This is an example that quickly shows how to use the `go-libp2p` stack,
including Host/Basichost, Network/Swarm, Streams, Peerstores and
Multiaddresses.
This is an example that quickly shows how to use the `go-libp2p` stack, including Host/Basichost, Network/Swarm, Streams, Peerstores and Multiaddresses.
This example can be started in either listen mode, or dial mode.
In listen mode, it will sit and wait for incoming connections on the
`/echo/1.0.0` protocol. Whenever it receives a stream, it will write the
message `"Hello, world!"` over the stream and close it.
In listen mode, it will sit and wait for incoming connections on the `/echo/1.0.0` protocol. Whenever it receives a stream, it will write the message `"Hello, world!"` over the stream and close it.
In dial mode, the node will start up, connect to the given address, open a
stream to the target peer, and read a message on the protocol `/echo/1.0.0`.
In dial mode, the node will start up, connect to the given address, open a stream to the target peer, and read a message on the protocol `/echo/1.0.0`.
## Build
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@@ -31,8 +26,7 @@ From `go-libp2p` base folder:
2017/03/15 14:11:32 listening for connections
```
The listener libp2p host will print its `Multiaddress`, which indicates how it
can be reached (ip4+tcp) and its randomly generated ID (`QmYo41Gyb...`)
The listener libp2p host will print its `Multiaddress`, which indicates how it can be reached (ip4+tcp) and its randomly generated ID (`QmYo41Gyb...`)
Now, launch another node that talks to the listener:
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@@ -40,52 +34,19 @@ Now, launch another node that talks to the listener:
The new node with send the message `"Hello, world!"` to the
listener, which will in turn echo it over the stream and close it. The
listener logs the message, and the sender logs the response.
The new node with send the message `"Hello, world!"` to the listener, which will in turn echo it over the stream and close it. The listener logs the message, and the sender logs the response.
and takes care of maintaining streams, connections, multiplexing different
protocols on them, handling incoming connections etc.
The `makeBasicHost()` function creates a [go-libp2p-basichost](https://godoc.org/github.com/libp2p/go-libp2p/p2p/host/basic) object. `basichost` objects wrap [go-libp2 swarms](https://godoc.org/github.com/libp2p/go-libp2p-swarm#Swarm) and should be used preferentially. A [go-libp2p-swarm Network](https://godoc.org/github.com/libp2p/go-libp2p-swarm#Network) is a `swarm` which complies to the [go-libp2p-net Network interface](https://godoc.org/github.com/libp2p/go-libp2p-net#Network) and takes care of maintaining streams, connections, multiplexing different protocols on them, handling incoming connections etc.
In order to create the swarm (and a `basichost`), the example needs:
The example makes use of all of this to enable communication between a
listener and a sender using protocol `/echo/1.0.0` (which could be any other thing).
- An [ipfs-procotol ID](https://godoc.org/github.com/libp2p/go-libp2p-peer#ID) like `QmNtX1cvrm2K6mQmMEaMxAuB4rTexhd87vpYVot4sEZzxc`. The example autogenerates a key pair on every run and uses an ID extracted from the public key (the hash of the public key). When using `-secio`, it uses the key pair to encrypt communications.
- A [Multiaddress](https://godoc.org/github.com/multiformats/go-multiaddr), which indicates how to reach this peer. There can be several of them (using different protocols or locations for example). Example: `/ip4/127.0.0.1/tcp/1234`.
- A [go-libp2p-peerstore](https://godoc.org/github.com/libp2p/go-libp2p-peerstore), which is used as a address book which matches node IDs to the multiaddresses through which they can be contacted. This peerstore gets autopopulated when manually opening a connection (with [`Connect()`](https://godoc.org/github.com/libp2p/go-libp2p/p2p/host/basic#BasicHost.Connect). Alternatively, we can manually [`AddAddr()`](https://godoc.org/github.com/libp2p/go-libp2p-peerstore#AddrManager.AddAddr) as in the example.
A `basichost` can now open streams (bi-directional channel between to peers) using [NewStream](https://godoc.org/github.com/libp2p/go-libp2p/p2p/host/basic#BasicHost.NewStream) and use them to send and receive data tagged with a `Protocol.ID` (a string). The host can also listen for incoming connections for a given
`Protocol` with [`SetStreamHandle()`](https://godoc.org/github.com/libp2p/go-libp2p/p2p/host/basic#BasicHost.SetStreamHandler).
The example makes use of all of this to enable communication between a listener and a sender using protocol `/echo/1.0.0` (which could be any other thing).
