web4

Web4 is a new way to distribute decentralized apps. You only need to deploy one smart contract using WebAssembly to host your app HTTP backend, static resources and blockchain logic.

How it works?

There is an HTTP gateway to NEAR blockchain which allows smart contract to handle arbitrary GET requests. Every smart contract on NEAR also gets corresponding API endpoint which can be accessed through regular HTTP requests.

Example contract

export function web4_get(request: Web4Request): Web4Response {
    if (request.path == '/test') {
        // Render HTML with form to submit a message
        return htmlResponse(form({ action: "/web4/contract/guest-book.testnet/addMessage" }, [
            textarea({ name: "text" }),
            button({ name: "submit" }, ["Post"])
        ]));
    }


    if (request.path == '/messages') {
        const getMessagesUrl = '/web4/contract/guest-book.testnet/getMessages';
        // Request preload of dependency URLs
        if (!request.preloads) {
            return preloadUrls([getMessagesUrl]);
        }

        // Render HTML with messages
        return htmlResponse('messages: ' + util.bytesToString(request.preloads.get(getMessagesUrl).body)!);
    }

    if (request.accountId) {
        // User is logged in, we can welcome them
        return htmlResponse('Hello to <b>' +  request.accountId! + '</b> from <code>' + request.path + '</code>');
    }

    // Demonstrate serving content from IPFS
    if (request.path == "/") {
        return bodyUrl('ipfs://bafybeib72whzo2qiore4q6sumdteh6akewakrvukvqmx4n6kk7nwzinpaa/')
    }

    // By default return 404 Not Found
    return status(404);
}

Basically smart contract just needs to implement web4_get method to take in and return data in specific format.

Request

@nearBindgen
class Web4Request {
    accountId: string | null;
    path: string;
    params: Map<string, string>;
    query: Map<string, Array<string>>;
    preloads: Map<string, Web4Response>;
}

Response

@nearBindgen
class Web4Response {
    contentType: string;
    status: u32;
    body: Uint8Array;
    bodyUrl: string;
    preloadUrls: string[] = [];
}

Loading data

You can load any required data in web4_get by returning list of URLs to preload in preloadUrls field.

E.g. contract above preloads /web4/contract/guest-book.testnet/getMessages. This class getMessages view method on guest-book.testnet contract.

After data is preloaded web4_get gets called again with loaded data injected into preloads.

Posting transactions

You can post transaction by making a POST request to corresponding URL.

E.g contract above preloads has form that gets posted to /web4/contract/guest-book.testnet/addMessage URL. This URL submits transacion which calls addMessage method on guest-book.testnet contract.

Note that both JSON and form data are supported. When transaction is processed by server user gets redirected to wallet for signing this transaction.

In future there is a plan to allow sending app-specific key as a cookie to sign limited subset of transactions without confirmation in wallet.

near.page

You can access your deployed smart contract on https://near.page. This is hosted web4 gateway provided to all .near accounts. For now it's free, but in future you might have to pay depending on how much traffic you get.

Every contract gets corresponding domain, e.g. check out https://web4.near.page rendered by web4.near contract.

testnet.page

This works same as near.page but for contracts deployed on testnet. Every account.testnet gets corresponding account.testnet.page domain.