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Utilities for creating links 🔗.

Links are sort of middlewares, they allow us to control a request flow.

A link receives a request and pass it forward to the next link, unless it is a "terminating" link, in this case, the link does something of that request, for example sends it to the server.

A link returns an observable for the previous link to subscribe to.

The flow looks like:

request  -> | LINK1 | -> | LINK2 | -> server   |
response <- |       | <- |       | <- result <-|


A Link for logging how long it took to resolve the request, called logger

request  -> logger creates   -> forward to next and subscribe -> request goes to server  |
response <- logger does log( <- bubble the chain of handlers  <- response from server  <-|

There are 2 types of Links:

  • stateless
  • stateful

A little bit like a react component can be:

const myComponent: React.FunctionComponent = () => <p>Hello</p>;


class MyComponent extends React.Component {
  render() {
    return <p>Hello</p>;

A Link can be

const link: Link = (operation: Operation, forward: Link) => forward(operation);


class MyLink extends StatefulLink {
  request(operation: Operation, forward: NextLink) {
    return forward(operation);


some links

setMethod link that sets the method of the request (GET, POST, etc...)

poll link that polls every x seconds

triggerFetch (terminal link)


concat concat 2 links together

pipe compose all links into 1

toLink transforms a stateless link into a stateful link

toPromise transform an observable into a promise