I would like to get USD price of DeFi tokens from Chainlink.
However, it looks like, I can get the price of an asset through either the Chainlink API calls, or Chainlink price feeds.
What are the costs associated with each and the differences and tradeoffs?
With Chainlink price feeds, each data feed is updated by a decentralized oracle network. Each oracle in the set publishes data during an aggregation round. That data is validated and aggregated by a smart contract, which forms the feed's latest and trusted answer.
Each oracle operator is rewarded for publishing data. On mainnet, sponsors are paying the LINK associated to keep those feeds live, decentralized, and secure, so they are not free. This allows the network to be a shared resource where everyone chips in a tiny bit and makes them even cheaper than running even your own centralized feed.
That being said, the price feeds are currently a simple view function, and anyone can technically use them as access controls are on the roadmap to be built at some point. It’s not really economical or fair for those backers who are paying to support them for everyone else. Until access controls are built, please reach out if you are using them on mainnet and learn how you can contribute to keep them reliable honest, and secure.
With API calls, Chainlink enables your contracts to access any external data source, through their decentralized oracle network. Making a HTTP GET request will fail unless your deployed contract has enough LINK to pay for it, therefore one needs to fund that smart contract.
If your contract is calling a public API endpoint, an Oracle job may already exist for it. To check available jobs and GET request prices, visit https://market.link/
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Is there a REST or Node.JS library API that provides global network metadata for Bitcoin and/or Etherum ?
The metadata I'm looking for is -
Average wait time for a transaction confirmation on the network
Average fee cost per transaction on the network
I know I could crawl/parse one of the many sites that provide this data, but that's not ideal. Hence I'm looking for a dedicated API to obtain this information.
Eventually I found out of places like CryptoCompare that provide that data
Coinbase stopped publishing it's user stats in 2017, so I haven't been able to find a way to see how many users currently use the exchange.
My (albeing limited) understanding is I should be able to work this information out from querying the Blockchain.
Is this possible?
I'am not sure about Ccinbase, but i know that a lot of exchanges creates completely different wallets(addresses) for each user, so its impossible to track them. You can do it for decentralized exchanges as Idex/Bancor/0x etc, because they are using specific smart-contract(only in Ethereum network)
I'm documenting in this blockchain world. Basically I would like to make some web application in which a user decides to make a donation, and would like to see who made the donation and to which entity. I have several doubts, the first one:
1-Is it possible to use blockchain using javascript? (can smartcontracts be done in javascript?)
2- If the donation is made using blockchain, is it necessary to use a cryptocurrency? or you can use real money and make the transaction (using some means like paypal)
3- Can real money be transferred by some means such as paypal using blockchain?
Thank you very much, your answers will document me much more
Is it possible to use blockchain using javascript? (can smartcontracts be done in javascript?)
Every blockchain has a SDK, the part of the software which lets you
interact with the real blockchain( A decentralise ledger). There
are generally two parts in the Blockchain , One is client and one
is processor.
As you must have guessed, Client is the one who sends the transaction,
This transaction must satisfy certain rules in order to be accepted by
the transaction processor. If the transaction gets validated by
transaction processor, The transaction will be added to the block alongwith
other transactions and this block will then be added to the blockchain.
Copied to all other nodes (Forks are a different story)
Generally Most blockchains lets you interact with the blockchain through
ABCI which is just an interface to convert your transaction into
a format understandable by the blockchain processor.
Some blockchains has their fixed transaction processing logic like Ethereum for
security and some lets you write your own transaction processing logic like
Sawtooth, Fabric etc.
Permissioned and some public blockchains like Hyperledger projects and
cosmos SDK lets you write your own application layer logic for Blockchain,
So yes, You can write those transactions in Javascript or any other programming
language, as long as it satisfies the interface.
Public blockchain deals with tokens having real worth. Their transaction logic
is already fixed, but some of them does provide javascript API's like NEO
(Not sure about that)
2- If the donation is made using blockchain, is it necessary to use a cryptocurrency? or you can use real money and make the transaction (using some means like paypal)
You can do that and put the donation receipt on Blockchain linked with
real identities of people. This way if anybody wants to check who pays
how much donation, They can query blockchain for the user address.
3- Can real money be transferred by some means such as paypal using blockchain?
This can also be done, but this will involve using a crypt exchange,
centralised or decentralise. You can convert the real money into crypto
of your choice at one end and vice versa at the other hand.
