The DevExpress Grid Control for WPF includes support for multiple binding modes, each designed to address a specific problem and to make working with data easier and faster. Alongside the standard binding mode, the grid also provides Server Mode. In the upcoming release of 2011.1, the WPF Grid will gain yet another feature from its WinForms counterpart, the Instant Feedback UI Mode.
Before looking at what the Instant Feedback mode is and how it can benefit you, let’s take a look at the existing methods and what scenarios they can be used in.
Standard Binding
The Standard Binding is the most common way of connecting any control to a set of data. In this scenario, data is fetched in its entirety from a data store and loaded into memory before being rendered within the grid control. This provides excellent, no-hassles, solution for quickly populating a grid with a small number of data, regardless of their source and connection latency of the data provider.
Server Mode Binding
Server Mode was introduced in the DXGrid to eliminate performance issues that result from binding to large datasets hosted remotely over slow connections. The problem arises when standard binding is used to load records from a database – over a slow or high-latency network - into memory before starting to populate the grid. That bottleneck, coupled with the performance and resources of the client machine may lead to extreme lag and delays when browsing the data. Server Mode operates differently from the standard binding solution: Instead of loading the entire dataset into the grid at once, it only loads portions required to populate the view. As the user then scrolls through the rows, more data is fetched and displayed on demand. As the grid has access to only portions of data at a time, data-aware operations such as sorting, grouping, filtering, and summaries are performed on the server itself. The results are then retrieved and displayed in the grid.
So, why is Instant Feedback UI needed and how can it improve the user experience?
Instant Feedback UI Mode
The Instant Feedback Mode is very similar in concept with the Server Mode in that data is retrieved only in portions that are required to populate the view and data-aware operations are performed on the server. Instant Feedback Mode is, however, an asynchronous server mode. The difference lies in how the grid behaves when data is being retrieved and populated. When a user scrolls through the records in Server Mode, the grid first waits for the partial data to be fetched before populating the rows. Depending on the data source performance, the volume of data being retrieved, and the network connectivity, the user may notice a considerable control freeze. Instant Feedback Mode addresses this issue by continuing to respond to the user’s actions while the data is being retrieved. The user can continue to scroll through records, and even re-sort, re-group and re-filter the control’s data. If required, the control will cancel the previous request and initiate a new request to the data source. To provide visual feedback, the Instant Feedback binding mode also includes options to display an animation indicating the status of operations within the grid.
The following short animation demonstrates the Instant Feedback mode in action. There are 100,000 records being retrieved from a SQL Server database and as would be expected, it requires a short amount of time to process the Grid’s requests and retrieve data. In this quick demo, you can see that data management features such as grouping are also performed on the server and take advantage of the Instant Feedback UI functionality.
Stay tuned for a video demo and tutorial demonstrating how to implement the Instant Feedback UI mode.