Serving Web Pages

The Connection Manager can be used to serve your own web pages, in a similar manner to the Remote Administration pages. This is done by defining an <alias> in kconf.xml. The list of aliases can be viewed and edited by selecting the Display/Update web aliases link on the KCML System Configuration page.

An alias maps the URL that a browser will use to request the web page to a file or directory on the host's filesystem. An alias has the follow properties:

Let's take an example of an alias called TestAlias. The Connection Manager will then use this alias when processing requests for a URL of the form http://hostname:790/TestAlias.

Alias Types

The behaviour of the web server, when processing a requested URL, depends on the Type of the alias.

• Directory : The Real Name property points to a directory, for example /user1/myapp/docs. Characters after the Alias Name, in the requested URL, are treated as components of a pathname. So the URL http://hostname:790/TestAlias/index.htm would map to a file with the pathname /user1/myapp/docs/index.htm. Sub-directories are also allowed, for example the URL http://hostname:790/TestAlias/misc/appendix.htm would map to a file with the pathname /user1/myapp/docs/misc/appendix.htm. For regular files, like the previous examples, the contents of the file will be downloaded to the browser. If the URL is a request for a directory, then the contents of the directory will be listed. The filenames in this table, will be links to files or subdirectories. The headings of the table are links which can be used to sort the listing by modification date and size.
• UrlAlias : This is very similar to the Directory type. The difference is that the URL must point to a regular file. Requests for directory listings are not allowed.
• FileHTML : This type is used to display a specific file. Characters after the Alias Name are not allowed. For example, if the Real Name has the value /user1/myapp/readme.htm, then the page can be downloaded using the URL http://hostname:790/TestAlias.
• CGIScript : The Connection Manager also supports the generation of web pages from a CGI script. The CGIScript type is used to map a URL to such a script. The Real Name must point to a regular file, which can be a command script (such a Unix shell script, or a DOS batch file) or a KCML program. If the Real Name value does not contain a dot extension, eg .bat, .sh or .src, then the Connection Manager will attempt to look for files in the following order:-

  Extension	Description	Supported platform
  	No extension, try to open the specified file first	All
  .cmd	DOS command script	Windows only
  .bat	DOS batch file	Windows only
  .ksh	Unix Korn Shell script	All
  .sh	Unix Shell script	All
  .src	KCML source code program	All

  If the Real Name is the pathname to a KCML program, then the program is executed as a KCML script. The CGI script will inherit environment variables from the General section of kconf.xml, plus a set of CGI environment variables.

  Variable	Typical Value or example	Purpose
  SERVER_NAME	Hostname or IP address	Derived the hostname in a HTTP URL.
  SERVER_PORT	integer, typically 790	Network port number that the Connection Manager is listening on.
  SERVER_SOFTWARE	kwebserv/06.90.00.nnnn	Program identifier and version
  PATH_INFO	myalias/cgi.ksh	HTTP URI, without query string
  PATH_TRANSLATED	/user1/app/htdocs/info/cgi.ksh	URI which has been translated to a file or directory on the host's filesystem
  QUERY_STRING		HTTP query string, ie the part of a URL after a ? character

  These environment variables can then be used by a CGI script to construct URLs for subsequent web pages.

• CGIDirectory : This alias type allows any command script or KCML program in the directory specified by the Real Name value to be executed as a CGI script. The execution of the script follows the same rules as the CGIScript alias.
• UserDirectory : The Real Name value specifies a directory containing subdirectories for user accounts on the host system. For example, a Real Name value of /user1/myapp/reports would allow a user kcc to access files in /user1/myapp/reports/kcc at the URL http://hostname:790/aliasname/kcc. Access to files within this directory always require authentication and are restricted to the owner of the account.

Per-Service aliases

The Connection Manager also allows a service to define its own aliases. When requesting pages that are defined in a per-service alias, the service name is used in the URL. For Example:

http://hostname:790/serviceName/TestAlias

The Connection Manager will expand any environment variables that are used in the Real Name value. Scripts that are executed using a CGIScript and CGIDirectory alias type will also inherit the service's environment variables.

Include files

It may be more convenient to define a list of aliases outside of kconf.xml. This can be achvied, in KCML 6.20 onwards, by storing the aliases in an included XML file. This include file is then referenced by adding an alias, in kconf.xml, with a Alias Name of 'include' and a Real Name which is the location of the the XML file.

Caching

From KCML 6.20 onwards, the Connection Manager supports HTTP Caching. When a web page is downloaded to a browser, the datestamp of the file is also sent. The web browser now 'knows' how old the file is. If the browser then requests the web page again, it sends this datestamp to the Connection Manager. The Connection Manager then compares this datestamp to the modification time of the file on host's filesystem. If the file has not changed, a tiny HTTP packet is sent back to the browser. This instructs the browser that its cached copy is up to date. If the file has been modified since, then the Connection Manager will resend the new page to the browser. The use of caching can greatly reduce the amount of network traffic for frequently requested web pages.

File Types

When a file is downloaded to a browser, the browser is told what type of data it is receiving. The browser can then decide how to process the data. This file type information called the MIME type and is deduced from the dot extension of the file's pathname. If the file has no dot extension, the contents of the file are scanned. However, this can be inefficient on large files. The list of MIME types and filename extensions that the Connection Manager recognized are as follows