CouchDB Mobile App in 1 Hour

44

Peter Friese / Stefan Reichert, Zühlke Engineering

CouchDB mobile
From Couch To 5k in 1 Hour

Peter Friese

@peterfriese
peter.friese@zuehlke.com
xing.to/peter
http://peterfriese.de

Stefan Reichert

@stefanreichert

stefan.reichert@zuehlke.com

xing.to/stefanreichert

http://blog.wickedshell.net/

What we will cover today

1 What is CouchDB?

2 Serious amount of demos!

3 Couch25K - A Runner’s App

CouchDB is...
CouchDB is...
A NoSQL Database.

CouchDB is...
Document-Oriented.
{
! "name": "Peter",
! "company": "Zühlke Engineering",
! "email": "peter.friese@zuehlke.com",
! "languages": [
! ! "Objective-C",
! ! "Java",
! ! "C#",
! ! "JavaScript"
! ]
}

CouchDB is...
Schema-Free.

Put anything
you like into
your CouchDB.
Really.

CouchDB is...
Erlang-Powered.

CouchDB is...
RESTful.

GET
PUT Fully embraces
POST HTTP verbs
DELETE

CouchDB uses...

http://research.google.com/archive/mapreduce.html
Map/Reduce (JavaScript).

CouchDB uses...


Input
{"ip": "212.23.45.12","traffic": “18278", date: “2012-03-11”},
{"ip": "74.12.345.1","traffic": “345", date: “2012-03-11”},
{"ip": "212.23.45.12","traffic": “112244", date: “2012-03-12”},
{"ip": "212.23.45.12","traffic": “8657", date: “2012-03-13”},
{"ip": "74.12.345.12","traffic": “12", date: “2012-03-12”},
{"ip": "10.122.111.22","traffic": “122222", date: “2012-03-11”}

CouchDB uses...


Mapper Input for Reducer
212.23.45.12 18278 212.23.45.12 18278
74.12.345.1 345 212.23.45.12 112244
212.23.45.12 112244 212.23.45.12 8657
212.23.45.12 8657
74.12.345.1 12 74.12.345.1 12
10.122.111.22 122222 74.12.345.1 345

10.122.111.22 122222

CouchDB uses...

Input for Reducer After Reduce
212.23.45.12 18278 212.23.45.12 139179
212.23.45.12 112244
212.23.45.12 8657

74.12.345.1 12 74.12.345.1 357
74.12.345.1 345

10.122.111.22 122222 10.122.111.22 122222

CouchDB features...
Robust Replication.

CouchDB features...
Robust Replication.
Laptop

Phone

Server

Calling Home

curl localhost:5984

{"couchdb":"Welcome","version":"1.1.0"}

Creating a New DB

curl -X PUT localhost:5984/helloworld

{"ok":true}

Deleting a Database
curl -X DELETE http://
localhost:5984/helloworld

{"ok":true}

Creating a New Document
curl
-X POST
-H "Content-Type: application/json"
localhost:5984/helloworld
-d @peter.json

{"ok":true,"id":"f8e42aaa4bc77124c28
6be13f000054e","rev":"1-4dc37117e0da
26d9c50dc92d4cbb04cc"}

Curious? GET Your Document!
curl http://localhost:5984/helloworld/
f8e42aaa4bc77124c286be13f000054e

{
"_id": "f8e42aaa4bc77124c286be13f000054e",
"_rev": "1-4dc37117e0da26d9c50dc92d4cbb04cc",
"name": "Peter",
"company": "Zühlke Engineering",
"email": "peter.friese@zuehlke.com"
}

Anatomy of a Document
{
"_id": "f8e42aaa4bc77124c286be13f000054e",
"name": "Peter",
}

UUID - very
unique identifier

Anatomy of a Document
{
"_id": "f8e42aaa4bc77124c286be13f000054e",
"name": "Peter",
}

revision revision hash (body,
number counter attachment,
_deleted flag)

Welcome to Futon!

