Are you looking to discover, visual, catalog, share, and reuse your Kafka event streams, but don't know how and or where to begin. Or does your organization look something like the picture below and you are struggling to understand what is the data that is really going through your Kafka clusters?

Kafka Organization

Well you have come to the right place, and in this guided walk through, we will show you how to:

We expect with this knowledge you will be able to scan your own Kafka clusters to discover & visualize new event streams or consumer groups you may not be aware off.

To make this walk through engaging and meaningful, we will make use of a real-world use, which we will jump into a bit, and ask you to transport yourself to be an employee of a new company. We also cover some foundational concepts so we all aligned on the same page.

So let's get started!

You are a member of the engineering team at the NYC Modern Taxi Co, a fictional taxi cab company based in New York City. Your team is playing from behind and racing to catch up with technology innovation introduced to the industry by Rideshare competitors such as Uber and Lyft. In order for the company to survive and eventually thrive your team has convinced the board that transforming the companies' IT systems is of utmost importance. Your team has done it's research and determined that moving to an Event-Driven Architecture is essential to future rapid innovation and has already kicked this initiative off by deploying a Solace Event Mesh and updating the taxi fleet to stream real-time events that include ride and location information. We know what the fleet is up to! Now it's time to start to continually improve and provide a world class customer experience.

In order to react in a real-time manner the team has decided that we want to process the updates as they stream in from the fleet of taxis instead of putting them directly into a datastore and then having to retrieve them to do processing later. To prototype this work, you'll see a high level design in the diagram below. Since we already have the taxi fleet streaming their updates into our PubSub+ Event Mesh we need to do three things:

  1. 🚖 Capture this high level design in the PubSub+ Event Portal where we can define our Event-Driven Architecture, including its' components: Applications, Events and Schemas. This will allow us to define the details needed to implement, visualize and extend the architecture as it evolves, and share/collaborate with our entire engineering team as we continue to innovate.
  2. 🚕 Next up we're going to create the RideDropoffProcessor microservice which will subscribe to the stream of dropoff taxi updates from the fleet, capture events for a specified time window (we'll use 20 seconds to make it easy), calculate the averages, and publish a new RideAverageUpdate event for each window.
  3. 🚖 Lastly we'll create a RideDropoffConsumer that receives the stream of RideAverageUpdate events and captures them for display and further processing.


Before we dive deeper, let ensure we are all aligned with Kafka objects and concepts we will use in PubSub+ Event Portal.

Consumer Groups

Event Portal supports the concept of Kafka's consumer groups. A consumer group is used by Kafka to group consumers into a logical subscriber for a topic. In Event Portal, you can model consumer groups in Designer. This enables the Event Portal's runtime discovery to associate a discovered consumer group to an existing application.

Kafka consumers that belong to the same consumer group share a group ID. The consumers in a group divide the topic partitions, as fairly as possible, so that each consumer consumes only a single partition from the group.

A few examples of Consumers Groups from our NYC Taxi Analytics use case would be:


Topics are an important part of the Event Portal. Think of a topic as a concept of the publish-subscribe (pub/sub) architectural pattern. They are used to route data or events (in the form of messages) between distributed applications, often using a message broker or an event broker.

A Solace topic and an Apache Kafka topic might seem fundamentally the same but there are quite a few differences between them. Later in this CodeLab, when you run a discovery scan against a Kafka cluster the Topic Scheme for events discovered will be Kafka format.

Here are some examples from our use case:


In simple terms, a schema represents the contract to describe the payload of an event. Producers and consumers of an event can trust that the event's payload matches the schema definition assigned to that event. Schemas define a type of payload through JSON, AVRO, XML, Binary, or Text. JSON, AVRO, and XML schemas have content that describes each property of the schema.

In our use case all events are in AVRO Schema format.

