IServiceContainer Interface

Provides a container for services.

Namespace:  System.ComponentModel.Design
Assembly:  System (in System.dll)

[ComVisibleAttribute(true)]
public interface IServiceContainer : IServiceProvider

A service container is, by definition, a service provider. In addition to providing services, it also provides a mechanism for adding and removing services. Services are a foundation of the .NET Framework design-time architecture. Services provide design-time objects access to specific features and methods implemented by a service object that provides a service or services.

To obtain a service at design time, call the GetService method of a component sited in design mode. Designers and other objects can add or remove services at design time through the IDesignerHost interface.

Service containers can be contained by other service containers, forming a tree of service containers. By default, the IServiceContainer interface adds services to the closest service container. When a service is added, it can be added with instructions to promote it. When a service is promoted, it is added to any parent service container, on up until the top of the service container tree is reached. This allows a designer to provide a global service that other objects in the process can use.

The following code example contains the code for a Form that is configured to demonstrate the behavior of a network of linked service containers.

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Windows.Forms;
using System.Windows.Forms.Design;

namespace ServiceArchitectureExample
{
    // This sample contains a Form class that is configured to demonstrate  
    // the behavior of a network of linked service containers.    

    // Notes regarding this IServiceContainer and IServiceProvider  
    // implementation: 
    // 
    // When implementing the IServiceContainer interface, you may want to  
    // implement support for a linked service container system 
    // which enables access to and sharing of services throughout a  
    // container tree or network. 
    // 
    // To effectively share a service, a GetService, AddService or  
    // RemoveService method must be able to locate a service  
    // that has been added to a shared service container tree or network. 
    //         
    // One simple approach to sharing services, suitable for container networks  
    // where each container has one parent and the tree has 
    // one parentless container, is to store services only at the top node  
    // (the root or grandparent) of a tree. 
    // 
    // To store services in the root node of a tree, two types of  
    // consistencies must be maintained in the implementation:         
    // 
    //   >   The GetService, AddService and RemoveService implementations  
    //       must access the root through some mechanism. 
    //         The ServiceContainerControl's implementations of these  
    //         standard IServiceContainer methods call  
    //         the same method of a parent container, if the container  
    //         has been parented, to route methods to the root.   
    // 
    //   >   The services must be maintained at the root of the tree;  
    //       therefore, any new child's services should be copied to the root.                 


    // ServiceContainerControl provides an example user control implmentation  
    // of the IServiceContainer interface. This implementation of  
    // IServiceContainer supports a root-node linked service distribution,  
    // access. and removal architecture. 
    public class ServiceContainerControl : System.Windows.Forms.UserControl, IServiceContainer
    {                        
        // List of service instances sorted by key of service type's full name. 
        private SortedList localServices;               
        // List that contains the Type for each service sorted by each  
        // service type's full name. 
        private SortedList localServiceTypes;           

        // The parent IServiceContainer, or null. 
        private IServiceContainer parentServiceContainer;   
        public IServiceContainer serviceParent              
        {
            get
            {
                return parentServiceContainer;
            }
            set
            {
                parentServiceContainer = value;
                // Move any services to parent. 
                for( int i=0; i<localServices.Count; i++ )
                    parentServiceContainer.AddService(
                        (Type)localServiceTypes.GetByIndex(i), 
                        localServices.GetByIndex(i));
                localServices.Clear();
                localServiceTypes.Clear();
            }
        }

        // The current state of the control reflecting whether it has  
        // obtained or provided a text service. 
        private TextServiceState state_;
        public TextServiceState state              
        {                                          
            get
            {
                return state_;
            }
            set
            {
                if( (TextServiceState)value == 
                        TextServiceState.ServiceProvided )
                    this.BackColor = Color.LightGreen;
                else if( (TextServiceState)value == 
                        TextServiceState.ServiceNotObtained )                
                    this.BackColor = Color.White;                                   
                else if( (TextServiceState)value == 
                        TextServiceState.ServiceObtained )
                    this.BackColor = Color.LightBlue;
                else if( (TextServiceState)value == 
                        TextServiceState.ServiceNotFound )                                    
                    this.BackColor = Color.SeaShell;                
                state_ = value;
            }
        }

