Open Source Coherence VisualVM Plugin Released!

We are excited to announce that the open source Coherence VisualVM Plugin has been released and is now available to install directly from VisualVM 2.0.4 and higher.

The Plugin can connect to and display data for both Community and Commercial Coherence Clusters.

To install the Plugin it’s as simple as starting up VisualVM, going to Tools, Plugins, selecting the VisuaVM-Coherence Plugin from the Available Plugins tab and clicking Install.

Coherence VisualVM Plugin Install

Useful links:


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Presentation: Patterns of Domain-Driven Design with In-Memory Data Grids

A great presentation from Coherence Product Manager Randy Stafford, at the “In-Memory Computing Summit”. In his presentation he covers:

  • Domain Driven Design – DDD
  • In-Memory Data Grids – IMDG’s
  • Patterns of DDD with IMDG’s
  • Cool new stuff with with Oracle Coherence

The recording and slides can be found here:


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Hello, Coherence Community Edition, Part 2: Building the client

The second part of Aleks Seovic’s article in Java Magazine has now been published!

In part 2, Aleks walks through building React and JavaFX front ends to integrate with the REST API that was developed in part 1.

The React client uses REST and the JavaFX client uses our new gRPC based Java client and gRPC proxy server built upon Helidon’s gPRC Server. The new gRPC support provides a modern connection capability for Coherence clients. At the moment there is only a Java based gRPC client but there are plans to provide gRPC support for a number of languages. (watch this space!).

The article is available here – and is a great read!

The full example is available on GithHub –


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Coherence JavaScript Client Now Available for Community Edition

Exciting news overnight that the Coherence JavaScript client is now available for Coherence Community Edition 20.06.1!

Previously, the only way to access Coherence from a Node.js application was via REST, but now you have the capability to access Coherence caches via a native JS API with familiar Map interface along with the capabilities of querying, aggregations, in-place processing and events.

The JavaScript client communicates using gRPC ( to a gRPC enabled Proxy server on a the Coherence cluster. This is the second client (After Java gRPC client) to take advantage of our native support for gRPC and surely won’t be the last.

It’s as easy as adding the dependency to your package.json file:

"dependencies": {
    "@oracle/coherence": "^1.0.0",

Starting a gRPC enabled Coherence Docker image:

docker run -d -p 1408:1408 oraclecoherence/coherence-ce:20.06.1

and finally running your code:

const { Session } = require('@oracle/coherence')
let session = new Session()
let map = session.getMap('Test')
setImmediate(async () => {
  console.log("Map size is " + (await map.size))
  console.log("Inserting entry (key=1, value=One)")
  await map.set(1, "One")
  console.log("Map entry is " + (await map.get(1)))
  console.log("Deleting entry (key=1)")
  await map.delete(1)
  console.log("Map size is " + (await map.size))
  await session.close()

See here for Randy Stafford’s full post on the release on Medium.



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Recording Available: Managing State in Elastic Microservices

If you didn’t get a chance to attend Coherence Architect Aleks Seovic’s talk on “Managing State in Elastic Microservices”, then the recording is now available on YouTube. This was the September 2020 Jakarta Tech Talks session.

In this talk, Aleks runs through the Helidon Sock-Shop Demo, which is the modern day microservices equivalent of the old “Pet Store Demo”. The demo showcases Coherence Community Edition (CE) and the Helidon Microservices framework and how to write modern and scalable microservices applications.

I particularly liked the part where he scaled his Coherence cluster to 1TB running on Kuberenetes!

Scaled Coherence Cluster in Grafana

Useful Links:


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Coherence Architect Presenting “Managing State in Elastic Microservices”

Re-posted from Coherence Blog

On Tuesday September 1 at 11AM EDT, Coherence Architect Aleks Seovic will present a Jakarta Tech Talk on “Managing State in Elastic Microservices.” You can register for this event here. Jakarta Tech Talks are dedicated to the discussion of Jakarta EE and broader Cloud-Native Java technologies.  The abstract for this particular event is given below:

Scaling stateless services is easy, but scaling their stateful data stores, not so much. This is true whether you are using an “old fashioned” relational database, or one of the popular, “modern” KV data stores, such as MongoDB or Redis.

In this presentation we will discuss some of the issues with state management in elastic microservices today, and look into how Oracle Coherence, with its Helidon and Eclipse MicroProfile integration, provides a better alternative you can use tomorrow.

This will be a technical presentation by an architect who has deep technical understanding of microservices and data grid technologies, and real-world experience building and deploying mission-critical applications.  Aleks’ talk will include a demo showing how Java microservices can be easily scaled, including flexible scaling of the data store used by the microservices, using an example you can evaluate yourself following his talk.  The example is built with Helidon 2.0 and Coherence Community Edition  announced in June.  Both Helidon and Coherence can be used to build and evolve microservices applications, either on-premises or in the cloud, so the content will be relevant and thought-provoking for Coherence users.  Register today! 

Registration link:

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Post Update: Monitor Your Coherence Clusters using Grafana and Prometheus

In July I wrote a post about Monitoring your Coherence Clusters using Grafana and Prometheus. (See here for this post)

I’ve just updated this example and included the instructions for getting this working with our recently released open-source Coherence Community Edition or Coherence CE.

The updated GitHub repository and instructions can be found here –


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Java Magazine: Creating cloud native stateful applications that scale, Part 1

Aleks Seović, who is an architect from the Coherence Development team, has just written part 1 of a series of articles on “Creating cloud native stateful application that scale”.

This is an excellent article on using Coherence Community Edition and Helidon to write scalable and stateful modern applications.

The article is available at the following URL:

For more information, see the following:


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Medium Post: A Gentle Introduction to Coherence

Coherence architects Harvey Raja and Aleks Seovic have just posted and article providing a great overview of Coherence.

A Gentle Introduction to Coherence is a great read and gives a high-level overview of what Coherence is and how it can help greatly in the development of distributed applications.

There will be a number of follow up articles that will got into more detail.


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Updated Coherence Demo Released with Open Tracing and Coherence CE Support

To coincide with Coherence Community Edition (CE) release, the Coherence Demo has been updated to work with Coherence CE and the Coherence Operator version 3.0.0.

Coherence Demo

This version uses Coherence CE 14.1.1-0-1 by default and showcases Open Tracing to trace client calls from a JAX-RS call, through to the individual cache nodes saving the primary and backup, aggregations and integration with a JPA data store.

The Coherence Demo showcases different features of Coherence including:

  • Clustering and Data Sharding
  • Scalability and High Availability
  • Disk-Based Persistence
  • Parallel Queries
  • Efficient Aggregation
  • In-Place Processing
  • Federation (Grid Edition feature only)
  • Lambda Support
  • OpenTracing Support
  • Grafana Integration via Coherence Operator
Grafana Dashboard via the Coherence Operator

To learn more and run the demo, see


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