Freeway Technical Details (changes)

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Freeway

» Technical Details

Object Name

This is the name of an object.
An object name is unique within the set of objects of the same type within a site. Object names are terminated by a control character (and will return a terminator of zero on output), case independent, alphanumeric strings, created by users or application software. Maximum length is 64 bytes, including the terminator.

Object Descriptor

This provides extra information about the object.
Its format is undefined at this level – it has significance to higher-level application software. Object descriptors are arrays of bytes of any value, maximum length 255.

In Acorn Access+ the descriptor for type Discs indicates whether a disc is shared protected or unprotected, or as a CDROM or subdirectory, and visible or invisible to other desktop users.

The descriptor for type Printers is a ‘Printer Type’ string.

The descriptor for type Hosts is null.

Object Authentication Value

Objects are either authenticated or unauthenticated. Authenticated objects require an authentication value to be provided before their attributes are made visible. An authentication value is a 32-bit integer. The authentication value of zero is reserved and should not be used.

Refresh Interval

The Freeway software in each computer will periodically re-notify other computers about unauthenticated objects which are held by the local machine, so that they know that the objects continue to be accessible. This permits, for example, other machines to know when a computer holding Freeway objects has been powered down. The renotification period is called the “refresh interval”, and is determined by the Freeway software and is typically 30 seconds.

Type Number

This is a 16-bit integer identifying a Freeway type. The following type numbers are allocated to Acorn Access+. (Informal names with no significance in software will also be allocated, for easier human reference)

In Acorn Access, ShareFS is the controlling application for types Discs and Hosts, and !Printers is the controlling application for type Printers.

See also

• OS_UpCall 12