flows

package module
v0.2.9 Latest Latest
Warning

This package is not in the latest version of its module.

 Go to latest Published: Sep 24, 2023 License: GPL-3.0 Imports: 27 Imported by: 10

README

Flows

Simple declarative and functional dataflow with Kafka.

Developing

Tools Used

Please follow the tools setup guide in its respective repository or documentation.

  • Golang
  • Gomock
  • Podman / docker
  • Protoc
  • Protoc-gen-go
  • Psql
Commands

Makefile is heavily used.

Commands used when coding:

make test
make tidy
make update
make mocks
make proto
make cov
make htmlcov

Commands used when running examples locally:

make reset
make run
make listen
make group-delete

Main func is in main folder instead of the project root, as the project root is used for library package.

Running Example

See the source in example folder

docker-compose up -d
make reset
make run
  1. docker-compose up -d will start zookeeper, kafka, and postgresql with ports exposed to your host network detached from your terminal
  2. make reset will clean up the topics on kafka and postgresql table, and add some example events
  3. make run will start the example word count application

There are three examples, its manually switched via comments in the main folder in main.go

Test

Some tests uses testcontainers-go which are set up for rootless Podman based context. Switching between different container technology will be done some time in the future.

Principles

  • Container first
  • Do one thing, and only one thing well
  • Ease to change integrations
  • Protobuf as primary bytes encoding
  • Sane defaults
  • Simple format helpers, with bytes as default
  • Idiomatic golang

Integrations

  • Kafka using Sarama
  • Postgresql using Bun

Patterns

Flows sits at the core of the Kappa Architecture, where it tackles four elements:

  1. Stateless functions
  2. Stateful functions
  3. Join as combination of stateless and stateful functions
  4. Materialisation
  5. Collector
Stateless

Stateless functions can be used to perform simple operations such as:

  1. Basic event filtering
  2. Event mirroring
  3. Merging multiple topics into one
  4. Exploding events
  5. Interfacing with external parties with at least once semantic
Stateful

Stateful functions can be used to perform state machine operations on exactly one topic to perform operations such as:

  1. Reduce or aggregate
  2. Validation
Join

To ensure events are published for the multiple topics that are being joined, there are two options:

  1. Maintain publishing state for all topics (currently, the last result state is global per key, this can be changed to be per topic per key)
  2. Merge topics into one intermediate topic, and perform a stateful function

In this codebase, option two is the chosen option for reasons of:

  1. Avoiding to impose limits on the number of messages being published, which can increase the state size written into the store, which implication should be obvious
  2. Stateless map that can be used to merge topics are cheaper in terms of time latency than transaction locking failure
  3. Kafka can be configured to be scalable enough in terms of throughput
  4. Parallelism of the intermediate topic (partition count) can be higher than the source topics
  5. Avoiding transaction will reduce cost and increase speed especially for cloud services
  6. Avoiding distributed data contention allows local state caching, reducing data query latency for cache hits

Join Pattern

It is recommended to use your own custom intermediate topic mapper for better control of your dataflow. However, a standard implementation is provided as a reference.

Materialiser

Materialise function batch upserts into database.

Collector

In an extremely high throughput situation, it makes a lot of sense to:

  1. Pre-aggregate input topics
  2. Perform stateful operation against pre-aggregated output

This reduces the amount of state writes performed. Even when RAM based reliable redundant storage is used, it is still wise to pre-aggregate in a very high throughput situation against stateful operations.

Example:

  1. In an ecommerce inventory handling for orders, the orders can be pre-aggregated (to a certain extent where the message size does not blow up the Kafka cluster), and final inventory check is performed one time for all the pre-aggregated orders
  2. In an event space management system, the updates against seat booking can be pre-aggregated before checking against the entire section

Limitations

To keep the simplicity of implementation, temporal operations are not yet considered in this project. Examples of temporal operations that are not considered for implementation yet:

  1. End of time window only publishing. With states, a window can be emulated, but an output will be published for each message received instead of only at the end of the window.
  2. Per-key publication rate limiter. Combining state storage, commit offset, and real time ticks can be implemented, however that complicates the interfaces needed.

To Do

  1. Integrations
    1. MongoDB
    2. Cassandra
    3. AWS DynamoDB
    4. GCP Bigtable
  2. Local state caching
  3. Unit test coverage
  4. Replace prometheus with otel

Notes

This project solves dataflow in a very specific way. If you are interested to improve this project more or have some feedback, please contact me.

