Ultimate OpenDaylight Guide Part 1: Documentation & Testing

Ultimate OpenDaylight Guide | Part 1: Documentation & Testing

by Samuel Kontriš, Robert Varga, Filip Čúzy | Leave us your feedback on this post!

Welcome to Part 1 of the PANTHEON.tech Ultimate Guide to OpenDaylight! We will start off lightly with some tips & tricks regarding the tricky OpenDaylight documentation, as well as some testing & building tips to speed up development!


1. Website, Docs & Wiki

The differences between these three sources can be staggering. But no worries, we have got you covered!

  • OpenDaylight Docs – The holy grail for developers. The OpenDaylight Docs page provides developers with all the important information to get started or go further.
  • OpenDaylight Wiki – A Confluence based wiki, for meeting minutes and other information, regarding the governance, projects structure, and other related stuff.
  • OpenDaylight Website – general information, press releases & official documents needed for this product to be present – somewhere.

2. Dependencies between OpenDaylight projects & distributions

3. Contributing to OpenDaylight

4. Useful Mailing Lists

There are tens (up to hundreds) of mailing lists you can join, so you are up-to-date with all the important information about OpenDaylight – even dev talks, thoughts, and discussions!

Testing & Building

1. Maven “Quick” Profile

There’s a “Quick” maven profile in most OpenDaylight projects. This profile skips a lot of tests and checks, which are unnecessary to run with each build.

This way, the build is much faster:

mvn clean install -Pq

2. GitHub x OpenDaylight

The OpenDaylight code is mirrored on GitHub! Since more people are familiar with the GitHub environment, rather than Gerrit, make sure to check out the official GitHub repo of OpenDaylight!

3. Gerrit

Working with Gerrit can be challenging and new for newcomers. Here is a great guide on the differences between the two.

You can contact us at https://pantheon.tech/

Explore our Pantheon GitHub.

Watch our YouTube Channel.

OpenAPI 3.0 & OpenDaylight: A PANTHEON.tech Initiative

PANTHEON.tech has created a commit in the official OpenDaylight repository, which updates the version of Swagger generator to OpenAPI 3.0.

This feature allows us to easily generate a JSON with RESTCONF API documentation of OpenDaylight RESTCONF applications and import it into various services, such as ServiceNow®. This feature is not only about the generation of JSON with OpenAPI. It also includes Swagger UI based on generated JSON.


RESTCONF API is an interface, which allows access to datastores in the controller, via HTTP requests. OpenDaylight supports two versions of RESTCONF protocol:

What is OpenAPI?

OpenAPI, formerly known as Swagger UI, visualizes API resources and enables the user to interact with them. This kind of visualization provides an easier way to implement APIs in the back-end while automating the creation of documentation for the APIs in question.

OpenAPI Specification on the other hand (OAS for short), is a language-agnostic interface description for RESTful APIs. Its purpose is to visualize them and make the APIs readable for people and PCs alike, in YAML or JSON formats.

OAS 3.0 introduced several major changes, which made the specification structure clearer and more efficient. For a rundown of changes from OpenAPI 2 to version 3, make sure to visit this page detailing them.

How does it work?

OpenAPI is generated on the fly, with every manual request for the OpenAPI specification of the selected resource. The resource can be the OpenDaylight datastore or a device mount point. 

You can conveniently access the list of all available resources over the apidoc web application. The resources are located on the top right part of the screen. Once you select the resource you want to generate the OpenAPI specification for, you just pick the desired resource and the OpenAPI specification will be displayed below.

OpenAPI 3.0 (Swagger) in OpenDaylight

The apidoc is packed within the odl-restconf-all Karaf feature. To access it, you only need to type

feature:install odl-restconf-all

in the Karaf console. Then, you can use a web browser of your choice to access the apidoc web application over the following URL:


Once an option is selected, the page will load the documentation of your chosen resource, with the chosen protocol version.

The documentation of any resource endpoint (node, RPC’s, actions), is located under its module spoiler. When you click on the link:


you will get the OpenAPI JSON for the particular RESTCONF version and selected resource. Here is a code snippet from the resulting OpenAPI specification:

  "openapi": "3.0.3",
  "info": {
    "version": "1.0.0",
    "title": "simulator-device21 modules of RestConf version RFC8040"
  "servers": [
      "url": "http://localhost:8181/"
  "paths": {
    "/rests/data/network-topology:network-topology/topology=topology-netconf/node=simulator-device21/yang-ext:mount": {
      "get": {
        "description": "Queries the operational (running) datastore on the mounted hosted.",
        "summary": "GET - simulator-device21 - data",
        "tags": [
          "mounted simulator-device21 GET root"
        "responses": {
          "200": {
            "description": "OK"
    "/rests/operations/network-topology:network-topology/topology=topology-netconf/node=simulator-device21/yang-ext:mount": {
      "get": {
        "description": "Queries the available operations (RPC calls) on the mounted hosted.",
        "summary": "GET - simulator-device21 - operations",
        "tags": [
          "mounted simulator-device21 GET root"
        "responses": {
          "200": {
            "description": "OK"

You can look through the entire export by clicking here.

