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The Concursus Programming Model: Kotlin

April 29, 2016 | Software Consultancy

The Concursus Programming Model: Kotlin

In this post, I’ll demonstrate an alternative API which uses some of the advanced language features of the new Kotlin language from Jetbrains. As Kotlin is a JVM-based language, it interoperates seamlessly with Concursus’s Java 8 classes; however, it also offers powerful ways to extend their functionality.

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The Concursus Programming Model: Under the Hood

April 29, 2016 | Software Consultancy

The Concursus Programming Model: Under the Hood

In the previous two posts (part 1, and part 2), we looked at how Concursus uses method mapping to generate events from method calls on proxies, and to dispatch events to matching methods on event handlers and state class instances. This approach provides a concise, convenient client API to the Concursus event system; however the core of the system defines events and event-handling mechanisms without reference to any of the reflection-based machinery used to implement this API. It is perfectly possible (if comparatively cumbersome) to use a Concursus event store to read and write events without using reflection. In this post I’ll show how this is done, continuing with the “lightbulb” example introduced previously.

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The Concursus Programming Model: State

April 28, 2016 | Software Consultancy

The Concursus Programming Model: State

In a conventional RDBMS-with-ORM system, we are used to thinking of domain objects as mapped to rows in database tables, and of the database as a repository where the current state of every object exists simultaneously, so that what we get when we query for an object is the state that object was in at the time the query was issued. To perform an update, we can start a transaction, retrieve the current state of the object, modify it, save it back again and commit. Transactions move the global state of the system from one consistent state to another, so that the database transaction log represents a single, linear history of updates. We are therefore able to have a very stable, intuitive sense of what it means to talk about the “current state” of any domain object.

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The Concursus Programming Model: Events

April 27, 2016 | Software Consultancy

The Concursus Programming Model: Events

Concursus is an open source Java 8 framework for building distributed systems using CQRS and event sourcing patterns. One of its major differences from other such frameworks (such as Jdon, Axon and ES4J) is that it eschews a programming model where each event type is represented by a separate Java class, instead mapping event types to methods on interfaces.

 

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Model Matters: Graphs, Neo4j and the Future

February 25, 2013 | Neo4j

Model Matters: Graphs, Neo4j and the Future

As part of our work, we often help our customers choose the right datastore for a project. There are usually a number of considerations involved in that process, such as performance, scalability, the expected size of the data set, and the suitability of the data model to the problem at hand.

This blog post is about my experience with graph database technologies, specifically Neo4j. I would like to share some thoughts on when Neo4j is a good fit but also what challenges Neo4j faces now and in the near future.

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Akka Typed brings type safety to Akka framework

January 18, 2016 | Software Consultancy

Akka Typed brings type safety to Akka framework

Last time in this series I summarised all the Akka Persistence related improvements in Akka 2.4. Since then Akka 2.4.1 has been released with some additional bug fixes and improvements so perhaps now is a perfect time to pick up this mini-series and introduce some other new features included in Akka 2.4.x.

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Google Cloud Spanner: our first impressions

March 7, 2017 | Data Analysis, GCP

Google Cloud Spanner: our first impressions

Google has recently made its internal Spanner database available to the wider public, as a hosted solution on Google Cloud. This is a distributed relational/transactional database used inside for various Google projects (including F1, the advertising backend), promising high throughput, low latency and 99.999% availability. As such it is an interesting alternative to many open source or other hosted solutions. This whitepaper gives a good theoretical introduction into Spanner.

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Event Replaying with Hazelcast Jet

February 13, 2017 | Data Engineering

Event Replaying with Hazelcast Jet

One of the stated intentions behind the design of Java 8’s Streams API was to take better advantage of the multi-core processing power of modern computers. Operations that could be performed on a single, linear stream of values could also be run in parallel by splitting that stream into multiple sub-streams, and combining the results from processing each sub-stream as they became available.

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Terraform Infrastructure Design Patterns

September 14, 2015 | Cloud, DevOps

Terraform Infrastructure Design Patterns

If you are operating in the programmable infrastructure space, you will hopefully have come across Terraform, a tool from HashiCorp which is primarily used to manage infrastructure resources such as virtual machines, DNS names and firewall settings across a number of public and private providers (AWS, GCP, Azure, …).

