Project Merlin

Merlin manages configuration for deployable components

The purpose of this project is to help manage different sources of configuration for deployable apps. The intended foundation focuses on configuration sources read/write/transform utils and a set of classes expressing the configuration domain.

Developed in TDD manner

The project is developed in a TDD manner and all TDD steps are explicitly expressed in the commit history. This can serve the purpose of teaching TDD at workshops and seminars under the terms provided by the license attached.

Quick introduction

Case: reading from a config file (YAML)

Given a configuration file of YAML format:

environments:
- local
- test
parameters:
- maxThreads: 5
- listeningPort:
    description: a port number at which the process listens
    value: 8080
- cacheExpirationSecs:
    value:
    - local: 0
    - test: 30
- numberOfNodes:
    value:
    - test: 5
    - default: 1

This code loads it into the memory as strongly typed instances:

Stream sourceStream = CreateSourceStream();
Configuration config = new YamlConfigurationSourceDriver().Read(sourceStream);

var local = new ConfigurableEnvironment("local");

var val = config.Parameters.Where(p => p.Name == "cacheExpirationSecs").Values[local];

Case: writing into a config file (Excel 2003 XML)

The configuration represented in memory can be serialized into a stream in one of the supported formats (e.g. Excel 2003 XML):

Configuration config = LoadAndProcessConfig();
Stream outputStream = PrepareOutputStream();

new ExcelConfigurationSourceDriver().Write(outputStream, config);

produces Excel XML containing a single table:

Name	Description	Default	local	test
maxThreads		5	5	5
listeningPort	a port number at which the process listens	8080	8080	8080
cacheExpirationSecs			0	30
numberOfNodes		1	1	5

Case: using a command line utility

merlin-console.exe -f initialYamlConfig.yml -t generatedExcelConfig.xml

generates a new representation of the configuration in the target format recognized by the file extension.