1.
@theburningmonk
tame
|> (cloud <| complexity)
|> with
|> (fsharp >> powered >> DSLs)

2.
Principal Engineer

3.
image by nerovivo license : https://creativecommons.org/licenses/by-sa/2.0/

4.
@theburningmonk
Under-Abstraction

5.
@theburningmonk
Oversimplification

6.
@theburningmonk
Impedance Mismatch

7.
@theburningmonk
Amazon
DynamoDB
Amazon
SimpleWorkflow
Amazon
CloudWatch
CASE STUDY

8.
@theburningmonk
F# DSLs. Awesome!

9.
@theburningmonk
Amazon
DynamoDB
Amazon
SimpleW
Amazon
CloudWatch
CASE STUDY

10.
@theburningmonk

11.
@theburningmonk
managed
key-value store

12.
@theburningmonk
redundancy
9-9s guarantee

13.
@theburningmonk
great performance

14.
@theburningmonk
name your
throughput

15.
@theburningmonk

16.
@theburningmonk
can be changed on-the-fly

17.
@theburningmonk

18.
@theburningmonk
infinitely scalable
(but you still have to pay for it)

19.
@theburningmonk

20.
Hash Key
Range Key

21.
@theburningmonk
Query:
given a hash key
filter on
range key, or
local secondary index

22.
@theburningmonk

23.
Hash Key Range Key
Local Secondary Index
Global Secondary Index

24.
@theburningmonk
Scan:
FULL TABLE search
(performance + cost concern)

25.
@theburningmonk

26.
Hash Key Range Key
Local Secondary Index
Global Secondary Index

27.
Hash Key Range Key
Local Secondary Index
Who are the TOP 3 players in “Starship
X” with a score of at least 1000?
Global Secondary Index

28.
@theburningmonk

29.
@theburningmonk
select GameTitle, UserId, TopScore
from GameScores
where GameTitle = “Starship X”
and TopScore >= 1000
order desc
limit 3
with (NoConsistentRead, Index(GameTitleIndex, true))

30.
DynamoDB.SQL
github.com/fsprojects/DynamoDb.SQL

31.
@theburningmonk
GOAL
Disguise
complexity

32.
@theburningmonk
GOAL
Prevent
abstraction leak

33.
@theburningmonk
GOAL
SELECT UserId, TopScore
FROM GameScore
WHERE GameTitle CONTAINS “Zelda”
ORDER DESC
LIMIT 3
WITH (NoConsistentRead)

34.
@theburningmonk
Query
AST
Execution

35.
F# & FParsec*
*www.quanttec.com/fparsec
External DSL
via

36.
@theburningmonk

37.
@theburningmonk
SELECT * FROM GameScore
Abstract Syntax Tree (AST)
FParsec

38.
@theburningmonk
SELECT * FROM GameScore
keyword keyword
* | attribute, attribute, …
table name

39.
@theburningmonk
SELECT * FROM GameScore
type Attributes =
| Asterisk
| Attributes of string[]

40.
@theburningmonk
SELECT * FROM GameScore
type Query =
{
Attributes : Attributes
Table : string
}

41.
@theburningmonk
SELECT * FROM GameScore
Parser for “SELECT” keyword
pSelect

42.
@theburningmonk
SELECT * FROM GameScore
pSelect
let pSelect = skipStringCI "select"

43.
@theburningmonk
SELECT * FROM GameScore
pSelect
let pSelect = skipStringCI "select"
matches the string “select” (Case
Insensitive) and ignores it

44.
@theburningmonk
SELECT * FROM GameScore
pFrom
let pFrom = skipStringCI "from"

45.
@theburningmonk
SELECT * FROM GameScore
Parser for a string that
represents the table name
pTableName

46.
@theburningmonk
SELECT * FROM GameScore
pTableName
let isTableName = isLetter <||> isDigit
let pTableName =
many1Satisfy isTableName

