Functional restrictions specific to file adapter

The file adapter for HULFT IoT EdgeStreaming has the following functional restrictions.

For details on the functional restrictions for HULFT IoT EdgeStreaming, refer to First Step Guide.

 

(1) Multi-byte characters

If you use multi-byte characters for File name, although no error will appear on the screen when you save, when you execute the script, the file name will be garbled when it is output.

The location where multi-byte file names will be garbled when they are output is as follows:

  • File adapter: File > Basic > Writing

Do not use multi-byte characters for File name.

 

(2) Existing file names and directory names

If a file or directory of the same name as your specification for File name already exists, when you execute the script, it behaves as described below.

 

Specification location of File name

  • File adapter: File > Basic > Writing

 

When the directory name specified for File name already exists

  • When there is nothing stored in the existing directory, the existing directory is deleted. After the directory is deleted, the file is created.

  • When there is something stored in the existing directory, the existing directory is renamed. After the directory is renamed, the file is created.

    The directory name after it is renamed is existing directory + script execution date and time.

    Example:

    Existing directory name: c:\aaa

    Directory name after it is renamed: c:\aaa-2020-05-13T02-12-32.876

 

When the file specified for File name already exists

  • The existing file is appended.

    If the specified file size is exceeded, the file is rotated and written from the beginning.

  • If the specified file fails to open for some reason, the existing file is renamed and backed up and then a new file for writing is created.

    In addition, if the execution environment is Linux, the file owner is changed to the "execution user of EdgeStreaming Runtime" when the existing file is renamed and backed up.

    If the file fails to open because of the permissions for the file (for example, the writing permission for the target file is not granted), changing the file owner also fails when the file is renamed and backed up. In this case, an error is output.

    The writing operation to a new file continues even if an error is output.

    Example of output error:

    2021-04-07T10:44:53 EES0AGENT01104 chown access.log: operation not permitted
2021-04-07T10:44:53 A tuple was dropped from the topology
chown bb.txt: operation not permitted