Note: This is based on my limited knowledge of Cryptocurrencies. Please consult more people or any professional company before acting on this advice.
I don't think any protocols offer the possibility to implement their smart contracts in Java Script, but you can build a translator between the two languages which could potentially benefit others in the open source community.
So you want have some engineers do some work for you, in this case build an web application. There are several ways you can get this done, here are some ideas:
a) issue tokens which pays profits based on the success of your new business, you might be able to do this on a protocol that is not tied to any specific crypto or fiat currency.
The users can use an exchange to convert your tokens to their favorite one.
b) approach a private equity or VC fund and get them to pay for it.
c) forget about blockchain, and just pay for the project to your favorite engineers.
I am trying to prototype a system that will display a list of choices to a user, and allow them to place an order for the one they select (an over simplification of the prototype, but sufficient to get to the point). I have the users credit card number, billing and shipping addresses, and other contact information, but I can't find any web services that will let me actually purchase something with this information to complete the prototype. I have checked directories such as Programmable Web and Xmethods, but they just seem to point to APIs that let you check for prices and availability, but not actually place an order. Does such a thing exist, or is there some reason (such as security) that I am missing, that prevents such a service from being offered?
The most important thing about online shopping is the security of transmitted information (e.g. credit card data). So the ideal case is to transmit these information directly to the related bank's (issuer of the credit card) payment services, rather than passing it via other service providers. This is what 3-D Secure does.
So when you use a common API this means putting an extra broker between, and passing the secure information to this party which increases vulnerability. Since such a broker cannot use 3-D secure (since it is not the merchant so not possible to make an agreement with the banks) and it should pass the information to online shopping site.
Moreover, an online shoping site can block traffic coming from such an intermediary webservice at any time if you do not make an obligatory agreement and making agreements for each online merchant is practically not very possible.
There is no such free API available the simple reason behind that information like credit card is very secure and confidential and there will security threat on free API's.
here is list of best 10 online payment system
http://sixrevisions.com/tools/online-payment-systems/
and this one who providing live demo
http://www.fastcharge.com/
I think it is possible though I don't know in depth information. I think this is what you see. In next steps you will be redirected to payment gateway of the bank and then you can complete the transactions just by answering some security questions. I think this is a service you should obtain from the bank. And I haven't seen any universal API that can perform the task you have mentioned.
Dialog GSM - Sri Lanka
Anything.lk - Sri Lanka
I've been tasked with setting up a society's website. I'm a full time Django (at al) web developer so I was happy to take on the task.
Going through the specs, they want to control memberships so that all applications need a "second" (read: sponsor, referee, etc) and then they need to pay a subscription fee to be part of the club.
This club has a number of events with variable ticket prices for lunches and talks to name two. Only members are allowed to see the price per ticket and therefore only members are allowed to buy the tickets.
I had originally planned on farming the event management off to EventBrite and pulling the upcoming events back to the website through EB's API but this members-only constraint looks like something EventBrite can't do.
Then there's processing members subscriptions. I had hoped to allow anybody to register a django.contrib.auth account but leave subscription payment offline but the client would be happier if they could mark accounts as "members", store the subscription data in the database and let the members pay online.
Like with EventBrite, I was hoping I could store rough membership data (whether or not they're allowed to subscribe, a unique token for the user on the API service, their level of membership and their membership's expiry) and there'd be something I could post users off to to process their subscription payment.
I basically don't want to touch any payment systems. Even something as simple as Paypal+IPN is something I'd rather not do (I can and have in the past on other projects) but it's the layer of management that I'd have to build around it (messaging members, creating recurring events, etc) that I'd like to farm out to a third party... Even if they do want an additional percent of the payments processed.
Do any of you know any suitable APIs that cover membership or events or both?
Or is this so complex that I should give up hoping for external help and just knuckle down and do it myself?
I think the google search you are looking for is online membership management. I don't know if any of them play particularly nicely with Django/python, but some of them do include APIs. Almost all of these are companies that charge, either for the system, or on a per-user basis.
If you don't mind installing something yourself, CiviCRM is a free, open source solution that I found with a bit of googling. It's integrates with either Joomla or Drupal (so probably PHP-based). You'd have to put the payment processing in yourself, but it does support payments using PayPal which would take handling payments mostly out of the equation. If you can, choose PayPal Express rather than PayPal Website Payments Pro since you may need to be PCI-DSS compliant to use the latter.