Presentation of Molecule, a meta-DSL for Datomic by the creator, Marc Grue. Talk from a Scala group MeetUp in Gothenburg, Sweden on April 25, 2017.

1. Scala meta-DSL for Datomic
Marc Grue
April 2017
Molecule

2. Molecule
Introduction to Datomic
Building a DSL with Scala macros
Tour of Molecule features
Molecule and domain modelling
2
3
1
4

3. Molecule
• Facts
• Entities
• Immutability
• Time
• Architecture
1
Datomic

4. Molecule
Key-Value
32 pizza

5. Molecule
Fact
Fred likes pizza

6. Molecule
Fact
Entity Attribute Value
Fred likes pizza

7. Molecule
Fact
Entity Attribute Value Time
Fred likes pizza 10:31

8. Molecule
Fact
Entity Attribute Value Time Op
Fred likes pizza 11:16 retract

9. Molecule
Datom
Entity Attribute Value Tx (time) Operation
fred (eid) likes pizza tx4 assert/retract

10. Molecule
Datom
fred likes pizza tx4 assert/retract
E A V T Op

11. Molecule
Datom
fred :person/likes pizza tx4 assert/retract
E A V T Op
Namespace

12. Molecule
Schema of attributes
eid :person/likes String value … …
E A V T Op
{":db/ident" ":person/likes"}
Attribute Value

13. Molecule
Schema of attributes
eid :person/likes String value … …
E A V T Op
string
boolean
long
bigint
float
double
big dec
ref
instant (date)
uuid
uri
bytes
keyword (enum)
Types
{":db/ident" ":person/likes"
":db/valueType" ":db.type/string"}

14. Molecule
Schema of attributes
eid :person/likes String value … …
E A V T Op
one
many
Cardinality{":db/ident" ":person/likes"
":db/valueType" ":db.type/string"
":db/cardinality" ":db.cardinality/one"}

15. Molecule
Schema of attributes
eid :person/likes String value … …
E A V T Op
{":db/ident" ":person/likes"
":db/valueType" ":db.type/string"
":db/cardinality" ":db.cardinality/one"
":db/doc" "What a Person likes"} doc
unique/value
unique/identity
index
fulltext
isComponent
noHistory
Options

16. Molecule
101 :person/name Fred
101 :person/likes pizza
101 :person/age 38
101 :person/addr 102
Common entity id
Entity

17. Molecule
Entity
101 :person/name Fred
101 :person/likes pizza
101 :person/age 38
101 :person/addr 102
101 :site/cat customer
Common entity id
Entities can span any attributes!

18. Molecule
Entity
eid 101
:person/name Fred
:person/likes pizza
:person/age 38
:person/addr 102
:site/cat customer
Group of facts with shared entity id

19. Molecule
Relationships
eid 102
:addr/street Baker st.
:addr/zip 90221
:site/cat identifier
eid 101
:person/name Fred
:person/likes pizza
:person/age 38
:person/addr 102
:site/cat customer

20. Molecule
Relationships
eid 104
:person/name Ben
:person/age 5
eid 101
:person/name Fred
:person/likes pizza
:person/age 38
:person/kids 103, 104
:site/cat customer
eid 103
:person/name Lisa
:person/age 7

21. Molecule
fred :person/likes pizza tx4 (10:31) assert
Mutable
E A V T Op
Immutable facts
Id likes
fred pizza
… …
Person table
{ id: fred
likes: “pizza” }
Person document

22. Molecule
Id likes created
fred pizza 10:31
… … …
Person table E A V T Op
fred :person/likes pizza tx4 (10:31) assert
Create Assert
{ id: fred
likes: “pizza”
created: “10:31” }
Person document

23. Molecule
fred :person/likes pizza tx5 (12:45) retract
fred :person/likes pasta tx5 (12:45) assert
Id likes created updated
fred pasta 10:31 12:45
… … …
fred :person/likes pizza tx4 (10:31) assert
Update
Person table
Retract-Assert
Person document
{ id: fred
likes: pasta
created: “10:31”
updated: “12:45” }
E A V T Op

24. Molecule
fred :person/likes pasta tx6 (17:10) retract
fred :person/likes pizza tx5 (12:45) retract
fred :person/likes pasta tx5 (12:45) assert
Id likes created updated
fred NULL 10:31 17:10
… … …
Delete
Person table
Retract
E A V T Op
Person document
{ id: fred
likes: null
created: “10:31”
updated: “17:10” }
fred :person/likes pizza tx4 (10:31) assert

25. Molecule
101 :person/likes pizza tx4 (10:31) assert
101 :person/likes pizza tx5 (12:45) retract
101 :person/likes pasta tx5 (12:45) assert
101 :person/likes pasta tx6 (17:10) retract
Read
E A V T Op [:find ?v
:where
[101 :person/likes ?v]]
=> Nil (no current likes)