Admin interface for CouchDB
CRUD for Documents
Manage Views
Manage Replication

Couch25K - A Runner’s App

3

Basic Idea

2-way 2-way

Phone IrisCouch Phone

CouchDB Mobile

n e ?
P h o
o u r
n y
o

CouchDB Mobile

Your app CouchCocoa lib Ektorp lib Your app

CouchDB CouchDB

CouchDB Mobile
Your app CouchCocoa lib Ektorp lib Your app

TouchDB lib TouchDB lib

SQlite SQlite

CouchDB Mobile

“TouchDB is a lightweight CouchDB-
compatible database engine suitable
for embedding into mobile or desktop
apps. Think of it this way: If
CouchDB is MySQL, then TouchDB
is SQLite.” - Jens Alfke, Couchbase
Labs

Start a Local Couch
CouchTouchDBServer *server =
[CouchTouchDBServer sharedInstance];
NSAssert(!server.error,
@"Error initializing TouchDB server: %@",
server.error);

self.database = [server
databaseNamed:@"couch25k"];

NSError *error;
if (! [self.database ensureCreated:&error]) {
// raise error
self.connected = false;
}

Start a Local Couch
try {
TDServer touchDBServer = new TDServer(filesDir);
!
HttpClient httpClient = new
TouchDBHttpClient(touchDBServer);
CouchDbInstance couchDBInstance =
new StdCouchDbInstance(httpClient);
!
CouchDbConnector couchDBConnector =
couchDBInstance.createConnector(COUCH25K_DB,true);
! ...
} catch (IOException e) {
! Log.e(TAG, "Error starting TDServer", e);
}

Trackpoints

{
"run": "run-peterfriese-19",
"user": "peterfriese",
"lon": "9.990512659959458",
"time": "2012-03-24 07:39:27 +0000",
"lat": "53.73176022303823"
}

Saving a Trackpoint
NSDictionary *trackpointProperties =
[NSDictionary dictionaryWithObjectsAndKeys: (...)

CouchDocument *trackpointDocument =
[database untitledDocument];

RESTOperation* op = [trackpointDocument
putProperties:trackpointProperties];

[op onCompletion: ^{
if (op.error)
NSLog(@"Couldn't save the new item");
}];
[op start];

Saving a Trackpoint
Ektorp: JPA for CouchDB
public class TrackPoint extends CouchDbDocument

Repository Support
public class TrackPointRepository extends
! CouchDbRepositorySupport<TrackPoint>

... so saving a TrackPoint is pretty easy
trackPointRepository.add(trackPoint);

Sync with the Server

NSURL *url = [NSURL
URLWithString:
@"http://peterfriese.iriscouch.com/couch25k"];

[self.database replicateWithURL:url exclusively: YES];

Pull from Server
ReplicationCommand commandPull = new
ReplicationCommand.Builder()
.source(COUCH25K_REMOTE_DB)
.target(COUCH25K_DB)
.continuous(true).build();

try {
couchDBInstance.replicate(commandPull);
} catch (Exception exception) {
Log.e(TAG, exception.getMessage(), exception);
}

Push to Server
ReplicationCommand commandPush = new
.source(COUCH25K_DB)
.target(COUCH25K_REMOTE_DB)
.continuous(true).build();

try {
couchDBInstance.replicate(commandPush);
} catch (Exception exception) {
Log.e(TAG, exception.getMessage(), exception);
}

Display List of Runs (JavaScript)

Map Reduce
function(keys, values)
function(doc) {
{
emit(doc.run, 1);
return sum(values);
}
}

run-1 1
run-1 1
run-1 3
run-1 1
run-2 2
run-2 1
run-2 1

Display List of Runs (Obj-C)

Map
[design defineViewNamed: @"runs" mapBlock: MAPBLOCK({
id run = [doc objectForKey:@"run"];
if (run) emit(run, nil);
})

Reduce
reduceBlock:REDUCEBLOCK({
return [NSNumber numberWithInt:values.count];
})

Display List of Runs (Java)

Map
new TDViewMapBlock() {
public void map(Map<String, Object> doc,
TDViewMapEmitBlock emitter) {
if (doc.containsKey("run")) {
emitter.emit(doc.get("run"), doc.get("_id"));
}
}
}

