# NIP-66: Relay Meta and Monitoring System

`draft` `optional`

This NIP defines four event kinds, `10066`, `30066`, `10166` and `1066`.


## `10066`: "Self-Reported Relay Meta"
 
### Summary
An event that contains data about a relay. These events are self-reported by relays from the `owner` pubkey defined in their Information Document (`NIP-11`). Hereinafter referred to as "Relay Meta" events

### Purpose
An event that makes relays discoverable.

### Schema 

#### `event.content`
**Should** be empty. 

#### `event.tags`
"Relay Meta" events have **one** (1) required tag.

"Relay Meta" events have **two** (2) non-standard, NIP-66 specific indexable tags. 
 
Tags should be used to represent the Relay's abilities and meta at any given point in time. The "tags schema" is expressed using pseudo-types for reasons of communication and brevity, for example `tagDescriptor[]`. This NIP utilizes `NIP-32` to expose indexable values. 

#### Tags
- `"r" == tagId[0]` The relay URL. The `#d` tag **must** be included in the `event.tags[]` array. `tagId[1]` **must** be the relay websocket URL. The URL **should** be [normalized](https://datatracker.ietf.org/doc/html/rfc3986#section-6)
  ```
  ["d", "wss://history.nostr.watch/"] //tagId[]
  ```

- `n`: Such as `clearnet`, `tor`, `i2p`, `cjdns`, etc  _in the context of **NIP-66 only**_
  ```
  [ "n", "clearnet" ]
  ```

- `desc == tagDesc[0]` The description from nip11. 
  ```
  [ "desc", "A nostr relay" ]
  ```

- `N`: Supported NIPs _in the context of **NIP-66 only**_
  ```
  [ "N", "1" ]
  [ "N", "11" ]
  [ "N", "33" ]
  ```

- `"count" == tagCount[0]` Meta values for arbitrary counts related to a relay. `tagCount[1]` is the value expressed as the string representation of an integer or float. `tagCount[2]` is the key and describes the count, such as `total_users` or `total_events`. Counts **should** only be included when representing unique or computationally expensive counts, not ones that can be easily achieved via `NIP-45` counts. There **may** be zero (0) to many count tags.

  ```
  ["count", "total_events", "502341"],
  ["count", "total_users", "52000"],
  ["count", "active_users_24h", "321"]
  ["count", "events_per_minute", "21.4"]
  ```

- `"infohash" == tagInfohash[0]` A SHA256 hash of the deterministically stringified `NIP-11` "Info Document" JSON at `tagInfohash[1]` 
  ```
  [ "infohash", "fj89as0n3inmcd89nefkdlsky2mfkdlsfds" ]
  ```

#### Label Tags <sup>NIP-32</sup>
- `relay_type`, for example `proxy`, `bridge` and `public` for example. There **may** be more than one type. There have not been efforts to atomize relay types at the time of writing this NIPs, so these values cannot be enumerated at this time.
  ```
  [ "L", "relay_type" ]
  [ "l", "proxy", "relay_type" ]
  [ "l", "public", "relay_type" ]
  ```

- `ipv4`/`ipv6`, relay ips.
  ```
  [ "L", "ipv4" ]
  [ "l", "1.1.1.1", "ipv4" ]
  [ "L", "ipv6" ]
  [ "l", "2001:db8:3333:4444:5555:6666:7777:8888"", "ipv6" ]
  ```

- `as`/`asn` the relay ISPs "Autonomous System (Number)"
  ```
  [ "L", "as" ]
  [ "l", "QUAD9-AS-1, CH", "as" ]
  [ "L", "asn" ]
  [ "l", "19281", "asn" ]
  ```

- String values from `NIP-11` using dot notation, for example
  ```
  [ "L", "nip11.tags" ]
  [ "l", "sfw-only", "nip11.tags"  ]
  [ "l", "bitcoin-only", "nip11.tags"  ]
  [ "L", "nip11.language_tags" ]
  [ "l", "en", "nip11.language_tags"  ]
  [ "l", "en-419", "nip11.language_tags" ]
  ```

- Boolean values from `NIP-11`, for example
  ```
  [ "L", "nip11.limitation" ]
  [ "l", "payment_required", "nip11.limitation" ] //nip11.limitation payment_required==true
  [ "l", "auth_required", "nip11.limitation" ] //nip11.limitation auth_required==true
  ```