47.
@theburningmonk
SELECT * FROM GameScore
pTableName
let isTableName = isLetter <||> isDigit
let pTableName =
many1Satisfy isTableName

48.
@theburningmonk
SELECT * FROM GameScore
pTableName
let isTableName = isLetter <||> isDigit
let pTableName =
many1Satisfy isTableName

49.
@theburningmonk
SELECT * FROM GameScore
pTableName
let isTableName = isLetter <||> isDigit
let pTableName =
many1Satisfy isTableName

50.
@theburningmonk
SELECT * FROM GameScore
pTableName
let isTableName = isLetter <||> isDigit
let pTableName =
many1Satisfy isTableName
parses a sequence of one or
more chars that satisfies the
predicate function

51.
@theburningmonk
SELECT * FROM GameScore
pAsterisk
*
pAttributeName
UserId, GameTitle, TopScore, …

52.
@theburningmonk
SELECT * FROM GameScore
pAsterisk
*
pAttributeName
UserId, GameTitle, TopScore, …
let pAsterisk = stringCIReturn "*" Asterisk

53.
@theburningmonk
SELECT * FROM GameScore
pAsterisk
*
pAttributeName
UserId, GameTitle, TopScore, …
let pAsterisk = stringCIReturn "*" Asterisk
matches the specified string
and return the given value

54.
@theburningmonk
SELECT * FROM GameScore
pAsterisk
*
pAttributeName
UserId, GameTitle, TopScore, …
let isAttributeName = isLetter <||> isDigit
let pAttributeName =
many1Satisfy isAttributeName

55.
@theburningmonk
SELECT * FROM GameScore
UserId, GameTitle, TopScore, …
pAttributeName pCommapAsterisk
*
let pComma = skipStringCI ","

56.
@theburningmonk
SELECT * FROM GameScore
UserId, GameTitle, TopScore, …
pAttributeName pCommapAsterisk
*
let pAttributeNames =
sepBy1 pAttributeName pComma

57.
@theburningmonk
SELECT * FROM GameScore
UserId, GameTitle, TopScore, …
pAttributeName pCommapAsterisk
*
let pAttributeNames =
sepBy1 pAttributeName pComma
parses one or more occurrences of
pAttributeName separated by pComma

58.
@theburningmonk
SELECT * FROM GameScore
UserId, GameTitle, TopScore, …
pAttributeName pComma
sepBy1
pAttributeNames
pAsterisk
*

59.
@theburningmonk
SELECT * FROM GameScore
pAsterisk
*
pAttributeNames
UserId, GameTitle, TopScore, …

60.
@theburningmonk
SELECT * FROM GameScore
pAsterisk
*
pAttributeNames
UserId, GameTitle, TopScore, …
let pAttribute =
pAsterisk <|> pAttributeNames

61.
@theburningmonk
SELECT * FROM GameScore
pAsterisk
*
pAttributeNames
UserId, GameTitle, TopScore, …
let pAttribute =
pAsterisk <|> pAttributeNames

62.
@theburningmonk
SELECT * FROM GameScore
pAsterisk
*
pAttributeNames
UserId, GameTitle, TopScore, …
choice
pAttribute

63.
@theburningmonk
SELECT * FROM GameScore
pAttribute

64.
@theburningmonk
SELECT * FROM GameScore
pAttribute pTableNamepFrompSelect

65.
@theburningmonk
SELECT * FROM GameScore
pAttribute pTableNamepFrompSelect
let pQuery =
tuple4 pSelect pAttribute
pFrom pTableName
|>> (fun (_, attributes, _, table) ->
{ Attributes = attributes
Table = table })

66.
@theburningmonk
SELECT * FROM GameScore
pAttribute pTableNamepFrompSelect
let pQuery =
tuple4 pSelect pAttribute
pFrom pTableName
|>> (fun (_, attributes, _, table) ->
{ Attributes = attributes
Table = table })

