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What follows is a step-by-step example using commands but, obviously, graphics would be used in a
consumer interface.

Step One - mount the different name spaces
The ‘namespace’ for each device is first of all mounted under a mount point on the machine that is to run
the application (in our case the PC). The mount point is /n/remote. Each mount specifies the type of
network (TCP in this case), the IP address and the port. The network type can be left out, and in these
examples the port is left off, defaulting to ‘Styx’ of course! At each of the IP addresses and ports specified
there must be a process that serves the Styx protocol.

mount tcp!182.1.1.2 /n/remote/vcr
mount tcp!182.1.1.3 /n/remote/camera

Step Two - bind the namespaces together
These name spaces are then bound into the name space that our application expects to see
/homenetwork.

bind -a /n/remote/vcr /homenetwork/vcr
bind -a /n/remote/camera /homenetwork/camera
bind -a ‘#Uc:/MyPhotos’/homenetwork/MyPhotos

The last bind command binds part of the Windows files system into the /homenetwork namespace. The
convention is that the # introduces a reference to a local device, in this case the U specifies the host OS
file system and the remainder of the text indicates a path within the host file system.

Step Three - run the application from the PC
In fact lets write the application using a shell script.

echo ‘record single frame’ > /homenetwork/vcr/ctl
echo ‘picture type jpg’ > /homenetwork/camera/ctl
while : ; do
echo ‘snap’ > /homenetwork/camera/ctl
photo=‘cat /homenetwork/status’
cp /homenetwork/camera/photos/$photo.jpg /homenetwork/MyPhotos
cp /homenetwork/camera/photos/$photo.jpg /homenetwork/vcr/data
echo ‘next frame’ > /homenetwork/vcr/ctl
echo ‘delete $photo’ > /homenetwork/camera/ctl
sleep 10
done
echo ‘record off’ > /homenetwork/vcr/ctl
echo ‘rewind’ > /homenetwork/vcr/ctl

This script initializes the camera and VCR and then it enters a loop that involves taking a photo, copying it
to the local store and the VCR and then pausing for 10 seconds before repeating the process again.
What you notice from this script is that the application operates on the namespace as if it were a
collection of files. As far as the application is concerned the namespace is indistinguishable from physical files
on the local machine. What you will also notice is that commands are written as text into these files, for
example:

echo ‘snap’ > /homenetwork/camera/ctl

The commands do not have to be text but there are advantages:
•
text is easy to read
•
scripting can be used to implement programs
The camera and VCR need to interpret the commands sent and to interact with the physical hardware,
but this would be true no matter what scheme were used. The advantage of the Inferno architecture is
that the commands to control the device are separated from the protocol for communication.
Extensions to the command set to control the device do not require modifications to the Styx
communication protocol.

Step 4 - run the application from the IPAQ
This is a trivial change for Inferno. In fact the application remains exactly the same whilst the initial
mount and binds are modified as follows:

mount 182.1.1.2 /n/remote/vcr
mount 182.1.1.3 /n/remote/camera
mount 182.1.1.3 /n/remote/ipaq
bind -a /n/remote/vcr /homenetwork/vcr
bind -a /n/remote/camera /homenetwork/camera
bind -a /n/remote/ipaq/MyPhotos /homenetwork/MyPhotos

As long as the application is presented with the same namespace it will operate on it regardless of where
the resources are located.

Step 5 - run on the iPAQ store on PC
Again there are no code changes at all in the application, it does not even have to be recompiled.
The namespace on the iPAQ will be composed as follows with the /MyPhotos directory coming from
the PC this time.

mount 182.1.1.2 /n/remote/vcr
mount 182.1.1.3 /n/remote/camera
mount 182.1.1.4 /n/remote/pc
bind -a /n/remote/vcr /homenetwork/vcr
bind -a /n/remote/camera /homenetwork/camera
bind -a /n/remote/pc/MyPhotos /homenetwork/MyPhotos