The document describes the design of a mobile scavenger hunt app. It includes 3 parts: 1) architecture and design, 2) geo-spatial indexing and queries, and 3) deployment readiness. The app allows users to create scavenger hunts by pinning waypoints. Players can search for hunts near their location and track their progress. The design involves collections for waypoints, users, messages, and notifications to support location-based games and social features.

1. Building a Mobile App!
Part 1
{ name: ‘Bryan Reinero’,
title: ‘Developer Advocate’,
twitter: ‘@blimpyacht’,
code: ‘github.com/breinero’
email: ‘bryan@mongdb.com’ }

2. 2
Track Agenda
• Part 1: Architecture and Application Design
• Part 2: Geo-Spatial Indexing and Queries
• Part 3:Deployment Readiness

3. 3
Mobile Applications
• Location based data
• User relevance
• Context Rich
• Social Engagement

4. 4
The Scavenger Hunt App
Users create
scavenger hunts by
“pinning” waypoints

5. 5
The Scavenger Hunt App
Players search for a
scavenger hunt
near their current
position

6. 6
The Scavenger Hunt App
Basic Requirements

7. 7
The Scavenger Hunt App
Basic Requirements
• Mark target points

8. 8
The Scavenger Hunt App
Basic Requirements
• Mark target points
• Identify our users

9. 9
The Scavenger Hunt App
Basic Requirements
• Mark target points
• Identify our users
• Mark users’ progress
during hunts

10. Schema Design

11. 11
The Scavenger Hunt App
Users create
scavenger hunts by
“pinning” waypoints

12. 12
Waypoint
{ _id: ObjectId(),
user: UUID,
tour: UUDI
name: "Doug's Dogs",
desc: "The best hot-dog",
clues: [
"Hungry for a Coney Island?",
"Ask for Dr. Frankenfurter",
"Look for the hot dog stand"
],
"geometry": {
"type": "Point",
"coordinates": [125.6, 10.1] }
};

13. 13
Waypoint
{ _id: ObjectId(),
user: UUID,
tour: UUDI
name: "Doug's Dogs",
desc: "The best hot-dog",
clues: [
"Hungry for a Coney Island?",
"Ask for Dr. Frankenfurter",
"Look for the hot dog stand"
],
"geometry": {
"type": "Point",
"coordinates": [125.6, 10.1] }
};

14. 14
Waypoint
{ _id: ObjectId(),
user: UUID,
tour: UUDI
name: "Doug's Dogs",
desc: "The best hot-dog",
clues: [
"Hungry for a Coney Island?",
"Ask for Dr. Frankenfurter",
"Look for the hot dog stand"
],
"geometry": {
"type": "Point",
"coordinates": [125.6, 10.1] }
};
Geospacial Index:
ensureIndex(
{ geometry: “2dsphere” }
)

15. 15
Waypoint
Mobile Client

16. 16
Waypoint
Application ServerMobile Client
RESTful Service
scavenger.com/waypoints?lat=40.87&lon=-73.87&max=100
HTTP GET

17. 17
Waypoint
Application Server DatabaseMobile Client
RESTful Service
scavenger.com/waypoints?lat=40.87&lon=-73.87&max=100
HTTP GET

18. 18
Waypoint
Application Server DatabaseMobile Client
RESTful Service
scavenger.com/waypoints?lat=40.87&lon=-73.87&max=100
HTTP GET
Query
{ ‘$geoNear’: {
‘$geometry’: {
type: "Point",
coordinates: [ -174.9559, 40.6544 ]
},
‘maxDistance’: 100
}

19. 19
The Scavenger Hunt App
Basic Requirements
• Mark target points
• Identify our users
• Mark users’ progress
during hunts

20. 20
The Checkpoint Document
{
_id: ObjectId(),
user: UUID,
huntId: UUID,
timestamp: ISODate(),
geometry: {
type: "Point",
coordinates: [ long, lat ]
}
}

21. 21
The Scavenger Hunt App
Social Requirements
• Allow users to follow one
another
• Allow users to exchange
messages
• Send users notifications

