- Atlas LBaaS provides load balancing APIs that update the database as the source of truth, with device configurations enforced to match the database. API operations that change state are asynchronous to allow for scaling. - Scaling in Atlas is achieved through asynchronous operations using ActiveMQ and a cluster of Atlas servers. - The Atlas infrastructure uses Java technologies like Spring, JAXB, and JPA for its core components, and allows for extensions through additional APIs, services, and adapters. - Adapters translate between the Atlas APIs and individual device configurations, and manage tasks like device onboarding, failure detection, and rolling back changes.

1. Atlas LBaaS Overview
September 2012

2. Atlas Architecture tenets
• Database is the source of truth
– Configuration on devices is enforced to match DB
• LBaaS APIs that change state are
asynchronous
– Operations return as soon as DB is updated
– Devices are updated in the background
• Scaling in Atlas is achieved through
– Use of async operations through ActiveMQ
– Use of Cluster of Atlas servers

3. Atlas Server scalable and HA
deployment

4. Atlas infrastructure dependency
• Atlas infrastructure is based on:
– Any Java Server (Jetty, Tomcat, Glassfish, JBOSS, etc.)
– Spring framework (IoC, annotations, xml config)
– JAXB (for generating API objects and mapping to REST)
– Dozer (utility to map between Java classes)
– Abstraction of persistence providers (JPA) => DB, ORM
and Transactions
– Abstraction of message queueing (JMS) => Message
Queues
– Unit testing framework (SureFire)

5. Tenant API specification
• Multi-Tenant API
• Specification: wiki.openstack.org/Atlas-LB
• Follows OpenStack API design recommendations
• Determined after careful research into the common
capabilities of open source and commercial load balancers.
• Specified using XML Schema file (XSD)
– API POJO classes generated from spec.
• Supports both JSON and XML
– JSON payload generated from XML schema
– ATOM support skeleton is there
• Can list active extensions
• Support account limits

6. Atlas Plugins and extensions
Core
API A
D
Core
A
P
Extension T
API E
Extension R

7. Atlas Core

8. Core Resource Model

9. REST
Layer
Persistence
Service
Layer
(transactions)
Persistence
Repository
Layer
(ORM)

10. REST
Layer
MQ
Consumers
Device
Adapter

11. Atlas
data-model Atlas API
component component
XML request
JSON request JAXB object JAX-RS (CXF)
JAXB
1 2 Resource
(XSD files) 3 JAXB object
9 classes
Response
Entity Entity 4
Atlas API 7 Object 5 Entity
Object Dozer
component Object
Mapper
Async Repository
Service Atlas API
classes Classes
classes component
(Hibernate)
8
6 Atlas persistence
Message component
Queue
(ActiveMQ)
DB

12. Message
Queue
(ActiveMQ)
Atlas adapter
1 Consume message component
Entity
Async 4 Object
ReverseProxy Adapter
classes Entity 6
Service classes
(Listeners) Object Endpoint
Entity 3 ID config Device-specific
2 8 Update 7
Object status
Reads API
5
Endpoint
Repository config
Classes Network
(Hibernate)
Atlas persistence
component
LB Device
LB Device
DB LB Device
LB Device
LB Device

13. Adapters

14. Adapter Tasks
• Minimum sharing with Core
– Only what is specified in the interface
• Translates Atlas APIs and semantics to device API or
configuration
• Manages IPv4 and IPv6 address pools
• Manages devices. Could include onboarding and failure
detection
• Manages rollback on failure to ensure device config
stays correct
• Decides on device placement for each load balancer
• Reports back any errors to core

15. Core Adapter Contract

16. Adapter Core Usage interface

17. Extensions

18. Rackspace Extended Adapter

19. Citrix Extended Adapter

20. Validation Framework

21. Notification Service

22. Scheduled Jobs

23. Atlas Extension Structure
• Extend the core XSD to specify new APIs or
extension into existing APIs
• Extend the resource layer
• Extend the Service Layer
• Extend the Repository layer
• Extend the Async layer
• Extend the adapter layer

24. Example of extending API

25. packaging
• Java WAR file
• Debian package
• Adapters are built as separate JAR files
• Extensions are built as separate JAR files

26. END