Yeah, apparently there is no API to rename a file.
However, you can indirectly achieve the "rename" functionality for file with existing APIs as discussed below:
# Assuming we want to rename file fileA to fileB. Both files are under /vol/myvol/mydir
Step 1: Execute file-get-file-info API for existing file:
<file-get-file-info>
<path>/vol/myvol/mydir/fileA</path>
</file-get-file-info>
Get the value of "file-size" from the API response (say, the obtained value is 14)
Step 2: Read the data from the file:
<file-read-file>
<length>14</length>
<offset>0</offset>
<path>/vol/myvol/mydir/fileA</path>
</file-read-file>
And get the value of "data" from the API response (say, the obtained value is 53756e204175672031322030303a)
Step 3: Write the data into the new non-existing file:
<file-write-file>
<data>53756e204175672031322030303a</data>
<offset>0</offset>
<path>/vol/myvol/mydir/fileB</path>
</file-write-file>
Step 4: Finally delete the original file:
<file-delete-file>
<path>/vol/myvol/mydir/fileA</path>
</file-delete-file>