ArcWeb & the Internet
ArcWeb handles the fetching via a
variety of different methods. Since ArcWeb uses only the socket level
interface provided by Acorn TCP/IP, it will also run over anything else
which provides an identical SWI interface (chunk &41200).
ArcWeb supports
- HTTP (HyperText Transfer Protocol)
- FTP (File Transfer Protocol)
- SMTP (Simple Mail Transfer Protocol
- NNTP (Network News Transfer Protocol)
- Finger
- Telnet
- Gopher
- WAIS
although WAIS
is achieved through the use of proxy
services such as those available at wwwcache.hensa.ac.uk. ArcWeb talks
HTTP to proxy servers which perform the interaction with the remote site and
send back the result via the HTTP protocol. Non-documents (eg. WAIS
menus) are returned as HTML documents generated by the proxy server. Proxy
servers are useful things to run on firewall machines as it allows people
inside the firewall to access the Web services.
Other facilities supported by ArcWeb include
- Transparent handling of Location indicating that a document has
moved. The redirection is detected whilst the original response is being
read and the query replaced by a request for the new URL. Note that if a
failure occurs whilst fetching the replacement URL, any errors reported will
be reported as having come from the original document requested and not the
resultant of the search. There is no limit to the number of
Location directives that may be chained together, ArcWeb will
continue following the trail until the answer is found
Testing your Configuration
You can test the configuration of the nameservers by using the dialogue
boxes accessed via the
menu. You can look up hosts by name or by IP address. Enter the query
in the writable icon and choose the lookup type in the radio icons, and
then press RETURN or click on the Run Query button. The answers will
be looked up and entered into the display icon below, with a menu to
see all the answers.