22. 22
Social Interactions
Eratosthenes
Democritus
Hypatia
Shemp
Euripides

23. 23
User Collection
{
_id: UUID,
name: “Bryan Reinero’,
email: “bryan@mongodb.com”,
pass: “dontyouwishyouknew”,
description: “I am just a guy”,
followers: [
“Achille”,
“Jason”,
“Steffan”,
“Norm”
]
}

24. 24
Social Interactions
Followers Collection
{ follower: ‘Shemp’, followed: ‘Euripides’},
{ follower:‘Shemp’, followed: ’Eratosthenes”},
{ follower: “Eratosthenes’, followed: ‘Shemp’ },
…
Eratosthenes
Democritus
Hypatia
Shemp
Euripides

25. 25
Social Interactions
Eratosthenes
Democritus
Hypatia
Shemp
Euripides
Followers Collection
{ follower: ‘Shemp’, followed: ‘Euripides’},
{ follower:‘Shemp’, followed: ’Eratosthenes”},
{ follower: “Eratosthenes’, followed: ‘Shemp’ },
…
! (Euripides -> Shemp )

26. 26
Social Interactions
db.followers.find( { follower:‘Shemp’ } );
Followers Collection
{ follower: ‘Shemp’, followed: ‘Euripides’},
{ follower:‘Shemp’, followed: ’Eratosthenes”},
{ follower: “Eratosthenes’, followed: ‘Shemp’ },
…

27. 27
Notifications / Messaging
Message
{
sender: “Hypatia”,
recipients: [
“Democritus”,
“Euripides”,
“Eratosthenes”
]
date: ISODate(),
message: “truth is a point of view, and
so is changeable”
}

28. 28
Notifications / Messaging
Message
{
sender: “Hypatia”,
recipients: [
“Democritus”,
“Euripides”,
“Eratosthenes”
]
date: ISODate(),
message: “truth is a point of view, and
so is changeable”
}
db.messages.find(
{ recipients: “Democritus”}
);

29. 29
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
Notifications / Messaging
db.messages.find( ‘outbox.user’: ‘Hypatia’ );
db.messages.find( ‘outbox.user’: ‘Euripides’);
db.messages.find( ‘outbox.user’: ‘Democritus’);
db.messages.find( ‘outbox.user’: ‘Shemp’);
Read

30. 30
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
Notifications / Messaging
db.messages.find( ‘outbox.user’: ‘Hypatia’ );
db.messages.find( ‘outbox.user’: ‘Euripides’);
db.messages.find( ‘outbox.user’: ‘Democritus’);
db.messages.find( ‘outbox.user’: ‘Shemp’);
Read

31. 31
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
Notifications / Messaging
db.messages.find( ‘outbox.user’: ‘Hypatia’ );
db.messages.find( ‘outbox.user’: ‘Euripides’);
db.messages.find( ‘outbox.user’: ‘Democritus’);
db.messages.find( ‘outbox.user’: ‘Shemp’);
Read

32. 32
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
OUTBOX
Notifications / Messaging
db.messages.find( ‘outbox.user’: ‘Hypatia’ );
db.messages.find( ‘outbox.user’: ‘Euripides’);
db.messages.find( ‘outbox.user’: ‘Democritus’);
db.messages.find( ‘outbox.user’: ‘Shemp’);
Read

33. 33
One Document per Message per Recipient
{
sender: “Hypatia”,
recipient: “Democritus”,
date: ISODate(),
message: “truth is a point of view, and so is changeable”
}
{
sender: “Hypatia”,
recipient: “Euripides”,
date: ISODate(),
message: “truth is a point of view, and so is changeable”
}
{
sender: “Hypatia”,
recipient: “Eratosthenes”,
date: ISODate(),
message: “truth is a point of view, and so is changeable”
}

34. 34
Inbox Buckets
Hypatia
Message
Message
Message
Hypatia
Message
Message
Message
Hypatia
Message
Message
Message
…

35. 35
Notifications / Messaging
{user: “Hypatia”,
ctime: ISODate(),
mtime: ISODate(),
count: 10,
inbox: [
<message>,
<message>,
<message>,
…
]
}