Kafka Migration

The way to migrate stateful functions to a mirrored Kafka cluster are by:

  1. Stopping the job
  2. Clearing the internal column / field
  3. Starting the job

Due to the fact that offset numbers are different in mirrored Kafka cluster, an additional application functionality side deduplication will be required to ensure that stateful operation does not get executed twice. Such deduplication can be peformed using a unique Kafka header identifier.

However, if the application functionality can already tolerate at least once execution, then there will be no problems with migration.

Functions

The functions are used as is, because function for pointer struct can be used as is. As proof, the following unit test will pass.

import (
	"testing"

	"github.com/stretchr/testify/assert"
)

type TestStruct struct {
	Test int
}

func (t *TestStruct) Inc() {
	t.Test += 1
}

type TestStructTwo struct {
	Test int
}

func (t TestStructTwo) Get() int {
	return t.Test
}

func Inc(fn func()) {
	fn()
}

func Get(fn func() int) int {
	return fn()
}

func TestPointerStuff(t *testing.T) {
	assert := assert.New(t)
	testOne := TestStruct{
		Test: 1,
	}
	Inc(testOne.Inc)
	assert.Equal(2, testOne.Test)

	testTwo := &TestStruct{
		Test: 4,
	}
	Inc(testTwo.Inc)
	assert.Equal(5, testTwo.Test)

	testThree := TestStructTwo{
		Test: 100,
	}
	assert.Equal(100, Get(testThree.Get))

	testFour := &TestStructTwo{
		Test: 200,
	}
	assert.Equal(200, Get(testFour.Get))
}

Rootless Podman

You only need to add DOCKER_HOST according to your podman info. Example:

export DOCKER_HOST=unix:///run/user/1000/podman/podman.sock

Microbatching

Microbatching is applied in this repository to achieve better throughput. Maximum batching wait time can be configured.

Documentation

Index

Constants

View Source 
const (
	QualifierKafkaConsumer              = "QualifierKafkaConsumer"
	QualifierKafkaConsumerHandler       = "QualifierKafkaConsumerHandler"
	QualifierKafkaConsumerBatchFunction = "QualifierKafkaConsumerBatchFunction"
	QualifierKafkaConsumerKeyFunction   = "QualifierKafkaConsumerKeyFunction"
	QualifierConsumerFunction           = "QualifierFlowStateless"
)
View Source 
const (
	AllInstances = "all_instances"
)
View Source 
const (
	QualifierPostgresqlConnection = "QualifierPostgresqlConnection"
)
View Source 
const (
	QualifierRetry = "QualifierRetry"
)
View Source 
const (
	QualifierRoute = "QualifierRoute"
)
View Source 
const (
	QualifierRuntime = "QualifierRuntime"
)

Variables

View Source 
var (
	QualifierKafkaProducer = "QualifierKafkaProducer"
)

Functions

func GetKafkaProducer added in v0.0.20 

func GetKafkaProducer(ctx context.Context, ci inverse.Container) (flow.Producer, error)

func GetPostgresqlConnection added in v0.2.3 

func GetPostgresqlConnection(ctx context.Context, ci inverse.Container) (runtime_bun.BunConnection, error)

func GetRetry added in v0.0.20 

func GetRetry(ctx context.Context, ci inverse.Container) (*runtime_retry.Retry, error)

func InjectedRuntimes added in v0.0.20 

func InjectedRuntimes(ci inverse.Container) []runtime.Runtime

func RegisterCollectorFunction added in v0.2.4 

func RegisterCollectorFunction(
	ci inverse.Container,
	topic string,
	persistenceIdFunction stateful.PersistenceIdFunction[[]byte, []byte],
	aggregator collect.Aggregator[structure.Bytes, structure.Bytes, structure.Bytes],
	collector collect.Collector,
)

func RegisterConsumer added in v0.1.0 

func RegisterConsumer(
	container inverse.Container,
	name string,
	broker string,
	configs []runtime.Configuration[*runtime_sarama.Consumer],
)

func RegisterConsumerConfig added in v0.1.4 

func RegisterConsumerConfig(ci inverse.Container, configs ...runtime.Configuration[*runtime_sarama.Consumer])