26. Molecule
101 :person/likes pizza tx4 (10:31) assert
101 :person/likes pizza tx5 (12:45) retract
101 :person/likes pasta tx5 (12:45) assert
101 :person/likes pasta tx6 (17:10) retract
asOf
E A V T Op [:find ?v
:in db.asOf(tx5)
:where
[101 :person/likes ?v]]
=> [pasta]

27. Molecule
101 :person/likes pizza tx4 (10:31) assert
101 :person/likes pizza tx5 (12:45) retract
101 :person/likes pasta tx5 (12:45) assert
101 :person/likes pasta tx6 (17:10) retract
History
E A V T Op [:find ?v ?t ?op
:in db.history
:where
[101 :person/likes ?v ?t ?op]]
=> [pizza tx4 assert ]
[pasta tx5 retract]
[pasta tx5 assert ]
[pasta tx6 retract]

28. Molecule
101 :person/likes pizza tx1 assert
102 :person/likes pasta tx2 assert
103 :person/likes sushi tx3 assert
104 :person/likes burger tx4 assert
Since
E A V T Op [:find ?v
:in db.since(tx2)
:where
[?e :person/likes ?v]]
=> [sushi burger]
(updated slide)

29. Molecule
101 :person/likes pizza tx4 (10:31) assert
101 :person/likes pizza tx5 (12:45) retract
101 :person/likes pasta tx5 (12:45) assert
101 :person/likes pasta tx6 (17:10) retract
With (the future!)
E A V T Op [:find ?v
:in db.with(testDataTx)
:where
[101 :person/likes ?v]]
=> [penne]
101 :person/likes penne tx7 assert
testDataTx = { id: 101
likes: “penne” }
As though we had created this fact

30. Molecule
Datomic
architecture
Expensive connection
App process (JVM)
App
All-in-one Database server

31. Molecule
App process (JVM)
Datomic
architectureApp
Peer
Transactor
• Separating Reads and writes in 2
processes!
• Peer lib in your app process
• Multiple Peers possible
• Not a client-server (optional)
• No network traffic
Reads
Writes

32. Molecule
App process (JVM)
Datomic
architectureApp
Peer
Query
Transactor
Transactions Storage Service
• In-memory
• SQL
• DynamoDB
• Cassandra
Reads
Writes

33. Molecule
App process (JVM)
Datomic
architectureApp
Peer
Commit
Query
Cache
Transactor
Transactions Storage Service

34. Molecule
App process (JVM)
Datomic
architectureApp
Peer
Commit
Query
Live Index
Cache
Transactor
TransactionsIndexing Storage Service

35. Molecule
App process (JVM)
Datomic
architectureApp
Peer
Commit
Query
Live Index
Cache
Transactor
TransactionsIndexing Storage Service
Memcached cluster

36. Molecule
Datomic
2

37. Molecule
[:find ?name ?age
:where
[?e :person/name ?name]
[?e :person/age ?age]]

38. Molecule
[:find ?name ?age
:where
[?e :person/name ?name]
[?e :person/age ?age]]

39. Molecule
[:find ?name ?age
:where
[?e :person/name ?name]
[?e :person/age ?age]]

40. Molecule

41. Molecule
(Previously `Seq`)

42. Molecule

43. Molecule

44. Molecule

45. Molecule
Macro should create this:

46. Molecule

47. Molecule

48. Molecule

49. Molecule

50. Molecule

51. Molecule
Molecule DSL
Molecules
Your domain terms
Namespace "Person"

52. Molecule
Molecule DSL
Molecules
Your domain terms
Namespace "Person"
Attribute :person/name
Person1[String]

53. Molecule
Molecule DSL
Molecules
Your domain terms
Namespace "Person"
Attribute :person/name
Person1[String]
No need to implement
here - macro
implements!
Only the return type is
needed!

54. Molecule
Molecule DSL
Molecules
Your domain terms
Namespace "Person"
Attribute :person/name
Person1[String]
Attribute :person/age
Person2[String, Int]

55. Molecule
Molecule DSL
MoleculesRuntime API
M2[String, Int]
Returns Seq[(String, Int)]

56. Molecule
Molecule DSL
MoleculesRuntime API
M2[String, Int]
Returns Seq[(String, Int)]
Implemented by macro

57. Molecule

58. Molecule
Molecule DSL
Molecules
A lot of redundant boilerplate code!

59. Molecule
Schema definition
Molecule DSL
SBT plugin generates
Molecules

60. Molecule
Schema definition
Molecule DSL
SBT plugin generates
Molecules
Namespaces

61. Molecule
Schema definition
Molecule DSL
SBT plugin generates
Molecules
Attributes

62. Molecule
Schema definition
Molecule DSL
SBT plugin generates
Molecules
Cardinality /Types

63. Molecule
Schema def DSL
Schema definition
Molecule DSL
SBT plugin generates
Molecules
Card/type
oneString
manyString
oneInt
manyInt
one[Address]
many[InvoiceLine]
...

