Say you want to trace eco paper rolls around the globe. What could the blockchain do for you? Who are the nodes/miners/coins in this application?
When you suspect some intermediate in the paper chain to exchange eco paper for cheaper ordinary paper, how does distributing the information that he has X rolls on store prevent this scenario.
Another feature is not related to inventory. Ledgers that have acute accountability features attached, where some stakeholders may have incentives to fake the records.
Like, for example transport truck driving schedules. Drivers are allowed only to drive so much, and there are penalties involved if the drivers don't rest enough. The main accountability measure here is the driving ledger. Whose maintainer has incentives to fudge it (the driver or the employer of the driver).
To understand this, first you have to understand why we structure mining. In the case of Bitcoin or Ethereum, you need a method that allows any arbitrary computational device to verify and add to a given blockchain. In lieu of trusting that device, the blockchain makes it do a massive amount of busywork, called mining, to prove it isn't bullshitting the network. Different implementations have different busywork, but it's designed to make it hard to change the network by arbitrary devices. This is why we can allow any untrusted device on the network.
In the case of logistics, we are already operating under some amount of trust. This is through a mechanism of certification of goods, suppliers, verifying the goods are what they say they are, and the verification of those approvals and certifications. Even in a trusted environment, managing that coordination of certifying and verifying is slow, bureaucratic, and grows with the size of the logistic network. Additionally, many supply chains generally certify new entrants before allowing them to contribute. This creates a barrier to entry when establishing trust in the same way busywork creates a barrier for devices. Then there are whole units of auditors that go through and recheck all those certifications to make sure the whole chain is authentic with regards to the goods moving through it.
Blockchain technology is a mechanism of creating certifications (signing a transaction) and verifying those certifications (miners/verifiers on a chain) that can operate in a decentralized but coordinated way. It allows for the whole system to better coordinate information and certification that used to be done manually.
Did you notice I never mentioned tokens?
In this model, I'll refer to it as Proof of Reputation (PoR), an actor might be a certified as a reputable party in the network. You might be a certified producer of bananas, verified and certified as fair trade and humane organic hand-crafted conditions by other organizations. I'm a buyer of bananas, but I want to make sure I'm buying fair trade bananas. I can look at your certification-of-origin and verify that you are reputable as fair trade. A port authority can confirm that I bought your bananas and put them on the USS Boaty McBoatface destined for Los Angeles to meet the huge banana split market. You as a consumer can check these certifications at the store.
As it stands, all of these processes operate haphazardly and it's insanely difficult for major countries to coordinate and verify what is going on. The coordination technologies, like Ethereum's GHOST implementation, combined with public-key infrastructure helps reduce the "deadlock" time of coordinating these large public and private bureaucracies.
I know I'm not explaining this well. I'm still working on a more concrete model. In my mind the process of creating, signing, and verifying a cryptotoken transaction is eerily similar to what logistics management is all about. You need to prove the origin, verify they made the transaction, and then have a reputable actor process said transaction. There's still a lot of manual work, but the system of sharing and coordinating that work is also painful and manual. The technologies that power cryptotokens can help with the latter problem.
How do you verify that the physical objects the digital certificate is attached to, is actually attached to the things it is meant to certify, and not replacement counterfeit?
At it's heart logistics is a global concurrency problem. The "locks" we use now are large sprawling bureaucracies that manually coordinate the transfer of information among many independently moving agents. Getting information into and out of this organization is a tedious, labor-intensive, and time consuming process. The technology that empowers cryptotokens is an alternate computerized concurrency management for this kind of information transfer and lookup that doesn't rely on a central organization or system.
Now how do you get "the blockchain" to know which paper rolls went into which shipping container.
The blockchain would be a decentralized papertrail accessible to all actors of the supply chain, down to the end consumer ideally, instead of the current nightmare of shipment papers, siloed ERPs and so on
bad actor: I manufacture the cheaper rolls, and stick labels for the expensive ones on, and scan them
How will "the blockchain" prevent either scenario
Bad actor: unless you intend to use rolls by yourself, what do you gain? You can't sell the better rolls as such, because you have broken chain of trust.
But such arguments lead nowhere. Of course you can come up with scenarios which can be misused. The real challenge (and one that is being solved by lots of people in crypto world - well, at least those that aren't consumed by greed) is finding scenarios that work. The ability to store information cheaply and immutably can change many industries, but technology must be deployed in such way that it makes sense.
I had professional experience in an industry where we had to go to the plants to ensure rolls of paper certified from suppliers using responsibly-managed forests were physically separated from the non-certified ones. We needed the paperwork coming from China, then another one from the transformation plant in Morocco, then in customer warehouses across Europe.
An external protocol that would provide universal tracability, usable by any actor of the chain, seem like a great solution to a real problem. Blockchain provides some "neutrality", ie no need for each actor to find its own certificate provider (I imagine that service shops would help larger companies set up their systems, but the back-end would be common across all actors).
I'm not very convinced by pseudo-decentralized apps in most domains, but in logistics... very bullish !