Networking API

The Networking API allows scripts to send HTTP requests to fetch data over the internet.

Networking

Functions	Description
static Networking.fetch(url: String): NetworkResponse<DataReader>	Fetch data from the corresponding URL. Returns a NetworkResponse wrapping a DataReader.
static Networking.fetch(url: String, requestOption: RequestOption): NetworkResponse<DataReader>	Fetch data from the corresponding URL, with custom Request Options applied. Returns a NetworkResponse wrapping a DataReader.

Show deprecated fields/functions

These functions are kept for backward compatibility, before the introduction of a unified Data Reading API.
You are advised to avoid using these functions for newly created scripts.

Functions	Description
static Networking.fetchString(url: String): NetworkResponse<String>	Fetch plain text content from the corresponding URL.
static Networking.fetchString(url: String, requestOption: RequestOption): NetworkResponse<String>	Fetch plain text content from the corresponding URL, with the request option applied. (See below for RequestOption)
static Networking.fetchImage(url: String): NetworkResponse<BufferedImage>	Fetch image from the corresponding URL.
static Networking.fetchImage(url: String, requestOption: RequestOption): NetworkResponse<BufferedImage>	Fetch image from the corresponding URL, with the request option applied. (See below for RequestOption)

RequestOption

This is a JavaScript Object that specifies connection-related details.

Field Name	Type	Description
method	string	The HTTP method used. Default to GET
connectionTimeout	number	Specify the max timeout in millisecond when sending the HTTP request.
readTimeout	number	Specify the max timeout in millisecond when retrieving data from an HTTP request.
headers	object	A JavaScript object which contains the HTTP header to apply when sending the request.
body	string	The request body to send. This is typically used for HTTP POST request. Note: The Content-Length header will be automatically set if this field is supplied.

NetworkResponse

Represents an HTTP response.

If request is successful, it will be wrapping a dynamic type (Annotated as DynamicType below) which you can obtain via getData().
(The type is specified in the Networking class in <angle bracket> syntax for the function you chose to invoke).

Functions	Description
NetworkResponse.getResponseCode(): int	Get the HTTP Response Code, a list can be found here.
NetworkResponse.success(): boolean	Whether the request succeeded. Note: This only returns whether a response is given back from the server, use NetworkResponse.ok() to check if the response code from server is in the OK range!
NetworkResponse.ok(): boolean	Whether the response code is within 200 - 299 range. Same as checking if NetworkResponse.getResponseCode() >= 200 and <= 299
NetworkResponse.getData(): DynamicType?	Obtain the fetched data. Null if the request failed.
NetworkResponse.exception(): Exception?	Returns the relevant java exception if the request failed. Null if the request succeeded (NetworkResponse.success())
NetworkResponse.getHeaders(): Map<String, List<String>>?	Obtain the headers in the HTTP response. Null if the request failed.

Example

/* GET request */
let response = Networking.fetch("https://api.modrinth.com/v2/project/minecraft-transit-railway");

if(dataResponse.success()) {
    if(dataResponse.ok()) {
        let data = response.getData();
        let mtrProjectStr = data.asString();
        let mtrProject = JSON.parse(mtrProjectStr);
        console.log(`The MTR mod is last updated on ${mtrProject.updated}`);
    } else {
        console.error(`Error: Server returned ${dataResponse.getResponseCode()}`);
    }
} else {
    console.error(`Failed to connect to server: ${dataResponse.exception().getMessage()}`);
}

/* POST request */
let dataResponse = Networking.fetch("https://localhost:7171", {
    method: "POST",
    connectTimeout: 1000, // in millisecond
    readTimeout: 1000, // in millisecond
    headers: {
        Accept: "application/json"
    },
    body: JSON.stringify(
        {
            key: "value"
        }
   )
});

... (AWT code)
if(onlineImage != null) {
    g.drawImage(onlineImage, 0, 0, null);
}

Background Fetching

You may combine this with the Background Worker API to perform non-blocking HTTP request.

Note on User-Agent

JCM always supplies a default User-Agent header with the value Joban Client Mod (https://jcm.joban.org).

This value cannot be overriden (Or rather, JCM will always overwrites your preferred UA) unless you disable Scripting Restrictions, in which case you may override the User-Agent when supplying the header fields via RequestOption.