64. Molecule
Schema def DSL
Schema definition
Molecule DSL
SBT plugin generates
Molecules
oneString.fulltext.doc("name of person")
manyString
oneInt.doc("age of person")
manyInt
one[Address]
many[InvoiceLine].subComponents
etc...
Card/type
Options

65. Molecule
Define
schema
Sbt compile
(once)
Molecule
DSL
Datomic
DSL
Compose
Molecules
Get/Set
Datomic
Data
Compile
Run
Schema
definition
DSL
Molecule eco system

66. Molecule
Define
schema
Sbt compile
(once)
Molecule
DSL
Datomic
DSL
Compose
Molecules
Get/Set
Datomic
Data
Compile
Run
Schema
definition
DSL
You'll be here most of the time
Molecule eco system

67. Molecule
Define
schema
Sbt compile
(once)
Molecule
DSL
Datomic
DSL
Compose
Molecules
Get/Set
Datomic
Data
Compile
Run
Schema
definition
DSL
A DSL to create
a DSL to create
a DSL
... must be a meta-DSL, no?
You'll be here most of the time
Molecule eco system

68. Tour...
Molecule
3

69. Molecule
Core
• Entities
• Attributes
• Expressions
• Relationships
• Composites
• CRUD
Extras
• Map attributes
• Input molecules
• Bidirectional refs
Time
• Tx data
• Tx meta data
• asOf
• history
• since
• with

70. Molecule
Entitieseid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
Groups of facts with common entity id

71. Molecule
Entitieseid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
Groups of facts with common entity id
How can we know what facts are grouped at runtime?
- the schema doesn't tell us...

72. Molecule
Entitieseid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
Entity API

73. Molecule
Entitieseid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
Entity API

74. Molecule
Attributes
eid 104
:person/name Ben
:person/likes pizza
:person/age 5
eid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
eid 103
:person/name Lisa
:person/age 7
Ns.attr --> :ns/attr
"Person names"

75. Molecule
Attributes
eid 104
:person/name Ben
:person/likes pizza
:person/age 5
eid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
eid 103
:person/name Lisa
:person/age 7
Ns.attr.attr2... -->
:ns/attr
:ns/attr2
...
"Person names and ages"

76. Molecule
Attributes
eid 104
:person/name Ben
:person/likes pizza
:person/age 5
eid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
eid 103
:person/name Lisa
:person/age 7 "Person names, ages and likes"

77. Molecule
Attributes
eid 104
:person/name Ben
:person/likes pizza
:person/age 5
eid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
eid 103
:person/name Lisa
:person/age 7
• Mandatory ("attr")
• Fact exists
• Value is returned
• Tacet
• Optional"Person names, ages and likes"

78. Molecule
Attributes
eid 104
:person/name Ben
:person/likes pizza
:person/age 5
eid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
eid 103
:person/name Lisa
:person/age 7
• Mandatory ("attr")
• Fact exists
• Value returned
• Tacet ("attr_")
• Fact exists
• Value not returned
• Optional
"Names and ages of Persons that like something"

79. Molecule
Attributes
eid 104
:person/name Ben
:person/likes pizza
:person/age 5
eid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
eid 103
:person/name Lisa
:person/age 7
• Mandatory ("attr")
• Fact exists
• Value returned
• Tacet ("attr_")
• Fact exists
• Value not returned
• Optional ("attr$")
• Fact may exists
• Option[Value] returned
"Names, ages and possibly likes of Persons"

80. Molecule
Expressions
eid 104
:person/name Ben
:person/likes pizza
:person/age 5
eid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
eid 103
:person/name Lisa
:person/age 7
• Equality
• Fulltext search
• Negation
• Null / Nil
• Comparison
• Aggregates
• Logical OR
"Names and likes of Persons that likes pizza"

81. Molecule
Expressions
• Equality + tacet
• Fulltext search
• Negation
• Null / Nil
• Comparison
• Aggregates
• Logical OR
eid 104
:person/name Ben
:person/likes pizza
:person/age 5
eid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
eid 103
:person/name Lisa
:person/age 7
"Names of persons that like pizza"

82. Molecule
Expressions
eid 104
:person/name Ben
:person/likes pizza
:person/age 5
eid 101
:person/name Fred Ben
:person/likes pizza
:person/age 38
:site/cat customer
eid 103
:person/name Lisa
:person/age 7
• Equality
• Fulltext search
• Negation
• Null / Nil
• Comparison
• Aggregates
• Logical OR

83. Molecule
Expressions
eid 104
:person/name Ben
:person/likes pizza
:person/age 5
eid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
eid 103
:person/name Lisa
:person/age 7
• Equality
• Fulltext search
• Negation
• Null / Nil
• Comparison
• Aggregates
• Logical OR

84. Molecule
Expressions
eid 104
:person/name Ben
:person/likes pizza
:person/age 5
eid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
eid 103
:person/name Lisa
:person/age 7
• Equality
• Fulltext search
• Negation
• Null / Nil
• Comparison
• Aggregates
• Logical OR
"Names of Persons that haven't stated what
they like"
:person/likes fact not asserted for Lisa
- or it has been retracted!

