88 lines
3.1 KiB
Plaintext
88 lines
3.1 KiB
Plaintext
|
|
A Ping extension for ActivityPub
|
|
|
|
This is merely a draft.
|
|
|
|
-- rationale
|
|
|
|
Diagnosing communication failures between federated servers often requires
|
|
sending test messages. There is no dedicated activity type for this purpose,
|
|
however, and thus many operators use normal notes. This creates unnecessary
|
|
noise. It would be better to have a side effect free message that can be
|
|
triggered and sent on demand.
|
|
|
|
The proposed Ping and corresponding Pong activities are similar to the ICMP
|
|
echo request and echo reply messages. (c.f. the familiar ping tool.)
|
|
|
|
Other online social contexts often use the term ping to refer to a variety
|
|
of activities. The activity here is unrelated to any user visible activity or
|
|
action.
|
|
|
|
-- message format
|
|
|
|
The ping message has a type of Ping. Here, user pinger on server
|
|
h1.example.com is sending a Ping to testrcpt on h2.example.com.
|
|
|
|
{
|
|
"@context": "https://www.w3.org/ns/activitystreams",
|
|
"type": "Ping",
|
|
"id": "https://h1.example.com/u/pinger/ping/r4nd0m1d",
|
|
"actor": "https://h1.example.com/u/pinger",
|
|
"to": "https://h2.example.com/u/testrcpt"
|
|
}
|
|
|
|
The Pong message is similar, but includes an object field quoting the Ping id
|
|
field.
|
|
|
|
{
|
|
"@context": "https://www.w3.org/ns/activitystreams",
|
|
"type": "Pong",
|
|
"id": "https://h2.example.com/u/testrcpt/pong/0pp0s1t3",
|
|
"actor": "https://h2.example.com/u/testrcpt",
|
|
"to": "https://h1.example.com/u/pinger",
|
|
"object": "https://h1.example.com/u/pinger/ping/r4nd0m1d"
|
|
}
|
|
|
|
Ping and Pong id fields look like URLs, but need not be fetchable. They are
|
|
only intended as transient messages.
|
|
|
|
-- semantics
|
|
|
|
The Ping message should be sent from one actor to another, delivered to their
|
|
inbox. Upon receipt of a Ping message, a server should reply with a Pong
|
|
message. The Pong reply should quote the id of the Ping (just the id, not the
|
|
whole message) in the object field.
|
|
|
|
Random ids may used. They should be probabilistically unique.
|
|
|
|
The usual access and verification checks performed for other messages should
|
|
be performed for Ping and Pong as well. (If HTTP signatures are in use,
|
|
messages should be signed by senders and verified by receivers.)
|
|
|
|
Ping and Pong messages should be queued using the normal facilities. (Don't
|
|
fast track.) Messages should not be retried. After one failure, drop the
|
|
message.
|
|
|
|
As these messages are intended as administrator aids, they should not be
|
|
displayed to end users. They should not cause any lasting change in the state
|
|
of either the sending or receiving server.
|
|
|
|
Rate limiting and abuse controls apply as usual. Servers may choose to impose
|
|
length restrictions on maximum id length. A minimum of 256 bytes should be
|
|
supported.
|
|
|
|
Servers which do not understand the Ping activity will hopefully ignore it.
|
|
|
|
-- usage
|
|
|
|
It is unspecified how one initiaties a ping, but it is expected to be a manual
|
|
operation performed by a system adminstrator. This will generate traffic,
|
|
which may then be logged. The admin reads the logs and solves the problem.
|
|
Specific problem solving instructions are not provided here.
|
|
|
|
-- future
|
|
|
|
It may be helpful to have a variant of Ping that does perform retries to test
|
|
recovery after disconnect.
|
|
|