Display List of Runs (Java)
(Re-) reduce
new TDViewReduceBlock() {
public Object reduce(List<Object> keys, List<Object>
values, boolean rereduce) {
if (rereduce) {
int sum = 0;
for (Object object : values) {
sum += (Integer) object;
}
return sum;
}
return values.size();
}
};

Filtering
Peter Stefan

Filter by name

sync 2-way sync 2-way

Phone IrisCouch Phone 2

Filtering
CouchDB
by_user:

function(doc, rq) {
if(doc.user == rq.query.username) {
return true;
}
return false;
}

Filtering
NSArray *replications =
[self.database replicateWithURL:url exclusively: YES];

CouchPersistentReplication *from =
[replications objectAtIndex:0];
from.continuous = YES;

from.filter = @"couch25k/by_user";
NSDictionary *filterParams = [NSDictionary
dictionaryWithObjectsAndKeys:
@"peterfriese", @"username", nil];
from.query_params = filterParams;

Filtering
Map<String, Object> queryParams =
new HashMap<String, Object>();
queryParams.put("username", "stefanreichert");

ReplicationCommand commandPull = new
.source(COUCH25K_REMOTE_DB)
.target(COUCH25K_DB).continuous(true)
.filter("by_user")
.queryParams(queryParams).build();
try {
! couchDBInstance.replicate(commandPull);
} catch (Exception e) {
! Log.e(TAG, exception.getMessage(), e);
}

Query Trackpoints by Run
Map
mapBlock: MAPBLOCK({
NSString *run = (NSString *)[doc objectForKey:@"run"];
id time = [doc objectForKey:@"time"];
NSMutableArray *key = [[NSMutableArray alloc] init];
[key addObject:run];
[key addObject:time];
emit(key, doc);})

[run-peter-1, 2012-03-23 10:10] {lat:..., lon:...}
[run-peter-1, 2012-03-23 10:11] {lat:..., lon:...}
[run-peter-2, 2012-03-26 20:05] {lat:..., lon:...}
[run-peter-2, 2012-03-26 20:06] {lat:..., lon:...}
[run-peter-2, 2012-03-26 10:07] {lat:..., lon:...}

Query
CouchQuery *query = [[self.database
designDocumentWithName: @"couch25k"]
queryViewNamed: @"waypoints_by_run"];

CouchLiveQuery *livequery = [query asLiveQuery];

[livequery setStartKey:
[NSArray arrayWithObjects:self.runKey, nil]];

[query setEndKey:
[NSArray arrayWithObjects:self.runKey, @"ZZZ", nil]];

Map
new TDViewMapBlock() {
public void map(Map<String, Object> document,
TDViewMapEmitBlock emitter) {
if (document.containsKey("run")) {
document.get("run"), document.get("_id"));
}
}

Query
ViewQuery viewQuery = new
ViewQuery().designDocId("_design/TrackPoint")
.viewName("trackpoint_by_run")
.key(runId);
ViewResult result = db.queryView(viewQuery);
List<TrackPoint> trackPoints = new
ArrayList<TrackPoint>();

for (Row row : result.getRows()) {
TrackPoint trackPoint = get(row.getValue());
trackPoints.add(trackPoint);
}
return trackPoints;

And finally...

http://josephta.me/about-joseph-tame/

... a Tribute to Steve Jobs
GPX
of J cou
rtes
ose y
ph
- T Tam
han e
ks!

http://bit.ly/HbDRod

Thanks!
Peter Friese
Principal Consultant
rt @peterfr
Zühlke Engineering GmbH @stef anreiche iese
Am Sandtorkai 66
20457 Hamburg Availa
ble fo
+49 151 108 604 72 discu r con
ssing sultin
all th g,
rt
Reiche Engineer mobil ings
Stefan
Software
e and
Senior H frost
nginee
rin g Gmb y beve
E
Zühlke torkai 66 rages
nd
Am Sa rg
Hambu
20457
6
961 43 3
+ 49 173

PS: we’re hiring...

CouchDB Mobile App in 1 Hour

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