V2 Inspector2 Specification

V2Master | V2HighLevelDesign

Introduction

Development

• See V2Inspector2Todo

Main Menu

• Home -

• Inspection Records - Displays a list of Inspection Records

• Inspection Items - Displays a list of Inspection Items

• Synchronize - Displays counts of Inspection Records and Inspection Items. Buttons for Upload and Download data.

• Preferences -

• About Inspector - Displays Inspector version number and release date

• Contact Us

Screens

• Home

• Inspection Records (list)

• Inspection Record Detail

• Inspection Record New/Edit

• Inspection Items (list)

• Inspection Item Detail

• Inspection Item New/Edit

• Synchronize

• Statistics

• Preferences

• About Inspector

• Contact Us

Data Synchronization

Key data fields for synchronization:

• local_id - Primary key in the device (local) database

• local_is_dirty - If set to on-zero, then the record has been changed on the device

• local_is_conflict - If set, then the record has been change on the device and the server, and cannot be uploaded

• id - The server's primary key

• update_count - The server's update count. The device should never change this field

Download

• Data in JSON format is download from the server, from the following tables:

  • tags - Inspection Items

  • scans - Inspection Records

  • photos - Inspection Photos (not implemented yet)

Download Algorithm

For a single downloaded record:

  table = name of the table being processed
  new_record = record downloaded from server

  old_record = db.getById(table, record.id) -- Record from client device database

  if ( old_record == null ) {

    new_record.local_is_dirty = 0;
    new_record.local_is_conflict = 0
    db.insert(table, new_record) -- local_id is set by the database server

  } else {

    if ( new_record.update_count != old_record.update_count ) { // Server record was updated

      if ( old_record.local_is_dirty ) {

        db.updateById(table, old_record.id, {local_is_conflict: 1}) -- Set old_record.local_is_conflict = 1

      } else {

        record.local_is_conflict = 0
        db.updateById(table, new_record.id, new_record) -- Replace old_record with new_record (or delete & insert?)

      }
    }
  }

Data Upload

Upload Algorithm

1. Only upload records records that meet one the following conditions:

   1. local_is_dirty != 0

   2. id == null

2. Do not upload records where local_is_conflict != 0

To Do What are the responses from the server in the following cases:

1. Success

   1. Insert On a new record does the server respond with the new id value or path to access the new record?

   2. Update Does the server respond with the updated update_count. If not, can we always guarantee it is incremented by one

2. Conflict What is the response when the update_count of uploaded record doesn't not match that on the server

Possible responses to an insert/update:

• inserted: id updated: update_count conflict: an error code

For a single record to upload:

  table = name of the table being processed
  record = record to upload

  create a JSON string from the record, which does not include the following fields:
    local_id
    local_is_dirty
    local_is_conflict

  if ( record.id == null ) { // Insert a new record

    POST JSON to "http://{url}/{table}.json"

    record.id = id from server     -- how to get the new id from server?
    record.local_is_dirty = 0
    record.local_is_conflict = 0
    record.update_count = 1 (or 0?)

    db.updateByLocalId(record.local_id, record)

  } else { // Update existing record

    PUT JSON to "http://{url}/{record.id}/{table}.json

    if (response == OK) {

      -- do nothing or download record again to get new update_at value? 
      record.update_count = record.update_count + 1

      db.updateByLocalId(record.local_id, record)

    } else if ( response == conflict ) {

      db.updateById(record.id, {local_is_conflict: 1}) -- Set old_record.local_is_conflict = 1

    } else {

      report error

    }
  }