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Exploring How Policy-as-Code and OPA Fit into the K8s World

November 4, 2021 | Kubernetes

Exploring How Policy-as-Code and OPA Fit into the K8s World

We always read that ‘security is everyone’s responsibility’. For any organisation, big or small, security should always be the primary concern—not a mere afterthought. In terms of Kubernetes, securing a cluster is challenging because it has so many moving parts and, apart from securing our Kubernetes environment, we also want to control what an end-user can do in our cluster.

To achieve these goals, we can start with the built-in features provided by Kubernetes like Role-Based Access Control (RBAC), Network Policies, Secrets Management, and Pod Security Policies (PSP). But we know these features are not enough. For example, we may want specific policies like ‘all pods must have specific labels’. And even if we have the policies in place, the next big question is how to enforce them on our Kubernetes cluster in an easy and repeatable manner.

In this blog post, we’ll address this challenge and other questions pertaining to OPA and how it can integrate into Kubernetes.

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A Pragmatic Introduction to Machine Learning for DevOps Engineers

January 23, 2018 | Data Engineering, DevOps

A Pragmatic Introduction to Machine Learning for DevOps Engineers

Machine Learning is a hot topic these days, as can be seen from search trends. It was the success of Deepmind and AlphaGo in 2016 that really brought machine learning to the attention of the wider community and the world at large.

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Writing a custom JupyterHub Spawner

January 11, 2018 | Data Engineering

Writing a custom JupyterHub Spawner

The last few years have seen Python emerge as a lingua franca for data scientists. Alongside Python we have also witnessed the rise of Jupyter Notebooks, which are now considered a de facto data science productivity tool, especially in the Python community. Jupyter Notebooks started as a university side-project known as iPython in circa 2001 at UC Berkeley.

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Riak, the Dynamo paper and life beyond Basho

August 8, 2017 | Cassandra

Riak, the Dynamo paper and life beyond Basho

Recently, the sad news has emerged that Basho, which developed the Riak distributed database, has gone into receivership. This would appear to present a problem for those who have adopted the commercial version of the Riak database (Riak KV) supported by Basho.

 

This blog is written exclusively by the OpenCredo team. We do not accept external contributions.

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[Past event] Voxxed Days Bristol 2017

Join Lorenzo Nicora at Voxxed Days Bristol 2017 for his talk on Event Sourcing and CQRS! Voxxed Days is a series of tech events organised by local community groups where local and international speakers converge at a wide range of locations around the world. This means each event retains a unique regional flavour, whilst being part of the overall Voxxed movement. Topics covered at Voxxed Days fall under the same radar as Voxxed.com, including: Server Side Java, Java Language, Cloud and Big Data, Web & HTML, Mobile, Programming Languages, Architecture & Security, Methodology, Culture and Future Technologies.

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[Past event] OOP Konferenz 2017

Join Andrew Morgan  and Daniel  Bryant at OOP Conference 2017! By combining software and business, OOP Conference 2017 is the meeting point for people who work primarily in the enterprise environment. Technical experts (architects, developers, business analysts, and testers), technical (project) managers and leaders gain an excellent view on the state-of-the-art in modern software engineering. […]

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Reactive event processing with Reactor Core: a first look

January 26, 2017 | Data Engineering

Reactive event processing with Reactor Core: a first look

Suppose you are given the task of writing code that fulfils the following contract:

  • You will be given a promise that, at some point in the future, some data – a series of values – will become available.
  • In return, you will supply a promise that, at some point in the future, some data representing the results of processing that data will become available.
  • There may be more values to process than you can fit in memory, or even an infinite series of values.
  • You are allowed to specify what will be done with each individual value, as and when it becomes available; this includes discarding some values.
  • Whenever you want to use some external service to do something with a value, that service can only return you a promise that, at some point in the future, some data representing the result of processing that value will become available.

 

This blog is written exclusively by the OpenCredo team. We do not accept external contributions.