        // Parent form reference for main program function access. 
        private ServiceForm parent;                 
        // String for label displayed on the control to indicate  
        // the control's current service-related configuration state. 
        public string label;  

        public ServiceContainerControl(Size size, Point location, 
            ServiceForm parent) : this(null, size, location, parent){}      
        public ServiceContainerControl(IServiceContainer ParentServiceContainer, 
            Size size, Point location, ServiceForm parent)
        {
            this.state_ = TextServiceState.ServiceNotObtained;
            localServices = new SortedList();
            localServiceTypes = new SortedList();

            this.BackColor = Color.Beige;            
            this.label = string.Empty;            
            this.Size = size;
            this.Location = location;
            this.parent = parent;
            this.serviceParent = ParentServiceContainer;

            // If a parent is specified, set the parent property of this  
            // linkable IServiceContainer implementation. 
            if( ParentServiceContainer != null )
                serviceParent = ParentServiceContainer;
        }

        // IServiceProvider.GetService implementation for a linked  
        // service container architecture. 
        public new object GetService(System.Type serviceType)
        {
            if( parentServiceContainer != null )
                return parentServiceContainer.GetService(serviceType);            

            object serviceInstance = localServices[serviceType.FullName];
            if( serviceInstance == null )
                return null;
            else if( serviceInstance.GetType() == typeof(ServiceCreatorCallback) )
            {
                // If service instance is a ServiceCreatorCallback, invoke  
                // it to create the service. 
                return ((ServiceCreatorCallback)serviceInstance)(this, serviceType);                                
            }
            return serviceInstance;
        }

        // IServiceContainer.AddService implementation for a linked  
        // service container architecture. 
        public void AddService(System.Type serviceType, 
            System.ComponentModel.Design.ServiceCreatorCallback callback, bool promote)
        {
            if( promote && parentServiceContainer != null )            
                parentServiceContainer.AddService(serviceType, callback, true);            
            else
            {
                localServiceTypes[serviceType.FullName] = serviceType;
                localServices[serviceType.FullName] = callback;
            }
        }

        // IServiceContainer.AddService implementation for a linked  
        // service container architecture. 
        public void AddService(System.Type serviceType, 
            System.ComponentModel.Design.ServiceCreatorCallback callback)
        {
            AddService(serviceType, callback, true);
        }

        // IServiceContainer.AddService implementation for a linked  
        // service container architecture. 
        public void AddService(System.Type serviceType, 
            object serviceInstance, bool promote)
        {
            if( promote && parentServiceContainer != null )            
                parentServiceContainer.AddService(serviceType, serviceInstance, true);            
            else
            {
                localServiceTypes[serviceType.FullName] = serviceType;
                localServices[serviceType.FullName] = serviceInstance;
            }
        }

        // IServiceContainer.AddService (defaults to promote service addition). 
        public void AddService(System.Type serviceType, object serviceInstance)
        {
            AddService(serviceType, serviceInstance, true);
        }

        // IServiceContainer.RemoveService implementation for a linked  
        // service container architecture. 
        public void RemoveService(System.Type serviceType, bool promote)
        {
            if( localServices[serviceType.FullName] != null )
            {
                localServices.Remove(serviceType.FullName);
                localServiceTypes.Remove(serviceType.FullName);
            }
            if( promote )
            {
                if( parentServiceContainer != null )
                    parentServiceContainer.RemoveService(serviceType);
            }
        }

        // IServiceContainer.RemoveService (defaults to promote  
        // service removal) 
        public void RemoveService(System.Type serviceType)
        {
            RemoveService(serviceType, true);
        }

        // Paint method override draws the label string on the control. 
        protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
        {
            e.Graphics.DrawString(label, new Font("Arial", 8), 
                new SolidBrush(Color.Black), 5, 5);            
        }

        // Process mouse-down behavior for click. 
        protected override void OnMouseDown(
            System.Windows.Forms.MouseEventArgs e)
        {
            //  This example control responds to mouse clicks as follows: 
            // 
            //      Left click - control attempts to obtain a text service  
            //      and sets its label text to the text provided by the service 
            //      Right click - if the control has already provided a text  
            //      service, this control does nothing. Otherwise, the control  
            //      shows a dialog box to specify text to provide as a new text  
            //      service, after clearing the tree's services. 

