Will messages between WCF Services hop over a WiFi Network/WLAN?

Question

In my office building we have laptops on multiple floors all running a WCF Service. When WCF services communicate with each other, will a message for an out-of-range device automatically reach it by multi-hopping? Does WCF/the WLAN device driver handle this? Or do I have to detect if a device is not contactable/out-of-range and implement hopping in my own service?

Answer 1

As long as you have a connection from your WCF client to the service - yes, all avenues will be used. You shouldn't have to concern yourself with things like what network path your messages take - the network just has to be present and stable for the duration of a call ;-)

There's nothing in WCF to deal with this, really - this should be handled way lower in the network stack, by the driver or the OS.

Answer 2

it has nothing to do with WCF....

if there is a connection between the computers, on the IP, then the message will get through...

Answer 3

Short answer

With WCF can do either or both of these:

• Rely on an underlying protocol like IP to handle roaming
• Use custom channel code that handles retries, roaming, etc the way you want it

No special mechanism for enhancing roaming is provided in the WCF classes Microsoft provides, but the framework itself is easily capable of supporting this seamlessly if you write or find a channel implementation to do this.

Full answer

WCF is not an on-the-wire protocol. It is a framework that allows you to communicate using a wide variety of protocols and network stacks. This allows you to use the same client and server code whether you are using HTTPS, raw TCP, named pipes, or any other protocol.

WCF ships with many channels in the box, and you can add your own. For example if you want to communicate over BlueTooth or IRDA, just create a new channel that talks these protocols and you can use your WCF services over it. These channels can also be found online or purchased from vendors.

Most networking today is done using the IP protocol, and if you are using WCF to communicate between desktop machines you will probably be using some protocol(s) on top of IP, for example TCP or HTTP. In this case, IP's normal routing rules will be used, so if the two machines can exchane IP packets you can communicate using WCF.

So if your WiFi access points allow seamless roaming you will be able to tap into that functionality using WCF.

If your WiFi routing doesn't have seamless roaming, you will have to do some extra work if you want to maintain a connection during roaming. Specifically you will need to create a channel that will respond to a closed connetion by re-resolving the server nane and retrying the request. Of course you will have to use DNS or another protocol so the server can update its registration as its IP address changes.

WCF is flexible enough to allow you to create such a channel and use it without your application code ever realizing it. But nothing like this comes in the box: You would have to build it, or download or purchase it.