Thursday, October 4, 2012

SQL Azure and Entity Framework

Recently I was asked by a friend “How to deal the Transient Fault handling framework against SQL Azure while using Entity Framework?”. How really?

Here are a bunch of resources that describe in detail what the Transient faults are, how to deal with them, and in particular how to use the TFHF (Transient Fault Handling Framework) along with Entity Framework:

A concrete sample from the Windows Azure CAT (CAT states for Customer Advisory Team) team site:

// Define the order ID for the order we want.
int orderId = 43680;

// Create an EntityConnection.
EntityConnection conn = new EntityConnection("name=AdventureWorksEntities");

// Create a long-running context with the connection.
AdventureWorksEntities context = new AdventureWorksEntities(conn);

// Explicitly open the connection inside a retry-aware scope.
sqlAzureRetryPolicy.ExecuteAction(() =>
if (conn.State != ConnectionState.Open)

// Execute a query to return an order. Use a retry-aware scope for reliability.
SalesOrderHeader order = sqlAzureRetryPolicy.ExecuteAction<SalesOrderHeader>(() =>
return context.SalesOrderHeaders.Where("it.SalesOrderID = @orderId",
new ObjectParameter("orderId", orderId)).Execute(MergeOption.AppendOnly).First();

// Change the status of the order.
order.Status = 1;

// Delete the first item in the order.

// Save changes inside a retry-aware scope.
sqlAzureRetryPolicy.ExecuteAction(() => { context.SaveChanges(); });

SalesOrderDetail detail = new SalesOrderDetail
SalesOrderID = 1,
SalesOrderDetailID = 0,
OrderQty = 2,
ProductID = 750,
SpecialOfferID = 1,
UnitPrice = (
UnitPriceDiscount = 0,
LineTotal = 0,
rowguid =
ModifiedDate =


// Save changes again inside a retry-aware scope.
sqlAzureRetryPolicy.ExecuteAction(() => { context.SaveChanges(); });
// Explicitly dispose of the context and the connection.

Well, this is the raw source provided. To be hones, I would extract it / encapsulate in some more generalized way (for instance create some Extension methods to call for all CRUD operations; or even better – create my own DataService on top of the EF, so my code will never work with the bare boned EF context, but some contract instead.

Wednesday, October 3, 2012

SQL Azure Federations Talk at SQL Saturday 152 / Bulgaria

Last Saturday we had the first edition of SQL Saturday for Bulgaria – SQL Saturday 152. I submitted my talk in the early stages of event preparation. It is “An intro to SQL Azure Federations”. I rated it as “beginners”, as it is intended to put the grounds on scaling out with SQL Azure. However it turned out that the content is for at least level 300 technical talk, and the audience shall have foundations for SQL Azure to attend the talk. Anyway, I think it went smoothly and funny. You can find the slides here. And I hope to pack a GitHub project soon for the extensions on EF Code First I used to get data out from Federation Members and perform Fan-out Queries.

Already looking forward for the next appearance of SQL Saturday in Bulgaria.