Hi everybody... Richard Brown, CTO of R3, the firm behind Corda, here.
As Mike says, we're somewhat unusual in that there are many live, successful Corda deployments around the world. Mike's comment about how Corda is blockchain-like but not, strictly speaking, a chain of blocks is at the heart of this I think. Here's what I mean:
How many 'introductory' presentations have you been to (or, worse, given) to semi-technical people, where Bitcoin and other public blockchains are 'explained' by describing the components? You probably know the sort of pitch I mean: they laboriously build up the concepts - transactions, signatures, hashes, blocks, chains of blocks, mining, etc, etc. Such presentation are usually correct. But they impart almost no intuition. It's little wonder that so many 'business people' come away from them thinking that a blockchain is some sort of mysterious and magical technology.
There's a presentation I like to give where I go the other way. I give a one-line description of the problem Bitcoin solves [1] and then I help the audience 'invent' Bitcoin for themselves from first principles. There's an old blog post of mine that gives the rough idea [2]. The point is that successful architectures solve well-stated problems. Cargo culting never works.
Where I think many corporate deployments of blockchain went wrong was that they saw the huge enthusiasm for 'blockchain tech', had a vague intuition that 'inter-firm' or 'market-level' problems were ripe to be solved, but they never fully internalised that Bitcoin's (or Ethereum's) architecture isn't some sort of inviolable, handed-down-from-high blueprint... it's merely a very elegant engineering solution to a well-stated 'business problem'.
Yet many 'enterprise blockchain' platforms seemed to begin with the architecture of a public blockchain, and then tweaked it to make it palatable to businesses (eg engineering cumbersome privacy solutions on top to work around the inherently broadcast nature of the public chains). This always felt a bit weird to me.
With Corda, we were fortunate to have been given the time and space by our backers to write down our equivalent of the Bitcoin problem statement, and then to engineer a solution to that problem. Yes - of course, we knew we were in the 'inter-firm business process' space, and we knew the problem we were trying to solve was in some way 'blockchainy' But we did try really quite hard to write down the problem statement [3] and then go forward from there, rather than starting with a pre-existing architecture and then modifying it.
Yes - as Mike says, architecturally it looks a lot like Bitcoin (eg it has an unspent-transaction output data model). But it also has a bunch of other things that, to this day, no other Blockchain has... eg the Flow Framework that allows decentralised inter-firm workflows to be modelled (think temporal.io but without any centralised infrastructure). And, like Mike says, Corda passes data point-to-point and confirms each transaction one at a time - no blocks, no broadcast.
You would not believe HOW MUCH GRIEF we got from the blockchain community for that design in the early days. Yet - several years on, it seems to be working.
[1] I claim that the 'requirement' for which Bitcoin is the solution is: "build me a system of un-censorable digital cash."
[2] https://gendal.me/2014/05/21/bitcoin-mining-the-first-techno...
[3] Our problem statement? "Build me a platform that enables multiple firms to record and manage the lifecycle of the business contracts they have with each other, minimising the need for any new third parties." At least, that's what I thought I was building. Mike might disagree, however... I know he likes the "decentralised database" interpretation of Corda.