#### NIP-11 Integer Values 
Any NIP-11 values that are integers should not be included as NIP-32 labels, instead they should use the `nip11` tag.

```
[ "nip11", "65535", "limitation.max_message_length" ]
```

#### NIP-11 Nested Objects 
NIP-11 nested objects are not supported by NIP-66 at this time (For example, fees)

#### Geo tags <sup>NIP-YAGT</sup>
- `NIP-66` leverages a draft NIP for geo tags, see [YAGT](https://github.com/nostr-protocol/nips/pull/952)
  ```
  [ 'G', 'countryCode' ]
  [ 'g', 'US', 'countryCode', 'alpha-2' ]
  [ 'g', 'USA', 'countryCode', 'alpha-3' ]
  [ 'g', '840', 'countryCode', 'numeric' ]
  [ 'G', 'regionCode' ]
  [ 'g', 'US-CA', 'regionCode']
  [ 'g', '9r1652whz' ]
  [ 'g', '9r1652wh' ]
  [ 'g', '9r1652w' ]
  [ 'g', '9r1652' ]
  [ 'g', '9r165' ]
  [ 'g', '9r16' ]
  [ 'g', '9r1' ]
  [ 'g', '9r' ]
  [ 'g', '9' ]
  ```

#### Topic Tags 
- `NIP-66` leverages topics [`t` tags] and optionally adds values at positions `tag[2]` and `tag[3]`. If `tag[2]` is set, it **should** be a string-integer representing the number of tags on the relay. If `tag[2]` is set, `tag[3]` **should** be set and be a string-integer representing the timeframe for the value set as `tag[2]`. This tag is used to indicate topics relevant to the relay through event analysis (as oppossed to 'tags' from `NIP-11` document)

  ```
   //69 events with "meme" topic in the last hour
  ["t", "meme", "69", "3600"]
  ```

## `30066`: "Relay Status" Events

### Summary
`30066` is a parameterized replaceable event [NIP-33], referred to as a "Relay Status" event. These events store the existence and optionally some data relating to the relay. 

### Purpose 
To store useful, computationally expensive relay meta-data about relays. `30066` should be used to give a canonical reference to the last known functional state of a relay, to be evaluated subjectively by a client and/or user to derive conclusions from.

### NIPs Used
- `NIP-32` Labels
- `NIP-33` Parameterized Replacable Events
- `NIP-40` Expirable Events
- [YAGT](https://github.com/nostr-protocol/nips/pull/952) _draft_

### Schema
`30066` events are almost identical to `10066` except a few key differences.

_**Different referencial tag**_

- `30066` uses a `d` tag instead of an `r` tag for the normalized relay URL since it is a Parameterized-Replaceable Event

_**It adds some additional tags**_

- `"rtt" == tagRtt[0]` Round-trip time of websocket ping/pong in milliseconds. Example values for `tagRtt[1]` are `open`, `read` and `write`. Where `open` represents the round-trip time forWebsocket to open, `read` represents the round-trip time of a Websocket `REQ` (subscription) message's response, and `write` represents the round-trip time of a Websocket `EVENT` (publish) message and subsequent `ok` message. `tagRtt[2...]` are strings with the millisecond values. At a minimum `tagRtt[2]` **should** be set. When more than one value is provided, values **may** be treated as an array to find `min`, `max`, `average` and `median` values. There **may** be zero `rtt` tags.

  ```
  ["rtt", "open", "201", "190", "540"],
  ["rtt", "read", "35", "60", "46"],
  ["rtt", "write", "701", "497", "508"]
  ```


#### Methodology 
A Relay Monitor publishes `30066`` events exclusively when a relay is operational. This approach ensures that the last known active state of the relay is maintained and recorded. Based on this data, several inferences can be drawn about the relay's status and characteristics

1. Clients and/or users can set a custom threshold to establish a cutoff timestamp for filtering events using `since`. This timestamp helps in identifying which relays are currently online. Selecting a lower threshold value results in a stricter criterion for relay uptime, making the filter more sensitive to brief downtimes. Conversely, choosing a higher threshold value creates a more lenient filter, allowing relays with longer downtimes to still be considered as online.

