Daniel Meyer | Camunda

Super Fast Workflow

Request Response

SystemClient

Request

Response

Do some calculation

Client waits for the response

Async Work

SystemClient

Request

Ack

Do some calculationlater

Callback

Overview

• My goal• The current Workflow Engine Architecture• The next Generation Workflow Engine

Architecture

My Goal

• Build a better Workflow Engine

• > 100x better throughput• Horizontally Scalable• Easy to use• Updates without downtime• Data Replication• Simple, Composable Architecture

What we have today

• In the open source space: embeddable Java Workflow Engines Activiti Bonita Camunda JBPM ...

Embeddable WF Engines

• Added as a library to an application (used in-process)

• Can also be used remotely via REST but were not designed for this

Embeddable WF Engines

• Design Choices

Shared Database for Persistence Synchronous / blocking Execution Multi-Threaded Execution

Embeddable WF Engines

• Immediate Consequences (Camunda)

Limited Scalability Optimistic Locking at synchronization points

Still Deadlocks (although very low probability)

Embeddable WF Engines

• Other Consequences (Camunda)

Hard to update without downtime Hard use as a platform Different Api & Usage model for Remote vs. Local

> we can to do better

•How can we make this •a lot faster?

Design Principles

• Brokered Architecture• Replicated, Append only Logs• Single Writer Principle• Sharding• Recative, composable Architecture

Design Principles

• Brokered Architecture• Replicated, Append only Logs• Single Writer Principle• Sharding• Recative, composable Architecture

New Architecture

Client

Broker

TCP/IP

ReqestBuffer

ResponseBuffer

LogBuffer

Log

Worker

poll()

poll()

write()

write() read()

append()

Async Task Protocol

BrokerClient

1. create_task()

2. poll_and_lock_tasks()

3. complete_task()

Async Task Protocol

BrokerClient

1. create_task()

2. poll_and_lock_tasks()

3. abort_task()

State Machines and Logs

• Task Instance State Machine (simplified):

• NEW → LOCKED → COMPLETED

...1NEW

1LOCKED

1COMPLETED

Append next

Continuations

complete()

ack

Continue ?

State Machines, Logs and Contiunations

...7COMPLETED

...1NEW

1LOCKED

1COMPLETED

AsyncTask Instance Log

...7ACTIVE

Flow Node Instance Log

...

...

Result

Camunda 7 New Prototype

Create Async Taskwith 512 Bytes payload

~720 / second ~310K / second (in a burst of 1M Tasks)

On this Laptop: Samusung SSD 250G, Intel(R) Core(TM) i7-3520M CPU 4 cores

What's next?

• Finish • Replication & Distribution

• We need feedback from potential Users• This is a long shot

Thank You

• The name is: Daniel Meyer

• Leading the Runtime Infrastructure and Applications Team at Camunda.org

• Twitter: @MeyerDan

What about User / Human Tasks?

25

=> Just a predefined “Worker” with own DB and Tasklist UI

Broker

Tasklist UI

complete_task()query_tasks()claim_task()assign_task()...

User Task Service poll_and_lock()

complete()

API

User Task DB

UserTaskTable

What about Cockpit and History?

26

=> “Downloads” all topics and stores in a DB, indexed and optimized for Querying

BrokerqueryXX()

History Servicepoll(topic,offset)

API

History DB

Table

offset

Topic“Everything that happened”

0 1Cockpit UI