85. Molecule
Expressions
eid 104
:person/name Ben
:person/likes pizza
:person/age 5
eid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
eid 103
:person/name Lisa
:person/age 7
• Equality
• Fulltext search
• Negation
• Null / Nil
• Comparison
• Aggregates
• Logical OR

86. Molecule
Expressions
eid 104
:person/name Ben
:person/likes pizza
:person/age 5
eid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
eid 103
:person/name Lisa
:person/age 7
• Equality
• Fulltext search
• Negation
• Null / Nil
• Comparison
• Aggregates
• Logical OR
"Minimum age of all persons"
"Count of all persons with an age asserted"
"Average age of persons (with age asserted)"

87. Molecule
Expressions
eid 104
:person/name Ben
:person/likes pizza
:person/age 5
eid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
eid 103
:person/name Lisa
:person/age 7
• Equality
• Fulltext search
• Negation
• Null / Nil
• Comparison
• Aggregates
• Logical OR
"Names and ages of Persons that are 5, 6 or 7
years old"

88. Molecule
Relationships
• Card-one
• Card-many
Defining relationships in schema definition

89. Molecule
Relationships
• Card-one
• Card-many

90. Molecule
Relationships
• Card-one
• Card-many
eid attr value
- :person/name -
- :person/home -
- :addr/street -
- :addr/city -

91. Molecule
Relationships
• Card-one
• Card-many
eid attr value
101 :person/name Fred
101 :person/home 102
102 :addr/street Baker St. 7
102 :addr/city Boston

92. Molecule
Relationships
• Card-one
• Card-many
eid attr value
101 :person/name Fred
101 :person/home 102
102 :addr/street Baker St. 7
102 :addr/city Boston
eid 101
:person/name Fred
:person/home 102
eid 102
:addr/street Baker St. 7
:addr/city Boston

93. Molecule
Relationships
• Card-one
• Card-many
eid attr value
101 :person/name Fred
101 :person/home 102
102 :addr/street Baker St. 7
102 :addr/city Boston
eid 101
:person/name Fred
:person/home 102
eid 102
:addr/street Baker St. 7
:addr/city Boston

94. Molecule
Relationships
• Card-one
• Card-many

95. Molecule
Relationshipseid 101
:person/name Fred
:person/home 102
:person/work 103
• Card-one
• Card-manyeid 102
:addr/street Baker St. 7
:addr/city Boston
eid 103
:addr/street Downtown 1
:addr/city Boston
?

96. Molecule
Relationshipseid 101
:person/name Fred
:person/home 102
:person/work 103
• Card-one
• Card-manyeid 102
:addr/street Baker St. 7
:addr/city Boston
eid 103
:addr/street Downtown 1
:addr/city Boston
Back reference (2)
1
2
3

97. Molecule
Relationshipseid 101
:person/name Fred
:person/home 102
:person/work 103
• Card-one
• Card-manyeid 102
:addr/street Baker St. 7
:addr/city Boston
eid 103
:addr/street Downtown 1
:addr/city Boston

98. Molecule
Relationships
More "arms" to the molecule...
• Card-one
• Card-many

99. Molecule
Relationships
• Card-one
• Card-many
eid 101
:order/id 1
:order/items 102, 103
eid 102
:lineItem/qty 3
:lineItem/product Milk
:lineItem/price 12.0
eid 103
:lineItem/qty 2
:lineItem/product Coffee
:lineItem/price 46.0

100. Molecule
Relationships
• Card-one
• Card-many
eid 101
:order/id 1
:order/items 102, 103
eid 102
:lineItem/qty 3
:lineItem/product Milk
:lineItem/price 12.0
eid 103
:lineItem/qty 2
:lineItem/product Coffee
:lineItem/price 46.0

101. Molecule
Relationships
• Card-one
• Card-many
eid 101
:order/id 1
:order/items 102, 103
eid 102
:lineItem/qty 3
:lineItem/product Milk
:lineItem/price 12.0
eid 103
:lineItem/qty 2
:lineItem/product Coffee
:lineItem/price 46.0

102. Molecule
Relationships
• Card-one
• Card-many
eid 101
:order/id 1
:order/items 102, 103
eid 102
:lineItem/qty 3
:lineItem/product Milk
:lineItem/price 12.0
eid 103
:lineItem/qty 2
:lineItem/product Coffee
:lineItem/price 46.0

103. Molecule
Relationshipseid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
The black sheep

104. Molecule
Relationshipseid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
No relationship...

105. Molecule
Relationshipseid 101
:person/name Fred
:person/likes pizza
:person/age 38
:person/site 103
eid 103
:site/cat customer