2. In determining whether a relay is 'dead,' the decision is solely at the discretion of the client or user. The are responsible for setting and applying arbitrary thresholds using `until` filters or post-processing to make this determination. This approach underscores that the classification of a relay as 'dead' is a subjective decision, varying according to each client's or user's assessment criteria, rather than a fixed status provided by the monitor.

3. For relay status events that have become outdated, the retained data points remain valuable. They offer insights and information about the relay's characteristics and performance, which might not be currently accessible due to the relay being offline.

#### Important Notes
- `NIP-11` values are provided as means to filter and discover relays, however **should not** be used as a replacement to `NIP-11`.
- A particular relay's retention policy could conflict with subjective thresholds used in determination of "online" or "dead" relays and so care should be taken with regards to chosen relays by both monitors and consumers.

#### Examples 

##### Minimum Requirements, "Relay was online at `Date(created_at)`"
```json
{
  "id": "<eventid>",
  "pubkey": "<pubkey>",
  "created_at": "<created_at>",
  "signature": "<signature>",
  "content": "",
  "tags": [  
    ["d","wss://some.relay/"]
  ]
}
```

##### Relay is checked and online example, "Relay is online and here's some meta-data this monitor believes is accurate"
```json
{
  "id": "<eventid>",
  "pubkey": "<monitor's pubkey>",
  "created_at": "<created_at  [some recent date ...]>",
  "signature": "<signature>",
  "content": "{}",
  "tags": [  
    ["d","wss://some.relay/"],
    ["n", "clearnet"]
    ["N", "1"],
    ["N", "7"],
    ["rtt", "open", "201", "190", "540"],
    ["rtt", "read", "35", "60", "46"],
    ["rtt", "write", "701", "497", "508"],
    ["ssl", "valid", "timestamp", "timestamp"],
    ["count", "21.4", "events_per_minute"],
    ["g", "ww8p1r4t8"],
    ["G", "countryCode"]
    ["g", "NL", "countryCode"],
    ["L", "ipv4"],
    ["l", "1.1.1.1", "ipv4" ],
    ["L", "ipv6"],
    ["l", "2001:db8:3333:4444:5555:6666:7777:8888", "ipv6"],
    ["L", "nip11.tags" ],
    ["l", "sfw-only", "nip11.tags" ],
    ["l", "bitcoin-only", "nip11.tags" ]
    ["L", "nip11.language_tags" ],
    ["l", "en", "nip11.language_tags"  ],
    ["l", "en-419", "nip11.language_tags" ],
    ["nip11", "65535", "limitation.max_message_length" ]
  ]
}
```

#### Testing Criteria
The testing criteria to determine conditions defined in event's tags **may** be subjective and **may** vary between monitors.

#### Limitations
The data in `30066` **may** be erroneous, intentionally or otherwise. Where accuracy is required, the data in `30066` events **should** be subscribed to by populating the `authors` filter array with the pubkeys of trusted **monitors** and where security or privacy is a concern any republished values (such as NIP-11 values) should instead be attained from the source. All data is for informational purposes and to make finding and filtering through relays through nostr a possiblity.

#### Appending NIP-66
Any test results that cannot be expressed through `NIP-66` **should** be ammended to the nip following discussion and general consensus

### Use Cases
1. **Geographic Relay Discovery**: Identify relays situated near a specific geographic location or within a particular country, facilitating localized network interactions.

2. **NIP Support Filtering**: Search for relays based on their support for specific Nostr Improvement Proposals (NIPs), ensuring compatibility with desired protocol features.

3. **Accessibility Search**: Locate relays that are free to use, helping users find cost-effective or no-cost options for their network interactions.

4. **Real-Time Status Monitoring**: Utilize a status client to display up-to-date statuses of various relays, providing insights into their current operational state.

5. **Relay Network Analysis**: Analyze connections and patterns between relays using their IP addresses, aiding in network topology understanding and security assessments.

6. **Error Detection in Relay Listings**: Spot and rectify erroneous entries in relay lists, ensuring the accuracy and reliability of relay data.

7. **Performance Benchmarking**: Compare relays based on performance metrics like round-trip times and uptime, aiding in the selection of the most efficient relays for specific needs.