func RegisterConsumerFunctionInjector added in v0.2.4 

func RegisterConsumerFunctionInjector(injector inverse.Injector[ConsumerFunction], ci inverse.Container)

func RegisterConsumerFunctionInstance added in v0.2.4 

func RegisterConsumerFunctionInstance(instance ConsumerFunction, ci inverse.Container)

func RegisterConsumerKeyedHandlerConfig added in v0.2.6 

func RegisterConsumerKeyedHandlerConfig(ci inverse.Container, configs ...runtime.Configuration[*runtime_sarama.KeyedHandler])

func RegisterJoinStatefulFunction added in v0.2.6 

func RegisterJoinStatefulFunction(
	ci inverse.Container,
	topic string,
	tableName string,
	fn stateful.SingleFunction,
	key stateful.PersistenceIdFunction[structure.Bytes, structure.Bytes],
)

func RegisterMaterialiseFunction added in v0.2.4 

func RegisterMaterialiseFunction[T any](
	ci inverse.Container,
	topic string,
	fn materialise.MapFunction[structure.Bytes, structure.Bytes, T],
)

func RegisterPostgresql added in v0.0.20 

func RegisterPostgresql(
	container inverse.Container,
	name string,
	connectionString string,
	configs []runtime.Configuration[*runtime_bun.PostgresqlConnection],
)

func RegisterPostgresqlConfig added in v0.1.4 

func RegisterPostgresqlConfig(ci inverse.Container, configs ...runtime.Configuration[*runtime_bun.PostgresqlConnection])

func RegisterProducer added in v0.0.20 

func RegisterProducer(
	container inverse.Container,
	broker string,
	configs []runtime.Configuration[*runtime_sarama.Producer],
)

func RegisterProducerConfig added in v0.0.20 

func RegisterProducerConfig(ci inverse.Container, configs ...runtime.Configuration[*runtime_sarama.Producer])

func RegisterRetry added in v0.0.20 

func RegisterRetry(
	container inverse.Container,
	configs []runtime.Configuration[*runtime_retry.Retry],
)

Retry

func RegisterRoute added in v0.0.20 

func RegisterRoute(
	container inverse.Container,
	port int,
	configs []runtime.Configuration[*runtime_bunrouter.Router],
)

func RegisterRouteConfig added in v0.1.4 

func RegisterRouteConfig(ci inverse.Container, configs ...runtime.Configuration[*runtime_bunrouter.Router])

func RegisterRuntime added in v0.2.4 

func RegisterRuntime(qualifier string, ci inverse.Container)

func RegisterStatefulFunction added in v0.2.4 

func RegisterStatefulFunction(
	ci inverse.Container,
	topic string,
	tableName string,
	fn stateful.SingleFunction,
	key stateful.PersistenceIdFunction[structure.Bytes, structure.Bytes],
)

func RegisterStatelessBatchFunction added in v0.2.5 

func RegisterStatelessBatchFunction(
	ci inverse.Container,
	topic string,
	fn stateless.BatchFunction,
)

func RegisterStatelessSingleFunction added in v0.2.4 

func RegisterStatelessSingleFunction(
	ci inverse.Container,
	topic string,
	fn stateless.SingleFunction,
)

func RegisterStatelessSingleFunctionWithKey added in v0.2.4 

func RegisterStatelessSingleFunctionWithKey(
	ci inverse.Container,
	topic string,
	fn stateless.SingleFunction,
	key stateful.PersistenceIdFunction[structure.Bytes, structure.Bytes],
)

func ResolveConsumerBatchFunction added in v0.2.4 

func ResolveConsumerBatchFunction(ctx context.Context, ci inverse.Container) (runtime.Configuration[*runtime_sarama.KeyedHandler], error)

func ResolveConsumerHandlerConfiguration added in v0.2.4 

func ResolveConsumerHandlerConfiguration(ctx context.Context, ci inverse.Container) (runtime.Configuration[*runtime_sarama.Consumer], error)

func ResolveConsumerKeyFunction added in v0.2.4 

func ResolveConsumerKeyFunction(ctx context.Context, ci inverse.Container) (runtime.Configuration[*runtime_sarama.KeyedHandler], error)

func ResolveConsumerTopics added in v0.2.4 

func ResolveConsumerTopics(ctx context.Context, ci inverse.Container) (runtime.Configuration[*runtime_sarama.Consumer], error)

func ResolveRouteProducer added in v0.2.4 

func ResolveRouteProducer(ctx context.Context, ci inverse.Container) (runtime.Configuration[*runtime_bunrouter.Router], error)