106. Molecule
Relationshipseid 101
:person/name Fred
:person/likes pizza
:person/age 38
:person/site 103
eid 103
:site/cat customer

107. Molecule
Compositeseid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
"Names, likes, and ages of Persons
+ their Site category"

108. Molecule
Compositeseid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
Independent &
Intrinsic

109. Molecule
[:find ?name ?likes ?age ?cat
:where
[?e :person/name ?name ]
[?e :person/likes ?likes]
[?e :person/age ?age ]
[?e :site/cat ?cat ]
]
=> [Fred pizza 38 customer]
Compositeseid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer

110. Molecule
[:find ?v1 ?v2 ?v3 ?v4
:where
[?e :xlwk/liawj ?v1]
[?e :iauw/sokqx ?v2]
[?e :kzmm/wwpai ?v3]
[?e :ajdg/tybnq ?v4]
]
Attributes can have any name
Namespaces are not tables
Entity ids tie facts together

111. Molecule
Compositeseid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer

112. Molecule
Compositeseid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
:site/status good
"Names, likes, and ages of Persons
+ their Site category and status"

113. Molecule
Compositeseid 101
:person/name Fred
:person/likes pizza
:person/age 38
:site/cat customer
:site/status good
:loc/tag city
"Names, likes, and ages of Persons
+ their Site category and status
+ their Location tag"

114. Molecule
• Create
• Save
• Read
• Update
• Delete
CRUD

115. Molecule
• Create
• Save
• Insert
• Read
• Update
• Delete
CRUD

116. Molecule
• Create
• Save
• Insert
• 2-step insert
• Read
• Update
• Delete
CRUD

117. Molecule
• Create
• Save
• Insert
• 2-step insert
• Read
• Update
• Delete
CRUD

118. Molecule
• Create
• Save
• Insert
• 2-step insert
• Read
• Update
• Card-one
• Delete
CRUD

119. Molecule
• Create
• Save
• Insert
• 2-step insert
• Read
• Update
• Card-one
• Delete
CRUD
fred :person/likes pizza tx4 assert
fred :person/likes pizza tx5 retract
fred :person/likes pasta tx5 assert
E A V T Op

120. Molecule
• Create
• Save
• Insert
• 2-step insert
• Read
• Update
• Card-one
• Delete
CRUD
fred :person/likes pizza tx4 assert
fred :person/likes pizza tx5 retract
fred :person/likes pasta tx5 assert
fred :person/likes pasta tx6 retract
E A V T Op

121. Molecule
• Create
• Save
• Insert
• 2-step insert
• Read
• Update
• Card-one
• Card-many
• Delete
CRUD

122. Molecule
• Create
• Save
• Insert
• 2-step insert
• Read
• Update
• Card-one
• Card-many
• Delete
CRUD

123. Molecule
Core
• Entities
• Attributes
• Expressions
• Relationships
• Composites
• CRUD
Extras
• Map attributes
• Input molecules
• Bidirectional refs
Time
• Tx data
• Tx meta data
• asOf
• history
• since
• with

124. Molecule
Map attributes

125. Molecule
Map attributes

126. Molecule
Map attributes

127. Molecule
Map attributes

128. Molecule
Input molecules

129. Molecule
Input molecules

130. Molecule
Input molecules

131. Molecule
Bidirectional refs

132. Molecule
Bidirectional refs

133. Molecule
Bidirectional refs

134. Molecule
Bidirectional refs

135. Molecule
Bidirectional refs
Ann
Ben
Joe

136. Molecule
Bidirectional refs
Ann
Ben
Joe

137. Molecule
Bidirectional refs
Ann
:knows/weight 7
Ben
:knows/weight 4
Gus
:knows/weight 6
Joe

138. Molecule
Core
• Entities
• Attributes
• Expressions
• Relationships
• Composites
• CRUD
Extras
• Map attributes
• Input molecules
• Bidirectional refs
Time
• Tx data
• Tx meta data
• asOf
• history
• since
• with

139. Molecule
Tx data
e5 :person/name Fred tx4 (10:31) assert
e5 :person/likes pizza tx4 (10:31) assert
E A V T Op

140. Molecule
Tx data
e5 :person/name Fred tx4 (10:31) assert
e5 :person/likes pizza tx4 (10:31) assert
E A V T Op Magic
tx4?

141. Molecule
Magic
tx4
Tx data
e5 :person/name Fred tx4 assert
e5 :person/likes pizza tx4 assert
tx4 :db/txInstant 10:31 ...? assert
E A V T Op
Transaction is an entity!
(here with entity id tx4...)

