CADEC 2007 presentation on three major trends all embodied in CouchDB.
- 1.Niklas Gustavsson [email_address]
www.callistaenterprise.se
2. CouchDB, Slide Copyright 2008, Callista Enterprise AB Be
warned 3. CouchDB, Slide Copyright 2008, Callista Enterprise AB
Won't replace your relational database You (probably) won't be
using it any time soon 4. CouchDB, Slide Copyright 2008, Callista
Enterprise AB Forget about relationaldatabases for a while 5.
CouchDB, Slide Copyright 2008, Callista Enterprise AB Open source
projectstarted by Damien Katz http://couchdb.org Soon to be an
Apache project 6. CouchDB, Slide Copyright 2008, Callista
Enterprise AB How does it work? 7. CouchDB, Slide Copyright 2008,
Callista Enterprise AB Document oriented Documents are JSON
{firstName:Niklas, lastName: Gustavsson} Schema less 8. CouchDB,
Slide Copyright 2008, Callista Enterprise AB Views Pre-computed,
indexed table Incrementally updated Written in JavaScript 9.
CouchDB, Slide Copyright 2008, Callista Enterprise AB // sort and
retrieve documents by first name function (doc) {
map(doc.firstName, doc); } // retrieve squares by size function
(sq) { map(sq.width * sq.height, {color: sq.color}); } 10. CouchDB,
Slide Copyright 2008, Callista Enterprise AB 1 2 3 So why should I
care? 11. CouchDB, Slide Copyright 2008, Callista Enterprise AB
First reason Sometimes availability trumps consistency 1 2 3 12.
CouchDB, Slide Copyright 2008, Callista Enterprise AB CAP theorem -
pick two: Consistency Availability Partitioning 13. CouchDB, Slide
Copyright 2008, Callista Enterprise AB Eventual Consistency
http://www.allthingsdistributed.com/2007/12/eventually_consistent.html
14. CouchDB, Slide Copyright 2008, Callista Enterprise AB NODES the
number of nodes that store a replica WRITES the number nodes that
confirm a commit READS the number of nodes that are contacted at a
read operationWRITES+READS > NODES : strong consistency
http://www.allthingsdistributed.com/2007/12/eventually_consistent.html
15. CouchDB, Slide Copyright 2008, Callista Enterprise AB
Synchronous DB replication NODES = 2 WRITES = 2 READS = 1 2 + 1
> 2->Strong consistency
http://www.allthingsdistributed.com/2007/12/eventually_consistent.html
16. CouchDB, Slide Copyright 2008, Callista Enterprise AB
Asynchronous DB replication NODES = 2 WRITES = 1 READS = 1 1 + 1
> 2->Eventual consistency
http://www.allthingsdistributed.com/2007/12/eventually_consistent.html
17. CouchDB, Slide Copyright 2008, Callista Enterprise AB What if
NODES is 10 or 100 or 1000? Every increase in WRITES means less
chance for a write to succeed 18. CouchDB, Slide Copyright 2008,
Callista Enterprise AB
http://www.allthingsdistributed.com/2007/12/eventually_consistent.html
http://aws.amazon.com/simpledb http://lucene.apache.org/hadoop/
Read more 19. CouchDB, Slide Copyright 2008, Callista Enterprise AB
Second reason: Moore haschanged tactic 1 2 3 20. CouchDB, Slide
Copyright 2008, Callista Enterprise AB CPUs are getting slower but
more plenty The Free Lunch is over -
http://www.gotw.ca/publications/concurrency-ddj.htm 21. CouchDB,
Slide Copyright 2008, Callista Enterprise AB We need to start
parallelizing our tasks Concurrency in Java is really, really hard
Share nothing Erlang processes and messaging Map/reduce 22.
CouchDB, Slide Copyright 2008, Callista Enterprise AB Used for
computing views in CouchDB map/reduce 23. CouchDB, Slide Copyright
2008, Callista Enterprise AB
http://www.gotw.ca/publications/concurrency-ddj.htm
http://erlang.org/ http://www.scala-lang.org/
http://labs.google.com/papers/mapreduce.html Read more 24. CouchDB,
Slide Copyright 2008, Callista Enterprise AB Third reason Web
friendly 1 2 3 25. CouchDB, Slide Copyright 2008, Callista
Enterprise AB REST - HTTP used right 26. CouchDB, Slide Copyright
2008, Callista Enterprise AB REST based API Everything is a
resource Every resource has a URL Every resource has the same
uniform interface Links guides through states Stateless 27.
CouchDB, Slide Copyright 2008, Callista Enterprise AB REST freebies
API easily usable from any platform (AJAX, Java, Ruby, COBOL,
Powerpoint...) Works with existing infrastructureCaches, proxies,
firewalls Optimistic locking 28. CouchDB, Slide Copyright 2008,
Callista Enterprise AB
http://www.ics.uci.edu/~fielding/pubs/dissertation/top.htm
http://www.infoq.com/articles/rest-introduction
http://www.burtongroup.com/Guest/Aps/RestWorkshop.aspx Read more
29. CouchDB, Slide Copyright 2008, Callista Enterprise AB I'm
getting sleepy,show me the goodies! 30. CouchDB, Slide Copyright
2008, Callista Enterprise AB Adding a to do var todoText =
$("todoinput").value; this.db.save({text: todoText }); 31. CouchDB,
Slide Copyright 2008, Callista Enterprise AB Adding a tag
if(!todo.tags) { todo.tags = [tag]; } else{
todo.tags[todo.tags.length] = tag; } this.db.save(todo); 32.
CouchDB, Slide Copyright 2008, Callista Enterprise AB The magic of
save() this.save = function(doc, options) { if (doc._id ==
undefined) { xhr.open("POST", this.url); } else { xhr.open("PUT",
this.url+ doc._id); } xhr.send(doc.toJSONString()); } 33. CouchDB,
Slide Copyright 2008, Callista Enterprise AB Questions? ? 34.
CouchDB, Slide Copyright 2008, Callista Enterprise AB Attributions
WHY? -http://www.flickr.com/photos/teflon/128827389/ Deep mud
-http://www.flickr.com/photos/hubmedia/133598031/ Banana
-http://flickr.com/photos/tim_ellis/154225908/ Forget me not
-http://flickr.com/photos/doblonaut/456339900/
