Overview

An easy-to-use dependency resolver using topological sorting.

Installation

npm install toposort-dependency-resolver

then in your code:

dependencyResolver = require('toposort-dependency-resolver')

Usage

This module resolves dependencies between various components and tells us the sequential order in which these components can be safely accessed. The underlying algorithm being used is topological-sorting via a Directed Acyclic Graph(DAG).

API

• resolveDependency(data, callback)

Examples : #1

	dependencyResolver.resolveDependency(
			[
				{
					component : "1", 
					dependsOn : [], 
				},
				{
					component : "2", 
					dependsOn : ["1"], 
				},
				{
					component : "3", 
					dependsOn : ["1","2"], 
				}

			],function(err, result) {})

		If the input forms a directed acyclic graph,
		err : null
		result: [{"component" : 1"}, {"component" : "2"}, {"component" : "3"}]

#2

	dependencyResolver.resolveDependency(
		   [
           		{
					component : "A", 
					dependsOn : ["B"], 
				},
				{
					component : "B", 
					dependsOn : ["A"], 
				},
				{
					component : "C", 
					dependsOn : ["B"], 
				}
		   ],function(err, result) {})

	   err.message : "Dependencies are cyclic"

• resolveDependencyAndMakeApiCalls(data, callback)

Example :

	dependencyResolver.resolveDependencyAndMakeApiCalls(
			[
           		{
					component : "A", 
					dependsOn : [],
					options : {
 						url : 'http://localhost:8080/api/bears',
						method:'GET',
						headers:{},
						data:{}
					} 
				},
				{
					component : "B", 
					dependsOn : ["A"],
					options : {
						url : 'http://localhost:8080/api/bears/',
						method : 'POST',
						headers : {},
						data : {}
					} 
				},
				{
					component : "C", 
					dependsOn : ["B","A"],
					options : {
						url : 'http://localhost:8080/api/bears/5b30774ebebd0f1700a39acf',
						method : 'PUT',
						headers : {},
						data : {}
				    } 
				}
		   ],function(err) {})

	If dependencies are cyclic, this function returns err("Dependencies are cyclic").
    If it is a directed acyclic graph and all the API calls are successful, err is null.

Unit Tests and coverage

Unit test have been added for all functionalities.

# Run tests
npm run test

# Run test along with code coverage
npm run coverage

Future Enhancements

• Return callback errors based on HTTP status codes of API calls.
• Save the progress of API calls made when an error occurs.
• Add retries to API calls.

Contributing

Contributions, questions and comments are all welcome and encouraged. For code contributions submit a pull request with unit tests.

License

This project is licensed under the MIT License

Meta

Ankita Sharma – [email protected]