Schema Example

Application Domain & Workspace

An application domain represents a namespace where applications, events, and schemas can live. Within this namespace, you can create a suite of applications, events and schemas that are independent of other application domains. In our NYC Taxi use case we introduced earlier, we may group application into different domains, for ex. we may have a domain for our rideshare apps and services, one for our back-office apps where we invoicing and background checks are being processed, and maybe another domains for analytics where we group apps that are responsible for analyzing the successful operation of our rideshare services.

In the Event Portal you will associate all objects like Consumer Groups, Topics, Schema, etc, to one or more Application Domains.

You can further group multiple domains into a Workspace, which will make it easier to review our Discovery scan. So our Analytics, Operations, and Back-Office Application Domain in the NYC taxi example could be part of a single Workspace.

Workspace Example


An application represents a piece of software that produces and consumes events. Applications connect to the event broker in an event-driven architecture and communicate with other applications via events. A single application represents a class of applications that are running the same code base; therefore, a Kafka consumer group can be associated with an Application object in the Event Portal.


A connector is used in Kafka for connecting Kafka brokers with external systems to stream data into or out of Apache Kafka. In the Event Portal, a Kafka Connector is an application class you select to configure associated published and/or subscribed events and a set of Kafka-native attributes like Connector Type, Class, Cluster ID, and Maximum Task.

With the foundational concepts out of the way, lets go through some prerequisites for running a Discovery scan.

In this walk through you have a choice to pick either of the following options:

  1. Scan our demo NYC Taxi Kafka cluster
  2. Download one of our pre-scanned Discovery file

You will find some prerequisites for both options below.

Option 1: Live Scan Requirements

If you want run a live scan on a Kafka cluster, you will need to download and install the Offline Discovery Agent. As with everything in life, you have two options again:

  1. Install the Agent as a Docker Container
  2. Install the Agent via a Binary Executable

The most easiest way install the agent is using Docker. Option 2 will require JDK/JRE 11; OpenJDK 11 is bundled with the agent installation package.

If you are on Mac OS or Linux and already have Docker for Desktop installed, then go ahead copy and paste the below command into a terminal window. The Discovery Agent may take a few minutes to initialize.

echo 'cMopz4m+GV60hBb8DysZna8uMP4tM84P' | docker login --username discovery-preview --password-stdin
	docker pull
	docker run \
	--env SPRING_APPLICATION_NAME=maas-event-discovery-agent-offline \
	--env MAAS_VMR_ENABLED=false \
	--name discovery_agent -p 8120:8120 \

To launch the Discovery Agent go to: http://localhost:8120.

Option 2: Pre-Scanned Discovery File

If you don't want to install the agent and run a live scan, you can still follow along in this CodeLab using the following pre-scanned JSON file.

Download:NYC Modern Taxi Co. Analytics Discovery File

Or run the curl/git clone command below to download the file:

curl -k -XGET -o NYC_Modern_Taxi_Co_Analytics.json

Some General Requirements

Regardless of the option you chose above, you should also:

  1. Sign into your Solace PubSub+ Cloud account. If you don't have an account yet, go ahead and create a trial account.
  2. Ensure that you have the correct user role and permission in Event Portal. At minimum you will need the "Event Portal Editor" permission. For instructions, refer to Managing Accounts, Roles, and Permissions.

If you are scanning your own Kafka clusters, then the following event brokers versions are currently supported:

Once the Offline Discovery Agent is installed, you can configure and run a scan on our NYC Taxi Kafka cluster from your browser.

Step 1: Go to the Discovery Agent

Go to http://localhost:8120

Here you'll see a list of Event Brokers the Discovery Agent supports. We are going to select Confluent as broker type, as that is the Kafka distribution our NYC Taxi service is using.

Run time broker type

Step 2: Configure Connection Details

Under the Target Cluster Authentication, copy and paste the following:

Select Add Connector and then copy and paste the Host and Port:

Add Connectors

Under Schema Registry Authentication, copy and paste the Host and Port:

And finally for the Event Scan Details, select Scan for all topics and click Start Scan.

