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24.23. Preventing Multiple, Simultaneous Document Changes
When synchronizing documents between your iPad and your LincDoc server, a check is performed, to verify that the versions match. This step prevents multiple users from editing and updating the same document and overriding each other's changes.
Note: This verification process is sometimes referred to as optimistic locking.
Proceed to one of the following topics for more information:
- About Feature Limitations
- About Synchronization Error Messages
- About Documents Updated on the LincDoc Server
- Resolving Synchronization Errors
About Feature Limitations
This feature guarantees that the version on the LincDoc server is always up-to-date, and that changes uploaded from an iPad cannot overwrite changes made (at the same time) to the same document either from other mobile devices or via the standard (web-based) LincDoc application.
However, this feature does not prevent changes from being made on a server while working with a document on a mobile device. When you download a document to your iPad, you take the risk of changes being made to the same document on the LincDoc server by another user. If this other version of the document is uploaded to the LincDoc server before your personal version, you will not be able to upload your version. In other words, the server version of the document is not locked after you download it, so other users can make changes to and upload the same document, which will render your changes non-syncable.
Important: The main purpose of the optimistic locking feature is to prevent your LincDoc server from containing conflicting data. It is a server-side feature, not a mobile app-side feature.
If a downloaded document has been updated on your LincDoc server, a message will appear adjacent to the document when viewed via the All Documents list, as shown below.
Documents displaying this message can no longer by synced. Instead, you should download the updated version from the LincDoc server, and then make updates using your mobile device. For more information, see Resolving Synchronization Errors below.
About Synchronization Error Messages
The following example shows the error message that will appear if the version of the document on the LincDoc server is newer than the version being synchronized from your iPad.
After you tap OK to close the error message, the form's information is displayed, and a Conflicts with Server message appears in the Sync Status field.
This message also appears if the document appears in a document list.
About Documents Updated on the LincDoc Server
If you access a downloaded document that has been updated on your LincDoc server, different options appear than with a standard document.
The following options allow you to either view the different versions of the document or resolve the synchronization error:
- View Local Copy. Open a preview of the document as it appears on your mobile device.
Important: This feature is only available with PDF-based documents. - View Server Copy. Open a preview of the document as it appears on your LincDoc server.
Important: This feature is only available with PDF-based documents. - Download From Server. Copy the version of the document on your LincDoc server to your mobile device.
- Delete Local Copy. Remove your local (out-of-date) document from your mobile device.
For more information on the last two options listed above, proceed to the next section below.
Resolving Synchronization Errors
If a sync error occurs, as described above, you can perform one of the following actions to resolve the issue. Remember, resolving the issue means that your local copy of the document, and all changes that you have made, will be lost and replaced with the updated copy from your LincDoc server.
Proceed to one of the following sections below for more details:
- If you want to replace your local copy with a server copy, and then re-create your lost changes, see Downloading the Server Version of the Document.
- If you simply want to remove your local copy, see Deleting the Local Copy.
Downloading the Server Version of the Document
You can replace the local version of the document with the version on your LincDoc server. Once replaced, the new version can again be edited, if desired.
- Access the document's options as described in About Documents Updated on the LincDoc Server above.
- Tap the Download From Server option.
- Tap Yes to verify the action.
The document's options are updated to show the standard set of options, and the Sync Status entry is no longer present (instead of displaying a server conflict or updated message).
In addition, the server version now appears in your list of documents (All Documents), and the Conflicts with Server message is no longer present. - (optional) Open the document and re-create your changes.
- Synchronize the document as soon as it is completed.
Deleting the Local Copy
If desired, you can simply delete the local copy, and then download the document again at a later time.
- Access the document's options as described in About Documents Updated on the LincDoc Server above.
- Tap the Delete Local Copy option.
- Tap Yes to verify the action.
The local copy is removed from your iPad, and no updated version from your LincDoc server is placed on your iPad. The document is simply no longer present in your All Documents list, as highlighted below. - (optional) Download the document again.
- Synchronize the document as soon as it is completed.