Apache Module mod_mvsds

Example configuration

• Allow dataset access under /mvsds

  LoadModule mvsds_module modules/mod_mvsds.so
  <Location /mvsds>
    MVSDS ON
    MvsdsDefaultTextType text/plain
  </Location>

• Map an arbitrary request URL to a dataset. Only the first two parameters vary.

  RewriteEngine ON
  RewriteRule ^/example.html /mvsds/'EXAMPLE.DSN' [PT,E=mvsds-handler:true]

Common Problems

Requesting MVSDS datasets with a .Z extension returns garbage in the response

A MVSDS dataset with a .Z extension will return garbage starting in IBM HTTP Server 9.0 and above. The issue is that mod_charset_lite will no longer translate responses with a Content-Encoding set unless it has a value of 7bit, 8bit, binary, or identity.

The Content-Encoding header is set for files containing a .Z in the filename because the default configuration includes the directive AddEncoding x-compress Z.

To remove the content encoding for MVSDS datasets, RemoveEncoding can be added to the MVSDS location stanza:

<Location /mvsds>
  MVSDS ON
  MvsdsDefaultTextType text/plain
  RemoveEncoding Z
</Location>

Content Type

If the MVS dataset being served is a member in a partitioned data set, and it has a valid file extension, the content-type related directives in mod_mime will be applied to it. Otherwise, the content type can be specified with ForceType or MvsdsDefaultTextType inside of LocationMatch. The MvsdsDefaultTextType will be applied to any dataset that a content type has not been determined by the name and has been determined to be a text file. ForceType can be used to set the content type, but this will override any file extension mapping or other directives.

Example: Setting Content-Type via MIME Type Mapping

A MIME type mapping can be specified for datasets that end with a certain extension using AddType. For example, the dataset 'MYDATASET.EXAMPLE.MYEXT' can have a Content-Type of 'text/plain' set using the configuration

<Location /mvsds>
    MVSDS ON
    AddType text/plain .MYEXT
</Location>

Note that content type mappings are searched from right to left, and the first mapping that is matched is applied. The dataset 'MYDATASET.INEXT.MYEXT' with the configuration below will result in the Content-Type being set to 'text/html' for example. Note: After PH09519, the directive MimeOptions can be used to ignore the "inner" extensions.

<Location /mvsds>
    MVSDS ON
    AddType text/xml  .MYEXT
    AddType text/html .INEXT
</Location>

Example: Forcing a Content-Type

A Content-Type can be forced for a particular location by using the ForceType directive. The following configuraiton will force the dataset 'MYDATASET.EXAMPLE.MYEXT' have a Content-Type of 'text/plain'.

<LocationMatch /mvsds/'MYDATASET.EXAMPLE.MYEXT'>
    MVSDS ON
    ForceType text/plain
</LocationMatch>

Binary vs Text

When a Content-Type has been determined by any of the means in the preceding section, and it does not match text/* nor application/x-javascript, this module reads the underlying dataset in binary mode. Files read in binary mode are not translated by the operating system while being read. See the z/OS documentation for the open() system call for more details.

Otherwise, files are read in text mode and may undergo some transformation by the operating system. For example, newline characters may be added each time a record boundary is encountered.

When no Content-Type is determined, this module uses a heuristic to detect if a file should be opened as binary. The directive MvsdsNoBinarySniff can be used to force such a file to be treated as text.

The internal environment variable mvsds-force-fread-text can be set to force files to be read in text mode, regardless of Content-Type or MvsdsNoBinarySniff outcome.

Interaction with other modules

After PI80187 directives that map requests to the filesystem, such as Alias, will prevent this module from running when they overlap with "MVSDS ON". Prior to PI80187, the interaction was undefined/non-dterministic.