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diff --git a/node/doc.go b/node/doc.go new file mode 100644 index 000000000..f009e6f85 --- /dev/null +++ b/node/doc.go @@ -0,0 +1,90 @@ +// Copyright 2016 The go-ethereum Authors +// This file is part of the go-ethereum library. +// +// The go-ethereum library is free software: you can redistribute it and/or modify +// it under the terms of the GNU Lesser General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. +// +// The go-ethereum library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU Lesser General Public License for more details. +// +// You should have received a copy of the GNU Lesser General Public License +// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. + +/* +Package node sets up multi-protocol Ethereum nodes. + +In the model exposed by this package, a node is a collection of services which use shared +resources to provide RPC APIs. Services can also offer devp2p protocols, which are wired +up to the devp2p network when the node instance is started. + + +Resources Managed By Node + +All file-system resources used by a node instance are located in a directory called the +data directory. The location of each resource can be overridden through additional node +configuration. The data directory is optional. If it is not set and the location of a +resource is otherwise unspecified, package node will create the resource in memory. + +To access to the devp2p network, Node configures and starts p2p.Server. Each host on the +devp2p network has a unique identifier, the node key. The Node instance persists this key +across restarts. Node also loads static and trusted node lists and ensures that knowledge +about other hosts is persisted. + +JSON-RPC servers which run HTTP, WebSocket or IPC can be started on a Node. RPC modules +offered by registered services will be offered on those endpoints. Users can restrict any +endpoint to a subset of RPC modules. Node itself offers the "debug", "admin" and "web3" +modules. + +Service implementations can open LevelDB databases through the service context. Package +node chooses the file system location of each database. If the node is configured to run +without a data directory, databases are opened in memory instead. + +Node also creates the shared store of encrypted Ethereum account keys. Services can access +the account manager through the service context. + + +Sharing Data Directory Among Instances + +Multiple node instances can share a single data directory if they have distinct instance +names (set through the Name config option). Sharing behaviour depends on the type of +resource. + +devp2p-related resources (node key, static/trusted node lists, known hosts database) are +stored in a directory with the same name as the instance. Thus, multiple node instances +using the same data directory will store this information in different subdirectories of +the data directory. + +LevelDB databases are also stored within the instance subdirectory. If multiple node +instances use the same data directory, openening the databases with identical names will +create one database for each instance. + +The account key store is shared among all node instances using the same data directory +unless its location is changed through the KeyStoreDir configuration option. + + +Data Directory Sharing Example + +In this exanple, two node instances named A and B are started with the same data +directory. Mode instance A opens the database "db", node instance B opens the databases +"db" and "db-2". The following files will be created in the data directory: + + data-directory/ + A/ + nodekey -- devp2p node key of instance A + nodes/ -- devp2p discovery knowledge database of instance A + db/ -- LevelDB content for "db" + A.ipc -- JSON-RPC UNIX domain socket endpoint of instance A + B/ + nodekey -- devp2p node key of node B + nodes/ -- devp2p discovery knowledge database of instance B + static-nodes.json -- devp2p static node list of instance B + db/ -- LevelDB content for "db" + db-2/ -- LevelDB content for "db-2" + B.ipc -- JSON-RPC UNIX domain socket endpoint of instance A + keystore/ -- account key store, used by both instances +*/ +package node |