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Idempotency it’s the ability to perform the same action multiple times while only producing “side effects” on the server once. An idempotent HTTP method is an HTTP method that can be called many times without different outcomes. Safe action: GET / HEAD / OPTIONS / TRACE Unsafe actions: PUT / POST / DELETE idempotent REST APIs POST is NOT idempotent. GET, PUT, DELETE, HEAD, OPTIONS and TRACE are idempotent. Safety and idempotency of HTTP methods Method Safe? Idempotent? GET Yes Yes HEAD Yes Yes OPTIONS Yes Yes PUT No Yes DELETE No Yes POST No No PATCH No No   How to make it idempotent call Constructing a retry mechanism for non-idempotent requests requires cooperation from the server. the client attaches a unique ID to each request (a GUID/UUID would suffice). When the server processes a request successfully, it saves the ID and a copy of the response it wants to send back. If that response never makes it back to the client, the client will send the request again, reusing the same ID. The server will recognize the ID, skip the actual processing of the request, and just send back the stored response. This makes all requests effectively idempotent from the client's point of view. private string Execute(string queryString){ // maxRequestTries is a private class member set to 3 by default, optionally set via a constructor parameter (not shown) var remainingTries = maxRequestTries; var exceptions = new List(); do { try { --remainingTries; return ExecuteSingle(queryString); } catch (Exception) { exceptions.Add(e); } } while (remainingTries > 0) throw new AggregateException(exceptions) //containing a list of all the exceptions thrown…

EF 6.0 overview Entity Framework 6.0 maintains connection and transaction internally when SaveChanges() method is called. It maintains a transaction for multiple entity insert, update and delete in a single SaveChanges() method. Each time calling this method EF creates a new connection and transaction. This become an issue in our UNDO feature, because context_info only available in the same transaction scope. In earlier version of EF, System.Transaction.TransactionScope was used to control the transaction. So passing information to triggers is as easy as adding one additional call to a stored procedure. However, in EF6 this approach was out. New API with EF 6.0 EF 6.0 introduced two new APIs for transaction. DbContext.Database.BeginTransaction: It allows us to start a transaction manually. It allows us to combine several operations to be combined within the same transaction and hence all the transactions are either committed or rolled back. This method allows us to specify the isolation level for the transaction. It returns a DbContextTransaction object. The BeginTransaction method has two overloads, one has no argument and the other accepts an explicit Isolation Level. DbContext.Database.UseTransaction: It allows DbContext to use a transaction that was started outside of the Entity Framework. It means using this API we can use any existing transaction with Entity Framework. Implementation In application: using(var tran = _context.Database.BeginTransaction()) { try { await CallProcAsync("dbo.USP_HIS_ContextInfo @empId={0}, @recordId={1}", UserId, 0); await _context.SaveChangesAsync(); tran.Commit(); } catch { tran.Rollback(); } } In trigger: ALTER trigger [dbo].[trg_update_TBL_E2DIALER_MSI_CellCodes] on [dbo].[TBL_E2DIALER_MSI_CellCodes] after update as begin SET NOCOUNT ON declare @empId varchar(50), @recordId int, @changeID int, @info binary(128) select @info = context_info(),@empId=replace(convert(varchar(255),@info),0x0,'')…