36. 36
Write to Bucket
function addToBucket( user, item,bucketSize )
{
var query = {
user: user,
count: { $lt: bucketSize }
};
db.notifications.update(
query,
{
$push: { messages: item },
$set: { mtime: ISODate() },
$inc: { count: 1 },
$setOnInsert: {
startDate: ISODate() }
},
{ upsert: true }
);
}

37. 37
Write to Bucket
Parameters
• user bucket owner
• item notification message
• bucketSize limits number of messages / document
function addToBucket( user, item, bucketSize )
{
var query = {
user: user,
count: { $lt: bucketSize }
};
db.notifications.update(
query,
{
$push: { messages: item },
$set: { mtime: ISODate() },
$inc: { count: 1 },
$setOnInsert: {
startDate: ISODate() }
},
{ upsert: true }
);
}

38. 38
Write to Bucket
Parameters
• user bucket owner
• item notification message
• bucketSize limits number of messages / document
Query
Don’t update full bucket
function addToBucket( user, item,bucketSize )
{
var query = {
user: user,
count: { $lt: bucketSize }
};
db.notifications.update(
query,
{
$push: { messages: item },
$set: { mtime: ISODate() },
$inc: { count: 1 },
$setOnInsert: {
startDate: ISODate() }
},
{ upsert: true }
);
}

39. 39
Write to Bucket
Parameters
• user bucket owner
• item notification message
• bucketSize limits number of messages / document
Query
Don’t update full bucket
Update
• Append item to message array,
• Update the mtime with current timestamp
• Increment the size of the bucket
function addToBucket( user, item,bucketSize )
{
var query = {
user: user,
count: { $lt: bucketSize }
};
db.notifications.update(
query,
{
$push: { messages: item },
$set: { mtime: ISODate() },
$inc: { count: 1 },
$setOnInsert: {
startDate: ISODate() }
},
{ upsert: true }
);
}

40. 40
Write to Bucket
Parameters
• user bucket owner
• item notification message
• bucketSize limits number of messages / document
Query
Don’t update full bucket
Update
• Append item to message array,
• Update the mtime with current timestamp
• Increment the size of the bucket
Upsert
Create a new bucket
function addToBucket( user, item,bucketSize )
{
var query = {
user: user,
count: { $lt: bucketSize }
};
db.notifications.update(
query,
{
$push: { messages: item },
$set: { mtime: ISODate() },
$inc: { count: 1 },
$setOnInsert: {
startDate: ISODate() }
},
{ upsert: true }
);
}

41. 41
Personal Timeline / Hotlist
{
_id: UUID,
user: ”Democritus",
hotList" : [
{
message: "New scavenger hunt tomorrow!",
url: "http://bit.ly/1hKn9ff",
date" : ISODate()
},
{
message: "Get 50% off at Toga City",
url: "http://bit.ly/1KnlFHQ",
date: ISODate()
}
],
atime: ISODate("20150313T04:38:43.606Z")
}

42. 42
Personal Timeline / Hotlist
Notifications of highest
user relevance
{
_id: UUID,
user: ”Democritus",
hotList" : [
{
message: "New scavenger hunt tomorrow!",
url: "http://bit.ly/1hKn9ff",
date" : ISODate()
},
{
message: "Get 50% off at Toga City",
url: "http://bit.ly/1KnlFHQ",
date: ISODate()
}
],
atime: ISODate("20150313T04:38:43.606Z")
}

43. 43
Personal Timeline / Hotlist
db.user.update(
{"user" : "Democritus"},
{$push : { ”hotList” : {
$each : [ { <MESSAGE> } ],
$slice : -50 }
}},
false, false)

44. 44
Production Ready Architecture
Application Servers Replica SetMobile Client
L.B.

45. Thanks!
{ name: ‘Bryan Reinero’,
title: ‘Developer Advocate’,
twitter: ‘@blimpyacht’,
code: ‘github.com/breinero’
email: ‘bryan@mongdb.com’ }