org.eclipse.jetty.alpn

Class ALPN

java.lang.Object

org.eclipse.jetty.alpn.ALPN

public class ALPN
extends Object

ALPN provides an API to applications that want to make use of the Application Layer Protocol Negotiation.

The ALPN extension is only available when using the TLS protocol, therefore applications must ensure that the TLS protocol is used:

 SSLContext context = SSLContext.getInstance("TLSv1");
 

Refer to the list of standard SSLContext protocol names for further information on TLS protocol versions supported.

Applications must register instances of either SSLSocket or SSLEngine with a ALPN.ClientProvider or with a ALPN.ServerProvider, depending whether they are on client or server side.

The ALPN implementation will invoke the provider callbacks to allow applications to interact with the negotiation of the protocol.

Client side typical usage:

 SSLSocket sslSocket = ...;
 ALPN.put(sslSocket, new ALPN.ClientProvider()
 {
     @Override
     public boolean supports()
     {
         return true;
     }

     @Override
     public List<String> protocols()
     {
         return Arrays.asList("spdy/3", "http/1.1");
     }

     @Override
     public void unsupported()
     {
     }

     @Override
     public void selected(String protocol)
     {
         System.out.println("Selected protocol: " + protocol);
     }
  });
 

Server side typical usage:

 SSLSocket sslSocket = ...;
 ALPN.put(sslSocket, new ALPN.ServerProvider()
 {
     @Override
     public void unsupported()
     {
     }

     @Override
     public String select(List<String> protocols)
     {
         return protocols.get(0);
     }
  });
 

Applications must ensure to deregister SSLSocket or SSLEngine instances, because they are kept in a global map. Deregistration should typically happen when the application detects the end of the protocol negotiation, and/or when the associated socket connection is closed.

In order to help application development, you can set the debug field to true to have debug code printed to System.err.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	ALPN.ClientProvider The client-side provider interface that applications must implement to interact with the negotiation of the protocol.
static interface	ALPN.Provider Base, empty, interface for providers.
static interface	ALPN.ServerProvider The server-side provider interface that applications must implement to interact with the negotiation of the protocol.

Field Summary

Fields

Modifier and Type	Field and Description
static boolean	debug Flag that enables printing of debug statements to System.err.

Method Summary

Modifier and Type	Method and Description
static ALPN.Provider	get(SSLEngine engine)
static ALPN.Provider	get(SSLSocket socket)
static void	put(SSLEngine engine, ALPN.Provider provider) Registers a SSLEngine with a provider.
static void	put(SSLSocket socket, ALPN.Provider provider) Registers a SSLSocket with a provider.
static ALPN.Provider	remove(SSLEngine engine) Unregisters the given SSLEngine.
static ALPN.Provider	remove(SSLSocket socket) Unregisters the given SSLSocket.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

debug

public static boolean debug

Flag that enables printing of debug statements to System.err.

Method Detail

put

public static void put(SSLSocket socket,
                       ALPN.Provider provider)

Registers a SSLSocket with a provider.

Parameters:

socket - the socket to register with the provider

provider - the provider to register with the socket

See Also:

remove(SSLSocket)

get

public static ALPN.Provider get(SSLSocket socket)

Parameters:

socket - a socket registered with put(SSLSocket, Provider)

Returns:

the provider registered with the given socket

remove

public static ALPN.Provider remove(SSLSocket socket)

Unregisters the given SSLSocket.

Parameters:

socket - the socket to unregister

Returns:

the provider registered with the socket

See Also:

put(SSLSocket, Provider)

put

public static void put(SSLEngine engine,
                       ALPN.Provider provider)

Registers a SSLEngine with a provider.

Parameters:

engine - the engine to register with the provider

provider - the provider to register with the engine

See Also:

remove(SSLEngine)

get

public static ALPN.Provider get(SSLEngine engine)

Parameters:

engine - an engine registered with put(SSLEngine, Provider)

Returns:

the provider registered with the given engine

remove

public static ALPN.Provider remove(SSLEngine engine)

Unregisters the given SSLEngine.

Parameters:

engine - the engine to unregister

Returns:

the provider registered with the engine

See Also:

put(SSLEngine, Provider)