filenames containing colons: good or bad practice?

Plugins & Plugin Development General Plugin Discussion
1

I’m making some basic design decisions about a new database file structure for a dataMine substitute. I’ve settled on the Graphite/Whisper concept which, amongst other things, uses a hierarchical directory structure. A natural outcome of this is that an ideal database directory tree for Vera would be of the form “machineId/deviceNo/serviceId/variable”.

My question is this: Am I wise to allow an unfiltered serviceId into the directory name, viz: “Vera-12345/42/urn:micasaverde-com:serviceId:EnergyMetering1/Watts” ?

I’ve tried this on Vera itself and my iMac (and it’s fine) but not on a Windows machine. Given that the directory structure could end up residing almost anywhere on the network, am I likely to run into problems? I know this was a limitation of older file systems. I can obviously substitute any other character (say, underscore) for the colon, but I want to be absolutely certain that it’s not one which might turn up as part of a variable name or serviceId.

I’m certainly not expert in any operating/file system, so advice is welcomed and much needed. TIA.

2

I know colons (:slight_smile: are not allowed for file names in windows. So you may have to use some sort of substitution. it may be wise to remove the special characters with a substitute. Maybe replace with an underscore.

  • Garrett
3

A filename cannot contain any of the following characters: \ / : * ? " < > |

4

OK, thanks, well that settles it (partially).

So the question becomes: what character is valid in filenames but not valid in a UPnP variable name or serviceId?

5

Service IDs are URIs (source: UPnP spec). URIs can contain these characters: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-._~:/?#[]@!$&'()*+,;= (source: RFC 3986) and % has special meaning.

Candidate ASCII characters you could use instead of colon: ^ { } `

Or you could invent an escaping system, where : is replaced with (say) = and = is replaced with ==.

There’s a long history of colons in special filenames on Unix. Dig through /proc or /dev and you’ll see bucketloads of them. But certain filesystem protocols (SSH, CIFS spring to mind) treat colon magically, making it hard to use them literally in all cases.

6

Just map illegal characters to “_”.
You will not likely have any collisions.

7

Thanks to all the illustrious names who’ve helped to answer this question… I think this confirms that it was worth asking.
(Or, quite possibly, that you are very kind and I am very stupid.)

If I can get away with a simple [tt]gsub[/tt] to do the transformation, unambiguously, both ways, that would be best.

So I think that @futzle’s impeccable information (as always), along with that of oTi@, leads me to the use of the caret:

x =  "urn:micasaverde-com:serviceId:Volume1"
y = x:gsub (':','^')
z = y:gsub ('%^',':')

giving:

y = "urn^micasaverde-com^serviceId^Volume1"
z = "urn:micasaverde-com:serviceId:Volume1"

I simply couldn’t have lived with the asymmetry that ‘{’ or ‘}’ implied in the resultant filename.

Job done! Thanks again everyone.