Selection functions
lookup
Commentary
added in 0.0.5
Retrieves a previously generated event from the supplied collection, optionally drilling into it with a path. This lets you create relationships, through shared identifiers, across different data sets.
ShadowTraffic guarantees that events will only be available for lookup after they have been successfully written to the target collection.
By default, the event chosen from a lookup is entirely random. But if you like, you can bias how the event is chosen from the population using a histogram. 1
Examples
Kafka lookup
Look up data in another Kafka topic.
{
"generators": [
{
"topic": "a",
"key": {
"id": {
"_gen": "string",
"expr": "#{Name.firstName}"
}
}
},
{
"topic": "b",
"value": {
"_gen": "lookup",
"topic": "a",
"path": [
"key",
"id"
]
}
}
],
"connections": {
"kafka": {
"kind": "kafka",
"producerConfigs": {
"bootstrap.servers": "localhost:9092",
"key.serializer": "io.shadowtraffic.kafka.serdes.JsonSerializer",
"value.serializer": "io.shadowtraffic.kafka.serdes.JsonSerializer"
}
}
}
}
[
{
"topic": "a",
"key": {
"id": "Wyatt"
},
"value": null,
"headers": null
},
{
"topic": "b",
"key": null,
"value": "Wyatt",
"headers": null
},
{
"topic": "a",
"key": {
"id": "Frederica"
},
"value": null,
"headers": null
},
{
"topic": "b",
"key": null,
"value": "Frederica",
"headers": null
},
{
"topic": "a",
"key": {
"id": "Victor"
},
"value": null,
"headers": null
}
]
Postgres lookup
Look up data in a Postgres table.
{
"generators": [
{
"table": "a",
"row": {
"id": {
"_gen": "string",
"expr": "#{Name.firstName}"
}
}
},
{
"table": "b",
"row": {
"id": {
"_gen": "lookup",
"table": "a",
"path": [
"row",
"id"
]
}
}
}
],
"connections": {
"postgres": {
"kind": "postgres",
"connectionConfigs": {
"host": "localhost",
"port": 5432,
"username": "postgres",
"password": "postgres",
"db": "mydb"
}
}
}
}
[
{
"table": "a",
"row": {
"id": "Bryon"
},
"op": null,
"where": null
},
{
"table": "b",
"row": {
"id": "Bryon"
},
"op": null,
"where": null
},
{
"table": "a",
"row": {
"id": "Esta"
},
"op": null,
"where": null
},
{
"table": "b",
"row": {
"id": "Esta"
},
"op": null,
"where": null
},
{
"table": "a",
"row": {
"id": "Vanesa"
},
"op": null,
"where": null
}
]
Periodic lookups
Sometimes make a new key, sometimes use a previously generated one.
{
"generators": [
{
"topic": "users",
"key": {
"_gen": "weightedOneOf",
"choices": [
{
"weight": 5,
"value": {
"_gen": "string",
"expr": "#{Name.fullName}"
}
},
{
"weight": 5,
"value": {
"_gen": "lookup",
"topic": "users",
"path": [
"key"
]
}
}
]
}
}
],
"connections": {
"kafka": {
"kind": "kafka",
"producerConfigs": {
"bootstrap.servers": "localhost:9092",
"key.serializer": "io.shadowtraffic.kafka.serdes.JsonSerializer",
"value.serializer": "io.shadowtraffic.kafka.serdes.JsonSerializer"
}
}
}
}
[
{
"topic": "users",
"key": "Rudolf Nitzsche",
"value": null,
"headers": null
},
{
"topic": "users",
"key": "Willie Bruen",
"value": null,
"headers": null
},
{
"topic": "users",
"key": "Kerry Raynor",
"value": null,
"headers": null
},
{
"topic": "users",
"key": "Kerry Raynor",
"value": null,
"headers": null
},
{
"topic": "users",
"key": "Erich Grant",
"value": null,
"headers": null
},
{
"topic": "users",
"key": "Juana Becker V",
"value": null,
"headers": null
},
{
"topic": "users",
"key": "Kerry Raynor",
"value": null,
"headers": null
},
{
"topic": "users",
"key": "Ron Stroman II",
"value": null,
"headers": null
}
]
Explicit connections
Explicitly supply the connection name when there are multiple connections.
