Using the Client Cache Directory

When the thin client needs to use a bitmap (.bmp), wave (.wav), or ActiveX resource file, it downloads the file from the server to a local cache directory. This directory is the one identified by the value in the TEMP environment variable. If no directory is designated in the TEMP variable, the file is downloaded to the client's current working directory.

The client downloads a particular bitmap, wave, or resource file on subsequent requests only if the file on the server is a different size or has a later timestamp than the corresponding file in the client cache directory, or if the file in the cache is deleted for any reason.

The thin client assigns a unique name to each file that it downloads to the cache. This name includes characters from the server name, port number, alias name, COBOL program archive or library name, server path, and server file name. For example, two bitmap files with the same name might be uniquely identified in the cache directory as shown:


If your application calls the WIN$PLAYSOUND library routine, and the named sound refers to a disk file on the server or a resource in the program or a library, the client downloads the file to its cache directory, even from a UNIX server. Another use for the cache directory includes storing keystroke files from the W$KEYBUF library routine. See Using Files Containing Keystrokes for information about using W$KEYBUF.

If your application calls the W$BITMAP routine, there may be a limit to the number of characters you may use in a file name. You are limited to 127 characters if the name passed to W$BITMAP is a file name and extension only and you want W$BITMAP to search for a matching file in the following directories and the order shown below:

  1. The directory in which an application is loaded.
  2. The current directory.
  3. The Windows system directory.
  4. The 16-bit Windows system directory.
  5. The Windows directory.
  6. The directories that are listed in the PATH environment variable.