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What I Don’t Like About Error Handling in Go, and How to Work Around It

January 23, 2017 | Data Analysis

What I Don’t Like About Error Handling in Go, and How to Work Around It

More often than not, people who write Go have some sort of opinion on its error handling model. Depending on your experience with other languages, you may be used to different approaches. That’s why I’ve decided to write this article, as despite being relatively opinionated, I think drawing on my experiences can be useful in the debate. The main issues I wanted to cover are that it is difficult to force good error handling practice, that errors don’t have stack traces, and that error handling itself is too verbose.

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From Java to Go, and Back Again

October 13, 2016 | Data Analysis

From Java to Go, and Back Again

In Lisp, you don’t just write your program down toward the language, you also build the language up toward your program. As you’re writing a program you may think “I wish Lisp had such-and-such an operator.” So you go and write it. Afterward you realize that using the new operator would simplify the design of another part of the program, and so on. Language and program evolve together…In the end your program will look as if the language had been designed for it. And when language and program fit one another well, you end up with code which is clear, small, and efficient – Paul Graham, Programming Bottom-Up

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[Past event] ThingMonk 2016

Running from the 12th-14th of September, ThingMonk brings together technologists and designers building core infrastructure for IoT for 2 days of great talks by industry practitioners. Join Tareq and Dominic Fox at ThingMonk 2016 and hear them talk about the event sourcing framework, Concursus!

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Concursus: Event Sourcing for the Internet of Things

May 10, 2016 | Data Engineering, White Paper

Concursus: Event Sourcing for the Internet of Things

In this technical report, we present Concursus, a framework for developing distributed applications using CQRS and event sourcing patterns within a modern, Java 8-centric, programming model. Following a high-level survey of the trends leading towards the adoption of these patterns, we show how Concursus simplifies the task of programming event sourcing applications by providing a concise, intuitive API to systems composed of event processing middleware.

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Is it Time for Your ‘Microservices Checkup’?

March 2, 2016 | DevOps, Microservices

Is it Time for Your ‘Microservices Checkup’?

Many of our clients are currently implementing applications using a ‘microservice’-based architecture. Increasingly we are hearing from organisations that are part way through a migration to microservices, and they want our help with validating and improving their current solution. These ‘microservices checkup’ projects have revealed some interesting patterns, and because we have experience of working in a wide-range of industries (and also have ‘fresh eyes’ when looking at a project), we are often able to work alongside teams to make significant improvements and create a strategic roadmap for future improvements.

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Facebook’s React, and the Signal:Noise Ratio

January 15, 2016 | Software Consultancy

Facebook’s React, and the Signal:Noise Ratio

So, you’ve started to hear a lot about React, the Javascript library developed by Facebook, but is it something you need to investigate? It’s time to distil the signal from the noise, position React amongst its rivals, and provide an indication of where it currently would – and would not – be a suitable fit.

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JavaOne: Debugging Java Applications Running in Docker

November 3, 2015 | Software Consultancy

JavaOne: Debugging Java Applications Running in Docker

My JavaOne experience was rather busy this year, what with three talks presented in a single day! The first of these talks “Debugging Java Apps in Containers: No Heavy Welding Gear Required” was delivered with my regular co-presenter Steve Poole, from IBM, and we shared our combined experiences of working with Java and Docker over the past year.

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Our Thoughts on DevOps and Cloud at JAX London

October 18, 2015 | Cloud, DevOps

Our Thoughts on DevOps and Cloud at JAX London

DevOps, Cloud and Microservices: “All Hail the Developer King/Queen”

Last week Steve Poole and I were once again back at the always informative JAX London conference talking about DevOps and the Cloud. This presentation built upon our previous DevOps talk that was presented last year, and focused on the experiences that Steve and I had encountered over the last year (the slides for our 2014 “Moving to a DevOps” mode talk can be found on SlideShare, and the video on Parleys).

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Software Circus: Thinking Fast and Slow with Software Development

September 13, 2015 | DevOps

Software Circus: Thinking Fast and Slow with Software Development

Making Good Decisions within Software

Last week I was privileged to be able to present my “Thinking Fast and Slow with Software Development” talk at the inaugural Software Circus conference in Amsterdam. The conference was amazing, and I’ll write more about this later, but in this post I was keen to share the presentation slides and the thinking behind this talk…

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