# RPC
LLMS index: [llms.txt](/llms.txt)
---
- [Remote Procedure Call (RPC) Attributes](#remote-procedure-call-rpc-attributes)
- [Deprecated RPC Attributes](#deprecated-rpc-attributes)
## Remote Procedure Call (RPC) Attributes
This document defines attributes for remote procedure calls.
**Attributes:**
| Key | Stability | Value Type | Description | Example Values |
| --- | --- | --- | --- | --- |
| `rpc.method` |  | string | The fully-qualified logical name of the method from the RPC interface perspective. [1] | `com.example.ExampleService/exampleMethod`; `EchoService/Echo`; `_OTHER` |
| `rpc.method_original` |  | string | The original name of the method used by the client. | `com.myservice.EchoService/catchAll`; `com.myservice.EchoService/unknownMethod`; `InvalidMethod` |
| `rpc.request.metadata.` |  | string[] | RPC request metadata, `` being the normalized RPC metadata key (lowercase), the value being the metadata values. [2] | `["1.2.3.4", "1.2.3.5"]` |
| `rpc.response.metadata.` |  | string[] | RPC response metadata, `` being the normalized RPC metadata key (lowercase), the value being the metadata values. [3] | `["attribute_value"]` |
| `rpc.response.status_code` |  | string | Status code of the RPC returned by the RPC server or generated by the client [4] | `OK`; `DEADLINE_EXCEEDED`; `-32602` |
| `rpc.system.name` |  | string | The Remote Procedure Call (RPC) system. [5] | `grpc`; `dubbo`; `connectrpc` |
**[1] `rpc.method`:** The method name MAY have unbounded cardinality in edge or error cases.
Some RPC frameworks or libraries provide a fixed set of recognized methods
for client stubs and server implementations. Instrumentations for such
frameworks MUST set this attribute to the original method name only
when the method is recognized by the framework or library.
When the method is not recognized, for example, when the server receives
a request for a method that is not predefined on the server, or when
instrumentation is not able to reliably detect if the method is predefined,
the attribute MUST be set to `_OTHER`. In such cases, tracing
instrumentations MUST also set `rpc.method_original` attribute to
the original method value.
If the RPC instrumentation could end up converting valid RPC methods to
`_OTHER`, then it SHOULD provide a way to configure the list of recognized
RPC methods.
The `rpc.method` can be different from the name of any implementing
method/function.
The `code.function.name` attribute may be used to record the fully-qualified
method actually executing the call on the server side, or the
RPC client stub method on the client side.
**[2] `rpc.request.metadata.`:** Instrumentations SHOULD require an explicit configuration of which metadata values are to be captured.
Including all request metadata values can be a security risk - explicit configuration helps avoid leaking sensitive information.
For example, a property `my-custom-key` with value `["1.2.3.4", "1.2.3.5"]` SHOULD be recorded as
`rpc.request.metadata.my-custom-key` attribute with value `["1.2.3.4", "1.2.3.5"]`
**[3] `rpc.response.metadata.`:** Instrumentations SHOULD require an explicit configuration of which metadata values are to be captured.
Including all response metadata values can be a security risk - explicit configuration helps avoid leaking sensitive information.
For example, a property `my-custom-key` with value `["attribute_value"]` SHOULD be recorded as
the `rpc.response.metadata.my-custom-key` attribute with value `["attribute_value"]`
**[4] `rpc.response.status_code`:** Usually it represents an error code, but may also represent partial success, warning, or differentiate between various types of successful outcomes.
Semantic conventions for individual RPC frameworks SHOULD document what `rpc.response.status_code` means in the context of that system and which values are considered to represent errors.
**[5] `rpc.system.name`:** The client and server RPC systems may differ for the same RPC interaction. For example, a client may use Apache Dubbo or Connect RPC to communicate with a server that uses gRPC since both protocols provide compatibility with gRPC.
---
`rpc.system.name` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
| --- | --- | --- |
| `connectrpc` | [Connect RPC](https://connectrpc.com/) |  |
| `dubbo` | [Apache Dubbo](https://dubbo.apache.org/) |  |
| `grpc` | [gRPC](https://grpc.io/) |  |
| `jsonrpc` | [JSON-RPC](https://www.jsonrpc.org/) |  |
## Deprecated RPC Attributes
Deprecated rpc message attributes.