8. **Security and Compliance Checks**: Evaluate relays for adherence to security standards and regulatory compliance, essential for users with specific security and privacy requirements.

9. **Language and Content Filtering**: Identify relays catering to specific languages or content types, enabling users to engage in a more targeted and relevant social networking experience.

10. **Data-Driven Relay Selection**: Make informed choices about which relays to connect to, based on comprehensive metadata including user counts, event frequencies, network types and more.

## `10166`: "Relay Monitor" Events

### Summary 
`10166` is a replacable event herein referred to as "Relay Monitor" events. These events contain information about a publisher's intent to monitor and/or aggregate relays and publish data as `30066` events.

### Purpose 
To provide a directory of monitors, their intent to publish, their criteria and parameters of monitoring activities.

### Schema
`10166` events have no required tags.

- `"url" == tagUrl[0]` A URL with human readable information about the monitor's activities. If not included, it is assumed these details are included in the monitor's kind 0 for the pubkey that signed the `10066` event. 

- `"timeout" == tagTimeout[0]` The timeout values for various tests. `tagTimeout[1]` is the monitor's timeout in milliseconds. `tagTimeout[2]` describes what test the timeout is used for, for example `open`, `read`, `write`, `info`, etc. If no `tagTimeout[2]` is provided, it is inferred that the timeout provided applies to all tests. 
  ```
  [ "timeout", "2000", "open" ]
  [ "timeout", "2000", "read" ]
  [ "timeout", "3000", "write" ]
  [ "timeout", "2000", "info" ]
  ```

- `"ssl" == tagSsl[0]` SSL certificate check. `tag[1]` is either `valid` or `invalid`. `tag[2]` is the validate start date. `tag[3]` is the validity end date. Can include reference via `e` or `a` to raw SSL data for indepdent validation.
  ```
  ["ssl", "valid", "timestamp", "timestamp"],
  ```

- `"kind === tagKind[0]"` The kind(s) this monitor publishes. 
  ```
  [ "kind", "30066" ]
  [ "kind", "1066" ]
  ```

- `"frequency" == tagFrequency[0]` The frequency at which the monitor publishes events. A string-integer at `tagFrequency[1]` represents the frequency a event kind is published. The string-integer at `tagFrequency[2]` represents the kind bound to the frequency. If `tagFrequency[2]` is undefined, it is inferred the timeout applies to all events published by the monitor. A frequency **should not** be created for this kind [`1006`]. If a kind is referenced in `tagFrequency` that is not set in `tagKind` it should be disregarded.
  ```
  [ "frequency", "3600", "30066" ]
  [ "frequency", "3600", "1066" ]
  ```

#### Label Tags <sup>NIP-32</sup>

- `checks` **should** be a lowercase string describing the check(s) conducted by a monitor. Some examples are: `websocket`, `nip11`, `ssl`, `dns`, `geo`

  ```
  [ "L", "checks" ]
  [ "l", "websocket", "checks" ]
  [ "l", "nip11", "checks" ]
  [ "l", "ssl", "checks" ]
  [ "l", "dns", "checks" ]
  [ "l", "geo", "checks" ]
  ```

#### Geo tags <sup>NIP-YAGT</sup>
- `NIP-66` leverages a draft NIP for geo tags, see [YAGT](https://github.com/nostr-protocol/nips/pull/952)

### Other Requirements
- Monitors **should** have a published `10002` event that defines the relays the monitor publishes to.

## `1066`: "Relay Status History" Events

### Summary
`1066` is a standard nostr event, referred to as a "Relay Status History" event. These events store the history of a relay at a periodic interval (defined in `10166`).

#### Schema
Relay History events can contain any of the tags defined for kind `30066` (Including the `d` tag which is used to filter these events by relay). There is one new indexable tag

#### Special Considerations
- These events can potentially demand a lot of disk space if not used wisely. 

#### Guidelines 
Tags representing less-volatile values, for instance `nip11.software` vs `rtt`, contained with this event should only be included when their respectiive values have changed compared to the last Relay History event of the same `d` tag. If there have been no changes, then the event should not be published. 

##### Use Cases
- Generate a time series from one or  data-point(s) for a specific relay.
- Generate network-wide aggregated statistics