因为最近做的项目需要对一些资源做简单的权限管理。老项目用的是 node_acl。功能比较全，但是对于简单的 acl 也需要连数据库。于是就在想可不可以把 ACL 搞的简单一点。

对于简单的 ACL，表达的是 role 是否被 allow 对一个 resource 做某个操作。

这其实可以使用一个三维矩阵来： 行代表 role 列代表 resource 第三维代表权限。

于是做了这个小库： acl-matrix

下面复制了下 readme, 欢迎讨论

Usage

1. Install

npm install acl-matrix

1. Require it

const AclMatrix = require('acl-matrix');

const roles = ['admin', 'member', 'guest'];
const resources = ['blog', 'comment'];
const allows = ['get', 'add', 'update', 'delete'];

// Each element in matrix stores the permissions of a role to a resource.
const matrix = [
    //   admin        member         guest
    [[1, 1, 1, 1], [1, 0, 1, 1], [1, 0, 0, 0]], // blog
    [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 0]], // comment
];

const acl = new AclMatrix(roles, resources, allows, matrix);

// 0
acl.isAllowed('member', 'blog', 'add');

// 1
acl.isAllowed('member', 'blog', 'get');

Concepts

• roles are the types of user trying to access resources
• allows describes the oprations user will need to do
• matrix describes the allows relation between roles and resources;
• third dimension of the matrix is an array of 0 and 1s, the length of array should equal to allows's. This array describes the permissions.

For example: in the above sample code, matrix[0][2] ([1, 0, 0, 0]) means the guest role is able to 'get' the 'blog' resource, but not others.

Parameter limits

• Row number of matrix should eauql to resources length;
• Collum number of matrix should eauql to role length;
• Element number of matrix should eauql to allows length;

Pros and Cons

Pros

node_acl is good, but it acquires database to store the acls. And it is relatively hard to mantain and update acl using node_acl.

Benefits of using acl-matrix:

1. Three dimensional matrix is the simplest way to store acl;
2. Simple to config and simple for future change;
3. No dependency, acl matrix can be easily shared between frontend and backend;
4. Performance: no database needed, checking permissions is justing reading elemet in array

Cons

1. By using node_acl you are able to save relations between users and roles. You will need to store the role of the user youself using acl-matrix
2. By default, permissions of each roles are fixed, which is suitable for most projects. But if you want to allow user define the acl, you will need to store multiple acl matrices

TODOs

Add more method for the class maybe?