Compaq FTAM Responder Support of | Mapping Between FTAM Contents Types and |
ISO FTAM Functions | Compaq File Structures |
Table 4-5. Document Types and Parameters Supported by the Compaq FTAM Responder (continued)
FTAM | | |
Document | Parameters | Parameter Values |
Types |
| | |
| maximum-string-length | 1-4072 (in bytes) |
| string-significance | fixed or variable** |
NBS-9 | Not applicable | <filename>*** |
| | |
FTAM-2 files are relative (sequential) files, and each logical record of a relative file can be a maximum of 4072 bytes. Each string is stored as a logical record in a relative file. Therefore, the practical size limit of a string during data transfer is 4072.
∗∗If the string-significance parameter is set to fixed or variable, the file is an entry-sequenced file and is subject to the maximum logical record length of 4072 bytes. However, if a DEFINE by the name _ZOSF_FIXED_AS_UNSTRUCT exists when the FTAM processes are started then with the string-significance set to FIXED, the file will be an unstructured file with a maximum-string-length of 4096 bytes.
∗∗∗This value represents the Compaq FTAM responder default for NBS-9 files. If you open an NBS-9 file without specifying the file attributes to return, the Compaq responder defaults the parameter setting to the filename attribute only. If you do specify file attributes, the Compaq responder returns the specified file attributes.
Mapping Between FTAM Contents Types and Compaq File Structures
The FTAM virtual filestore (VFS) supports the Compaq responder by providing an interface to the Guardian file system. The Compaq implementation of the VFS maps Compaq FTAM file structures and attributes to Guardian file structures and attributes, and vice versa. Tables 4-6 and 4-7 show mappings of FTAM document types to file types.
Create Mappings
Table 4-6 shows the Guardian file structures created when you use the F-CREATE service to create FTAM files, provided either the file does not exist or the override parameter is set to delete and create with new attributes. (If the file exists and the override parameter is set either to select the old file or to create a new file with the old attributes, the existing file attributes are not checked and are left unchanged.) The table also shows the default parameter values for the FTAM-1, FTAM-2, and FTAM-3 document types. This table indicates the default parameter values for the document types that Compaq supports, whereas Table 4-5, earlier in this section, indicates the full range of parameter values for these document types.
For the create service to succeed, the maximum-string-length parameter is optional, because the ISO FTAM default value for this parameter, unbounded, is supported by the Compaq responder. Further, the value of the maximum-string-length parameter must
4-5