Our Commitment to Open-Source

PANTHEON.tech is one of the largest contributors to the OpenDaylight source-code, with extensive knowledge that goes beyond a general service or integration.

This just goes to show, that PANTHEON.tech is heavily involved in the development and progress of OpenDaylight. We are glad to be part of the open-source community and contributors.

You can contact us at https://pantheon.tech/

Explore our PANTHEOn.tech GitHub.

Watch our YouTube Channel.

[Hands-On] Network Automation with ServiceNow® & OpenDaylight

by Miroslav Kováč | Leave us your feedback on this post!

PANTHEON.tech s.r.o., its products or services, are not affiliated with ServiceNow®, neither is this post an advertisement of ServiceNow® or its products.

ServiceNow® is a complex cloud application, used to manage companies, their employees, and customers. It was designed to help you automate the IT aspects of your business – service, operations, and business management. It creates incidents where using flows, you can automate part of the work that is very often done manually. All this can be easily set up by any person, even if you are not a developer.

An Example

If a new employee is hired in the company, he will need access to several things, based on his position. An incident will be created in ServiceNow® by HR. This will trigger a pre-created, generic flow, which might, for example, notify his direct supervisor (probably manager) and he would be asked to approve this request of access.

Once approved, the flow may continue and set everything up for this employee. It may notify the network engineer, to provision the required network services like (VPN, static IPs, firewall rules, and more), in order to give a new employee a computer. Once done, he will just update the status of this task to done, which may trigger another action. It can automatically give him access to the company intranet. Once everything is done, it will notify everyone it needs to, about a successful job done, with an email or any other communication resource the company is using.

Showing the ServiceNow® Flow Designer


Setting Up the Flow

Let’s take it a step further, and try to replace the network engineer, who has to manually configure the services needed for the device.

In a simple environment with a few network devices, we could set up the ServiceNow® Workflow, so that it can access them directly and edit the configuration, according to the required parameters.

In a complex, multi-tenant environment we could leverage a network controller, that can serve the required service and maintain the configuration of several devices. This will make the required service functional. In that case, we will need ServiceNow® to communicate with the controller, which secures this required network service.

The ServiceNow® orchestration understands and reads REST, OpenDaylight & lighty.io – in our case, the controller. It provides us with the RESTCONF interface, with which we can easily integrate ServiceNow®, OpenDaylight, or lighty.io, thanks to the support of both these technologies.

Now, we look at how to simplify this integration. For this purpose, we used OpenAPI.

This is one of the features, thanks to which we can generate a JSON according to the OpenAPI specification for every OpenDaylight/lighty.io application with RESTCONF, which we can then import into ServiceNow®.

If your question is, whether it is possible to integrate a network controller, for example, OpenDaylight or lighty.io, the answer is yes. Yes, it is.

Example of Network Automation

Let’s say we have an application with a UI, that will let us manage the network with a control station. We want to connect a new device to it and set up its interfaces. Manually, you would have to make sure that the device is running. If not, we have to contact IT support to plug it in, create a request to connect to it. Once done, we have to create another request to set up the interfaces and verify the setup.

Using flows in ServiceNow® will let you do all that automatically. All your application needs to do, is create an incident in ServiceNow ®. This incident would be set up as a trigger, for a flow to start. It would try to create a connection using a REST request, that would be chosen from API operations, which we have from our OpenAPI JSON. This was automatically generated from YANG files, that are used in the project.

If a connection fails, then it would automatically send an email to IT support, creating a new, separate incident, that would have to be marked as done before this flow can continue. Once done, we can try to connect again using the same REST. When the connection is successful, we can choose a new API operation again, that would process the interfaces.

After that, we can choose another API operation that would get all the created settings and send that to the person, that created this incident using an email and mark this incident as done.

OpenAPI & oneOf

Showing the ServiceNow® API Operation

Since the “New York” release of ServiceNow®, the import of OpenAPI is a new feature, it has some limitations.

During usage, we noticed a few inconsistencies, which we would like to share with you. Here are some tips, what you should look out for when using this feature.

OpenAPI & ServiceNow®

OpenAPI supports the oneOf feature, which is something that is needed for choice keywords in YANG. You can choose, which nodes you want to use. Currently, the workaround for this is to use the Swagger 2.0 implementation, which does not support the oneOf feature and will list all the cases that exist in a choice statement. If you go to input variables, you may delete any input variables that you don’t want yourself.

JSONs & identical item names

Another issue is when we have a JSON that contains the same item names in different objects or levels. So if I need the following JSON:

    "username": "foo",
    "password": "bar":,
    "another-log-in": {
        "username": "foo",
        "password": "bar"

The workaround is, to add other input variables manually, that will have the same name, like the one that is missing. Suddenly, it may appear twice in input variables, but during testing, it appears only once – where it’s supposed to. Therefore, you need to manually fill in all the missing variables using the “+” button in the input variables tab.we have the username and password twice. However, it would appear in the input variables just once. When testing the action, I was unable to fill it in like the above JSON.

showing the ServiceNow® inputs

Input Variables in ServiceNow®

The last issue that we have, is with ServiceNow® not requiring input variables. Imagine you create an action with REST Step. If there are some variables that you don’t need to set up, you would normally not assign any value to that variable and it would not be set.