{
"generators": [
{
"connection": "postgres",
"table": "a",
"row": {
"email": {
"_gen": "string",
"expr": "#{Internet.emailAddress}"
}
}
},
{
"connection": "kafka",
"topic": "b",
"value": {
"_gen": "lookup",
"connection": "postgres",
"table": "a",
"path": [
"row",
"email"
]
}
}
],
"connections": {
"kafka": {
"kind": "kafka",
"producerConfigs": {
"bootstrap.servers": "localhost:9092",
"key.serializer": "io.shadowtraffic.kafka.serdes.JsonSerializer",
"value.serializer": "io.shadowtraffic.kafka.serdes.JsonSerializer"
}
},
"postgres": {
"kind": "postgres",
"connectionConfigs": {
"host": "localhost",
"port": 5432,
"username": "postgres",
"password": "postgres",
"db": "mydb"
}
}
}
}
[
{
"table": "a",
"row": {
"email": "rhett.douglas@hotmail.com"
},
"op": null,
"where": null
},
{
"topic": "b",
"key": null,
"value": "rhett.douglas@hotmail.com",
"headers": null
},
{
"table": "a",
"row": {
"email": "efrain.gutkowski@hotmail.com"
},
"op": null,
"where": null
},
{
"topic": "b",
"key": null,
"value": "efrain.gutkowski@hotmail.com",
"headers": null
},
{
"table": "a",
"row": {
"email": "majorie.waters@hotmail.com"
},
"op": null,
"where": null
}
]
Controlling distribution
Use a histogram to control how the element is selected from the population. This invocation chooses 20% of the elements 80% of the time from a Kafka topic.
{
"generators": [
{
"topic": "a",
"key": {
"id": {
"_gen": "string",
"expr": "#{Name.fullName}"
}
}
},
{
"topic": "b",
"value": {
"_gen": "lookup",
"topic": "a",
"path": [
"key",
"id"
],
"histogram": {
"_gen": "histogram",
"bins": [
{
"bin": 0.2,
"frequency": 8
},
{
"bin": 0.8,
"frequency": 2
}
]
}
}
}
],
"connections": {
"kafka": {
"kind": "kafka",
"producerConfigs": {
"bootstrap.servers": "localhost:9092",
"key.serializer": "io.shadowtraffic.kafka.serdes.JsonSerializer",
"value.serializer": "io.shadowtraffic.kafka.serdes.JsonSerializer"
}
}
}
}
[
{
"topic": "a",
"key": {
"id": "Loraine Hermann"
},
"value": null,
"headers": null
},
{
"topic": "b",
"key": null,
"value": "Loraine Hermann",
"headers": null
},
{
"topic": "a",
"key": {
"id": "Miss Kyle Dibbert"
},
"value": null,
"headers": null
},
{
"topic": "b",
"key": null,
"value": "Loraine Hermann",
"headers": null
},
{
"topic": "a",
"key": {
"id": "Giovanni Bayer"
},
"value": null,
"headers": null
},
{
"topic": "b",
"key": null,
"value": "Loraine Hermann",
"headers": null
},
{
"topic": "a",
"key": {
"id": "Renato Purdy"
},
"value": null,
"headers": null
},
{
"topic": "b",
"key": null,
"value": "Loraine Hermann",
"headers": null
},
{
"topic": "a",
"key": {
"id": "Julie Graham"
},
"value": null,
"headers": null
},
{
"topic": "b",
"key": null,
"value": "Julie Graham",
"headers": null
}
]
Multiple lookups
If you need to look up multiple fields, be careful not to use lookup more than once in the same generator. Multiple calls are not consistent. In other words, they won't return the same event in each call.
Instead, call lookup just once by using a variable and setting path to [] to grab then entire event. Then pick out the relevant fields.
[
{
"topic": "a",
"key": {
"name": {
"_gen": "string",
"expr": "#{Name.fullName}"
},
"magicNumber": {
"_gen": "uniformDistribution",
"bounds": [
0,
100
],
"decimals": 0
}
}
},
{
"topic": "b",
"vars": {
"result": {
"_gen": "lookup",
"topic": "a",
"path": []
}
},
"value": {
"lookedUpName": {
"_gen": "var",
"var": "result",
"path": [
"key",
"name"
]
},
"lookedUpNumber": {
"_gen": "var",
"var": "result",
"path": [
"key",
"magicNumber"
]
}
}
}
]
[
{
"topic": "a",
"key": {
"name": "Theodora Emard",
"magicNumber": 52
},
"value": null,
"headers": null
},
{
"topic": "b",
"key": null,
"value": {
"lookedUpName": "Theodora Emard",
"lookedUpNumber": 52
},
"headers": null
},
{
"topic": "a",
"key": {
"name": "Nannie Wehner III",
"magicNumber": 72
},
"value": null,
"headers": null
},
{
"topic": "b",
"key": null,
"value": {
"lookedUpName": "Nannie Wehner III",
"lookedUpNumber": 72
},
"headers": null
},
{
"topic": "a",
"key": {
"name": "Gale Dicki",
"magicNumber": 66
},
"value": null,
"headers": null
},
{
"topic": "b",
"key": null,
"value": {
"lookedUpName": "Nannie Wehner III",
"lookedUpNumber": 72
},
"headers": null
},
{
"topic": "a",
"key": {
"name": "Sammie Kuhlman",
"magicNumber": 35
},
"value": null,
"headers": null
},
{
"topic": "b",
"key": null,
"value": {
"lookedUpName": "Nannie Wehner III",
"lookedUpNumber": 72
},
"headers": null
},
{
"topic": "a",
"key": {
"name": "Mora Will",
"magicNumber": 87
},
"value": null,
"headers": null
},
{
"topic": "b",
"key": null,
"value": {
"lookedUpName": "Sammie Kuhlman",
"lookedUpNumber": 35
},
"headers": null
}
]
Specification
JSON schema
Lookups against different connection types have different schemas. Each schema is listed below in array form.
