ELK Server

This project wraps the Eclipse Layout Kernel (ELK) in a standalone Java application. It can be connected to a client via a process pipe (standard I/O) or a socket (useful for debugging).

Usage

Start the application with the --stdio argument to connect via a process pipe, or with the --socket argument to connect via a socket.

Input

The input of the server is an ELK graph in JSON format. The server responds to an input graph as soon as the full JSON data has been received (detected with the closing '}' character).

Output

The output is a JSON object mapping element identifiers to their layout information. The following TypeScript definitions specify the output format:

interface LayoutData {
    [id: string]: LayoutElement
}

type LayoutElement = ShapeLayoutElement | EdgeLayoutElement

interface ShapeLayoutElement {
    position: Point
    size: Dimension
}

interface EdgeLayoutElement {
    route: Point[]
}

interface Point {
    x: number
    y: number
}

interface Dimension {
    width: number
    height: number
}

In case the request cannot be fulfilled due to a Java exception, the server responds with an error description with the following format:

interface Error {
    message: string
    name: string
    stack: string
}

Client Implementation

A client for elk-server is available for Sprotty in the sprotty-elk package. See the examples in the Sprotty repository for more details.