C# 4 and .NET 4

Building P2P applications ❘ 1347
system.net.PeerToPeer
The classes in the System.Net.PeerToPeer namespace encapsulate the API for PNRP and enable you to
interact with the PNRP service. You will use these classes for two main tasks:
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Registering peer names
Resolving peer names
In the following sections, all the types referred to come from the System.Net.PeerToPeer namespace
unless otherwise specified.
registering Peer names
To register a peer name you must carry out the following steps:
1. Create a secured or unsecured peer name with a specified classifier.
2. Configure a registration for the peer name, providing as much of the following optional information
as you choose:
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A TCP port number
The cloud or clouds with which to register the peer name (if unspecified, PNRP will register
the peer name in all available clouds)
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Up to 4,096 bytes of additional data
Whether to generate endpoints for the peer name automatically (the default behavior, where
endpoints will be generated from the IP address or addresses of the peer and, if specified, the
port number)
A collection of endpoints
3. Use the peer name registration to register the peer name with the local PNRP service.
After Step 3 the peer name will be available to all peers in the selected cloud (or clouds). Peer registration
continues until it is explicitly stopped, or until the process that registered the peer name is terminated.
To create a peer name you use the PeerName class. You create an instance of this class from a string representation
of a P2P ID in the form authority.classifier or from a classifier string and a PeerNameType.
You can use PeerNameType.Secured or PeerNameType.Unsecured. For example:
PeerName pn = new PeerName("Peer classifier", PeerNameType.Secured);
Because an unsecured peer name uses an authority value of 0, the following lines of code are equivalent:
PeerName pn = new PeerName("Peer classifier", PeerNameType.Unsecured);
PeerName pn = new PeerName("0.Peer classifier");
After you have a PeerName instance you can use it along with a port number to initialize a
PeerNameRegistration object:
PeerNameRegistration pnr = new PeerNameRegistration(pn, 8080);
Alternatively, you can set the PeerName and (optionally) the Port properties on a PeerNameRegistration
object created using its default parameter. You can also specify a Cloud instance as a third parameter of
the PeerNameRegistration constructor, or through the Cloud property. You can obtain a Cloud instance
from the cloud name or by using one of the following static members of Cloud:
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Cloud.Global — This static property obtains a reference to the global cloud. This may be a private
global cloud depending on peer policy configuration.
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