[
{
"name": "Kafka",
"schema": {
"type": "object",
"properties": {
"connection": {
"type": "string"
},
"topic": {
"type": "string"
},
"path": {
"type": "array",
"items": {
"oneOf": [
{
"type": "integer",
"minimum": 0
},
{
"type": "string"
}
]
}
}
},
"required": [
"topic",
"path"
]
}
},
{
"name": "Postgres",
"schema": {
"type": "object",
"properties": {
"connection": {
"type": "string"
},
"table": {
"type": "string"
},
"path": {
"type": "array",
"items": {
"oneOf": [
{
"type": "integer",
"minimum": 0
},
{
"type": "string"
}
]
}
}
},
"required": [
"table",
"path"
]
}
},
{
"name": "sqlServer",
"schema": {
"type": "object",
"properties": {
"connection": {
"type": "string"
},
"table": {
"type": "string"
},
"path": {
"type": "array",
"items": {
"oneOf": [
{
"type": "integer",
"minimum": 0
},
{
"type": "string"
}
]
}
}
},
"required": [
"table",
"path"
]
}
},
{
"name": "Proton",
"schema": {
"type": "object",
"properties": {
"connection": {
"type": "string"
},
"stream": {
"type": "string"
},
"path": {
"type": "array",
"items": {
"oneOf": [
{
"type": "integer",
"minimum": 0
},
{
"type": "string"
}
]
}
}
},
"required": [
"stream",
"path"
]
}
},
{
"name": "Timeplus",
"schema": {
"type": "object",
"properties": {
"connection": {
"type": "string"
},
"stream": {
"type": "string"
},
"path": {
"type": "array",
"items": {
"oneOf": [
{
"type": "integer",
"minimum": 0
},
{
"type": "string"
}
]
}
}
},
"required": [
"stream",
"path"
]
}
},
{
"name": "S3",
"schema": {
"type": "object",
"properties": {
"connection": {
"type": "string"
},
"bucket": {
"type": "string"
},
"path": {
"type": "array",
"items": {
"oneOf": [
{
"type": "integer",
"minimum": 0
},
{
"type": "string"
}
]
}
}
},
"required": [
"bucket",
"path"
]
}
},
{
"name": "googleCloudStorage",
"schema": {
"type": "object",
"properties": {
"connection": {
"type": "string"
},
"bucket": {
"type": "string"
},
"blobPrefix": {
"type": "string"
},
"path": {
"type": "array",
"items": {
"oneOf": [
{
"type": "integer",
"minimum": 0
},
{
"type": "string"
}
]
}
}
},
"required": [
"bucket",
"blobPrefix",
"path"
]
}
},
{
"name": "azureBlobStorage",
"schema": {
"type": "object",
"properties": {
"connection": {
"type": "string"
},
"container": {
"type": "string"
},
"path": {
"type": "array",
"items": {
"oneOf": [
{
"type": "integer",
"minimum": 0
},
{
"type": "string"
}
]
}
}
},
"required": [
"container",
"path"
]
}
},
{
"name": "fileSystem",
"schema": {
"type": "object",
"properties": {
"connection": {
"type": "string"
},
"fileName": {
"type": "string"
},
"path": {
"type": "array",
"items": {
"oneOf": [
{
"type": "integer",
"minimum": 0
},
{
"type": "string"
}
]
}
}
},
"required": [
"fileName",
"path"
]
}
},
{
"name": "EventStore",
"schema": {
"type": "object",
"properties": {
"connection": {
"type": "string"
},
"stream": {
"type": "string"
},
"path": {
"type": "array",
"items": {
"oneOf": [
{
"type": "integer",
"minimum": 0
},
{
"type": "string"
}
]
}
}
},
"required": [
"stream",
"path"
]
}
},
{
"name": "Webhook",
"schema": {
"type": "object",
"properties": {
"connection": {
"type": "string"
},
"url": {
"type": "string"
},
"path": {
"type": "array",
"items": {
"oneOf": [
{
"type": "integer",
"minimum": 0
},
{
"type": "string"
}
]
}
}
},
"required": [
"url",
"path"
]
}
}
]