Here you will learn about Corda technology which was developed by the company called R3. They made the Corda ecosystem specifically for financial institutions and their goal is to replace the outdated banking technologies.
Corda, just like Blockchain, is using the so called Distributed Ledger Technology, but the whole interpretation of DLT is somewhat different to the traditional cryptocurrency technology, Blockchain.
Firstly, one of the major difference between Corda and the Blockchain is that while the latter works with programming based smart contracts, Corda system uses regular "law" based contracts. One of the reasons behind this is to be compatible with the really strict regulations towards the financial institutions.
The major information about these contracts are programmed into the so called States. For example, here is an IOU (I owe you), where Alice says that she will pay for Bob at a specific time. The major information could be the amount, deadline, interest rate.
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| Starting States (from: Corda training materials) |
All of these States can have an additional word-based contract attached to it, which now can be an actual legal contract based on the State.
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| Legal Template + Information from State = Legal Contract (from: Corda training materials) |
The structure of the ledger is similar to the Blockchain of Bitcoin as both of them represents the actual status of the system with the unspent transaction output (UTXO). But instead of using coins the Corda system uses the States, mentioned above, which represents the contracts. The ledger record the evolution of these contract, because when a contract changes a new State is created with new parameters and the previous State becomes Historic.
In our example Alice owed Bob 10 pounds and already paid back 5 pound, now the contract is going to be actualized. Which means that the original State of owing 10 pounds will become historic and a new State is created with owing 5 more pounds. Here we can see that the whole systems actual status is represented by the non-historic States.
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| Structure of the ledger (from: Corda training materials) |
Other major characteristics of the Corda ledger is that there is no global ledger which is replicated at all the nodes in the system like in a regular Blockchain. The reason is that this system would publicly store the data at each node which in a financial environment is not recommended to say the least.
On the other hand Corda system is uses so called biparty or multiparty non-historic States, which are only visible to certain nodes and roles of the system. For example on the figure below we can see a system with 9 current State, which can be seen from different roles. Like State 1 and 7 is only visible for Alice and Bob or State 3 can only be seen by Carl, Ed and Demi, etc.
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| Local visibility on the ledger (from: Corda training materials) |
These States represents the whole systems actual status. Instead of global transactions the platform only sends the information to the participants who must see them (need to know protocol).
This of course is not as safe as the usual Blockchain but Corda is planned to work in different consortium environments where the nodes represent enterprises and probably run on an internal banking system.
There are other components to the system which are not as important as the above mentioned but are needed to be mentioned. like the Oracle node which is used to validate and integrate data from outside sources or the Notary services which is needed to validate and register things to the ledger. The last interesting part worth mentioning is the Flow framework which can be used to customize the communication protocol.
The programming language can give another advantage to Corda too. Unlike major Blockchain based solutions where can be several types of languages used, like Solidity for Ethereum or C++ for EOS and Bitcoin or Go for Hyperledger Fabric. Corda uses Kotlin, a Java based programming language. As many current financial solutions were written in the tried and tested Java language, the US regulators just recently said that Corda was the only technology to pass their strict criteria.
Summary
I would say that Corda uses a very special distributed ledger technology. It aims to collaborate with banks and other financial institutions to change the old, almost 50 years old, way of conducting their business.