Types

type CollectorOneToOneConfiguration added in v0.1.3 

type CollectorOneToOneConfiguration[S any, IK any, IV any, OK any, OV any] struct {
	Name                       string
	InputTopic                 flow.Topic[IK, IV]
	OutputTopic                flow.Topic[OK, OV]
	Aggregator                 collect.Aggregator[S, IK, IV]
	Collector                  collect.OneToOneCollector[S, OK, OV]
	InputBroker                string
	OutputBroker               string
	HttpPort                   int
	StateFormat                format.Format[S]
	StateKeyFunction           stateful.PersistenceIdFunction[IK, IV]
	KafkaProducerConfiguration []runtime.Configuration[*runtime_sarama.Producer]
	KafkaConsumerConfiguration []runtime.Configuration[*runtime_sarama.Consumer]
	RetryConfiguration         []runtime.Configuration[*runtime_retry.Retry]
	RouteConfiguration         []runtime.Configuration[*runtime_bunrouter.Router]
}

Wiring configuration

func (CollectorOneToOneConfiguration[S, IK, IV, OK, OV]) Register added in v0.1.3 

func (c CollectorOneToOneConfiguration[S, IK, IV, OK, OV]) Register(ci inverse.Container)

type ConsumerFunction added in v0.2.4 

type ConsumerFunction struct {
	Topic string
	Fn    stateless.BatchFunction
	Key   stateful.PersistenceIdFunction[structure.Bytes, structure.Bytes]
}

type JoinPostgresqlFunctionConfiguration 

type JoinPostgresqlFunctionConfiguration struct {
	Name                       string
	StatefulFunctions          map[string]stateful.SingleFunction
	PersistenceIdFunctions     map[string]stateful.PersistenceIdFunction[[]byte, []byte]
	IntermediateTopicName      string
	InputBroker                string
	OutputBroker               string
	HttpPort                   int
	PostgresConnectionString   string
	PostgresTable              string
	PostgresqlConfiguration    []runtime.Configuration[*runtime_bun.PostgresqlConnection]
	KafkaProducerConfiguration []runtime.Configuration[*runtime_sarama.Producer]
	KafkaConsumerConfiguration []runtime.Configuration[*runtime_sarama.Consumer]
	RetryConfiguration         []runtime.Configuration[*runtime_retry.Retry]
	RouteConfiguration         []runtime.Configuration[*runtime_bunrouter.Router]
}

func (JoinPostgresqlFunctionConfiguration) Register added in v0.1.1 

func (c JoinPostgresqlFunctionConfiguration) Register(ci inverse.Container)

type Main 

type Main interface {
	Runtimes(i string, r func(inverse.Container) []runtime.Runtime) error
	Prebuilt(i string, rf func(ci inverse.Container) Prebuilt) error
	Start(i string) error
}

func NewMain added in v0.0.10 

func NewMain() Main

func NewMainAllInstance added in v0.2.7 

func NewMainAllInstance(allInstanceName string) Main

type MaterialisePostgresqlOneToOneFunctionConfiguration added in v0.0.17 

type MaterialisePostgresqlOneToOneFunctionConfiguration[S any, IK any, IV any] struct {
	Name                       string
	InputTopic                 flow.Topic[IK, IV]
	Function                   materialise.MapFunction[IK, IV, S]
	InputBroker                string
	OutputBroker               string
	HttpPort                   int
	PostgresConnectionString   string
	PostgresqlConfiguration    []runtime.Configuration[*runtime_bun.PostgresqlConnection]
	KafkaConsumerConfiguration []runtime.Configuration[*runtime_sarama.Consumer]
	KafkaProducerConfiguration []runtime.Configuration[*runtime_sarama.Producer]
	RetryConfiguration         []runtime.Configuration[*runtime_retry.Retry]
	RouteConfiguration         []runtime.Configuration[*runtime_bunrouter.Router]
}