Here, it would automatically set it to a default value or an empty string if there is no default value, which can cause some problems with decimals as well – since you should not put strings into a decimal variable.

Again, the workaround is to remove all the input variables, that you are not going to use.

This concludes our network automation with the ServiceNow guide. Leave us your feedback on this post!

You can contact us at https://pantheon.tech/

Explore our Pantheon GitHub.

Watch our YouTube Channel.

YANG Tools 2.0.1 integrated in ODL Oxygen

YANG Tools 2.0.1 integrated in OpenDaylight Oxygen

OpenDaylight’s YANG Tools project, forms the bottom-most layer of OpenDaylight as an application platform. It defines and implements interfaces for modeling, storing and transforming data modeled in RFC7950, known as YANG 1.1 — such as a YANG parser and compiler.

What is YANG Tools?

Pantheon engineers started developing yangtools some 5 years ago. It originally supported RFC6020, going through a number of different versions. After releasing yangtools-1.0.0, we introduced semantic versioning as an API contract. Since then, we have retrofitted original RFC6020 meta-model to support RFC7950. We also implemented the corresponding parser bits, which were finalized in yangtools-1.2.0 and shipped with the Nitrogen Simultaneous Release.

This release entered its development phase on August 14th 2017. yangtools-2.0.0 was released on November 27th 2017, which is when the search of an integration window started. Even though we had the most critical downstream integration patches prepared, most of down-streams did not have their patches even started. Integration work and coordination was quickly escalated to the TSC. The integration finally kicked off on January 11, 2018.

Integration was mostly complicated by the fact that odlparent-3.0.x was riding with us, along with the usual Karaf/Jetty/Jersey/Jackson integration mess. It is now sorted out, with  yangtools-2.0.1 being the release to be shipped in the Oxygen simultaneous Release.

What is new in yangtools-2.0.1?

  • 309 commits
  • 2009 files changed
  • 54126 insertions(+)
  • 45014 deletions(-)

The most user-visible change is that in-memory data tree now enforces mandatory leaf node presence for operational store by default. This can be tweaked via the DataTreeConfiguration interface on a per-instance basis, if need be, but we recommend against switching it off.

For downstream users using karaf packaging, we have split our features into stable and experimental ones. Stable features are available from features-yangtools and contain the usual set of functionality, which will only expand in its capabilities. Experimental features are available from features-yangtools-experimental and carry functionality which is not stabilized yet and may get removed — this currently includes ObjectCache, which is slated for removal, as Guava’s Interners are better suited for the job.

Users of yang-maven-plugin will find that YANG files packaged in jars now have their names normalized to RFC7950 guidelines. This includes using the actual module or submodule name as well as capturing the revision in the filename.

API Changes

From API change perspective, there are two changes which stand out. We have pruned all deprecated methods and all YANG 1.1 API hacks marked with ‘FIXME: 2.0.0’ have been cleared up. This results in better ergonomics for both API users and implementors.

yang-model-api has seen some incompatible changes, ranging from renaming of AugmentationNode, TypedSchemaNode and ChoiceCaseNode to some targetted use of Optional instead of nullable returns. Most significant change here is the introduction of EffectiveStatement specializations — I will cover these in detail in a follow-up post, but these have enabled us to do the next significant item.

YANG parser has been refactored into multiple components. Its internal structure changed, in order to hide most of the implementation classes and methods. It is now split into:

  • yang-parser-reactor (language-independent inference pipeline)
  • yang-parser-rfc7950 (hosting baseline RFC6020/RFC7950 parser)
  • yang-parser-impl (being the default-configured parser instance)
  • and a slew of parser extensions (RFC6536, RFC7952, RFC8040)

There is an yang-parser-spi artifact, too, which hosts common namespaces and utility classes, but its layout is far from stabilized. Overall the parser has become a lot more efficient, better at detecting and reporting model issues. Implementing new semantic extensions has become really a breeze.

YANG Codecs

YANG codecs have seen a major shift, with the old XML parser in yang-data-impl removed in favor of yang-data-codec-xml. yang-data-codec-gson gains the ability to parse and emit RFC7951 documents. This allows RFC8040 NETCONF module to come closer to full compliance. Since the SchemaContext is much more usable now, with Modules being indexed by their  NameModule, the codec operations have become significantly faster.

Overall, we are in a much better and cleaner shape. We are currently not looking at a 3.0.0 release anytime soon and can actually deliver incremental improvements to YANG Tools in a much more rapid cadence than previously possible with the entire OpenDaylight simultaneous release cycle being in the way.

We already have another round of changes ready for yangtools-2.0.2 and are looking forward to publishing them.

Robert Varga