sync tactics

sync_tactics.md

settings

server side settings

• updated_at : update time
• pk (guid) : identifier which is unique belong all devices.
• is_active (is_deleted)
• is_conflicted(transient, default=false)

client side settings

• updated_at: the same as server side
• pk: the same as server side
• sync_state (default=SYNCD, EDITED, DELETED, CREATED) : SYNCD just after syncing to server data. when modified data in client side, this param won't be SYNCD state.
• data (json)：raw data from server.
• edited_data (json, transient?)：store the edited field and values which is caused in client side.
• is_uploading (transient, default=false): for row level lock while syncing.

diagram

1. client side

1. start!

• is_uploading = true
• max_updated_at = MAX(updated_at in items)
• (if sync_state == SYNCED)
  • get
• (if sync_state != SYNCED)
  • post(put, delete)

2. server side

1. (if get method) ->
   • is_conflicted = false
2. (if post method) ->
   • is_conflicted = max_updated_at < updated_at
3. (if is_conflicted == true)
   • 変更を適用
4. return [item ∈ max_updated_at < updated_at]

3. client side

1. (is_conflicted == true)
   • jump to 4
2. (is_conflicted == fale)
   • renew data
   • renew update_at
   • sync_state = SYNCED
   • edited_data = nil
   • is_uploading = false

4. conflict tactics

1. take the server side data
   • jump to 3.2

• take the client side data
  • renew update_at
  • jump to 1.5
• inform to user
  • jump to 4.1
  • jump to 4.2
• auto merge
  • renew update_at
  • renew data by data from server
  • modified by edited_data
  • jump to 1.5