TouchDB –scaling down CouchDB Stefan Baggström 20th Nov 2012
Background• We are a research team ”Felix” in TUT/BME developing new ICT solutions in the area of health and wellness technology• We have built a system prototype with CouchDB technologies – to iterate the product concept rapidly – to pilot with potential customers 2
Prototyping a wellnessapplication with CouchDB• Goals for prototype: – Can be used with any Internet devices – Good offline functionality• Being agile: – Data model evolves across increments• There is a schedule to meet: – Consider tech learning curves and development time 3
System to be builtCustomer Wellness Professional 4
CouchDB http://couchdb.apache.org/• CouchDB has some interesting features – JSON document storage – Distributed architecture – Eventual consistency – Bi-directional replication – Serving applications directly from database• Scaling up - see e.g. BigCouch 5
CouchDB – scaling down• There is CouchDB port for iOS and Android (Couchbase Mobile), but the project is dead – Erlang implementation as in CouchDB – Issues: size (~4MB) and slow startup (5-10s) Source: http://www.funny-potato.com/ 6
Meet TouchDB• TouchDB is a lightweight CouchDB-compatible database engine with similar REST API to CouchDB• Replicates with CouchDB• iOS and Android ports implemented with Objective-C / Java on top of SQLite• Native language access via CouchCocoa / Ektorp https://github.com/couchbaselabs/TouchDB-iOS/wiki 7
Personal Wellness App –What is needed and what not?• Good enough performance for – Relatively small data sets (may have large attachments) – A few relatively simple data queries – Good functionality when offline or with intermittent connectivity• Support for multi-device-ownership – Use with any device that suits your task and context 20.11.2012 8
How do we use TouchDB? (1/2)• All documents defined with ”type” property – Database schema emerging• Using Java Ektorp API for document CRUD• Using HTTP API for application resources and views – Implemented home brewn access control• Database provides changes feed – Used to trigger notifications and other actions 11
How do we use TouchDB? (2/2)• Single responsive HTML5 application for desktops, tablets, and smart phones – CouchApp used for deployment to CouchDB• Initial replication in foreground during first time use, and then continuous replication in background• Data model evolves all the time 12
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