Presentation #2 Josh developer silver spring, md RTI twin dad - PowerPoint PPT Presentation

Presentation #2

Josh —developer —silver spring, md —RTI —twin dad —canadian

Outline 1. What is Tangerine? 2. Where were we and what were we doing? 3. What went wrong? 4. How did we respond? 5. Q&A

Tangerine —Android —Data collection —Literacy assessments for early grades —Web interface for designing assessments —Mobile interface for collecting data

Technology Web application (Backbone.js) Apache Cordova CouchDB (document oriented database)

Context —Kenya —Rural —Intermittent connection —Low bandwidth

Problem 1. Users complain it doesn’t work. Timeouts. 2. Doesn’t finish. 3. No feedback.

Step 0 Geography Moved the server from New York to Frankfurt.

Step 1 Divide and conquer 1. Break up the data into logical chunks. (group of documents) 2. If at first you don’t succeed

Step 2 Psychology Display 3 pieces of information 1. Upload progress (chunk 1 out of 15 chunks) 2. Internet connection quality. (bad, poor, ok, good) 3. Upload history.

Step 3 LZ Compression LZ-String-1.3.3 —Compressed our JSON down to 38% of original size —AJAX —Base64 (60%)

Step 4 Ditching CouchDB replication —MVCC —Multiple requests

Steps —Geography —Divide and Conquer —Psychology —LZ Compression —Ditching CouchDB Replication

Result? —hour to minutes Thanks for listening The End

Q&A