142. Molecule
Tx data
e5 :person/name Fred tx4 assert
e5 :person/likes pizza tx4 assert
tx4 :db/txInstant date1 tx4 assert
E A V T Op

143. Molecule
Tx data
e5 :person/name Fred e4 assert
e5 :person/likes pizza e4 assert
e4 :db/txInstant date1 e4 assert
E A V T Op

144. Molecule
Tx data
e5 :person/name Fred tx4 assert
e5 :person/likes pizza tx4 assert
tx4 :db/txInstant date1 tx4 assert
E A V T Op

145. Molecule
Tx data
e5 :person/name Fred tx4 assert
e5 :person/likes pizza tx4 assert
tx4 :db/txInstant date1 tx4 assert
E A V T Op
List(
(17592186045445L, :person/name, "Fred", 13194139534340L, true),
(17592186045445L, :person/likes, "pizza", 13194139534340L, true),
(13194139534340L, :db/txInstant, "Tue Apr 26 18:35:41 CEST 2017", 13194139534340L, true)
)

146. Molecule
Tx data
e5 :person/name Fred tx4 assert
e5 :person/likes pizza tx4 assert
tx4 :db/txInstant date1 tx4 assert
E A V T Op
List(
(17592186045445L, :person/name, "Fred", 13194139534340L, true),
(17592186045445L, :person/likes, "pizza", 13194139534340L, true),
(13194139534340L, :db/txInstant, "Tue Apr 26 18:35:41 CEST 2017", 13194139534340L, true)
)
Long clojure.keyword Object (various types) Long Boolean

147. Molecule
Tx data
e5 :person/name Fred tx4 assert
e5 :person/likes pizza tx4 assert
tx4 :db/txInstant date1 tx4 assert
E A V T Op
List(
(17592186045445L, 147L, "Fred", 13194139534340L, true),
(17592186045445L, 148L, "pizza", 13194139534340L, true),
(13194139534340L, 18L, "Tue Apr 26 18:35:41 CEST 2017", 13194139534340L, true)
)
Long Long Object (various types) Long Boolean

148. Molecule
Tx data
e5 :person/name Fred tx4 assert
e5 :person/likes pizza tx4 assert
tx4 :db/txInstant date1 tx4 assert
E A V T Op
In what transaction was
Freds name asserted?

149. Molecule
Tx data
e5 :person/name Fred tx4 assert
e5 :person/likes pizza tx4 assert
tx4 :db/txInstant date1 tx4 assert
E A V T Op
When was Freds name asserted?

150. Molecule
Tx meta data
e5 :person/name Fred tx4 assert
e5 :person/likes pizza tx4 assert
tx4 :db/txInstant date1 tx4 assert
tx4 ... ... tx4 assert
tx4 ... ... tx4 assert
E A V T Op

151. Molecule
Tx meta data
e5 :person/name Fred tx4 assert
e5 :person/likes pizza tx4 assert
tx4 :db/txInstant date1 tx4 assert
tx4 :audit/user Lisa tx4 assert
tx4 ... ... tx4 assert
E A V T Op
Who did it?

152. Molecule
Tx meta data
e5 :person/name Fred tx4 assert
e5 :person/likes pizza tx4 assert
tx4 :db/txInstant date1 tx4 assert
tx4 :audit/user Lisa tx4 assert
tx4 :audit/uc survey tx4 assert
E A V T Op
Who did it?
Why?

153. Molecule
Tx meta data
e5 :person/name Fred tx4 assert
e5 :person/likes pizza tx4 assert
tx4 :db/txInstant date1 tx4 assert
tx4 :audit/user Lisa tx4 assert
tx4 :audit/uc survey tx4 assert
E A V T Op
Who did it?
Why?

154. Molecule
Tx meta data
e5 :person/name Fred tx4 assert
e5 :person/likes pizza tx4 assert
tx4 :db/txInstant date1 tx4 assert
tx4 :audit/user Lisa tx4 assert
tx4 :audit/uc survey tx4 assert
E A V T Op
Who did it?
Why?
"Lisa added Fred as part of a survey"

155. Molecule
Tx meta data
e5 :person/name Fred tx4 assert
e5 :person/likes pizza tx4 assert
tx4 :db/txInstant date1 tx4 assert
tx4 :audit/user Lisa tx4 assert
tx4 :audit/uc survey tx4 assert
E A V T Op
When did they do it?
Who did it?
Why?
"Lisa added Fred as part of a survey
onTuesday the 26th of April"

156. Molecule
Tx meta data
e5 :person/name Fred tx4 assert
e5 :person/likes pizza tx4 assert
tx4 :db/txInstant date1 tx4 assert
tx4 :audit/user Lisa tx4 assert
tx4 :audit/uc survey tx4 assert
E A V T Op
When did they do it?
Who did it?
Why?
"Fred was surveyed"

157. Molecule
Tx meta data
e5 :person/name Fred tx4 assert
e5 :person/likes pizza tx4 assert
tx4 :db/txInstant date1 tx4 assert
tx4 :audit/user Lisa tx4 assert
tx4 :audit/uc survey tx4 assert
E A V T Op
When did they do it?
Who did it?
Why?
"Lisas surveyee liked pizza"

158. Molecule
asOf
fred :person/name Fred t1 assert
fred :person/likes pizza t1 assert
E A V T Op

159. Molecule
asOf
fred :person/name Fred t1 assert
fred :person/likes pizza t1 assert
fred :person/likes pizza t2 retract
fred :person/likes pasta t2 assert
E A V T Op

160. Molecule
asOf
fred :person/name Fred t1 assert
fred :person/likes pizza t1 assert
fred :person/likes pizza t2 retract
fred :person/likes pasta t2 assert
E A V T Op
"What did Fred like before?"

