16 items found: Search results for "anti patterns" in all categories x
April 18, 2018 | Microservices
Quite a few of the anti-patterns we observe today on microservices projects are strongly related to how people approach the problem. Given their nature, these anti-patterns tend to be deeply ingrained and self-sustaining. Addressing them starts with increased awareness and by changing ways of approaching the problem, rather than by the introduction of yet another technical tool or framework.
September 6, 2016 | Cassandra
A growing number of clients are asking OpenCredo for help with using Apache Cassandra and solving specific problems they encounter. Clients have different use cases, requirements, implementation and teams but experience similar issues. We have noticed that Cassandra data modelling problems are the most consistent cause of Cassandra failing to meet their expectations. Data modelling is one of the most complex areas of using Cassandra and has many considerations.
March 23, 2017 | Cassandra, Data Analysis, Data Engineering
In recent years, Cassandra has become one of the most widely used NoSQL databases: many of our clients use Cassandra for a variety of different purposes. This is no accident as it is a great datastore with nice scalability and performance characteristics.
However, adopting Cassandra as a single, one size fits all database has several downsides. The partitioned/distributed data storage model makes it difficult (and often very inefficient) to do certain types of queries or data analytics that are much more straightforward in a relational database.
March 7, 2017 | Data Analysis, GCP
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.
January 25, 2017 | Cassandra
One of the simplest and best-understood models of computation is the Finite State Machine (FSM). An FSM has fixed range of states it can be in, and is always in one of these states. When an input arrives, this triggers a transition in the FSM from its current state to the next state. There may be several possible transitions to several different states, and which transition is chosen depends on the input.
September 27, 2016 | Cassandra, Data Engineering
If there is one thing to understand about Cassandra, it is the fact that it is optimised for writes. In Cassandra everything is a write including logical deletion of data which results in tombstones – special deletion records. We have noticed that lack of understanding of tombstones is often the root cause of production issues our clients experience with Cassandra. We have decided to share a compilation of the most common problems with Cassandra tombstones and some practical advice on solving them.
September 15, 2016 | Cassandra
Cassandra isn’t a relational database management system, but it has some features that make it look a bit like one. Chief among these is CQL, a query language with an SQL-like syntax. CQL isn’t a bad thing in itself – in fact it’s very convenient – but it can be misleading since it gives developers the illusion that they are working with a familiar data model, when things are really very different under the hood.
April 28, 2016 | Software Consultancy
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.
April 2, 2016 | Terraform Provider
When it comes to automating the creation of infrastructure in cloud providers, Terraform (version at time of writing 0.6.14) has become one of my core go to tools in this space. It provides a fantastic declarative approach to describing the resources you want, and then takes care of making it so for you, keeping track of the state in either a local file or a remote store of some sort. Various bits of sensitive data is often provided as input to terraform.
January 30, 2016 | Microservices
The OpenCredo team will be presenting two sessions on our recent learnings with implementing microservices at the OOP Conference, which will be running from the 1st – 5th February. We will also be running a booth, and so if you are interested in learning more about our recent projects, are keen to see if we can help you with your latest technical or organisational challenges, or want to join our team, then stop by and say hello!
January 8, 2016 | Microservices
Many of our clients are in the process of investigating or implementing ‘microservices’, and a popular question we often get asked is “what’s the most common mistake you see when moving towards a microservice architecture?”. We’ve seen plenty of good things with this architectural pattern, but we have also seen a few recurring issues and anti-patterns, which I’m keen to share here.
November 23, 2015 | Software Consultancy
Over a year ago, my colleague Tristan posted on the OpenCredo blog about a test automation quick start framework. It’s a prepackaged framework you can clone and get going with testing instantly, rather than wasting your time rebuilding your framework every single project. We have used this framework successfully used on many of our internal projects, and it relies upon a Java, Cucumber-JVM and Selenium stack.
November 1, 2015 | Microservices
To use or not to use hypermedia (HATEOAS) in a REST API, to attain the Level 3 of the famous Richardson Maturity Model. This is one of the most discussed subjects about API design.
The many objections make sense (“Why I hate HATEOAS“, “More objections to HATEOAS“…). The goal of having fully dynamic, auto-discovering clients is still unrealistic (…waiting for AI client libraries).
However, there are good examples of successful HATEOAS API. Among them, PayPal.
January 30, 2015 | Software Consultancy
When I first started programming in Scala a few years ago, Traits was the language feature I was most excited about. Indeed, Traits give you the ability to compose and share behaviour in a clean and reusable way. In Java, we tend deal with the same concerns by grouping crosscutting behaviour in abstract base classes that are subsequently extended every time we need to access shared behaviour in part or in total.
November 19, 2014 | Microservices
Undeniably, there is a growing interest in microservices as we see more organisations, big and small, evaluating and implementing this emerging approach. Despite its apparent novelty, most concepts and principles underpinning microservices are not exactly new – they are simply proven and commonsense software development practices that now need to be applied holistically and at a wider scale, rather than at the scale of a single program or machine. These principles include separation of concerns, loose coupling, scalability and fault-tolerance.
November 6, 2013 | Software Consultancy
In many organisations, development and test teams have a ready answer for this, and that answer is usually wrong. Commonly, teams use test counts and code coverage statistics, which alone are not enough to validate a test approach and run the risk of giving a false sense of security to stakeholders. In practice, we are not able to fully prove the efficacy of our test strategy until after a release. Once software is in use, new defects highlight where our tests are failing to validate the software and where we need to invest effort to improve coverage. This is where many teams fail to learn and improve.
