Server Mode

• Sep 09, 2019
• 2 minutes to read

The server mode is a special binding mode designed to handle massive amounts of data. Server-side data processing and on-demand data loading provide fast editor initialization and a smooth user experience regardless of the size of the data source.

The following data editors support the server mode natively:

• ComboBoxEdit;
• LookUpEdit;
• ListBoxEdit.

Overview

The editor running in server mode loads data in small portions as the user scrolls through the records. This approach significantly speeds up the editor initialization.

Additionally, you can use the asynchronous server mode. Asynchronous server mode ensures that the data loading operations are performed in a background thread, keeping the user interface responsive. The image below shows a combo box loading data in asynchronous server mode.

Note

The editors listed above support asynchronous server mode natively starting with version 16.1.

Activating the server mode

To activate the server mode, you need to bind the editor’s ItemsSource property to one of the following data sources:

• LinqServerModeDataSource
• LinqInstantFeedbackDataSource
• EntityServerModeDataSource
• EntityInstantFeedbackDataSource
• WcfServerModeDataSource
• WcfInstantFeedbackDataSource
• ODataServerModeSource
• ODataInstantFeedbackSource
• PLinqServerModeDataSource
• PLinqInstantFeedbackDataSource

Limitations

When a lookup control is bound to an asynchronous data source and is used in in-place mode inside the GridControl, its values cannot be exported or printed correctly.

Multi-select editors does not work in Instant Feedback mode.

Example

This example demonstrates how to use editors from the DXEditors suite with Server Mode data sources.

Note

A complete sample project is available at https://github.com/DevExpress-Examples/how-to-use-editors-with-server-mode-data-sources-e4560.

MainWindow.xaml

<Window x:Class="DXGridSample.MainWindow" 
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
        xmlns:dxe="http://schemas.devexpress.com/winfx/2008/xaml/editors" 
        xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid"
        xmlns:dxlc="http://schemas.devexpress.com/winfx/2008/xaml/layoutcontrol"
        Title="MainWindow" Height="350" Width="525">

    <dxlc:LayoutControl Orientation="Vertical">
        <dxlc:LayoutItem Label="ComboBoxEdit">
            <dxe:ComboBoxEdit ValidateOnTextInput="True" AutoComplete="True" DisplayMember="Subject" ValueMember="ID" ItemsSource="{Binding Source.Data}"/>
        </dxlc:LayoutItem>
        <dxlc:LayoutItem Label="LookUpEdit">
            <dxg:LookUpEdit ValidateOnTextInput="True" AutoComplete="True" DisplayMember="Subject" ValueMember="ID" ItemsSource="{Binding Source.Data}"/>
        </dxlc:LayoutItem>
        <dxlc:LayoutItem Label="ListBoxEdit" VerticalAlignment="Stretch">
            <dxe:ListBoxEdit DisplayMember="Subject" ValueMember="ID" ItemsSource="{Binding Source.Data}"/>
        </dxlc:LayoutItem>
    </dxlc:LayoutControl>
</Window>

MainWindow.xaml.cs

using System;
using System.Windows;
using DXGridSample.ServiceReference1;
using DevExpress.Xpf.Core.ServerMode;

namespace DXGridSample {
    public partial class MainWindow : Window {
        public WcfInstantFeedbackDataSource Source { get; set; }
        public MainWindow() {
            Source = new WcfInstantFeedbackDataSource();
            Source.GetSource += ((d, e) => {
                e.KeyExpression = "Oid";
                e.Query = new SCEntities(new Uri(@"http://demos.devexpress.com/Services/WcfLinqSC/WcfSCService.svc")).SCIssuesDemo;
                e.Handled = true;
            });
            DataContext = this;
            InitializeComponent();
        }
    }
}

MainWindow.xaml.vb

Imports System
Imports System.Windows
Imports DXGridSample.ServiceReference1
Imports DevExpress.Xpf.Core.ServerMode

Namespace DXGridSample
    Partial Public Class MainWindow
        Inherits Window

        Public Property Source() As WcfInstantFeedbackDataSource
        Public Sub New()
            Source = New WcfInstantFeedbackDataSource()
            AddHandler Source.GetSource, (Sub(d, e)
                e.KeyExpression = "Oid"
                e.Query = (New SCEntities(New Uri("http://demos.devexpress.com/Services/WcfLinqSC/WcfSCService.svc"))).SCIssuesDemo
                e.Handled = True
            End Sub)
            DataContext = Me
            InitializeComponent()
        End Sub
    End Class
End Namespace