PersistentConnection

Persistent Connections (Server)

A PersistentConnection is the base class that has an api for exposing a SignalR service over http.

To create a new endpoint. Create a new class that derives from PersistentConnection.

public class MyEndPoint : PersistentConnection 
{
}

To make this endpoint accessible, add a route to Application_Start (or something similar):

using System;
using System.Web.Routing;
using SignalR;

namespace WebApplication1
{
    public class Global : System.Web.HttpApplication
    {
        void Application_Start(object sender, EventArgs e)
        {
            RouteTable.Routes.MapConnection<MyEndPoint>("echo", "echo/{*operation}");
        }
    }
}

This will expose /echo as a SignalR endpoint.

PersistentConnection API

Task OnConnectedAsync(IRequest request, string connectionId)

Called when a new connection is made.

• request - The request associated with this connection.
• connectionId - The id of the new connection.

Example

public class MyEndPoint : PersistentConnection 
{
    protected override Task OnConnectedAsync(IRequest request, string connectionId)
    {
        return Connection.Broadcast("Connection " + connectionId + " connected");
    }
}

Task OnReconnectedAsync(IRequest request, IEnumerable groups, string connectionId)

Called when a connection is restored.

• request - The request associated with this connection.
• groups - A list of groups the client is a part of.
• connectionId - The id of the new connection.

Example

public class MyEndPoint : PersistentConnection 
{
    protected override Task OnReconnectedAsync(IRequest request, IEnumerable<string> groups, string clientId)
    {
        return Connection.Broadcast("Client " + clientId + " re-connected");
    }
}

Task OnReceivedAsync(IRequest request, string connectionId, string data)

Called when data is received on the connection.

• request - The request associated with the connection that sent the data.
• connectionId - The id of the connection that sent the data.
• data - The payload received from the client.

Example

public class MyEndPoint : PersistentConnection 
{
    protected override Task OnReceivedAsync(IRequest request, string connectionId, string data) 
    {
        return Connection.Broadcast("Connection " + connectionId+ " sent " + data);   
    }
}

Task OnDisconnectAsync(string connectionId)

Called when a connection goes away (client is no longer connected, e.g. browser close).

• connectionId - The id of the client that disconnected

Example

public class MyEndPoint : PersistentConnection 
{
    protected override Task OnDisconnectAsync(string connectionId) 
    {
        return Connection.Broadcast("Connection " + connectionId+ " disconncted");   
    }
}

Task OnErrorAsync(Exception error)

Called when an error occurs on the connection.

• error - The error that occurred.

Example

public class MyEndPoint : PersistentConnection 
{
    protected override Task OnErrorAsync(Exception error) 
    {
        return Connection.Broadcast("Error ocurred " + error);
    }
}

IConnection Connection

• Gets the IConnection for this PersistentConnection.

IConnection API

Task Broadcast(object value)

Broadcasts a message to all on this connection.

• NOTE: the value is JSON serialized

Broadcasting over a connection from outside of a PersistentConnection

Sometimes you have some arbitrary code in an application that you want to be able to notify all clients connected when some event occurs. An example of this might be a background task that sends data at a certain interval.

You can use the dependency resolver for the current host to resolve the IConnectionManager interface which allows you to get ahold of the connection object.

In these scenarios, you can get an IConnection for a specific persistent connection by calling connectionManager.GetConnectionContext<T>:

    using SignalR;

    var context = GlobalHost.ConnectionManager.GetConnectionContext<MyEndPoint>();
    context.Connection.Broadcast("Hello from outside of the connection!");

Once you have the connection, you can call Broadcast to send a message to all clients.