Programming WCF Services, 3rd Edition

Addresses

In WCF, every service is associated with a unique address. The address provides two important elements: the location of the service and the transport protocol, or transport scheme, used to communicate with the service. The location portion of the address indicates the name of the target machine, site, or network; a communication port, pipe, or queue; and an optional specific path, or URI (Universal Resource Identifier). A URI can be any unique string, such as the service name or a globally unique identifier (GUID).

WCF supports the following transport schemes:

• HTTP/HTTPS

• TCP

• IPC

• Peer network

• MSMQ

• Service bus

Addresses always have the following format:

[base address]/[optional URI]

The base address is always in this format:

[transport]://[machine or domain][:optional port]

Here are a few sample addresses:

http://localhost:8001
http://localhost:8001/MyService
net.tcp://localhost:8002/MyService
net.pipe://localhost/MyPipe
net.msmq://localhost/private/MyQueue
net.msmq://localhost/MyQueue

The way to read an address such as:

http://localhost:8001

is like this: “Using HTTP, go to the machine called localhost, where on port 8001 someone is waiting for my calls.”

If there is also a URI, as in:

 http://localhost:8001/MyService

the address will read as follows: “Using HTTP, go to the machine called localhost, where on port 8001 someone called MyService is waiting for my calls.”

TCP Addresses

TCP addresses use net.tcp for transport and typically include a port number, as in:

net.tcp://localhost:8002/MyService

When a port number is not specified, the TCP address defaults to port 808:

net.tcp://localhost/MyService

It is possible for two TCP addresses (from the same host, as discussed later in this chapter) to share a port:

net.tcp://localhost:8002/MyService
net.tcp://localhost:8002/MyOtherService

TCP-based addresses are used throughout this book.

Note

You can configure TCP-based addresses from different service hosts to share a port.

HTTP Addresses

HTTP addresses use http for transport and can also use https for secure transport. You typically use HTTP addresses with outward-facing Internet-based services, and you can specify a port as shown here:

http://localhost:8001

If you do not specify the port number, it defaults to 80 (and port 443 for HTTPS). As with TCP addresses, two HTTP addresses from the same host can share a port, even on the same machine.

HTTP-based addresses are also used throughout this book.

IPC Addresses

IPC (Inter-Process Communication) addresses use net.pipe for transport, to indicate the use of the Windows named pipe mechanism. In WCF, services that use IPC can only accept calls from the same machine. Consequently, you must specify either the explicit local machine name or localhost for the machine name, followed by a unique string for the pipe name:

net.pipe://localhost/MyPipe

You can open a named pipe only once per machine, so it is not possible for two named pipe addresses to share a pipe name on the same machine.

IPC-based addresses are used throughout this book.

Note

The IPC address format as provided by Microsoft is incorrect, indicating the mechanism instead of the protocol. The correct scheme format should have been net.ipc instead of net.pipe, much like the TCP address uses net.tcp rather than net.socket.

MSMQ Addresses

MSMQ addresses use net.msmq for transport, to indicate the use of the Microsoft Message Queue (MSMQ). You must specify the queue name. When you’re dealing with private queues, you must also specify the queue type, but you can omit that for public queues:

net.msmq://localhost/private/MyService
net.msmq://localhost/MyService

Chapter 9 is dedicated to making queued calls.

Service Bus Addresses

Windows Azure AppFabric Service Bus addresses use sb, http, or https for transport, and must include the service bus address along with the service namespace, for example:

sb://MyNamespace.servicebus.windows.net/

Chapter 11 covers the service bus in depth.