**Attributes:**
| Key | Stability | Value Type | Description | Example Values |
| --- | --- | --- | --- | --- |
| `message.compressed_size` | 
Deprecated, no replacement at this time. | int | Deprecated, no replacement at this time. | |
| `message.id` | 
Deprecated, no replacement at this time. | int | Deprecated, no replacement at this time. | |
| `message.type` | 
Deprecated, no replacement at this time. | string | Deprecated, no replacement at this time. | `SENT`; `RECEIVED` |
| `message.uncompressed_size` | 
Deprecated, no replacement at this time. | int | Deprecated, no replacement at this time. | |
| `rpc.connect_rpc.error_code` | 
Replaced by `rpc.response.status_code`. | string | Deprecated, use `rpc.response.status_code` attribute instead. | `cancelled`; `unknown`; `invalid_argument` |
| `rpc.connect_rpc.request.metadata.` | 
Replaced by `rpc.request.metadata`. | string[] | Deprecated, use `rpc.request.metadata` instead. | `["1.2.3.4", "1.2.3.5"]` |
| `rpc.connect_rpc.response.metadata.` | 
Replaced by `rpc.response.metadata`. | string[] | Deprecated, use `rpc.response.metadata` instead. | `["attribute_value"]` |
| `rpc.grpc.request.metadata.` | 
Replaced by `rpc.request.metadata`. | string[] | Deprecated, use `rpc.request.metadata` instead. | `["1.2.3.4", "1.2.3.5"]` |
| `rpc.grpc.response.metadata.` | 
Replaced by `rpc.response.metadata`. | string[] | Deprecated, use `rpc.response.metadata` instead. | `["attribute_value"]` |
| `rpc.grpc.status_code` | 
Use string representation of the gRPC status code on the `rpc.response.status_code` attribute. | int | Deprecated, use string representation on the `rpc.response.status_code` attribute instead. | `0`; `1`; `2` |
| `rpc.jsonrpc.error_code` | 
Use string representation of the error code on the `rpc.response.status_code` attribute. | int | Deprecated, use string representation on the `rpc.response.status_code` attribute instead. | `-32700`; `100` |
| `rpc.jsonrpc.error_message` | 
Use the span status description when reporting JSON-RPC spans. | string | Deprecated, use the span status description when reporting JSON-RPC spans. | `Parse error`; `User already exists` |
| `rpc.jsonrpc.request_id` | 
Replaced by `jsonrpc.request.id`. | string | Deprecated, use `jsonrpc.request.id` instead. | `10`; `request-7`; `` |
| `rpc.jsonrpc.version` | 
Replaced by `jsonrpc.protocol.version`. | string | Deprecated, use `jsonrpc.protocol.version` instead. | `2.0`; `1.0` |
| `rpc.message.compressed_size` | 
Deprecated, no replacement at this time. | int | Compressed size of the message in bytes. | |
| `rpc.message.id` | 
Deprecated, no replacement at this time. | int | MUST be calculated as two different counters starting from `1` one for sent messages and one for received message. [6] | |
| `rpc.message.type` | 
Deprecated, no replacement at this time. | string | Whether this is a received or sent message. | `SENT`; `RECEIVED` |
| `rpc.message.uncompressed_size` | 
Deprecated, no replacement at this time. | int | Uncompressed size of the message in bytes. | |
| `rpc.service` | 
Value should be included in `rpc.method` which is expected to be a fully-qualified name. | string | Deprecated, use fully-qualified `rpc.method` instead. | `myservice.EchoService` |
| `rpc.system` | 
Replaced by `rpc.system.name`. | string | Deprecated, use `rpc.system.name` attribute instead. | `grpc`; `java_rmi`; `dotnet_wcf` |
**[6] `rpc.message.id`:** This way we guarantee that the values will be consistent between different implementations.
---
`message.type` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
| --- | --- | --- |
| `RECEIVED` | received |  |
| `SENT` | sent |  |
---
`rpc.connect_rpc.error_code` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
| --- | --- | --- |
| `aborted` | aborted |  |
| `already_exists` | already_exists |  |
| `cancelled` | cancelled |  |
| `data_loss` | data_loss |  |
| `deadline_exceeded` | deadline_exceeded |  |
| `failed_precondition` | failed_precondition |  |
| `internal` | internal |  |
| `invalid_argument` | invalid_argument |  |
| `not_found` | not_found |  |
| `out_of_range` | out_of_range |  |
| `permission_denied` | permission_denied |  |
| `resource_exhausted` | resource_exhausted |  |
| `unauthenticated` | unauthenticated |  |
| `unavailable` | unavailable |  |
| `unimplemented` | unimplemented |  |
| `unknown` | unknown |  |
---
`rpc.grpc.status_code` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
| --- | --- | --- |
| `0` | OK |  |
| `1` | CANCELLED |  |
| `2` | UNKNOWN |  |
| `3` | INVALID_ARGUMENT |  |
| `4` | DEADLINE_EXCEEDED |  |
| `5` | NOT_FOUND |  |
| `6` | ALREADY_EXISTS |  |
| `7` | PERMISSION_DENIED |  |
| `8` | RESOURCE_EXHAUSTED |  |
| `9` | FAILED_PRECONDITION |  |
| `10` | ABORTED |  |
| `11` | OUT_OF_RANGE |  |
| `12` | UNIMPLEMENTED |  |
| `13` | INTERNAL |  |
| `14` | UNAVAILABLE |  |
| `15` | DATA_LOSS |  |
| `16` | UNAUTHENTICATED |  |
---
`rpc.message.type` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
| --- | --- | --- |
| `RECEIVED` | received |  |
| `SENT` | sent |  |
---
`rpc.system` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
| --- | --- | --- |
| `apache_dubbo` | Apache Dubbo |  |
| `connect_rpc` | Connect RPC |  |
| `dotnet_wcf` | .NET WCF |  |
| `grpc` | gRPC |  |
| `java_rmi` | Java RMI |  |
| `jsonrpc` | JSON-RPC |  |
| `onc_rpc` | [ONC RPC (Sun RPC)](https://datatracker.ietf.org/doc/html/rfc5531) |  |