README ¶
Echo client/server with libp2p
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 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
From go-libp2p
base folder:
> make deps
> go build ./examples/echo
Usage
> ./echo -l 10000
2017/03/15 14:11:32 I am /ip4/127.0.0.1/tcp/10000/ipfs/QmYo41GybvrXk8y8Xnm1P7pfA4YEXCpfnLyzgRPnNbG35e
2017/03/15 14:11:32 Now run "./echo -l 10001 -d /ip4/127.0.0.1/tcp/10000/ipfs/QmYo41GybvrXk8y8Xnm1P7pfA4YEXCpfnLyzgRPnNbG35e -secio" on a different terminal
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...
)
Now, launch another node that talks to the listener:
> ./echo -l 10001 -d /ip4/127.0.0.1/tcp/10000/ipfs/QmYo41GybvrXk8y8Xnm1P7pfA4YEXCpfnLyzgRPnNbG35e
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.
Details
The makeBasicHost()
function creates a
go-libp2p-basichost
object. basichost
objects wrap
go-libp2 swarms
and should be used preferentially. A
go-libp2p-swarm Network
is a swarm
which complies to the
go-libp2p-net Network interface
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:
- An
ipfs-procotol 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,
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,
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()
. Alternatively, we can manuallyAddAddr()
as in the example.
A basichost
can now open streams (bi-directional channel between to peers)
using
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()
.
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).
Documentation ¶
There is no documentation for this package.