67.
@theburningmonk
SELECT * FROM GameScore
pAttribute pTableNamepFrompSelect
let pQuery =
tuple4 pSelect pAttribute
pFrom pTableName
|>> (fun (_, attributes, _, table) ->
{ Attributes = attributes
Table = table })

68.
@theburningmonk
SELECT * FROM GameScore
pAttribute pTableNamepFrompSelect
let pQuery =
tuple4 pSelect pAttribute
pFrom pTableName
|>> (fun (_, attributes, _, table) ->
{ Attributes = attributes
Table = table })
Query

69.
@theburningmonk
SELECT * FROM GameScore
pAttribute pTableNamepFrompSelect
tuple4
pQuery

70.
@theburningmonk

71.
@theburningmonk
< 50 lines of code

72.
@theburningmonk
Amazing
F# + FParsec
=

73.
@theburningmonk
Recap

74.
@theburningmonk

75.
@theburningmonk
select GameTitle, UserId, TopScore
from GameScores
where GameTitle = “Starship X”
and TopScore >= 1000
order desc
limit 3
with (NoConsistentRead, Index(GameTitleIndex, true))

76.
@theburningmonk
Amazon
DynamoDB
Amazon
SimpleWorkflow
Amazon
CloudWatch
CASE STUDY

77.
@theburningmonk

78.
@theburningmonk
Decision Worker

79.
@theburningmonk
Decision Worker
Poll

80.
@theburningmonk
Decision Worker
Decision
Task

81.
@theburningmonk
Decision WorkerDecide

82.
@theburningmonk
Activity Worker
Decision Worker

83.
@theburningmonk
Activity Worker
Decision Worker
Poll

84.
@theburningmonk
Activity Worker
Decision Worker
Activity
Task

85.
@theburningmonk
Activity Worker
Decision Worker
Complete

86.
@theburningmonk
Workers can run from
anywhere

87.
@theburningmonk

88.
@theburningmonk
input = “Yan”
result = “Hello Yan!”
Start
Finish
Activity

89.
@theburningmonk

90.
image by Ryan Hageman license : https://creativecommons.org/licenses/by-sa/2.0/

91.
SWF-based Application

92.
API

93.
Heartbeats
Error
Handling
Polling
API

94.
Activity
Worker
Decision
Worker
Heartbeats
Error
Handling
Polling
API

95.
Activity
Worker
Decision
Worker
Heartbeats
Error
Handling
Polling
API
Boilerplate

96.
– Kris Jordan
“Good simplicity is less with
leverage, not less with less.
Good simplicity is complexity
disguised, not complexity denied.”

97.
http://bit.ly/1pOLeKl

98.
Start
Finish
Activity
?

99.
@theburningmonk
the workflow is
implied by decision
worker logic…

100.
@theburningmonk
instead..

101.
@theburningmonk
the workflow should
drive decision
worker logic

102.
@theburningmonk
the workflow should
driveautomate
decision worker logic

103.
Amazon
.SimpleWorkflow
.Extensions
github.com/fsprojects/Amazon.SimpleWorkflow.Extensions

104.
@theburningmonk
GOAL
Remove
boilerplates

105.
@theburningmonk
GOAL
Code that matches
the way you think

106.
@theburningmonk
Start
Finish
Activity

107.
Start
Finish
Activity

108.
@theburningmonk
Workflows can be
nested

109.
input
result

110.
@theburningmonk
Recap

111.
Activity
Worker
Decision
Worker
Heartbeats
Error
Handling
Polling
API

112.
@theburningmonk
Amazon
DynamoDB
Amazon
SimpleW
Amazon
CloudWatch
CASE STUDY

113.
@theburningmonk

114.
@theburningmonk

115.
@theburningmonk

116.
@theburningmonk
wanna find
correlations?

117.
@theburningmonk
wanna find
correlations?
you can DIY it!
;-)

118.
@theburningmonk
“what latencies spiked
at the same time as
payment service?”