Wiring configuration

func (MaterialisePostgresqlOneToOneFunctionConfiguration[S, IK, IV]) Register added in v0.1.1 

func (c MaterialisePostgresqlOneToOneFunctionConfiguration[S, IK, IV]) Register(ci inverse.Container)

type Prebuilt added in v0.2.7 

type Prebuilt interface {
	Register(ci inverse.Container)
}

type RouterAdapterConfiguration added in v0.0.16 

type RouterAdapterConfiguration[Request any, InputKey any, InputValue any] struct {
	Name                       string
	ProduceTopic               flow.Topic[InputKey, InputValue]
	ProduceBroker              string
	RequestBodyFormat          format.Format[Request]
	RequestMapFunction         stateless.OneToOneFunction[structure.Bytes, Request, InputKey, InputValue]
	HttpPort                   int
	KafkaProducerConfiguration []runtime.Configuration[*runtime_sarama.Producer]
	RouteConfiguration         []runtime.Configuration[*runtime_bunrouter.Router]
}

Wiring configuration

func (RouterAdapterConfiguration[Request, InputKey, InputValue]) Register added in v0.1.1 

func (c RouterAdapterConfiguration[Request, InputKey, InputValue]) Register(ci inverse.Container)

type RuntimeFacade added in v0.0.13 

type RuntimeFacade struct {
	Runtimes []runtime.Runtime
}

func (*RuntimeFacade) Start added in v0.0.13 

func (r *RuntimeFacade) Start() error

func (*RuntimeFacade) Stop added in v0.0.13 

func (r *RuntimeFacade) Stop()

type StatefulPostgresqlOneToOneFunctionConfiguration added in v0.0.15 

type StatefulPostgresqlOneToOneFunctionConfiguration[S any, IK any, IV any, OK any, OV any] struct {
	Name                       string
	InputTopic                 flow.Topic[IK, IV]
	OutputTopic                flow.Topic[OK, OV]
	Function                   stateful.OneToOneFunction[S, IK, IV, OK, OV]
	InputBroker                string
	OutputBroker               string
	HttpPort                   int
	StateFormat                format.Format[S]
	StateKeyFunction           stateful.PersistenceIdFunction[IK, IV]
	PostgresTable              string
	PostgresConnectionString   string
	PostgresqlConfiguration    []runtime.Configuration[*runtime_bun.PostgresqlConnection]
	KafkaProducerConfiguration []runtime.Configuration[*runtime_sarama.Producer]
	KafkaConsumerConfiguration []runtime.Configuration[*runtime_sarama.Consumer]
	RetryConfiguration         []runtime.Configuration[*runtime_retry.Retry]
	RouteConfiguration         []runtime.Configuration[*runtime_bunrouter.Router]
}

Wiring configuration

func (StatefulPostgresqlOneToOneFunctionConfiguration[S, IK, IV, OK, OV]) Register added in v0.1.1 

func (c StatefulPostgresqlOneToOneFunctionConfiguration[S, IK, IV, OK, OV]) Register(ci inverse.Container)

type StatefulPostgresqlOneToTwoFunctionConfiguration added in v0.0.15 

type StatefulPostgresqlOneToTwoFunctionConfiguration[S any, IK any, IV any, OK1 any, OV1 any, OK2 any, OV2 any] struct {
	Name                       string
	InputTopic                 flow.Topic[IK, IV]
	OutputTopicOne             flow.Topic[OK1, OV1]
	OutputTopicTwo             flow.Topic[OK2, OV2]
	Function                   stateful.OneToTwoFunction[S, IK, IV, OK1, OV1, OK2, OV2]
	InputBroker                string
	OutputBroker               string
	HttpPort                   int
	StateFormat                format.Format[S]
	StateKeyFunction           stateful.PersistenceIdFunction[IK, IV]
	PostgresTable              string
	PostgresConnectionString   string
	PostgresqlConfiguration    []runtime.Configuration[*runtime_bun.PostgresqlConnection]
	KafkaProducerConfiguration []runtime.Configuration[*runtime_sarama.Producer]
	KafkaConsumerConfiguration []runtime.Configuration[*runtime_sarama.Consumer]
	RetryConfiguration         []runtime.Configuration[*runtime_retry.Retry]
	RouteConfiguration         []runtime.Configuration[*runtime_bunrouter.Router]
}

