SECTION 10.9
957
Web Capture
The
E
(expiration) entry specifies an expiration date for each source location
associated with a content set. If the current date and time are later than those
specified, the contents of the content set should be considered out of date with
the original source.
URL Alias Dictionaries
When a URL is accessed via HTTP, a response header may be returned indicating
that the requested data is at a different URL. This
redirection
process may be re-
peated in turn at the new URL and can potentially continue indefinitely. It is not
uncommon to find multiple URLs that all lead eventually to the same destination
through one or more redirections. A
URL alias dictionary
represents such a set of
URL chains leading to a common destination. Table 10.42 shows the contents of
this type of dictionary.
TABLE 10.42 Entries in a URL alias dictionary
KEY
TYPE
VALUE
U
ASCII
string
array
(Required)
The destination URL to which all of the chains specified by the
C
entry lead.
(Optional)
An array of one or more arrays of strings, each representing a chain of URLs
leading to the common destination specified by
U
.
C
The
C
(chains) entry should be omitted if the URL alias dictionary contains only
one URL. If
C
is present, its value is an array of arrays, each representing a chain
of URLs leading to the common destination. Within each chain, the URLs are
stored as ASCII strings in the order in which they occur in the redirection se-
quence. The common destination (the last URL in a chain) may be omitted, since
it is already identified by the
U
entry. (See implementation note 166 in Appendix
Command Dictionaries
A Web Capture
command dictionary
represents a command executed by Web
Capture to retrieve one or more pieces of source data that were used to create new
pages or modify existing pages. The entries in this dictionary represent
parameters that were originally specified interactively by the user who requested
that the Web content be captured. This information is recorded so that the com-