Event Scan Details

The agent is now discovering the Topics that are being produced and consumed, inspecting the Scheme Registry, discovering consumer groups, and looking at various connectors that consuming or producing data with the cluster.

Step 3: Download the Scan File

Once the scan completes download the scan file to your desktop. The scan file will be in JSON format.

Download Scan File

Now on to the fun part where we will upload the scan to Event Portal and visualize the result.

This is where all the exciting stuff will happen with your Discovery scans. A few things you can do here:

So lets start by uploading the scan file first.

Uploading Your Scan File

Open your PubSub+ Cloud Console account and navigate to the Event Portal Discovery. Here you can upload your scan file you download in the last step or use our pre-scanned file instead. For the purpose of walk through we will be using the pre-scanned file below.

Upload Scan File

Assign to Workspace

One of the first things we want to do is to organize our work in a Workspace. Click on your scan file from the table and select Assign to Workspace.

Assign to Workspace

Lets create a new Workspace called NYC Modern Tax Co and select Run Synchronization Audit.

Assign to Workspace

Once your workspace is created you'll see the Staging view. What you essentially have here is all the objects the Discovery Agent found in the Kafka cluster it scanned which includes

Staging View

Now that you have uploaded your scan file and staged your events, let's go ahead and create an application domain to map topics, events and consumer groups

Creating an Application Domain

First we need to associate the Consumer Groups, Connectors, Topics, and Schema that were discovered from our NYC Taxi Analytics cluster to an Application Domain.

To do this click on the "+ Create" button and select *Create Application Domain.

Create Application Domain

Double click on the domain that was created to rename it. We will call this Domain: NYC Modern Taxi Co - Analytics

Rename Domain

Assigning Consumer Groups, Topics, Schemas to the Application Domain

Now lets assign our discovered Analytics Consumers Groups, Connectors, Topics, and Schema to the application domain we created.

Notice at the bottom of your discovery view, you can see a list of all Objects in the workspace Workspace Objects

Assign the following objects to your newly created application domain:

This is done by

  1. Clicking on the respected tab
  2. Checking the objects you want to assign
  3. Click on the application Domain

Filter and select Consumer Groups:

Consumers Groups to Application DomainSet App Domain

Repeat for Connectors, Topics and Schemas

Consumers Groups to Application DomainConsumers Groups to Application DomainConsumers Groups to Application Domain

With the objects associated to an Application Domain, click on the Domain name tab at the top navigation bar to see a graph view of what has been mapped. Menu Tab

The Event Portal will automatically attempt to reverse engineer to map those Consumer Groups, Connectors, and Topics to an Applications and Events.

You will notice that some consumer groups like the taxinyc_analytics_frauddetection_group and topic like where not mapped to an application. These discrepancies are identified by the little orange circle icon on the object itself and need to resolved before we can commit our work to the Event Portal.


This is where your domain expertise will come in handy and considering you are part of the NYC Taxi Analytics team you know that the taxinyc_analytics_frauddetection_group maps to the say the Fraud Detection Application.

Application Mapping

Click on the "+ Create" button at the top right corner of page and select Create Application. Call this application: Fraud Detection Application. Then drag and drop the consumer group taxinyc_analytics_frauddetection_group to the newly created application.

Map Fraud Application

Similarly map the taxinyc_analytics_passengersurgedetection_group to a new application called Passenger Surge Detection, and the taxinyc_analytics_driverincentivecalc_group to a new application called Driver Incentive Calc.

Map Fraud Application

Topic Mapping

Now we have one Topic, remaining that needs to be mapped. You being an expert in NYC Taxi Analytics team, you know this Topic is produced by the Fraud Detection App. So we can drag the topic to that app now.

Map Fraud Application

What about the topic that is being consumed by the two Connectors (SolaceSinkConnectorOPS and the ElasticsearchSink-Connector)? After talking with our domain expert we identified that this is an event published by both the Passenger Surge Detection & Drive Incentive Calc application. So go ahead and make those association.

