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Rendezvous Tools

Background

In Mac OS X 10.2, Apple introduced an adaptation of an increasingly popular technology, known as "Zero Config". Apple's implementation of this technology is appropriately known as "Rendezvous".
In theory, a zero config (zeroconf) network would require absolutely no network configuration. It should auto-discover other devices on your network and potentially also set themselves up ready for use.

How does it work?

Rendezvous works by using a special kind of DNS responder that broadcasts across a local network no matter how it is set up. Any Rendezvous enabled host can 'broadcast' a service which any other Rendezvous enabled host can see across the network. The resolution of a service happens much like the old AppleTalk system: You choose a service type to browse (like AFP or LaserWriter in the old Chooser) and start the browser. You then see anyone who is broadcasting a service under the same name. When they go offline, they disappear from the list. By performing a 'lookup' on anyone on that list Rendezvous is able to resolve their IP address and the port that their service is running on.
An example of this is the "Connect to Server" facility in Mac OS X. This uses Rendezvous to look for other AFP (File Sharing) hosts.
Anyone can use Rendezvous in their applications for either integration with existing services, or creation of new, purpose-built ones. The Rendezvous tools in Net Tool Box allow you to broadcast a test service, browse any service on your network and lookup the IP, Port and rendezvous message from any host.

How do I use it?

Rendezvous Browser
To browse your network for existing Rendezvous services, you must use a "Rendezvous Browser". You will find this in the "Rendezvous" menu on the toolbar. Before you start, you must choose a service to browse. You can either manually type a service name (which must be in the format of "servicetype.protocol." e.g. "_http._tcp.") or you can choose one from the presets list (the drop down menu next to the "Service Type" field). Once the service details are entered, click "Start". The Rendezvous browser will then start probing your network for type-matched services being broadcast by other machines. When one is found, it will be added to the list, when one goes offline, or is no longer visible by the browser, it will be removed from the list. Double clicking on a service in the list will open a "Lookup" window and should automatically perform a lookup on the service.

Rendezvous Lookup
Once you know a service's name, type and domain properties, you can perform a 'Lookup' on it to give you the real IP address and port number of the originating machine. Some services also broadcast a "Message" value which is used in some applications for an auxiliary purpose.
The easiest way to perform a lookup on a service is to double click on one in a Rendezvous Browser window, as explained above, however if you know the exact credentials of the service, you can manually type them into a "Rendezvous Lookup" window (available in the "Rendezvous" toolbar menu), or choose a preset from the drop-down menu next to the "Service Type" field. Once you have entered the details click "Lookup" and the relevant values should appear. If the lookup doesn't happen within a few seconds, click "Stop" and check the details.

Rendezvous Browser
You may find that at some point you want to broadcast a service manually, possibly because a server application you use does not yet support Rendezvous, or maybe you are testing your 'client' software and do not have the server-side resources to do so. In this case you can use the "Rendezvous Broadcaster" tool to simulate the behavior of a Rendezvous enabled server application.
To start, open a "Broadcaster" window from the "Rendezvous" toolbar menu and enter the desired properties of your service. Again, you can choose a preset from the drop-down menu if you already have it in your presets list. Once your details are all entered correctly, click the "Register" button. This will start broadcasting your service across your network. To stop broadcasting, click "Close". You can test your service with any supporting client software, or alternatively the Net Tool Box "Rendezvous Browser" tool.
A good example would be the "_http._tcp." example which ships already in the presets. By broadcasting this service, you can see it under the "Rendezvous" menu in Safari and other enabled Web Browsers. You can even try it on a different machine on your network.

Note: Rendezvous Presets
Net Tool Box comes with a "Presets" facility for Rendezvous. By default there are a few well-known services for you to try, however you can add your own to the list and modify them whenever you like. To access the Rendezvous Presets, choose "Edit Presets" from the drop-down menu on any of the Rendezvous tools.

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© Charlie Boisseau 2005
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