1. The Making of the Census Bureau’s First Official Mobile App
Alec Permison, ADIT/ASD
Paul Milbourne, ADIT/ASD
Gustavo Torrico, ADEP/EPD

2. Agenda
• Overview
• Front-end Architecture
• Back-end Architecture
• Project Challenges
• Lessons Learned

3. Overview
• First Census Bureau mobile app for
Android/iOS both phone & tablet
• Developed as part of ongoing Web
Transformation effort
• Displays 16 economic indicators
• 13 from Census Bureau Central
Indicators Database Repository
• 2 from Bureau of Economic Analysis
• 1 from Bureau of Labor Statistics

4. Overview
• Collaborative team effort
• Communications Directorate – product owner & manager
• Contractor – front-end development
• Economics Directorate – data experts and back-end
development
• IT Directorate – technical guidance, back-end development,
and technical support

5. Overview
• Mobile app front-end displays data
• Three back-end API‟s supply data at
App
startup, refresh, and indicator release
• CIDR Private API developed by Econ
• BLS Private API developed by IT
• BEA Public API
• Config file on server queried at CIDR BLS BEA
startup
BoC Private

6. Front End Architecture
• Adobe Flex 4.6
• Adobe AIR 3.3
• SWIZ 1.4
• iOS 4+
• Android 2.2+

7. Front End Architecture

8. Front End Architecture

9. Front End Architecture

10. Front End Architecture

11. Front End Architecture
Phone Core Tablet

12. Front End Architecture
• Skills Required • Tools Required
– Adobe Flash Builder 4.6
– ActionScript
– Xcode and Eclipse for some
– CSS native components
– XML

13. Front End Architecture
• Pros of Adobe Flex • Cons of Adobe Flex
– Device agnostic from a – Larger footprint
single code base (especially on iOS)
– Easier than native – Android support varies by
development device
– Broad developer – Slower performance
community
– Requires AIR runtime

14. Back End Architecture (CIDR)
• LAMP stack: • JSON-based :
– RHEL 5.8 – Economic dashboard data
– Historical economic indicator
– Apache 2.2.3
data
– Mysql 5.0.95 – Simple format derived from
– PHP 5.1.6 mobile application mockups.
– Private through hash based
“authentication”
• Zend Framework 1.6
– Text-based, easily parse-
– Simple, loosely-coupled able.
component library for web
– Data available as soon as
applications upload process is completed
on internal Census servers.

15. Back End Architecture (CIDR)
dashboard_data
category
time_slot data_type
display_cell
geo_level error_type

16. Back End Architecture (CIDR)
• JSON export of dashboard_data table

17. Back End Architecture (CIDR)
• Historical data available in CIDR database (display_cell table)

18. Back End Architecture (CIDR)
• Basic hash-key based authentication
• Example URL:
– http://www.census.gov/econ/currentdata/api/dashboard?id=sapient&ha
sh=89704299208e7e9d16380e4384861396f3398cb0
• Calculating hash:
– sha1(secret key + time stamp + path requested)
1. Secret key – a 40 character alpha-numeric string
2. Time stamp – in the format YYYY-MM-DD 24HH (e.g. „2012-05-14 17‟)
using UTC timestamp.
3. Path requested – excluding id and hash parameters.
„/econ/currentdata/api/dashboard‟

19. Back End Architecture
• Skills Required • Tools Required
– Dev/test environment
– LAMP web dev
– IDE
– Enterprise-scale
development experience
(not for newbie‟s)
– REST interface design

20. Back End Architecture
• Pros of Private API • Cons of Private API
– Fast performance for – Additional skilled
database on our server resources required
– Customized to need of – Additional application to
front-end developer support
– Access more data than – Dependent on your
public API infrastructure
– Under your control

21. Project Challenges
• Limited insight into technical design and code at handoff
(25,000+ LOC, few comments or technical docs initially)
• Security framework still under development
• Lack of dev/test tools & environment for mobile
• Standardizing data formats from 3 API‟s (e.g. timestamps)
• Timely technical support from other agencies
• Coordination with external contractor (e.g. config updates)

22. Lessons Learned
• Early involvement with contractor on technical design
• Schedule time for review and feedback at milestones
• Early engagement from security to address framework
• Identify and procure tools far in advance
• Test external API‟s for reliability/accuracy