Trigger last put file of office online server on clicking save button

Question

I am integrating Office Online Server in a web application project, as I read in some documents oos automatically saves changes of word document every 30 seconds. The problem is I am using oos as text editor so I want to save last changes when user clicks the save button to the file and after that program takes the file from wopi host and do the rest of the process.

I have implemented the wopi service and it works just fine whenever oos send put file request it saves the changes to the file. the challenge is that it sends the request every 30 second and if user close the window before oos call the put file all the changes after last save is not being saved to the file.

I have searched a lot over internet for solution and I have found that I should send postMessage of type UI_Close Then oos navigates to the url of closeUrl property which I provided in CheckFileInfo response but when I send the postMessage nothing happens by the way I haven't found a proper sample or example for how to send that.

I really need to solve this problem so I appreciate any help.

I have found some links to Wopi.Readthedocs.io which all of them return 404 and couldn't read the content and I don't know if the pages are not really available or there is other problem.

links of the post and link to the documents are:

https://social.msdn.microsoft.com/Forums/en-US/d540b24c-8e69-4764-a104-6a92586986af/office-online-server-wopi-interface-reduce-the-time-taking-to-make-auto-save-frequency?forum=os_office

https://wopi.readthedocs.io/en/latest/faq.html

https://wopi.readthedocs.io/en/latest/faq/edit_save.html

https://wopi.readthedocs.io/en/latest/faq/editing_finished.html

I really appreciate if anyone help me to find the documents or provide some other sources or even help me to solve the problem in any other ways.