Calling upload API

We are trying to use the set of APIs to send a file to a channel from an andriod app. Here are the set of APIs if we trace through the mattermost.log

/api/v1/files/upload -> this is use to upload the file
/api/v1/files/get_info//........../errors.txt -> this returns the file details..
/api/v1/channels//update_last_viewed_at
/api/v1/channels/posts/ to collect allprevious post

We can send the file using /api/v1/files/upload however we are taking time to debug through the code to find which api or event is triggered to refresh the file across all other users at the designated channel.

We do see that the file is uploaded and database entry is also marked in the Post table. The file doesnt just shows up at the channel room when i check it from the web version.

Can someone help in finding the exact api or trigger used to do this?

Thanks in advance