Defining Web rules

Other web servers usually have a configuration file which defines the rules by which the server will run. The Janus Web Server uses Janus subcommands. These subcommands are typically executed in Model 204's CCAIN stream or from a procedure. Because the rules become complex, and because Janus allows the rules to be changed while the server is running, it is useful to keep the commands for defining a particular port in a Model 204 procedure.

For information about the actions taken for the various subcommands of the JANUS DEFINE and JANUS WEB commands, see "Command execution order".

Any number of web clients may simultaneously access a Model 204 online that has Janus Web Server, limited only by the number of Janus Web Server threads the site is licensed for.

Each web server is associated with a specific port number. By convention, web servers usually run at port 80, and test ports typically use ports 8000, 8001, and 8080. However, you may use any port number available on the Janus TCP/IP Base, from 1 to 65535. If you want to have multiple port numbers available for web clients, issue JANUS DEFINE commands for WEB servers at those port numbers.

Here is a typical set of rules for defining a Janus Web Server port, associating Web rules with it, and starting it:

* First make sure the port definition isn't * already there. * JANUS FORCE WEBBY JANUS DELETE WEBBY * * Then define WEBBY at port 80, allowing 300 * connections, opening a file and executing a * UTABLE command. * JANUS DEFINE WEBBY 80 WEBSERV 300 WEBUSER - WWWUSER OPEN GROUP WEBDOCS - CMD 'UTABLE LSTBL 12000' * * Then define a group of IP addresses that will * be granted access to the port (deleting previous * definitions first). * JANUS DELETEIPGROUP PRIVILEGED JANUS DEFINEIPGROUP PRIVILEGED - 198.242.244.0-3 169.231.0.0-24 184.194.222.7 * * Then define a group of user IDs that will be * granted access to the port (deleting previous * definitions first). * JANUS DELETEUSGROUP CLOWNS JANUS DEFINEUSGGROUP CLOWNS MILKY* BOZO* * * Specify any redirection — here we transfer * any requests for Java applications to another * web server. * JANUS WEB WEBBY NOREDIRECT JANUS WEB WEBBY REDIRECT *.jav - http://sirius-software.com:8080/java/*.jav * * Revoke all access globally to clear old rules, * then re-grant access based on the above-defined * groups. * JANUS WEB WEBBY DISALLOW * JANUS WEB WEBBY ALLOW IPGROUP PRIVILEGED JANUS WEB WEBBY ALLOW USGROUP CLOWNS JANUS WEB WEBBY DISALLOW IPADDR 198.242.244.41 * * Specify content type with the TYPE subcommand. * JANUS WEB WEBBY TYPE *.PDF application/pdf * * Use "ON" commands to specify actions that are * taken when incoming requests contain the * specified string. * JANUS WEB WEBBY ON /*.HTML SEND HTML_* JANUS WEB WEBBY ON /*.GIF SEND GIF_* JANUS WEB WEBBY ON /COMMAND/* CMD * JANUS START WEBBY

Each execution of a JANUS WEB subcommand adds to the set of rules for the specified Web Server port. Individual rules cannot be deleted nor modified; all rules can be deleted only by stopping and deleting the port definition. However, this should not be necessary, as long as you follow two guidelines:

1. Specify the most general rules first and most specific last.
2. Specify a first rule that will clear all related rules.

That is why the above examples specify a global rule first that revokes all previous definitions before new privileges or directives are defined. For example, look at the ALLOW directives: The first rule eliminates all previous permissions with a DISALLOW * before any ALLOWs are specified.

The DEFINE command near the top of the sample rules specifies a World Wide Web server to be created at port 80 and to be called WEBBY. It allows up to 300 simultaneous connections, and connections requesting URLs that don't require logons will appear in Model 204 as being associated with the userid WWWUSER (in the journal, in LOGWHO commands, etc.).

A group named WEBDOCS is opened. The CMD sets LSTBL to 12000 for WWW users. URL processing is handled by rules specified on JANUS WEB subcommands — this is the default processing when CMD doesn't re-route processing to either an APSY or a User Language procedure.

The JANUS WEB subcommand defines how the web server will act. Most of the other commands are common to any Janus port. See JANUS WEB for the full JANUS WEB command syntax.

Command execution order

JANUS WEB rules are executed in a strict order which guarantees consistent access control and processing for URLs.

That order is:

1. OPEN and CMD processing from the JANUS DEFINE subcommand.

   These commands are always the first to execute on any port. For Web Servers, the OPEN command might open the file containing HTML procedures, and the CMD command can be used to reset UTABLE settings.

2. REDIRECT/NOREDIRECT

   Any requests that are being handled outside the Web Server are immediately routed out.

3. ALLOW/NOALLOW

   Access security rules are applied. Anytime a USER or USGROUP is specified, Model204 logon processing is invoked.

4. JANUS WEB TYPE definitions

   Datatype (mime) specifications are applied to URLs.

5. OPEN and CMD processing from the JANUS DEFINE command

   The OPEN and CMD commands on the DEFINE statement can initiate a generic web driver procedure to be used to collect usage activity for the port — perhaps based on URL, userid, or IP address.

6. JANUS WEB ON directives

   The OPEN parameter in an ON rule opens a file or group specific to the URL, and the CMD, SEND, or RECEIVE parameter indicates the action to be taken for matching URLs.

Within the above order, the JANUS WEB rules are searched in reverse order for the first match; that is, the last matching rule specified takes precedence over all previous rules.