Due to a ransomware attack, the wiki was reverted to a July 2022 version. . We apologize for the lack of a more recent valid backup.
...
| Table of Contents | ||
|---|---|---|
|
Design Goals
ONOS is a multi-module project whose modules are managed as OSGi bundles. ONOS is designed with a few points in mind:
...
We take a succinct look at each below.
Run-Time Extensibility
ONOS is written to leverage Apache Karaf as its OSGi framework. In addition to dependency resolution at startup and dynamic module loading at runtime, Karaf provides the following:
- Enable use of standard JAX-RS API to develop our REST APIs and make them secure
- The notion of features as a set of bundles allowing assembly of custom setups
- Strict semantic versioning of code bundles, including third-party dependencies
- Local and remote ssh console with easily extensible CLI
- The notion of run-time log levels
Code Organization and Modularity
The project is comprised of a set of sub-projects, each with their own source tree that can be built independently. To do this, the ONOS source tree is organized in a hierarchical fashion that takes advantage of Maven's notion of a hierarchical POM file organization. Each sub-project has its own pom.xml file, and intermediate directories have parent aggregate pom.xml files. The latter contains shared dependencies and configurations for those sub-projects, enabling them to be built independent of unrelated sub-projects. The ONOS root contains the top-level pom file used to build the full project and all of its modules.
...
| Info |
|---|
For implementation details of the source tree and POM file organization, refer to [Appendix C] of the Developer's Guide. |
Separation of Concern
ONOS is partitioned into :
...
The aim of this clear separation of concern is greater extensibility and modularity.
Protocol Agnosticism
If ONOS needs to support a new protocol, a provider may be built against the southbound API as a plugin that may be loaded into the system.
The Remaining Sections
The remaining sections of the Architecture Guide elaborate on the design and implementation of the subsystems that make up the above-mentioned tiers, and the OpenFlow provider that ships with ONOS. We begin with the lowest tier and work our way up.