            if( e.Button == MouseButtons.Left )
            {
                if( state_ != TextServiceState.ServiceProvided )
                {
                    // Attempt to update text from service, and set  
                    // color state accordingly.
                    TextService ts = 
                        (TextService)GetService(typeof(TextService));
                    if( ts != null )
                    {
                        this.label = ts.text;
                        state = TextServiceState.ServiceObtained;
                    }
                    else
                    {                    
                        this.label = "Service Not Found";                        
                        state = TextServiceState.ServiceNotFound;
                    }
                }
            }
            if( e.Button == MouseButtons.Right )
            {
                if( state_ == TextServiceState.ServiceProvided )
                {
                    // Remove the service if the container provided it. 
                    if( GetService(typeof(TextService)) != null )
                    {
                        RemoveService(typeof(TextService), true);
                        state = TextServiceState.ServiceNotObtained; 
                        this.label = "Service Removed";                                                                   
                    }                    
                }
                else
                {
                    // Obtain string and provide text service. 
                    using (StringInputDialog form =
                        new StringInputDialog("Test String"))
                    {
                        form.StartPosition = FormStartPosition.CenterParent;
                        if (form.ShowDialog() == DialogResult.OK)
                        {
                            if (GetService(typeof(TextService)) != null)
                                RemoveService(typeof(TextService), true);
                            parent.ResetServiceTree(this, new EventArgs());

                            AddService(typeof(TextService),
                                new TextService(form.inputTextBox.Text), true);

                            // The following commented method uses a service creator callback. 
                            // AddService(typeof(TextService),  
                            //  new ServiceCreatorCallback(this.CreateTextService));                                                

                            state = TextServiceState.ServiceProvided;
                            this.label = "Provided Text: " + form.inputTextBox.Text;
                        }
                    }
                }
            }
            parent.UpdateServiceCoverage();
        }

        // Method accesses the TextService to test the visibility of the  
        // service from the control, and sets the UI state accordingly. 
        public void ReflectServiceVisibility()
        {
            if( state_ == TextServiceState.ServiceObtained )
            {
                if( GetService(typeof(TextService)) == null )  
                    this.BackColor = Color.CadetBlue;
            }
            else if( state_ != TextServiceState.ServiceProvided )
            {
                if( GetService(typeof(TextService)) == null )
                {
                    this.BackColor = Color.White;
                    return;
                }

                // Service available.         
                if( state_ == TextServiceState.ServiceNotFound )                
                    this.BackColor = Color.Khaki;                
                else if( state_ == TextServiceState.ServiceNotObtained 
                         && label != "Service Removed" )
                    this.BackColor = Color.Khaki;       
            }
        }

        // ServiceCreatorCallback method creates a text service. 
        private object CreateTextService(IServiceContainer container, 
            System.Type serviceType)
        {
            return new TextService("Test Callback");
        }
    }

    // Example form provides UI for demonstrating service sharing behavior  
    // of a network of IServiceContainer/IServiceProvider controls. 
    public class ServiceForm : System.Windows.Forms.Form
    {
        // Root service container control for tree. 
        private ServiceContainerControl root;                
        // Button for clearing any provided services and resetting tree states. 
        private System.Windows.Forms.Button reset_button;   
        // Color list used to color code controls. 
        private Color[] colorkeys;                       
        // Strings used to reflect text service. 
        private string[] keystrings;                         

        public ServiceForm()
        {
        InitializeComponent();        
            colorkeys = new Color[] { Color.Beige, Color.SeaShell, Color.LightGreen, Color.LightBlue, Color.Khaki, Color.CadetBlue };
            keystrings = new string[] { "No service use", "Service not accessible", "Service provided", "Service obtained", "Service accessible", "No further access" };
            CreateServiceControlTree();                        
		}

        private void CreateServiceControlTree()
        {
            // Create root service control
            ServiceContainerControl control1 = new ServiceContainerControl(
                null, new Size(300, 40), new Point(10, 80), this);
            root = control1;
            // Create first tier - pass parent with service object control 1.
            ServiceContainerControl control2 = new ServiceContainerControl(
                control1, new Size(200, 30), new Point(50, 160), this);
            ServiceContainerControl control3 = new ServiceContainerControl(
                control1, new Size(200, 30), new Point(50, 240), this);
            // Create second tier A - pass parent with service object control 2.
            ServiceContainerControl control4 = new ServiceContainerControl(
                control2, new Size(180, 20), new Point(300, 145), this);
            ServiceContainerControl control5 = new ServiceContainerControl(
                control2, new Size(180, 20), new Point(300, 185), this);
            // Create second tier B - pass parent with service object control 3.
            ServiceContainerControl control6 = new ServiceContainerControl(
                control3, new Size(180, 20), new Point(300, 225), this);
            ServiceContainerControl control7 = new ServiceContainerControl(
                control3, new Size(180, 20), new Point(300, 265), this);
            // Add controls 
            this.Controls.AddRange( new Control[] { control1, control2, 
                control3, control4, control5, control6, control7 } );
        }

        internal void ResetServiceTree(object sender, EventArgs e)
        {
            // Remove the service from the service tree. 
            if( root.GetService(typeof(TextService)) != null )            
                root.RemoveService(typeof(TextService), true);