119.
Amazon
.CloudWatch
.Selector
github.com/fsprojects/Amazon.CloudWatch.Selector

120.
@theburningmonk
Find metrics whose 5
min average exceeded
1 second during last
12 hours

121.
@theburningmonk
cloudWatch.Select(
unitIs “milliseconds” +
average (>) 1000.0
@ last 12 hours
|> intervalOf 5 minutes)

122.
@theburningmonk
cloudWatch.Select(“
unitIs ‘milliseconds’ and
average > 1000.0
duringLast 12 hours
at intervalOf 5 minutes”)

123.
@theburningmonk
“did any cache
nodes’ CPU spike
yesterday?”

124.
@theburningmonk
cloudWatch.Select(
namespaceLike “elasticache” +
nameLike “cpu” +
max (>) 80.0
@ last 24 hours
|> intervalOf 15 minutes)

125.
@theburningmonk
cloudWatch.Select(
namespaceLike “elasticache” +
nameLike “cpu” +
max (>) 80.0
@ last 24 hours
|> intervalOf 15 minutes)
Regex

126.
@theburningmonk

127.
@theburningmonk

128.
@theburningmonk

129.
@theburningmonk
namespaceIs ‘JustEat’ and
nameLike ‘cpu’ and
unitIs ‘milliseconds’ and
average > 1000.0
duringLast 12 hours
at intervalOf 5 minutes

130.
@theburningmonk
namespaceIs ‘JustEat’ and
nameLike ‘cpu’ and
unitIs ‘milliseconds’ and
average > 1000.0
duringLast 12 hours
at intervalOf 5 minutes
Filters

131.
@theburningmonk
namespaceIs ‘JustEat’ and
nameLike ‘cpu’ and
unitIs ‘milliseconds’ and
average > 1000.0
duringLast 12 hours
at intervalOf 5 minutes
TimeFrame

132.
@theburningmonk
namespaceIs ‘JustEat’ and
nameLike ‘cpu’ and
unitIs ‘milliseconds’ and
average > 1000.0
duringLast 12 hours
at intervalOf 5 minutes
Period

133.
@theburningmonk
type Query =
{
Filter : Filter
TimeFrame : TimeFrame
Period : Period option
}

134.
@theburningmonk
Query
Internal
DSL
External
DSL

135.
@theburningmonk
namespaceIs ‘JustEat’ and
nameLike ‘cpu’ and
unitIs ‘milliseconds’ and
average > 1000.0
duringLast 12 hours
at intervalOf 5 minutes

136.
@theburningmonk
type MetricTerm = Namespace | Name
type Filter =
| MetricFilter of MetricTerm * (string -> bool)

137.
@theburningmonk
namespaceIs ‘JustEat’ and
nameLike ‘cpu’ and
unitIs ‘milliseconds’ and
average > 1000.0
duringLast 12 hours
at intervalOf 5 minutes

138.
@theburningmonk
type MetricTerm = Namespace | Name
type Unit = | Unit
type Filter =
| MetricFilter of MetricTerm * (string -> bool)
| UnitFilter of Unit * (string -> bool)

139.
@theburningmonk
namespaceIs ‘JustEat’ and
nameLike ‘cpu’ and
unitIs ‘milliseconds’ and
average > 1000.0
duringLast 12 hours
at intervalOf 5 minutes

140.
@theburningmonk
type MetricTerm = Namespace | Name
type Unit = | Unit
type StatsTerm =
| Average | Min | Max | Sum | SampleCount
type Filter =
| MetricFilter of MetricTerm * (string -> bool)
| UnitFilter of Unit * (string -> bool)
| StatsFilter of StatsTerm * (float -> bool)

141.
@theburningmonk
namespaceIs ‘JustEat’ and
nameLike ‘cpu’ and
unitIs ‘milliseconds’ and
average > 1000.0
duringLast 12 hours
at intervalOf 5 minutes

