Design Considerations - Pro SQL Database for Windows Azure - page 26

• Error 233. The client was unable to establish a connection because of an error during the
initialization process before login. Possible causes include the following: the client tried
to connect to an unsupported version of SQL Server; the server was too busy to accept
new connections; or there was a resource limitation (insufficient memory or maximum
allowed connections) on the server:
provider: TCP Provider, error: 0 - An existing connection was forcibly closed
by the remote host.
• Error 10053. A transport-level error has occurred when receiving results from the server. An
established connection was aborted by the software in your host machine.
• Error 10054. A transport-level error has occurred when sending the request to the server:
provider: TCP Provider, error: 0 - An existing connection was forcibly closed
by the remote host.
• Error 10060. A network-related or instance-specific error occurred while establishing a
connection to SQL Server. The server was not found or was not accessible. Verify that the
instance name is correct and that SQL Server is configured to allow remote connections:
provider: TCP Provider, error: 0 - A connection attempt failed because the connected
party did not properly respond after a period of time, or established connection
failed because connected host has failed to respond.
To account for most of the errors identified previously, Microsoft released the Transient Fault Handling
Application Block. This framework is designed to account for transient errors for various cloud services, including
SQL Database. The framework also provides different retry strategies, including Incremental, Fixed Interval, and
Exponential Back Off options. Visit the Microsoft Enterprise Library Integration Pack for Microsoft Azure for more
information: http://msdn.microsoft.com/en-us/library/hh680934(v=PandP.50).aspx .
Not ■ in the context of sQL Database, throttling generally means terminating the database connection. Whatever the
reason for throttling is, the outcome is usually the same: the loss of a database connection.
Application Design Considerations
When considering how to design your application to best take advantage of SQL Database, you need to evaluate the
following items:
• Database roundtrips. How many roundtrips are necessary to perform a specific function in
your application? More database roundtrips mean a slower application, especially when the
connection is made over an Internet link and is SSL encrypted.
• Caching. You can improve response time by caching resources on the client machine or
storing temporary data closer to the consumer.
• Property lazy loading. In addition to reducing roundtrips, it's critical to load only the
data that's absolutely necessary to perform the required functions. Lazy loading can help
significantly in this area.
• Asynchronous user interfaces. When waiting is unavoidable, providing a responsive user
interface can help. Multithreading can assist in providing more responsive applications.
• Shards. A shard is a way of splitting your data across multiple databases in a manner that is as
transparent as possible to your application code, thus improving performance. Federation is
the sharding technology available in SQL Database.