ServerApplicationContext API Reference

For the latest documentation on Visual Studio 2017, see Visual Studio 2017 Documentation.

This article provides an overview of the ServerApplicationContext API, which lets you access the middle tier of a LightSwitch application from other clients.

Microsoft.LightSwitch.Framework.Server.ServerApplicationContext

Public MustInherit Class ServerApplicationContext(Of TServerApplicationContext As Microsoft.LightSwitch.Server.IServerApplicationContext, TApplication As Microsoft.LightSwitch.Server.IServerApplication, TDataWorkspace As Microsoft.LightSwitch.IDataWorkspace)

Inherits: System.Object

Member of: Microsoft.LightSwitch.Framework.Server

Remarks: Code that uses the ServerApplicationContext must execute on the same thread on which the Http request is handled. Once the request is handled, the objects encapsulated in the ServerApplicationContext are disposed. If you’re seeing InvalidOperationException, ObjectDisposedException, or similar exceptions with irregular frequency, check to make sure that your code is running on the same thread on which the Http request is handled. If you do need to start a new thread that will subsequently access the LightSwitch data, you’ll need to copy that data into a standalone collection or object graph before starting the thread.

Members

CreateContext()

Public Shared Function CreateContext() As TServerApplicationContext

Creates a new ServerApplicationContext based on the Application and DataWorkspace properties of the active LightSwitch application.

Remarks: Only one ServerApplicationContext can be present for a given logical request on the server. Each incoming request to one of the in-built LightSwitch server endpoints has its own ServerApplicationContext automatically created for the lifetime of the request. If you try to create a second ServerApplicationContext when one is already present, a ContextExistsException will occur.

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load  
        Dim ct As ServerApplicationContext = ServerApplicationContext.CreateContext()  
        For Each b As Birthday In ct.DataWorkspace.ApplicationData.Birthdays  
            If b.BirthDate = Date.Today Then  
                Response.Write(b.Id.ToString() + " " + b.Name + " " + b.BirthDate + "<br>" + vbCrLf)  
            End If  
        Next  
        Response.Write("Current user is: " + ct.Application.User.FullName)  
    End Sub  

protected void Page_Load(object sender, System.EventArgs e)  
{  
ServerApplicationContext ct = ServerApplicationContext.CreateContext();  
foreach (Birthday b in ct.DataWorkspace.ApplicationData.Birthdays) {  
if (b.BirthDate == System.DateTime.Today) {  
Response.Write(b.Id.ToString() + " " + b.Name + " " + b.BirthDate + "<br>" + Constants.vbCrLf);  
}  
}  
Response.Write("Current user is: " + ct.Application.User.FullName);  
}  
  

CreateContext(ServerApplicationContextCreationOptions)

Public Shared Function CreateContext(ServerApplicationContextCreationOptions) As TServerApplicationContext

Creates a new ServerApplicationContext based on the Application and DataWorkspace properties of the active LightSwitch application, with a parameter that specifies whether authentication is required.

Parameter: ServerApplicationContextCreationOptions of type Microsoft.LightSwitch.Server.ServerApplicationContextCreationOptions.

Values:

None (0) – Authentication is required, if enabled for the application.

SkipAuthentication (1) – Authentication is bypassed.

Remarks: Only one ServerApplicationContext can be present for a given logical request on the server. Each incoming request to one of the in-built LightSwitch server endpoints has its own ServerApplicationContext automatically created for the lifetime of the request. If you try to create a second ServerApplicationContext when one is already present, a ContextExistsException will occur.

If authentication is enabled for your LightSwitch application, ServerApplicationContext tries to enforce user authentication. Specifically, if in your web.config file the Authentication mode is Windows or Forms, when your code tries to create a new ServerApplicationContext by calling CreateContext, if there isn't a valid authenticated user already on the HttpContext, your call to CreateContext will throw an exception.

If you don’t want this behavior, you can tell CreateContext to skip the authentication check, by setting the ServerApplicationContextCreationOptions parameter to SkipAuthentication.

Using Context As ServerApplicationContext = ServerApplicationContext.CreateContext(ServerApplicationContextCreationOptions.SkipAuthentication)   
' allow in unauthenticated users   
' your code goes here   
End Using  

using (ServerApplicationContext Context = ServerApplicationContext.CreateContext(ServerApplicationContextCreationOptions.SkipAuthentication)) {  
// allow in unauthenticated users   
// your code goes here   
}  

Application

Public ReadOnly Property Application As TApplication

Gets the Application object for ththe LightSwitch application. The Application object provides access to active screens, methods of open screens, and access to the current user.

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load  
        Using Context As ServerApplicationContext = ServerApplicationContext.CreateContext()  
            Response.Write(Context.Application.Details.DisplayName)  
        End Using  
    End Sub  

protected void Page_Load(object sender, System.EventArgs e)  
{  
using (ServerApplicationContext Context = ServerApplicationContext.CreateContext()) {  
Response.Write(Context.Application.Details.DisplayName);  
}  
}  

Current

Public Shared ReadOnly Property Current As TServerApplicationContext

Returns the currently in-scope ServerApplicationContext if one exists; otherwise returns a NullReferenceException.

Remarks: The Current property can be used instead of the CreateContext() method when accessing the ServerApplicationContext from a server method such as Inserting or SaveChanges_Executing. If you attempt to call CreateContext() from a server method, a ContextExistsException will occur.

Private Sub Birthdays_Inserting(entity As Birthday)  
            For Each b As Birthday In ServerApplicationContext.Current.DataWorkspace.ApplicationData.Birthdays  
                If b.BirthDate = Date.Today Then  
                    MsgBox((b.Id.ToString() + " " + b.Name + " " + b.BirthDate))  
                End If  
            Next  
            MsgBox("Current user is: " + ServerApplicationContext.Current.Application.User.FullName)  
        End Sub  

private void Birthdays_Inserting(Birthday entity)  
{  
foreach (Birthday b in ServerApplicationContext.Current.DataWorkspace.ApplicationData.Birthdays) {  
if (b.BirthDate == System.DateTime.Today) {  
Interaction.MsgBox((b.Id.ToString() + " " + b.Name + " " + b.BirthDate));  
}  
}  
Interaction.MsgBox("Current user is: " + ServerApplicationContext.Current.Application.User.FullName);  
}  
  

DataWorkspace

Public ReadOnly Property DataWorkspace As TDataWorkspace

Gets the containing data workspace. The data workspace provides access to all data sources in the application.

Using Context As ServerApplicationContext = ServerApplicationContext.CreateContext()   
    Dim v = From c In Context.DataWorkspace.ApplicationData.Customers   
            Where c.Name.Contains("Joe")   
            Select c   
       For Each c As Customer In v   
        Response.Write(c.Name + "<br>" + vbCrLf)    
    Next   
End Using    

using (ServerApplicationContext context = ServerApplicationContext.CreateContext())   
{    
    var v = from c in context.DataWorkspace.ApplicationData.Customers   
            where c.Name.Contains("Joe")   
            select c;   
       foreach (Customer c in v) {    
        Response.Write(c.Name + "<br>\r\n");   
    }   
}  

See Also

Walkthrough: Inserting Data with the ServerApplicationContext
LightSwitch ServerApplicationContext