142.
@theburningmonk
type MetricTerm = Namespace | Name
type Unit = | Unit
type StatsTerm =
| Average | Min | Max | Sum | SampleCount
type Filter =
| MetricFilter of MetricTerm * (string -> bool)
| UnitFilter of Unit * (string -> bool)
| StatsFilter of StatsTerm * (float -> bool)
| CompositeFilter of Filter * Filter

143.
@theburningmonk
namespaceIs ‘JustEat’ and
nameLike ‘cpu’ and
unitIs ‘milliseconds’ and
average > 1000.0
duringLast 12 hours
at intervalOf 5 minutes

144.
@theburningmonk
type TimeFrame =
| Last of TimeSpan
| Since of DateTime
| Between of DateTime * DateTime

145.
@theburningmonk
namespaceIs ‘JustEat’ and
nameLike ‘cpu’ and
unitIs ‘milliseconds’ and
average > 1000.0
duringLast 12 hours
at intervalOf 5 minutes

146.
@theburningmonk
type Period = | Period of TimeSpan

147.
@theburningmonk
Active Patterns
a primer on

148.
@theburningmonk
allow patterns to be
abstracted away into
named functions

149.
@theburningmonk
Single-Case Patterns

150.
@theburningmonk
let (|Float|) input =
match Double.TryParse input with
| true, n -> n
| _ ->
failwithf “not a float [%s]” input

151.
@theburningmonk
let (|Float|) input =
match Double.TryParse input with
| true, n -> n
| _ ->
failwithf “not a float [%s]” input

152.
@theburningmonk
let (|Float|) input =
match Double.TryParse input with
| true, n -> n
| _ ->
failwithf “not a float [%s]” input
Float : string -> float

153.
@theburningmonk
match someString with
| Float 42.0 -> “ftw”
| Float 11.0 -> “palprime”
| Float x -> sprintf “just %f” x

154.
@theburningmonk
let (|Float|) input =
match Double.TryParse input with
| true, n -> n
match someString with
| Float 42.0 -> “ftw”
| Float 11.0 -> “palprime”
| Float x -> sprintf “just %f” x

155.
@theburningmonk
let (|Float|) input =
match Double.TryParse input with
| true, n -> n
match someString with
| Float 42.0 -> “ftw”
| Float 11.0 -> “palprime”
| Float x -> sprintf “just %f” x

156.
@theburningmonk
match someString with
| Float 42.0 -> “ftw”
| Float 11.0 -> “palprime”
| Float x -> sprintf “just %f” x
let (|Float|) input =
match Double.TryParse input with
| true, n -> n

157.
@theburningmonk
match someString with
| Float 42.0 -> “ftw”
| Float 11.0 -> “palprime”
| Float x -> sprintf “just %f” x
let (|Float|) input =
match Double.TryParse input with
| true, n -> n

158.
@theburningmonk
match “42” with
| Float 42.0 -> “ftw”
| Float 11.0 -> “palprime”
| Float x -> sprintf “just %f” x

159.
@theburningmonk
match “boo” with
| Float 42.0 -> “ftw”
| Float 11.0 -> “palprime”
| Float x -> sprintf “just %f” x
Error!!!

160.
@theburningmonk
Partial Patterns

161.
@theburningmonk
let (|Float|_|) input =
match Double.TryParse input with
| true, n -> Some n
| _ -> None

162.
@theburningmonk
let (|Float|_|) input =
match Double.TryParse input with
| true, n -> Some n
| _ -> None
Float : string -> float option

163.
@theburningmonk
match “boo” with
| Float 42.0 -> “ftw”
| Float 11.0 -> “palprime”
| Float x -> sprintf “just %f” x
| _ -> “not a float”

164.
@theburningmonk
match “boo” with
| Float 42.0 -> “ftw”
| Float 11.0 -> “palprime”
| Float x -> sprintf “just %f” x
| _ -> “not a float”