            // Set all controls to "not obtained" and clear their labels.
            for( int i=0; i<Controls.Count; i++ )
                if( !Controls[i].Equals(reset_button) ) 
                {
                    ((ServiceContainerControl)Controls[i]).state = 
                        TextServiceState.ServiceNotObtained;
                    ((ServiceContainerControl)Controls[i]).label = string.Empty;
                    ((ServiceContainerControl)Controls[i]).BackColor = 
                        Color.Beige;
                }
        }

        public void UpdateServiceCoverage()
        {
            // Have each control set state to reflect service availability. 
            for( int i=0; i<Controls.Count; i++ )
                if( !Controls[i].Equals(reset_button) )                 
                    ((ServiceContainerControl)Controls[i]).ReflectServiceVisibility();                                 
        }

            #region Windows Form Designer generated code
            private void InitializeComponent()
            {
            this.reset_button = new System.Windows.Forms.Button();
            this.SuspendLayout();
            //  
            // reset_button 
            //  
            this.reset_button.Location = new System.Drawing.Point(392, 88);
            this.reset_button.Name = "reset_button";
            this.reset_button.TabIndex = 0;
            this.reset_button.TabStop = false;
            this.reset_button.Text = "Reset";
            this.reset_button.Click += new System.EventHandler(this.ResetServiceTree);
            //  
            // ServiceForm 
            //  
            this.ClientSize = new System.Drawing.Size(512, 373);
            this.Controls.AddRange(new System.Windows.Forms.Control[] {
                                                                          this.reset_button});
            this.MinimumSize = new System.Drawing.Size(520, 400);
            this.Name = "ServiceForm";
            this.Text = "Service Container Architecture Example";
            this.ResumeLayout(false);

            }
            #endregion

            [STAThread]
            static void Main() 
            {
                Application.Run(new ServiceForm());
            }

        protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
        {            
            e.Graphics.DrawString("The following tree diagram represents a "+
                "hierarchy of linked service containers in controls.", 
                new Font("Arial", 9), new SolidBrush(Color.Black), 4, 4);
            e.Graphics.DrawString("This example demonstrates the propagation "+
                "behavior of services through a linked service object tree.", 
                new Font("Arial", 8), new SolidBrush(Color.Black), 4, 26);            
            e.Graphics.DrawString("Right-click a component to add or replace a "+
                "text service, or to remove it if the component provided it.", 
                new Font("Arial", 8), new SolidBrush(Color.Black), 4, 38);
            e.Graphics.DrawString("Left-click a component to update text from "+
                "the text service if available.", new Font("Arial", 8), 
                new SolidBrush(Color.Black), 4, 50);

            // Draw lines to represent tree branches.
            e.Graphics.DrawLine(new Pen(new SolidBrush(Color.Black), 1), 
                20, 125, 20, 258);
            e.Graphics.DrawLine(new Pen(new SolidBrush(Color.Black), 1), 
                21, 175, 45, 175);
            e.Graphics.DrawLine(new Pen(new SolidBrush(Color.Black), 1), 
                21, 258, 45, 258);
            e.Graphics.DrawLine(new Pen(new SolidBrush(Color.Black), 1), 
                255, 175, 285, 175);
            e.Graphics.DrawLine(new Pen(new SolidBrush(Color.Black), 1), 
                255, 258, 285, 258);
            e.Graphics.DrawLine(new Pen(new SolidBrush(Color.Black), 1), 
                285, 155, 285, 195);
            e.Graphics.DrawLine(new Pen(new SolidBrush(Color.Black), 1), 
                285, 238, 285, 278);            
            e.Graphics.DrawLine(new Pen(new SolidBrush(Color.Black), 1), 
                285, 155, 290, 155);
            e.Graphics.DrawLine(new Pen(new SolidBrush(Color.Black), 1), 
                285, 195, 290, 195);
            e.Graphics.DrawLine(new Pen(new SolidBrush(Color.Black), 1), 
                285, 238, 290, 238);
            e.Graphics.DrawLine(new Pen(new SolidBrush(Color.Black), 1), 
                285, 278, 290, 278);

