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Technology

This page lists the technologies and tools chosen for the project

Current technology choices

Technology Choices

Programming language - Java

Java 17 is chosen as programming language.

  • Java is well known in the energy sector
  • Developers are available
  • Java is familiar within LFE projects

Java build environment - Maven

For building the applications we use Maven. Maven is good supported in CI/CD.

Microservice deployment - Docker

Microservices are deployed as Linux based Docker container. Advantages of deployment in Docker container:

  • Deployment is independent of deployment platform/OS
  • Well supported for cloud deployment
  • Tooling readily available
  • Open source
  • Scalable, redundant
  • Images can be distributed easily

Database - BaseX

For the database BaseX](https://basex.org/) is chosen on following arguments:

Pros

  • Native XML database
  • Fully Open Source
  • BSD license
  • Easy to setup using available Docker image
  • Cross-platform available
  • Active community
  • Multiple API's, like REST(ful) and HTTP
  • ACID guarantees
  • Many usage examples available in different programming languages

Cons

  • No clear use cases using BaseX
  • Versioning is not out-of-the-box available. Need to use a second database to create 'versioning', which creates an archive database and a current database. And by using RESTXQ is relatively easy to create a versioning mechanism. BaseX gave SirixDB as a good alternative in case we want a NoSQL database with versioning mechanism.

XML Processing

XML Validation

Schematron

SCL XSD is the base schema for the SCL file validation. Even though, with XSD 1.1, it's somehow possible to define co-occurrence constraints with tags "key", "keyref" (combined with xpath selector) and restriction rules with "assert" (within a type definition), that is not enough to expressed complex and custom business logics.

Schematron is a rule-based validation language for making assertions about the presence or absence of patterns in XML trees. One doesn't need heavy environment to use Schematron. Schematron is XML, uses xml technologies (XPATH) and is very straightforward (less than seven basic elements) It has features for XML processing that other schema validators don't have:

  • inter-document constraints validation,
  • hint to fix file under validation.
  • Phase/Profile validation
  • Abstract rules definition that can be extended (inheritance)
  • Embeddable in XSD and Relax NG schema
  • etc.

It's optimally used in combination with XML schema (XSD, RELAX NG).

Java frameworks for XML processing

Pros JAXB

  • JAXB (Java Architecture for XML Binding) is a framework that allow mapping Java classes to XML representations
  • Memory efficient (for more information, take a look at the comparison in CIM - 61850 Mapping technologies)
  • Uses the XJC tool available in the JDK, that compiles an XML schema file into Java classes annotated with JAXB annotations suitable for (un)marshalling. This way, a XML file can be easily build by inserting data into the models.

Cons JAXB

  • JAXB was part of the Java language, but has been removed from the language since Java version 11. To use it, you have to add an extra dependency.
  • Dealing with large documents is not straightforward (cf. JAXB user guide.)

Java libraries for schematron

Other supports for Schematron specification

  • lxml (Python library)
  • libxml2 (C XML library)

RDF4J for IEC CIM configuration files

Pros RDF4J

  • Java library for querying RDF(XML) files
  • Well known in the Java community
  • Not having to re invent the wheel of processing incoming IEC CIM configuration files

Cons RDF4J

  • If you don't have experience with triples, it might take a while before understanding it all.

MapStruct

MapStruct is a Java framework to do bean mapping. MapStruct is for instance used in the CIM Mapping for mapping data between CIM classes and IEC 61850 classes. More information can be found on https://mapstruct.org/.

Pros

  • Mapping done in a separate interface (Mapper interface) with annotations
  • Active project on GitHub
  • MapStruct project is aware of Quarkus, see this article
  • Integration with all kind of IDEs
  • Performance also seems to be fast, because no Reflection used, but a generated classes. Baeldung Overview

Cons

  • Needs an annotation processor in Maven to generate the classes from the interface

Java framework - Quarkus

For the framework to be used with Java we choose Quarkus.

Pros

  • Java stack, and working experience is available in the community
  • Open Source
  • Hot reload for quick development
  • Less verbose code when developing REST API's, compared to for example Java Spring
  • Tailored for GraalVM (universal VM), which is also very interesting for us (usage of resources)
  • Huge decrease of memory huge compared to traditional cloud-native stacks like Java Spring.
  • Huge decrease in response times compared to traditional cloud-native stacks like Java Spring.
  • Backed by RedHat
  • Quickly settings up microservices with REST APIs

When looking at the memory usage (and response times) of Quarkus, it's definitely interesting for us. Also take a look at this comparison with Java Spring

Because CoMPAS is an application which also should run locally, memory usage is an important aspect. Together with being a modern microservice framework, backed by RedHat and being a Java framework (which we are having experience with) it's the best choice for now!

Cons

  • Doesn't support full set of some EE standards, like Enterprise JavaBeans. Expected is that it's not a game breaker for us.
  • Relatively new technology, framework could contain some "rookie mistakes". On the other hand, multiple researches are stating the maturity of the framework it achieved in this short time.
  • Not many developers are acquainted with Quarkus compared to e.g. the Spring framework.

Source control - GitHub

We choose GitHub for source control. This is good practice for open source development. The CoMPAS repositories can be found at https://github.com/com-pas/

CI/CD - GitHub actions

We choose GitHub Actions as mechanism for CI/CD.

Pros

  • Upcoming tool, really active in developing
  • Free tool for public GitHub repositories (which CoMPAS is)
  • Integrates perfectly with GitHub repositories

Cons

  • Software is proprietary
  • Adoption is growing within Alliander

Tool advise

This section lists the development tooling that is advised. Of course developers are free to use their own development tooling

SDE - Microsoft Visual Studio Code

Microsoft Visual Studio Code is a versatile development environment supporting many languages.