Readme for analog -- search arguments

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# Analog 4.16: Search arguments

Sometimes a URL contains arguments after a question mark. For example, the URL

    /cgi-bin/script.pl?x=1&y=2

runs the `/cgi-bin/script.pl` program with arguments `x=1` and `y=2`. (Sometimes the server records these arguments in a separate field in the logfile, but if so you can use the `%q` field in the `LOGFORMAT` command, and analog will translate the filename to the above format).

You can tell analog either to read or to ignore the arguments using the commands `ARGSINCLUDE` and `ARGSEXCLUDE` which we'll discuss in a minute. But by default, all arguments are read, and as this is usually what you want, you don't usually need those commands.

You don't always see the arguments in the reports, even if they're being read, because analog doesn't show them if there aren't enough of them. In order to see them, you have to set the corresponding `ARGSFLOOR` parameter low enough.

Also note that within a report, the search arguments are listed immediately under the file to which they refer. This temporarily interrupts the normal order of the files. It may be clearer if you turn the `N` column on.

Assuming that the arguments are being read, analog treats the file `/cgi-bin/script.pl?x=1&y=2` as a different file from `/cgi-bin/script.pl` (or from `/cgi-bin/script.pl?y=2&x=1` for that matter). It doesn't look like that in the Request Report because you see a grand total for `/cgi-bin/script.pl` with all its different arguments. But it matters if you want to do inclusions and exclusions or aliases on the file.

The reason is that, for example, the command

    FILEINCLUDE /cgi-bin/script.pl

doesn't match the file `/cgi-bin/script.pl?x=1&y=2`. To match that, you would have to use something like

    FILEINCLUDE /cgi-bin/script.pl*

instead. Similarly

    FILEALIAS /cgi-bin/script.pl /script.pl

will change `/cgi-bin/script.pl` itself, but not `/cgi-bin/script.pl?x=1&y=2`. You might want to use something like

    FILEALIAS /cgi-bin/script.pl?* /script.pl?$1

as well. (However, `PAGEINCLUDE` and `PAGEEXCLUDE` always refer to the part of the filename before the question mark.)

Conversely, because in the Request Report files with arguments are only included if their parent file is included, you can't just

    REQINCLUDE /cgi-bin/script.pl?*x=1*

or you will end up with nothing listed. You have to

    REQINCLUDE /cgi-bin/script.pl

as well.

The alternative is to tell analog not to read the search arguments. There are commands called `ARGSINCLUDE` and `ARGSEXCLUDE`, and `REFARGSINCLUDE` and `REFARGSEXCLUDE`, to do this. They work the same as the other `INCLUDE` and `EXCLUDE` commands which we discussed in the previous section. So, for example, if the command

    ARGSEXCLUDE /cgi-bin/script.pl

were given, analog would ignore the arguments to that file, and so read `/cgi-bin/script.pl?x=1&y=2` as just `/cgi-bin/script.pl`. On the other hand, if

    ARGSINCLUDE /cgi-bin/script.pl

were specified, analog would read the arguments, and so treat `/cgi-bin/script.pl?x=1&y=2` as a different file from `/cgi-bin/script.pl`. `REFARGSINCLUDE` and `REFARGSEXCLUDE` are the same for referrers.

Technical note: the check for whether the arguments should be included happens before the filename has been subject to either built-in or user-specified aliases. So you have to use the unaliased name, exactly as it occurs in the logfile. For example, `ARGSINCLUDE /~sret1/script.pl` won't match `/%7Esret1/script.pl` even though they are really the same file. It also means that you can't use "`pages`" in the `ARGSINCLUDE` or `ARGSEXCLUDE` command, because we don't know whether a file is a page until after it's been aliased.

There is a related command called `SEARCHENGINE`. If you have referrers with search arguments, usually from search engines, you can tell analog which field corresponds to the search term. It uses this information to compile the Search Query Report and the Search Word Report. For example, consider the referrer

    http://www.altavista.com/cgi-bin/query?pg=q&kl=XX&q=carrot+cake

The search term is in the field `q=` so the appropriate `SEARCHENGINE` command is

    SEARCHENGINE http://www.altavista.com/cgi-bin/query q

or even better

    SEARCHENGINE http://*altavista.*/* q

to allow for all their mirror sites in different countries.

Sometimes a search engine has two or more possible fields for the search term. In that case you can list all of them separated by commas, like this:

    SEARCHENGINE http://*webcrawler.*/* search,searchText

The rest of this section is a bit technical, and you usually don't need to worry about it. On a first reading, you might like to skip it.

I said previously that `%7E` in a URL is automatically converted to `~`, etc. In fact this is only done to the ASCII-printable characters `%20-%7E`, because these are the only characters that are the same in every character set. (In fact, even that isn't true. Experts might want to know that `?`, `&` and `=` aren't converted either, to distinguish them from query-string delimiters: an encoded `?`, `&` or `=` is one that is not intended to be a delimiter. Also `%` isn't converted, to avoid confusing `%25nm` with `%nm`.)

But in the Search Query Report and Search Word Report it is useful to be able to convert non-ASCII characters too, so that you can see the actual words people typed, rather than get the `%nm` codes in place of all accented letters. So in these reports analog also converts characters `%A0-%FF` (if you are using an ISO-8859-* character set) or `%80-%FF` (for other character sets, apart from ASCII).

However, there are reasons why you might not want this feature, and you can turn it off with the command

    SEARCHCHARCONVERT OFF

These reasons include:

1. The character set in which the query was submitted to the search engine may not be the same as that in which the page reached was written, or that in which the analog output page is being written. So converting to the character set of the analog output page may give garbage anyway. This is particularly a problem with languages, such as Russian or Chinese, which have two or more characters sets in common use. It is also a problem for sites which host resources in many languages.
2. Not all of the character positions correspond to printable characters in every character set. Analog knows that `%80-%9F` are non-printable in the ISO-8859-* character sets, but apart from that it converts everything in `%80-%FF`. So you may end up with non-printable characters in your output.
3. I have no idea how well, if at all, this feature will work with multibyte character sets (such as most East Asian languages). You will probably find you want to turn it off in this case.

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