165.
@theburningmonk
Multi-Case Patterns

166.
@theburningmonk
let (|Prime|NotPrime|NaN|) input =
match Double.TryParse input with
| true, n when isPrime n -> Prime n
| true, n -> NotPrime n
| _ -> NaN

167.
@theburningmonk
let (|Prime|NotPrime|NaN|) input =
match Double.TryParse input with
| true, n when isPrime n -> Prime n
| true, n -> NotPrime n
| _ -> NaN

168.
@theburningmonk
let (|Prime|NotPrime|NaN|) input =
match Double.TryParse input with
| true, n when isPrime n -> Prime n
| true, n -> NotPrime n
| _ -> NaN

169.
@theburningmonk
let (|Prime|NotPrime|NaN|) input =
match Double.TryParse input with
| true, n when isPrime n -> Prime n
| true, n -> NotPrime n
| _ -> NaN

170.
@theburningmonk
let (|Prime|NotPrime|NaN|) input =
match Double.TryParse input with
| true, n when isPrime n -> Prime n
| true, n -> NotPrime n
| _ -> NaN

171.
@theburningmonk
match someString with
| Prime n -> …
| NotPrime n -> …
| NaN -> …

172.
@theburningmonk
match someString with
| Prime n & Float 11.0 -> …
| Prime n -> …
| Float 42.0 | Float 8.0 -> …
| NotPrime n -> …
| NaN -> …

173.
@theburningmonk
match someString with
| Prime n & Float 11.0 -> …
| Prime n -> …
| Float 42.0 | Float 8.0 -> …
| NotPrime n -> …
| NaN -> …

174.
@theburningmonk
match someString with
| Prime (IsPalindrome n) -> …
| Prime (IsEven n) -> …
| _ -> …

175.
@theburningmonk
Tokenise
(string -> string list)

176.
@theburningmonk
[
“namespaceIs”; “‘JustEat’”; “and”;
“nameLike”; “‘cpu’”; “and”;
…
]

177.
@theburningmonk
Visual Studio time…

178.
@theburningmonk
Parse Filter
(string list -> Filter * string list)

179.
@theburningmonk
let rec loop acc = function
| NamespaceIs (filter, tl)
| NamespaceLike (filter, tl)
| NameIs (filter, tl) | NameLike (filter, tl)
| UnitIs (filter, tl)
| Average (filter, tl) | Sum (filter, tl)
| Min (filter, tl) | Max (filter, tl)
| SampleCount (filter, tl)
-> match tl with
| And tl -> loop (filter::acc) tl
| _ -> flatten (filter::acc), tl
| _ -> failwith “No filters?!?!?”

180.
@theburningmonk
let (|NamespaceIs|_|) = function
| StringCI "NamespaceIs"::QuotedString ns::tl
-> (eqFilter MetricFilter Namespace ns, tl)
|> Some
| _ -> None
let (|NamespaceLike|_|) = function
| StringCI "NamespaceLike"::QuotedString pattern::tl
-> (regexFilter MetricFilter Namespace pattern, tl)
|> Some
| _ -> None

181.
@theburningmonk
Parse
(string list -> Query)

182.
@theburningmonk
let parse (input : string) =
input
|> tokenize
|> parseFilter
|> parseTimeFrame
|> parsePeriod

183.
@theburningmonk
Amazing
F#
=

184.
@theburningmonk
usable from anywhere you
can run F# code
e.g. F# REPL, executable, ..
Internal DSL

185.
@theburningmonk
useful for building tools
e.g. CLI, …
External DSL

186.
@theburningmonk

187.
@theburningmonk

188.
@theburningmonk

189.
@theburningmonk
Recap

190.
@theburningmonk

191.
@theburningmonk

192.
@theburningmonk
Amazon
DynamoDB
Amazon
SimpleWorkflow
Amazon
CloudWatch
CASE STUDY

193.
@theburningmonk
theburningmonk.com
github.com/theburningmonk

194.
is hiring :-)
http://tech.just-eat.com/jobs