Sunday, October 28, 2018

Google+ Migration - Part II: Understanding the Takeout Archive

<- Part I: Takeout

Once we the takeout archive has been successfully generated we can download and unarchive/extract it to our local disks. At that point we should find a new directory called Takeout with the Google+ posts being located at the following directory location: Takeout/Google+ Stream/Posts.

This posts directory contains 3 types of files:
  • File containing data for each post in JSON format
  • Media files of images or videos uploaded and attached to posts, for example in JPG format
  • Metadata files for each media-file in CSV  forma with an additional extensions of .metadata.csv
The filenames are generated as part of the takeout archive generation process with the following conventions: the post filenames are structured as a date in YYYYMMDD format followed by a snippet of of the post text or the word "Post" if there is not text. The media filenames seem to be close to the original names of the files when they were uploaded.

Whenever a filename is not unique, an additional count is added like in these examples:

20180808 - Post(1).json
20180808 - Post(2).json
20180808 - Post(3).json
20180808 - Post.json
cake.jpg
cake(1).jpg


Filenames which contain unicode characters that are not in the base ASCII may not be correctly represented on all platforms and in particular appear corrupted in the .tgz archive. For the cases which I have been able to test, the default .zip encoded archive seems to handle unicode filenames correctly.

Each of the .json post files contains a JSON object with different named sub-objects which can themselves again be objects, lists of objects or elementary types like strings or numbers.

Based on the data which I have been able to analyze from my post archive, the post JSON object contains the following relevant sub-objects:
  • author - information about the user who created the post. In a personal takeout archive, this is always the same user.
  • creationTime and updateTime - timestamp of when post was originally created or last updated, respectively
  • content - text of the post in HTML like formatting
  • link, album, media or resharedPost etc. - post attachments of a certain type
  • location - location tag associated with post
  • plusOnes - record of users who have "plussed" the post
  • reshares - records of users who have shared the post
  • comments - record of comments, including comment author info as well as comment content
  • resourceName - unique ID of the post (also available for users, media and other objects)
  • postAcl - visibility of Post - e.g. public, part of a community or visible only to some circles or users.
In particular this list is missing the representation for collections or other post attachments like pools or events, as there are no examples for this among my posts.

An example JSON for a very simple post consisting of a single unformatted text line, an attached photo and a location tag - without any recorded post interactions:

{
  "url": "https://plus.google.com/+BernhardSuter/posts/hWpzTm3uYe3",
  "creationTime": "2018-07-15 20:43:51+0000",
  "updateTime": "2018-07-15 20:43:51+0000",
  "author": {
   ... 
  },
  "content": "1 WTC",
  "media": {
    "url": "https://lh3.googleusercontent.com/-IkMqxKEbkxs/W0uyBzAdMII/AAAAAAACAUs/uA8EmZCOdZkKGH5PN5Ct_Xj4oaY2ZNX3ACJoC/
                  w2838-h3785/gplus4828396160699980513.jpg",
    "contentType": "image/*",
    "width": 2838,
    "height": 3785,
    "description": "1 WTC",
    "resourceName": "media/CixBRjFRaXBNRUpjaXh6QTRyckdjNE5Nbmx5blVwTTBjd2lIblh3VWFCek0zMA\u003d\u003d"
  },
  "location": {
    "latitude": 40.7331168,
    "longitude": -74.0108977,
    "displayName": "Hudson River Park Trust",
    "physicalAddress": "353 West St, New York, NY 10011, USA"
  },
  "resourceName": "users/117832126248716550930/posts/UgjyOA5tNBvbgHgCoAEC",
  "postAcl": {
    "visibleToStandardAcl": {
      "circles": [{
        "type": "CIRCLE_TYPE_PUBLIC"
      }]
    }
  }
}

JSON is a simple standard data format that can easily be processed programmatically and many supporting libraries already exist. The Python standard library contains a module to parse JSON files and expose the data as native Python data objects to the code for further inspection and processing.

For example this simple Python program below can be used to determine whether a post has public visibility or not:

#!/usr/bin/python

import json
import sys

def is_public(acl):
  """Return True, if access control object contains the PUBLIC pseudo-circle."""
  if ('visibleToStandardAcl' in acl
      and 'circles' in acl['visibleToStandardAcl']):
    for circle in acl['visibleToStandardAcl']['circles']:
      if circle['type'] == 'CIRCLE_TYPE_PUBLIC':
        return True
  return False

# filter out only the posts which have public visibility.
for filename in sys.argv[1:]:
  post = json.load(open(filename))
  if is_public(post['postAcl']):
    print (filename)


Running this as ./public_posts.py ~/Download/Takeout/Google+\ Stream/Posts/*.json would return the list of filenames which contain the publicly visible posts only. By successfully parsing all the .json files in the (i.e. without trowing any errors), we can also convince ourselves that the archive contains data in syntactically valid JSON format.

Sunday, October 21, 2018

Google+ Migration - Part I: Takeout



For the last 7 years, I have been using Google+ as my primary social sharing site - with
automated link-sharing to Twitter. With Google+ going away, I am looking to migrate my public postings to a new site, where they can be presented in a similar way. As the target for the migration, I have chosen a local community-operated pod of the diaspora* network.

Migrating social media-data is particularly challenging. They are by definition an amalgamation of data from different sources: links, re-sharing, likes comments etc. - all potentially created by different users of the original social sharing platform. Also contrary to other data-sets (e.g. contact-lists, calendars or spreadsheets), there are no established, standardized data formats for exchanging social networking site activity in a platform independent way.

Without being an expert in copyright and data protection law, I am taking a very conservative approach to ownership and consent. Users of the original Google+ site were explicitly ok with the following cross-user interactions from the perspective of my post-stream:

  • re-sharing post of other users (while respecting the original scope)
  • other users liking ("plussing") my posts
  • other users commenting on my posts

Since none of these other users have ever granted my an explicit permission to replicate this content in a new form on another platform, I will only replicate my original content without any interactions, but in addition to public posts also include posts to communities, which I consider public. The purpose of this tutorial is to present some tools and methods that could be used to process and select data in a different way to implement a different policy.

For the technicalities of migration, I am making the following assumptions assumptions:

  • as input, only rely on data that is contained in the takeout-archive. This way the migration could be repeated after the original Google+ site is now longer accessible.
  • use the Python programming language for parsing, processing and re-formatting of the data.
  • use a bot with a Python API-library for diaspora* to repost (very slowly!) to the new target system.
While Python is highly portable, any examples and instructions in this tutorial will assume a unix-like operating system an be tested in particular on a current Debian GNU/Linux based system.

Ordering Takeout

For over 10 years, a Google team calling itself the Data Liberation Front, has been working on a promise that users should be able to efficiently extract any of the data they create online with Google services and take them elsewhere. The resulting service is takeout.google.com.

In order to get an archive suitable for processing, we need to request a takeout archive of the Google+ stream data in JSON format. Here are some basic instructions on how to request a new takeout archive.

For the purpose of this migration, we only need to select "Google+ Stream" in data selection. However, we need to open the extension panel and select JSON format instead of the default HTML. While the HTML export only contains the information necessary to display each post, the JSON export contains additional meta-data like access-rights in an easily machine readable format.

Given the high load on the service right now, archive creation for large streams can take a while or be incomplete. We should expect this process to become more reliable again in the next few weeks.


The next step will be to understand the structure of the data in the takeout archive.