Wiring configuration

func (StatefulPostgresqlOneToTwoFunctionConfiguration[S, IK, IV, OK1, OV1, OK2, OV2]) Register added in v0.1.1 

func (c StatefulPostgresqlOneToTwoFunctionConfiguration[S, IK, IV, OK1, OV1, OK2, OV2]) Register(ci inverse.Container)

type StatelessOneToOneConfiguration added in v0.0.15 

type StatelessOneToOneConfiguration[IK any, IV any, OK any, OV any] struct {
	Name                       string
	InputTopic                 flow.Topic[IK, IV]
	OutputTopic                flow.Topic[OK, OV]
	Function                   stateless.OneToOneFunction[IK, IV, OK, OV]
	ErrorHandler               stateless.ErrorHandlerFunction
	InputBroker                string
	OutputBroker               string
	HttpPort                   int
	KafkaProducerConfiguration []runtime.Configuration[*runtime_sarama.Producer]
	KafkaConsumerConfiguration []runtime.Configuration[*runtime_sarama.Consumer]
	RetryConfiguration         []runtime.Configuration[*runtime_retry.Retry]
	RouteConfiguration         []runtime.Configuration[*runtime_bunrouter.Router]
}

func (StatelessOneToOneConfiguration[IK, IV, OK, OV]) Register added in v0.1.1 

func (c StatelessOneToOneConfiguration[IK, IV, OK, OV]) Register(ci inverse.Container)

type StatelessOneToOneExplodeConfiguration added in v0.0.15 

type StatelessOneToOneExplodeConfiguration[IK any, IV any, OK any, OV any] struct {
	Name                       string
	InputTopic                 flow.Topic[IK, IV]
	OutputTopic                flow.Topic[OK, OV]
	Function                   stateless.OneToOneExplodeFunction[IK, IV, OK, OV]
	InputBroker                string
	OutputBroker               string
	HttpPort                   int
	KafkaProducerConfiguration []runtime.Configuration[*runtime_sarama.Producer]
	KafkaConsumerConfiguration []runtime.Configuration[*runtime_sarama.Consumer]
	RetryConfiguration         []runtime.Configuration[*runtime_retry.Retry]
	RouteConfiguration         []runtime.Configuration[*runtime_bunrouter.Router]
}

func (StatelessOneToOneExplodeConfiguration[IK, IV, OK, OV]) Register added in v0.1.1 

func (c StatelessOneToOneExplodeConfiguration[IK, IV, OK, OV]) Register(ci inverse.Container)

type StatelessOneToTwoConfiguration added in v0.0.15 

type StatelessOneToTwoConfiguration[IK any, IV any, OK1 any, OV1 any, OK2 any, OV2 any] struct {
	Name                       string
	InputTopic                 flow.Topic[IK, IV]
	OutputTopicOne             flow.Topic[OK1, OV1]
	OutputTopicTwo             flow.Topic[OK2, OV2]
	Function                   stateless.OneToTwoFunction[IK, IV, OK1, OV1, OK2, OV2]
	InputBroker                string
	OutputBroker               string
	HttpPort                   int
	KafkaProducerConfiguration []runtime.Configuration[*runtime_sarama.Producer]
	KafkaConsumerConfiguration []runtime.Configuration[*runtime_sarama.Consumer]
	RetryConfiguration         []runtime.Configuration[*runtime_retry.Retry]
	RouteConfiguration         []runtime.Configuration[*runtime_bunrouter.Router]
}

func (StatelessOneToTwoConfiguration[IK, IV, OK1, OV1, OK2, OV2]) Register added in v0.1.1 

func (c StatelessOneToTwoConfiguration[IK, IV, OK1, OV1, OK2, OV2]) Register(ci inverse.Container)

Source Files

View all Source files

Directories

Path Synopsis
example_word_collect
example_word_count
example_word_join
example_word_materialise
example_word_remap
materialise_bun
stateful_batch_state
stateful_bun
stateful_deduplicate_offset
stateful_error_handler
stateful_error_handler_skip_list
stateful_mock
stateless_error_handler
stateless_error_handler_skip_list
stateless_mock
stateless_one_to_one
Package mock is a generated GoMock package.
 Package mock is a generated GoMock package.

Jump to

Keyboard shortcuts

? : This menu
/ : Search site
f or F : Jump to
y or Y : Canonical URL
go.dev uses cookies from Google to deliver and enhance the quality of its services and to analyze traffic. Learn more.