161. Molecule
history
fred :person/name Fred t1 TRUE
fred :person/likes pizza t1 TRUE
fred :person/likes pizza t2 FALSE
fred :person/likes pasta t2 TRUE
E A V T Added
API changed from `.history.get` to `.getHistory`
All time filters now have the verb form `get<filter>`
This should avoid confusion with attribute names

162. Molecule
history
fred :person/name Fred t1 TRUE
fred :person/likes pizza t1 TRUE
fred :person/likes pizza t2 FALSE
fred :person/likes pasta t2 TRUE
E A V T Added

163. Molecule
history
E A/V T Op
Getting all generic data about the `like` attribute history:
Generic attributes tie to a single domain attribute

164. Molecule
history
E A V T Op
... or go fully generic and ask for any attribute history of an entity:

165. Molecule
history
"What has Fred liked?"

166. Molecule
history
"What has Fred disliked?"

167. Molecule
history
"Who have disliked what and when?"
Multiple mandatory attributes not allowed in history queries.
It would be like unifying multiple timelines into one timeline
which is not useful.

168. Molecule
history
"Who have disliked what and when?"
Instead, ask for entity ids with the generic `e`.

169. Molecule
history + tx meta data
Only one mandatory attribute! ...

170. Molecule
history + tx meta data
Use generic `e` to get entity id instead.

171. Molecule
history + tx meta data
"Who changed what taste
during interviews with Peter?"

172. Molecule
history + tx meta data
"Who changed what taste
during interviews with Peter and when?"
"Who disliked pizza
during an interview and when?"

173. Molecule
history + tx meta data
Who changed what taste
during interviews with Peter and when?
Who disliked pizza
during an interview and when?
Who liked what and when?
Who got the info in what use case?

174. Molecule
since
101 :person/likes pizza tx1 TRUE
102 :person/likes pasta tx2 TRUE
103 :person/likes sushi tx3 TRUE
104 :person/likes burger tx4 TRUE
E A V T Added
(updated slide)

175. Molecule
with
What if ...?
Would that work?
(presented as now deprecated `imagine`)

176. Molecule
with
What if we update Freds age?

177. Molecule
with
What if we save a new person?

178. Molecule
with
What if we insert 2 persons?

179. Molecule
with
What if we do all 3 things...?

180. Molecule
with
Test modulerized transactions...

181. Molecule
Core
• Entities
• Attributes
• Expressions
• Relationships
• Composites
• CRUD
Extras
• Map attributes
• Input molecules
• Bidirectional refs
Time
• Tx data
• Tx meta data
• asOf
• history
• since
• with
3
Questions?

182. Domain modelling
Molecule
4

183. Molecule
Person
• id
• name
• born
‣ doThis()
‣ doThat()

184. Molecule
Person
• id
• name
• born
‣ doThis()
‣ doThat()
‣ ctx1a()
‣ ctx1b()
‣ ctx2a()
Ctx 1
person1.doThis()
person2.ctx1a()
person1.ctx1b()
Ctx 2
person2.ctx2a()
Slow changing
Fast changing
Runtime

185. Molecule
Person
• id
• name
• born
‣ doThis()
‣ doThat()
‣ ctx1a()
‣ ctx1b()
‣ ctx2a()
‣ ctx2b()
‣ ctx3a()
‣ ctx3b()
‣ ctx4a()
‣ ctx4b()
‣ ctx5a()
‣ ctx5b()
‣ etc...
Ctx 1
person1.doThis()
person2.ctx1a()
person1.ctx1b()
Ctx 2
person2.ctx2a()
Slow changing
Fast changing
Ctx 4
person.ctx4b()
Runtime
Ctx 5
person.ctx5a()
Ctx 3
person.ctx3b()
Ctx 6
person2.ctx6a() C
person2

186. Molecule
Person
• id
• name
• born
‣ doThis()
‣ doThat()
Ctx 1
customer.doThis()
customer.buy()
Ctx 2
user.login()
Slow changing
Not so fast changing
Ctx 3
manager.add(p1)
Customer
‣ buy()
‣ complain()
User
‣ login()
‣ comment()
Manager
‣ add(person)
‣ getReport()
Faster changing
Runtime