Map Fraud Application

Commit to Event Portal

Alright, so now that we have associated and mapped all objects discovered during our scan it is time to commit this to the Event Portal so your architecture teams and developers can collaborate, design, and govern the NYC Taxi Analytics architecture.

To commit click on the Commit To Event Portal button.

Commit to Event Portal

And your done!! ...well almost. All the applications, events and linkages you made are now in sync with our Kafka cluster and have been cataloged, available for others in our teams to search and discover. For this we are next going to explore two other important features of the Event Portal, i.e. the Designer and Catalog.

Map Fraud Application

Now that our Consumers Groups, Topics, and other objects have been committed to the Event Portal, they can be viewed and searched from the Designer and Catalog.

In short the Designer is a tool to design and view all aspects of your event-driven architectures. It is through the Designer that you can create new events and applications for our NYC Taxi service as the use case evolves. It provides a graphical representation of application domains, applications, schemas, and events. You can use Designer to visualize the interaction of events between applications and to provision your architecture into the Event Portal.

Whereas, the Catalog acts as a storefront for all the applications, events, and schemas you've created in the Event Portal. Objects discovered & committed from our scan earlier, or created in Designer are automatically available in Catalog. Using Catalog's searchable interface, you can access all the existing events, schemas, and applications.

We will first take Designer for a test drive, so go ahead on open the Designer in Event Portal:

Designer Homepage

You'll notice the NYC Modern Taxi Co - Analytics domain we created in Discovery. Double click on that domain name or select the domain to see a quick summary and click on View Domain Details.

This is where you might want to spend some time to redraw you graph, maybe putting all custom apps one side and connectors on another, and have an understandable architecture diagram. Here is what ours looks like:

Designer Graph View

As we did this, we realized something that wasn't really right. From reorganizing the graph we noticed that there is an event that is produced by the Fraud Detection Application but not really consumed by anyone. We look at this as a opportunity as that event has some value, and can be used for a new business use case, maybe to have a new insight or customer experience. Ideally you could create a new application in the Designer, associate this event to be consumed by it, generate an AsyncAPI spec from the Event Portal, run it through code generators or code it up, connect it to Kafka, and re-scan where the Discovery would say our design is in sync with Kafka runtime.

But we don't live in an ideal world and say we didn't follow the above process, developed a quick Kafka application that consumed that event, and maybe we forgot to update it in the Designer. So lets say that happened. What would our Discovery Scan show if we re-ran the Discovery Agent? Well lets find out.

We already have a pre-scanned file for you to use here, which you can download from here directly or use curl/git clone as shown below.

curl -k -XGET -o NYC_Modern_Taxi_Co_Analytics-Audit.json

Once downloaded go back to Discovery and upload this new discovery file.

Discovery Audit

Like before we are going to assign the scan to a Workspace. Use the same Workspace you created last time and select Run Synchronization Audit. The Event Portal will now run an audit with your existing domain and check for any discrepancies. We noticed that there is a new Consumer Group taxinyc_analytics_fraudapp_group that wasn't there before.

New Consumer Group

Assign this new group to the NYC Modern Taxi Co - Analytics domain first. Then click on the domain from the tab menu. You may have to zoom out a little to see the Consumer Group that was discovered, which is now consuming the event.

New Consumer Group

We can right-click on this Consumer Group and Convert To Application, and finally Commit to Event Portal.

If you head back to the Designer, the new application is now part of the architecture diagram and our Kafka runtime is now synchronized with our design!

Designer New Fraud App

Hopefully your enjoyed the walk through of how to run discovery scans on a Kafka cluster, visualize them into an architecture diagram, and catalog all your Kafka event streams and applications for others in your organization to find and collaborate on.

Key Takeaways

Benefits of Event Portal

Next Steps

Solly Wave