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Daml abstracts the event sourcing model employed by blockchains and distributed ledgers. Event sourcing means that the current state of the system can be computed from the log of past events. Instead of keeping a global event log, Daml provides each stakeholder a consistent view on a virtual shared event log, called the virtual shared ledger, while distributing data on a strict need-to-know basis under the hood. This creates a system in which each participant has a consistent view of the (virtual) global system state, consisting of exactly the data they are entitled to. The virtual shared ledger is described in Daml’s Ledger Model and implemented in the Daml smart contract language and associated Ledger API.

virtual-shared-ledger


The Ledger API is the primary API to interact with Daml smart contracts and the virtual shared ledger. It is a high-performance reactive gRPC-based streaming API. It allows applications to subscribe to events that they are permissioned to view, get their current state, or submit commands to write new events. As such, the Ledger API and smart contracts are the primary mechanisms for abstracting away concrete blockchains or databases to instead develop against a virtual shared ledger. Any node in a network that exposes Daml’s Ledger API—and thus gives access to the shared ledgers—is called a participant node as it allows participation in the network.

participant-nodes


To enable an infrastructure like a blockchain or database to run Daml applications, it needs a Daml Driver that allows a matching participant node to connect into the network. Daml Drivers do not store any data and are typically deployed per node of the underlying blockchain or database. There are already numerous drivers, both open source and commercial, available in the Daml ecosystem, with more under development. See https://daml.com for an overview.

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