clientContext.ExecuteQuery();
Console.WriteLine("{0} added with {1} role.", oUser.Title, oRoleDefinition.Name);