187. Molecule
Person
• id
• name
• born
‣ doThis()
‣ doThat()
Ctx 1
customer.doThis()
customer.buy()
Ctx 2
user.login()
Slow changing
Not so fast changing
Ctx 3
manager.login()
manager.add(p1)
Customer
‣ buy()
‣ complain()
User
‣ login()
‣ comment()
Manager
‣ add(person)
‣ getReport()
Faster changing
Relatively faster changing
Runtime

188. Molecule
Person
• id
• name
• born
PersonService(p)
‣ p.doThis()
‣ p.doThat()
‣ p.ctx1a()
‣ p.ctx1b()
‣ p.ctx2a()
‣ etc...
Ctx 1
personService(p1).doThis()
personService(p2).ctx1a()
personService(p1).ctx1b()
Ctx 2
person2.ctx2a()
Fast changing RuntimeSlow changing

189. Molecule
Person
• id
• name
• born
PersonCmdCtx1(p)
‣ p.ctx1a()
‣ p.ctx1b()
Ctx 1
PersonCmdCtx1(p2).ctx1a()
PersonCmdCtx1(p1).ctx1b()
Ctx 2
PersonCmdCtx2.ctx2a()
PersonCmdCtx2(p)
‣ p.ctx2a()
Slow changing Fast changing Runtime

190. Molecule
Entity
• id
• attr1
• attr2
• etc...
Slow changing Fast changing
EntityConsumer(e)
‣ action1()
‣ action2()
‣ etc()
• Services
• Event source commands
• Ad hoc classes
• Etc..

191. Molecule
EntityConsumer(e)
‣ action1()
‣ action2()
‣ etc()
Person
• id
• name
• born
Customer
• status
User
• email
• passw
Manager
• clearance
• employees
Seldom changing
Often changing
Occassionally changing
And more subtypes...
Fast changing

192. Molecule
EntityConsumer(e)
‣ action1()
‣ action2()
‣ etc()
Person
• id
• born
• name
Customer
• status
User
• email
• passw
Manager
• clearance
• employees
Very seldom changing
Often changing
Occassionally changing
Never changing
And more subtypes...
Fast changing

193. Molecule
EntityConsumer(e)
‣ changePassw()
Molecular EntitiesAtomic Attributes
Person variations...
eid 101
:person/name
:user/email
:user/passw
:person/id
:person/born
:person/name
:user/email
:user/passw
:site/status
:auth/clearance
:mgt/employees
:mgt/employees
eid 101
:auth/clearance EntityConsumer(e)
‣ authorize(employee)
(User)
(Manager 1)
(Manager 2)
eid 101
:auth/clearance
:mgt/employees
EntityConsumer(e)
‣ add(employee)
Entity consumers

194. Molecule
EmployeeAdministration(eid)
‣ add(employee)
Authorization(eid)
‣ authorize(employee)
PasswChange(eid)
‣ setNew(passw)
Atomic Attributes
eid 101
:person/name
:user/email
:user/passw
:person/id
:person/born
:person/name
:user/email
:user/passw
:site/status
:auth/clearance
:mgt/employees
:mgt/employees
eid 101
:auth/clearance
(User)
(Manager 1)
(Manager 2)eid 101
:auth/clearance
:mgt/employees
Entity id consumers - with molecular entities

195. Molecule
EmployeeAdministration(eid)
‣ add(employee)
Authorization(eid)
‣ authorize(employee)
:person/id
:person/born
:person/name
:user/email
:user/passw
:site/status
:auth/clearance
:mgt/employees
:mgt/employees
eid 101
:auth/clearance (Manager 1)
(Manager 2)eid 101
:auth/clearance
:mgt/employees
no
domain
classes!?
PasswChange(eid)
‣ setNew(passw)
eid 101
:person/name
:user/email
:user/passw
(User)
Atomic Attributes Entity id consumers - with molecular entities

196. Molecule
Molecular entities
PasswChange(eid, newPassw)
‣ setNew(passw)
eid 101
:person/name
:user/email
:user/passw
(User)

197. Molecule
PasswChange(eid, newPassw)
Get current User data:
Check stuff...
Save:
Molecules

198. Molecule
Molecules• Get data from the app process
• No need to cast raw data from
a db server to populate rigid
domain classes, only to pull the
data out again
• Get/set exactly the data you
need
• Always typed data
• Easy type-safe migrations
• Use your domain terms directly
• Absolute minium of ceremony
• Maximum runtime performance
• Time
• Fun!
PasswChange(eid, newPassw)
Get current User data:
Check stuff...
Save:

199. Molecule
• Get data from the app process
• No need to cast raw data from
a db server to populate rigid
domain classes, only to pull it out
again
• Get/set exactly the data you
need
• Always typed data
• Easy type-safe migrations
• Use your domain terms directly
• Absolute minium of ceremony
• Maximum runtime performance
• Time
• Fun!
Thank you!
Questions?

200. Molecule
4
github.com/scalamolecule/molecule
scalamolecule.org
datomic.com
Marc Grue
April 2017