CheckPoint Restart

CheckPoint Restart stores records in a progress file when the adapter crashes. If the adapter crashes when processing a file, Publication Service continues to process the file from where it crashes upon restart. The restart information is stored in a progress file in the directory where the runtime adapter is executed.

To enable this functionality for Publication Service:

  • In Record Transfer mode, select the CheckPoint Restart check box in the Advanced tab.
  • In Simple File Transfer mode, specify the progress file name in the SFT tab. The name of the progress file is __InstanceNamePublicationServiceName.prg.

If Load Balancing mode is enabled, the subject or destination name is added to the progress file name. For example: __InstanceNamePublicationServiceNameSubjectName.prg.

Since Publication Service does not update the progress file or perform postprocessing on the file automatically, when the adapter exits abnormally, the following situations occur occasionally:

  • Duplicate Messages

    Because Publication Service does not publish messages or update the progress files automatically, duplicate files might be created when Publication Service resumes. The CheckPoint Restart function is used only if duplicated messages are tolerant in the project.

    When using Object (MInstance) or the grouping size of the Business document is one, only one duplicate file is generated. When using Business document, and the grouping size is greater than one, multiple duplicate files are generated.

    When you use the MInstance message format, the subscriber occasionally writes a duplicate message after a checkpoint restart.

    The MBusiness Doc format uses sequence numbers to prevent duplicate messages. This preventative feature is only effective if the Document Delay parameter is set to 0 (zero).

  • Missing File in the Working Directory

    Missing file in the working directory occurs when the postprocessing on the working file is completed but the progress file is not updated. Upon restart, the adapter prompts that the file in the working directory is missing.

    Note:
    • Enabling the CheckPoint Restart feature results in lower performance. Disabling this feature means a higher throughput is possible, but you have to restart the service manually.
    • When CheckPoint Restart is enabled, Publication Service sends duplicate messages, and Subscription Service might output duplicate messages even though Publication Service does not resend them.
    • Ensure that you set the progress directory if you want to enable the CheckPoint Restart feature.