DAML on Fabric

This is an implementation of DAML ledger that stores data (transactions and state) using Hyperledger Fabric 1.4 LTS.

Quick Start Guide

Prerequisites

These are the minimal requirements that this flow was tested with. It's good to use greater versions or sometimes even lower, but not advised.

• docker-compose version 1.24.0
• docker CE version 18.09.6
• Java / JDK version 1.8.0
• Scala version 2.12.7
• SBT version 1.2.8
• DAML SDK version 0.13.12

Docker and Docker-Compose are required to run a Hyperledger Fabric network, everything else is a typical dependency list for building and running a DAML ledger.

Note: running Docker as root is not recommended, this may cause issues.

Cloning DAML-on-Fabric

For the sake of cleanness, we are using the directory ~/daml-on-fabric as the root for the repository.

$ cd
$ git clone {to-do: insert production link to DAML-on-Fabric}/daml-on-fabric.git

Running a local Hyperledger Fabric network

This is achieved by running a Docker-Compose network which is a typical way to set up Fabric for development environments. Our particular example sets up a network of 5 peers, of which two will be used for endorsement.

$ cd ~/daml-on-fabric/src/test/fixture/
$ ./restart_fabric.sh

The script used is a shortcut for ./fabric.sh down && ./fabric.sh up that will erase all current data and start a fresh network.

DAML-on-Fabric command line and Services

The basic command to run the ledger right from the repository is like this:

$ sbt "run --role <roles> [--port NNNN] [DAMLArchive.dar DAMLArchive2.dar ...]"

Important: the ledger will connect to a Fabric network specified in config.json file.

Generally, if you run the ledger against a local network, you need to provide additional argument to SBT, like this:

$ sbt "run ..." -J-DfabricConfigFile=./config.local.json

Services, or "Roles"

You may have noticed that the required argument for DAML-on-Fabric is "role".

There are several roles that define which parts of the service are going to be executed:

• provision: will connect to Fabric and prepare it to be used as storage for a DAML ledger.
• ledger: will run a DAML Ledger API endpoint at a port specified with --port argument.
• time: will run a DAML time service, which writes heartbeats to the ledger. There should be exactly one time service per ledger.
• explorer: will run a block explorer service that exposes a REST API to view the content of blocks and transactions inside the Fabric network for debugging or demonstration purposes. The explorer will run at a port specified in config.json file. It provides REST API that responds at endpoints /blocks[?id=...] and /transactions[?id=...]

One ledger may perform multiple roles at the same time, in which case roles are separated with comma. Example of this will be given later (we are using a single node just for the example).

Running Java Quick Start against DAML-on-Fabric

Step 1. Start Hyperledger Fabric

$ cd ~/daml-on-fabric/src/test/fixture/
$ ./restart_fabric.sh

Step 2. Extract and build Quick Start project

$ cd
$ rm -rf quickstart
$ daml new quickstart quickstart-java
Created a new project in "quickstart" based on the template "quickstart-java".
$ cd ~/quickstart/
$ daml build
Compiling daml/Main.daml to a DAR.
Created dist/quickstart.dar.

Step 3. Run the Ledger with Quick Start DAR archive

$ cd ~/daml-on-fabric/
$ sbt "run --port 6865 --role provision,time,ledger,explorer ../quickstart/dist/quickstart.dar" -J-DfabricConfigFile=./config.local.json

Step 4. Run DAML Navigator

$ cd ~/quickstart/
daml navigator server localhost 6865 --port 4000

Step 5. Conclusion

Now you can explore your freshly setup DAML ledger.

You should have the following services running:

• DAML Navigator at http://localhost:4000/
• Hyperledger Fabric block explorer at http://localhost:8080/
• DAML Ledger API endpoint at localhost:6865

More information on Quick Start example and DAML in general can be found here:

https://docs.daml.com/getting-started/quickstart.html