In this document
The purpose of this module is to provide an abstract API for the rest of the application.
Under the hood, it uses the DerivAPIBasic package which is part of the @deriv/DerivAPI
package.
The reason we need such abstractions is to hide the complexities of dealing with API and keep accessing to the API data fast and easy.
Requests are sent via calls (usually a camelCase version of the message type). The requests return a Promise which resolves when the response comes back from the API regardless of the success or failure of the request.
The original response is returned to the caller wrapped in the resolved promise.
This is conceptually wrong, but it's a compromise to make the Deriv API work with the current FE code.
Other users of DerivAPI can simply rely on the resolve/reject/pending state
of the Promise based calls and RxJS subscriptions.
const poc = await WS.proposalOpenContract(contract_id);Subscription is done using subscribe[RequestType] calls available from the socket
base module. They all expect to receive a request and a callback, the callback is
called whenever there's a new response (regardless of success or failure).
Under the hood the subscribe calls are made on an RxJS based subscription, and
a Subscriber object is returned from each subscription.
The use is required to keep the Subscriber object for calling Subscriber.unsubscribe()
on that later.
const subscriber = WS.subscribeProposal(proposalRequest, cb);
// later
await WS.buy(buy_request);
subscriber.unsubscribe();WS.cache provides an in-memory fast cache that currently lives as long as the
page is visible, when you refresh the page, the cache will be reset automatically.
To use the cache you can call WS.cache following the method call:
const active_symbols = await WS.cache.activeSymbols('brief');Beware that using the cache will provide the method matching the DerivAPI
specifications, and any override we have in the socket base won't work, this results
in a potentially inconsistent API. Fortunately, currently most of the overridden
calls are not supposed to work with caching, so we've dodged that bullet for now.
In the future, it's best to avoid adding new method overrides in the Socket base and if a different set of arguments/behavior is desired, a middleware should be created for that.
Very similar to WS.cache, WS.storage provides an interface to read information
from permanent storage, if available. The permanent storage currently used is
the socket cache module, therefore the expiry of the fields related to the
storage is defined in there.
By default WS.cache looks up WS.storage first, if it's unavailable then looks up
the API.
Same as cache, method calls on the WS.storage are passed to DerivAPI so the method
overrides won't work.
There's a WS.authorized interface that can be used to make sure the API is authorized
before making the requests. The method calls used with authorize are passed
to the socket base and support overrides.
// Waits for the API to be authorized (by another call) or buys immediately if already authorized
const buy_response = await WS.authorized.buy(buy_params);WS.authorized can be used with cache and storage:
// This tries to lookup the storage for the payout currencies
// if not found it'll make the payout currencies request
// but all of this happens after the API is authorized
// NOTE: This doesn't prevent somewhere else from requesting an unauthorized
// payout currencies, and filling the storage with it, so use with caution
const payout_currencies = WS.authorized.storage.payoutCurrencies();