Databases Reference
In-Depth Information
your applications. So, you may want to consider using a
lazy loading
mechanism, by which certain properties of your
objects are loaded only when necessary. LINQ to SQL and the Entity Framework 4.0 support lazy loading (through the
use of the
DeferredLoadingEnabled
property).
Although lazy loading minimizes the amount of data loaded, it can create chattier applications. It's important
to strike the right balance between using bulk data transfers and minimizing the amount of data needed to run an
application function.
Caching
Another important technique used to minimize roundtrips is
caching
. Your application (or service) may use caching
to avoid unnecessary roundtrips if some of your data doesn't change often. This may also impact your database design
choices. For example, if you have a table that stores a list of states, the table will probably remain unchanged for a long
time, which makes it a great candidate for caching.
Caching can be performed in memory or on disk (in a local database, for example). You have a few options:
•
ASP.NET caching.
ASP.NET offers a cache object that provides good caching capabilities.
However, ASP.NET caching is tied to IIS. Restarting IIS clears the ASP.NET cache unless you've
taken the necessary steps to persist the cache.
•
Windows Server AppFabric.
The AppFabric offers a next-generation distributed cache
(previously known as Velocity ). This cache can run on multiple computers and is made
available through a .NET API. This caching library is only available on premise and cannot be
used in Windows Azure.
•
Windows Azure Caching Service.
This caching service is a subset of Windows Server
AppFabric caching. Some of the methods are not supported in Azure. The Azure Caching
Service is only practical for storing IIS session state, or for other key-value pair storage needs
in which the key is always known in advance. However the Azure cache can run on local
instances, a method that leverages the memcache protocol.
•
Enterprise Library.
The Enterprise Library offers a collection of application blocks that
Microsoft makes available under public license. The Enterprise Library contains a cache
mechanism that doesn't depend on ASP.NET. This caching mechanism is provided natively in
.NET 4.0 and can be found under the
System.Runtime.Caching
namespace.
Asynchronous User Interface
Ultimately, performance is a measure that impacts the user experience and can be controlled to a certain degree by
offering highly responsive user interfaces. A Windows application that becomes unresponsive while loading data, or
a web page that doesn't load until all the data has been retrieved, is perceived as slow. As a result, developing with
multithreading techniques may become more important to provide a better experience to your users.
For web development, you should consider using asynchronous controls (such as AJAX) that give you more
control over partial page loading. For Windows development, you may need to use a multithreaded user interface
development approach.
To implement a highly responsive application in WinForms, use the
Invoke
method, shown on line 3 of the
following example, to refresh your user interface on the UI thread:
1. void OnPassCompleted()
2. {
3. this.Invoke(new EventHandler(UpdateProgressBar), null);
4. }
5.
