Specifying Host-specific configuration files

• Introduction
• Defining host specific parameters
• The HOSTDATA.CFG file
  The several host-specific .CFG files
• The Default Host
• Example

1. Default parameters
2. Host-specific parameters

1. General parameters
2. Selector-specific parametesrs

where ...

1. define a host:
   This is done by modifying SREhttp/2's HOSTDATA.CFG file (in the SRE2003\SREHTTP2\CFG directory).
2. creating host-specific configuration files (which are referenced in the HOSTDATA.CFG file).

Notes:

HOSTDATA.CFG is used instead of SRE2003's HOSTINFO.CFG file. To add or view these host definitions, you can use the SREhttp/2 on-line configurator -- look for the Host Configurator link. Hosts that are not defined in HOSTINFO.CFG are automatically assigned the DEFAULT host-nickname. Actually, only the canonical host and all hosts mentioned in the SRE2003's DEFAULT_HOSTS parameter, are assigned the DEFAULT host-nickname. Note that DEFAULT_HOSTS is specified in SRE2003.CFG.

Step 1 is described in the next section. Basically, HOSTDATA.CFG is used to tell SREhttp/2 where to find host-specific configuration files, and when to use default parameters.

Step 2 is described in ATTRIBS.HTM. Basically, host-specific versions of ATTRIBS.CFG (and a few other files) can be used to specify general and selector-specific parameters. These parameters control authentication requirements, redirection, file location, and a variety of other features.

HOSTDATA.CFG is a text file that contains multi-line records, with each line having a mime-like structure.
The basic structure of HOSTDATA.CFG is:

   NICK: host_nickname
   HOST: domain_name or Ip_address (one or several)
   DATADIR: default_data_directory (for web accessible files)
   CFG: host_dir
   SUPERCEDING:   a_value
         
   NICK: host_nickname_2
   HOST: domain_name ...
        ....

NICK:	Required. A case insensitive host-nickname (which can not contain embedded spaces). host_nicknames are used throughout SREhttp/2 (and SRE2003) to define host specific parameters.
HOST:	Required. Either one, or several, domain name(s) (such as foo.bar.net) or IP address(es) (such as 192.155.3.2). If specifying several, seperate each domain name (or IP address) with one or more spaces. In general, SREhttp/2 will use the Host: header (sent by all modern browsers) to specify which host the client's request is directed to. The value of this Host: header will be compared to the various HOST: entries in HOSTDATA.CFG. If you define several domain names (or IP addresses) with a HOST:, then you are basically declaring that these different domain names (or IP addresses) are merely synonyms for a single site -- the site that is specified by the host nickname.
DATADIR:	Required. The default data directory for this host. Unless otherwise specified (say, through a selector-specific attribute). all requests to this host are assumed to refer to files that are relative to this host specfic data directory.
CFG:	Optional. host_dir should be a relative, or an absolute, directory. If a relative directory, it should be relative to the SREHTTP2\CFG directory. If not specified, then there will be no host-specific parameters (for this host_nickname). If specified, then this host_dir directory can contain the following files: SREHTTP2.CFG -- host-specific "general" parameters ATTRIBS.CFG -- host-specific "selector-specific" parameters SSI_VARS.CFG -- host-specific Server Side Include variables MIMETYPE.CFG -- host specific "extension to mimetype" mappings USERS.CFG -- host specific "username/password" entries All these files are optional -- if a file is not defined, then there will be no host-specific values for the types of parameters defined in the file. Note: the "defaults" for these five files are in the SREHTTP2\CFG directory.
SUPERCEDING:	Optional. a_value should be either: 0 = Not superceding (the default, if SUPERCEDING is not specified) 1 = Superceding 2 = Strictly superceding Superceding is used to control when the values of the default ATTRIBS parameters are used. For each value, the order of precedence are (with higher rules used whenever possible). Not superceding Exactly matching host-specfic parameter Exactly matching default parameters "Wildcarded" host-specific and wildcarded default parameters are pooled, and the "best" match is used. Superceding Exactly matching host-specfic parameter Wildcarded host-specific parameters Exactly matching default parameters "Wildcarded" default parameters Strictly superceding Exactly matching host-specfic parameter Wildcarded host-specific parameters Thus, requests to "strictly superceding" hosts never use default ATTRIBS parameters, while requests to "superceding" hosts use default ATTRIBS parameters only if there is no host-specific parameters. Non-superceding hosts favor host-specific parameters, but only if the match is exact. Reminder: default ATTRIBS parameters are defined in the ATTRIBS.CFG file typically located in SREHTTP2\CFG

   Host: Default

• The servername for the default host is defined using TCP/IP calls, or by the SERVERNAME_USE SRE2003 parameter.
• The default data directory for the default host is defined by the SRE2003 DATADIR parameter.
• The Default host always has a host-nickname of Default
• The Default host does not use a SUPERCEDING entry (that is, SUPERCEDING is ignored)

• If you do not specify a CFG entry, then use the five default .CFG files (SREHTTP2, USER, SSI_VARS, MIMTTYPE, and ATTRIBS), which are located in the SREHTTP2\CFG directory.

  However, just as with host-specific records, you can use CFG to point to a directory that contains the default CFG files.

• If you do not specify a Default host, than there will be no default parameter values. This implies that all hosts will be strictly superceding!

   Host: Default

   Nick: MAIN
   Host: 82.55.25.12  Mine.Oursite.net   
   CFG:  MY_CFGS
   Datadir: f:\www\d1

   Nick: HISHER_SITE
   Host: His.Oursite.net
   Datadir: f:\www\d2
   CFG:  E:\DATA\HFGS
   Superceding: 1

   Nick: HISHER_SITE
   Host: Her.Oursite.net
   Datadir: f:\www\d2
   CFG:  E:\DATA\HFGS
   Superceding: 1