            // Draw color key.
            e.Graphics.DrawRectangle(new Pen(new SolidBrush(Color.Black), 1), 20, 305, 410, 60);
            int y=0;
            for( int i=0; i<3; i++ )
            {
                e.Graphics.FillRectangle(new SolidBrush(colorkeys[y]), 
                    25+(i*140), 310, 20, 20);           
                e.Graphics.DrawRectangle(new Pen(new SolidBrush(Color.Black), 1), 
                    25+(i*140), 310, 20, 20);     
                e.Graphics.DrawString(keystrings[y], new Font("Arial", 8), 
                    new SolidBrush(Color.Black), 50+(i*140), 315);
                y++;
                e.Graphics.FillRectangle(new SolidBrush(colorkeys[y]), 
                    25+(i*140), 340, 20, 20);           
                e.Graphics.DrawRectangle(new Pen(new SolidBrush(Color.Black), 1), 
                    25+(i*140), 340, 20, 20);              
                e.Graphics.DrawString(keystrings[y], new Font("Arial", 8), 
                    new SolidBrush(Color.Black), 50+(i*140), 345);
                y++;
            }
        }
	}   

    // Example service type contains a text string, sufficient to  
    // demonstrate service sharing. 
    public class TextService
    {
        public string text;

        public TextService() : this(string.Empty)
        {
        }

        public TextService(string text)
        {
            this.text = text;
        }
    }

    public enum TextServiceState
    {
        ServiceNotObtained,
        ServiceObtained,
        ServiceProvided,
        ServiceNotFound
    }

    // Example Form for entering a string. 
    internal class StringInputDialog : System.Windows.Forms.Form
    {
        private System.Windows.Forms.Button ok_button;
        private System.Windows.Forms.Button cancel_button;
        public System.Windows.Forms.TextBox inputTextBox;

        public StringInputDialog(string text)
        {
            InitializeComponent();
            inputTextBox.Text = text;
        }

        private void InitializeComponent()
        {
            this.ok_button = new System.Windows.Forms.Button();
            this.cancel_button = new System.Windows.Forms.Button();
            this.inputTextBox = new System.Windows.Forms.TextBox();
            this.SuspendLayout();
            this.ok_button.Anchor = (System.Windows.Forms.AnchorStyles.Bottom | 
                System.Windows.Forms.AnchorStyles.Right);
            this.ok_button.Location = new System.Drawing.Point(180, 43);
            this.ok_button.Name = "ok_button";
            this.ok_button.TabIndex = 1;
            this.ok_button.Text = "OK";      
            this.ok_button.DialogResult = System.Windows.Forms.DialogResult.OK;            
            this.cancel_button.Anchor = (System.Windows.Forms.AnchorStyles.Bottom | 
                System.Windows.Forms.AnchorStyles.Right);
            this.cancel_button.Location = new System.Drawing.Point(260, 43);
            this.cancel_button.Name = "cancel_button";
            this.cancel_button.TabIndex = 2;
            this.cancel_button.Text = "Cancel";            
            this.cancel_button.DialogResult = System.Windows.Forms.DialogResult.Cancel;
            this.inputTextBox.Location = new System.Drawing.Point(6, 9);
            this.inputTextBox.Name = "inputTextBox";
            this.inputTextBox.Size = new System.Drawing.Size(327, 20);
            this.inputTextBox.TabIndex = 0;
            this.inputTextBox.Text = "";            
            this.inputTextBox.Anchor = ((System.Windows.Forms.AnchorStyles.Top | 
                System.Windows.Forms.AnchorStyles.Left) 
                | System.Windows.Forms.AnchorStyles.Right);
            this.ClientSize = new System.Drawing.Size(342, 73);
            this.Controls.AddRange(new System.Windows.Forms.Control[] {
                                                                          this.inputTextBox,
                                                                          this.cancel_button,
                                                                          this.ok_button});
            this.MinimumSize = new System.Drawing.Size(350, 100);
            this.Name = "StringInputDialog";
            this.Text = "Text Service Provide String Dialog";
            this.ResumeLayout(false);
        }
    }
}

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0
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