Key Points

References

Reference_description_with_linked_URLs__________________________________________	Notes________________________________________________________________
Resources
https://hyperledger-fabric.readthedocs.io/en/release-1.4/
https://www.hyperledger.org/projects/fabric
https://www.hyperledger.org/resources/tutorials
https://www.hyperledger.org/projects/composer
https://stackoverflow.com/questions/tagged/hyperledger-composer	stackoverflow


Composer Developer Notes
https://hyperledger.github.io/composer/latest/introduction/introduction.html	Composer docs
https://hyperledger.github.io/composer/latest/tutorials/tutorials.html	Base Tutorial ( includes build steps )
https://github.com/mahoney1/composer-knowledge-wiki/blob/latest/knowledge.md	Composer Knowledge Base
https://github.com/mahoney1/composer-knowledge-wiki/blob/latest/knowledge.md#fabricsetup	Fabric network issues
https://github.com/mahoney1/composer-sample-applications/tree/master/packages/ digitalproperty-app	Digital Property sample composer app - download, setup, run ( no build details ) > may not run against Fab v1.4x
https://github.com/mahoney1/composer-sample-applications	all composer, fab dev sample apps
https://github.com/mahoney1


Fabric Developer Notes


https://github.com/mahoney1/composer-sample-applications https://github.com/mahoney1/animaltracking	animal tracking app built with IBM VSCode extension
https://github.com/mahoney1/composer-knowledge-wiki/blob/latest/knowledge.md#fabricsetup	Fabric dev local env setup

Key Concepts

Potential Value Opportunities

Potential Challenges

Dealing with expired certs is indeed difficult. Use a blockchain service that has experience with preventing and resolving cert expirations.

How to manage key rotations to make ledger queries easier

Dave >>

I’ll also say that a cert rotation test using a single orderer node is not representative of production environments. Orderer nodes use the certs in the consenter section to identify each other. If there is only one orderer node it doesn’t have any other orderer nodes to identify! Everything else validates against the org-level issuing CAs configured in the channel MSPs, and since both the old and new certs were issued by the CAs configured in the channel MSPs, they are all still valid.

Baohua >>

It's normal as the old certs are still considered valid by the network.

When it's expired, the transactions signed with old credentials will be blocked.

On Tue, Mar 28, 2023 at 6:03 PM Vijaya Bhaskar <acvbhaskar94@gmail.com> wrote:

Hi All,

I am trying to renew the certificates (identity and tls) of the network.
Following are the steps i have followed.
1)created the network (on kubernetes)
2)executed some transactions and verified it in couch db
3) generated new set of certificates for orderer and peers (i have one orderer and one peer( one peer org))
4) since i have 2 channels , one system channel and one application channel,
a)did a system update (replacing the base64 of newly generated cert in the consenter section) for system channel
b) did another system update for application channel

now, before swapping the new certs, i tried to execute a transaction which went through successfully (the old certs are still not expired).
is this normal or am i missing something?

Rotate MPC shards as an option to Key rotations where feasible

Designing a Smart Contract process where oracles are needed

General idea,

avoid calling directly from the contract ( chaincode ) to an external service

in Fabric, all validator nodes that execute the contract will be calling the oracle first.

If any validator has an environment issue calling the oracle, it will slow overall execution ( approval ) of the contract transaction.

Better idea

1> call the oracle BEFORE submitting the contract transaction request - include any key data from the oracle in the request
all the validators will run faster with lower error risks

2> choreograph the workflow
use a parent ( or first contract ) that
calls the oracle with a single validator and writes the oracle result to the ledger
calls the normal contract transaction request with either the oracle result or a link to the result on the ledger or world state db

Candidate Solutions

Create a Fabric Write and Read channels for better performance, history

Fabric v2+ has 16 possible channels for separated ledgers

The limitations of the system channel have been eliminated

A performance option - create a fast write channel, automatically copy new blocks to a read channel

The write ledger can be shorter using purge and archive

Using block events, copy the latest block and write to the read channel

The read ledger can have more history

Implementing CQRS - command query responsibility segregation

Run GraphQL queries against the read historical ledger for traceability queries ( vs World State queries )

David Enyeart <enyeart@us.ibm.com> wrote:

It may be more efficient to ‘replay’ the blocks/transactions rather than use the chaincode APIs. See the sample of how to process all prior blocks/transactions using block events:
https://github.com/hyperledger/fabric-samples/tree/main/off_chain_data
Your block/transaction re-processing could for example write to a new chain. You could write the original state data as well as some of the original transaction metadata to the new chain to preserve as much historical record as possible.

Dealing with expired certs is indeed difficult. I would highly recommend using a blockchain service that has experience with preventing and resolving cert expirations.

Step-by-step guide for Example

sample code block

sample code block

khub

Fabric Developer Notes