Saturday, March 24, 2018

Blockchain applications in Supply Chain Management

Here is the whitepaper that started this post, which is admittedly outside my domain of expertise. Also here is some discussion we had on this on Twitter. 

The white paper includes quotes like "7 in 10 consumer industry executives expect to have a blockchain production network in 3 years" and "Blockchains are expected to greatly reduce nine frictions. Including: inaccessible marketplaces, restrictive regulations, institutional inertia, invisible threats, imperfect information, inaccessible information."

Man, if that last statement is true, the companies should just employ blockchain and fire their CEO's and management teams as they are no longer needed. Blockchain is a miracle worker indeed. It enters inaccessible marketplaces, it loosens restrictive regulations, eliminates institutional inertia, makes visible the invisible threats (watchout ninjas), corrects/curates the imperfect information, and makes all information accessible.

I know that I tend to go hypercritical when I am analyzing some new idea/application. It is a vocational disease. On another day, I may try to write a more positive article about blockchain applications in supply chains. But, since there are already many overly optimistic articles on the blockchain applications in supply chains, this is the article you get from me today.

Do you need blockchains for supply-chain management?

There is this nice paper, titled "Do you need a blockchain?", that explains the application context blockchains would be useful for. This figure is really nice. I will keep this handy here, and refer blockchain fanatics to this figure.


And this table provides a nice comparison of your options as well.


As a case study the paper looks at supply-chain management (SCM). In SCM, the flow of materials and services required in manufacturing a given product is managed. This includes various intermediate storage and production cycles across multiple companies. Consider how complex the SCM for Walmart is. And, while many people don't realize this, military SCM problems rival or even exceed that of giant corporations such as Walmart. (Military is the biggest consumer of RFIDs behind Walmart.) If the military screws up their SCM logistics that may mean life and death. Due to misallocation of resources, some troops in deployment may suffer while some others would have surplus food/items that may need to be thrashed. (Don't search for military applications of blockchain. I searched for it and regretted reading superficial first-mover articles hyping blockchain use for military supply chain management.)

Of course an immediate issue facing the use of blockchains for SCM is that too much transparency could be a bad thing for business strategy (even more dangerous for military strategy).

Here is another great takeaway from the "Do you need a blockchain?" paper.  Harkening back to Figure 1, what is the nature of trust to the writer of the blockchain entry? How is integrity enforced at entry time (for recording the type, quantity, and condition of the goods being shipped)? If we trust the writer, what is the benefit of the blockchain system, let's replicate it across some append-only stores (that is how accounting does ledgers anyway).
"This reasoning leaves us with the question whether all writers can be trusted. SCM has the inherent problem of the interface between the digital and the physical world. A human, or some machine under the control of a single writer, typically is required to register that a certain good has arrived in a warehouse, and if for example its quality is appropriate. If there is no trust in the operation of these employees, then the whole supply chain is technically compromised as any data can be supplied by a malicious writer. If, on the other hand, all writers are trusted, a blockchain is not needed as a regular database with shared write access can be used instead. Note that if through some technical means, the connection between the digital and physical world could be realized in a secure manner, then the previous reasoning might change."
If you like to avoid the too much transparency problem and have some trust in the writers (or can have leverage on them via no-payment and no-future-business threats), then instead of a permissionless/public blockchain, going with a private blockchain could be a better option. But then why not just use a database or Kafka streaming to a database. Hyperledger in its current form is pretty close to that actually. If you have trust issues with writers, run PBFT on top of that.

MAD questions

1. What are some SCM use-cases where (distributed) databases/datastores would not work, and we positively need blockchains?

2. How much data is SCM applications going to generate?
In my previous post, I wrote up my notes from Dr. Laura Haas's talk on data science challenges in food supply chains. The talk mentioned from one food testing sample for metagenomics, you can expect to see 2400 microbial species. As a result, one metagenomics file is 250 GB, and 50 metagenomics samples result in 149 workflows invoked 42K times producing 271K files and 116K graphs.

I was surprised by the size of this data. And this is only from the food safety aspect of SCM. So the data sizes SCM generate has a potential to grow big quickly and we have a big data problem in SCMs. Then how do we store this huge data on all blockchain nodes? Big data will not only overwhelm the storage resources of the nodes but also strain the network as well. Are we going to just store the hash of the big data? If so, why can't we store the hash in an append-only multiversion distributed datastore and call it a day.

Moreover, don't you need to run some analytics on this data? So you will need a database/data store any how. Instead of investigating ways to do SCM with blockchains, wouldn't it make more sense to look for ways to enforce existing database solutions with provenance/attestation? (I have been hearing about provenance work in databases but never had time to learn about them.)

3. How do we teach blockchains to keep secrets?
For SCM, organizations would not like other parties to know the information about goods being transported in order not to lose their strategic advantage. I guess there are some techniques to anonymize information and some blockchains use them. But given that this information is permanently stored, how hard is it for an incentivized third party to data-mine (in machine learning sense, not in blockchain sense :-) this information and de-anonymize the information.

4. One chain to rule them all?
If we use blockchains for SCM, how do we get the public miners on board? I guess we give some tokens via an ICO, and ask them to mine for more tokens. People say blockchains facilitate crowdfunding new initiatives and I certainly appreciate some of the advantages ICOs bring. On the other hand, if done responsibly (and not just playing to people's greed) I am sure this won't be as easy as it sounds. Would there be dozens of SCM blockchains? Would it be possible to maintain a healthy number of diverse miner pools? When things start to level off would we end up with blockchain graveyards? A responsible startup should also have an end-of-life plan, right?

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