SFgate is a gateway between the World Wide Web (WWW) and WAIS (Wide Area Information Servers) written in Perl. It is specially suited for usage with freeWAIS-sf, as it supports all its extensions. But all servers speaking the WAIS protocol can be contacted.
SFgate is designed as a CGI script so that it is usable with any WWW server supporting the CGI standard.
You can set up HTML forms as user interfaces to SFgate. This enables you to use the structured fields features of freeWAIS-sf in a simple manner and makes it easy to the user to specify his queries.
SFgate can interface to any number of databases anywhere on the net at the same time. You just have to specify them within the HTML form. To do this you can use every HTML FORM tag.
SFgate can be used to search databases containing WAIS source descriptions ("databases of databases"). The search result is converted to a query form on the fly.
SFgate is self contained. No call to waisq or waissearch is done. The script itself connects the servers. For local databases, it is not even necessary to connect to the WAIS server; databases residing on the same host as the HTTP server can be searched with the local search feature.
+-----+ +-------------------+ +---------+
|HTML | | HTML | | HTML |
|query| | headlines | |requested|
|form | | menu | |documents|
+-----+ +-------------------+ +---------+
| ^ | ^
query | Document request |
| headlines | documents
v | v |
+-----------------------------------------------------+
| SFgate |
+-----------------------------------------------------+
| ^ | ^ | ^ | ^ | ^
| | | | | | | | | |
v | v | v | v | v |
+------+ +------+ +------+ +------+ +------+
| WAIS | |local | |local | ... | WAIS | | WAIS |
|Server| | DB| | DB| |Server| |Server|
+------+ +------+ +------+ +------+ +------+
The most general case is that SFgate functions as a layer between an SFgate application form (WWW) and the WAIS databases queried. SFgate processes a query transmitted from the HTML form via HTTP and directs it to the WAIS server (respective local WAIS databases) which are specified within the form. The WAIS server process the query on their local WAIS databases and give back a ranking of headlines of query matching documents. The different rankings from the different WAIS databases are merged by SFgate and presented via HTTP to the user. Now the user can select documents from the single ranking. This request is piped through SFgate to the according WAIS server which return the selected documents to SFgate. SFgate now presents the documents to the user via HTTP again.
Alternatively the step to present the headlines can be disabled. Instead of presenting the headline overview you can get the documents directly.