JarCastingNova
1. Why?
The goal of this project is to provide a small and easy-to-use library that enables developers to rapidly build systems or services in an "event driven, asynchronous and reactive style".
The origins of the API were heavily influenced by Node.js and its underlying programming model, hence the name (Node for Java). This programming model, which (for those who have no experience with Node.js) is based on single-threaded event processing, prove itself to be very helpful in eliminating nasty concurrency bugs and to allow the programmer to fully concentrate on the business logic.
However, as everything in life, this also came with a downside. Mainly, there were three things we had to fight with
- call back hell for business logic that depends on multiple data sources,
- the need to split a long running execution into various parts and emit artificial "sub events", and
- improper event processing can easily block your one and only thread, rendering the whole service unresponsive
Therefore we changed the philosophy (and implementation) of the library and based it on RxJava (2.0) to promote a fully reactive way of programming.
- Being reactive makes it very easy to express business logic based on various information sources and define "if this than that" scenarios.
- To the client, it is completely transparent whether information is delivered synchronously or asynchronously
- The client is under full control over the threading model. It can chose to go single threaded (if it has to mutate shared state) or multi threaded (for full system performance) at will. Going fully functional even eliminates that question
2. What's included?
Nova provides a couple of very small libraries. Those libraries try to focus on one (and only one) problem and try to solve it in a consistent way, making it easy to combine them. They provide solutions for common, technical problems, allowing service developers to concentrate on the required business logic.
Currently, the following libraries exist:
-
Core functionality
- core: core functionality, used by all other components
-
Communication
- comm: communication base library providing protocol agnostic, reactive message sending and retrieval
- jms: reactive JMS messaging
- http: reactive HTTP communication
- rest: annotation based REST communication according to the JAX-RS spec
- websockets: reactive WebSocket communication
- kafka: reactive Kafka communication
-
Service related
- service: Small service skeleton with a defined lifecycle and easy access to Nova and its EventBus
- metrics-serialization: Utility to easily serialize MetricDumps
- metrics-elastic: Utility to push Metrics to Elasticsearch
- metrics-kafka: Utility to push Metrics to Kafka
3. How do I integrate it in my projects?
The easiest way is to retrieve Nova from Maven central. We recommend you are using maven's dependency management feature and import the BOM, so that you can be sure that all included modules properly work with each other:
<dependencyManagement>
<dependencies>
<dependency>
<groupId>ch.squaredesk.nova</groupId>
<artifactId>bom</artifactId>
<version>9.0.0</version>
<scope>import</scope>
<type>pom</type>
</dependency>
</dependencies>
</dependencymanagement>