Flowid

Category Theory is one of the hot topics in computer science. There are many blogs, youtube videos and books about it. It is an elusive subject, with the potential to be the ultimate unifier of everything (math, quantum physics, social justice), to allow us to write the best possible programs and many other lofty goals. I decided to explore the field and see how it can help me. Below is a summary of 12 weeks of reading and watching presentations about Category Theory. It took me some time to select the study material. In the end I decided to use David Spivak’s book (Category Theory for Sciences, David Spivak, 2014) and the youtube recording of a 2017 workshop. These provided both a rigorous approach and a lighter version in the youtube videos. In parallel we explored other sources for a more practical perspective. The CTfS book is a systematic introduction to Category Theory, with definitions and proofs. I liked that, it is a solid foundation. The examples are mostly from math (Set, ...

Performance testing  is challenging, frustrating, often underestimated typically getting attention only after an incident. How did we the performance test and what did we learn during the development and implementation of  web-services for a new CRM system?

“Defining Message Formats” is the title of a message posted on the Service Oriented Architecture mailing list [1]  which attracted a lot of attention.  The post summarizes  the dilemma faced by solution architects when they have to define a service interface: 1. Base the internal message format on the external message standard (MISMO for this industry). This message set is bloated, but is mature, supports most areas of the business, and is extensible for attributes specific to this company and its processes. 2. Create an XML-based message set based on the company's enterprise data model, which the company has invested a great amount of money into, and includes a very high percentage of all attributes needed in the business. In a nutshell, we've generated an XML Schema from ER Studio, and will tinker with that construct types that define the payloads for messages. 3. Use MISMO mainly for its entity definitions, but simplify the structure to improve usability. We benefit fr...

 Data consistency along with Multi-Step Process and Composite Application are the most common integration scenarios. At a very high level, multiple components manipulate and store the same entity. When one component modifies the entity the others must be notified of this change and ensure a consistent state of the entity across the whole system.  In real applications, to address the complexities around keeping the entity consistent in a distributed system, the business and system architects impose constraints that simplify the patterns of interaction and lead to a robust solution. The rest of these article contain typical approaches to Data Consistency. Depending on the type of entity there could be design variations but they all share the approach. To make this document more concrete, I will use the Customer entity as an example. One solution is to centralize all the Customer changes in one component, the “Customer Master,” and all the other component keep read-only copies of...