Edit

Share via

Built-in activities in .NET

  • Article

This is a reference for distributed tracing activities emitted natively by .NET's built-in ActivitySource instances.

System.Net activities

HTTP client request

SocketsHttpHandler and HttpClientHandler report the HTTP client request activity following the recommendations defined in OpenTelemetry HTTP Client Semantic Conventions. It describes the HTTP request sent by HttpClient's send overloads during the time interval the underlying handler completes the request. Completing the request includes the time up to reading response headers from the network stream. It doesn't include the time spent reading the response body. SocketsHttpHandler may retry requests, for example, on connection failures or HTTP version downgrades. Retries are not reported as separate HTTP client request activities.

Availability ActivitySource name OperationName DisplayName
.NET 9+ System.Net.Http System.Net.Http.HttpRequestOut {HTTP method}

Note

The System.Net.Http.HttpRequestOut activity is in fact available on earlier versions of .NET, however its Status, DisplayName, and attributes (tags) are only populated starting with .NET 9. On earlier versions, the OpenTelemetry.Instrumentation.Http package is recommended to fill the gaps of the built-in instrumentation.

Attributes (tags)

Attribute Type Description Examples Presence
http.request.method string HTTP request method. [1] GET; POST; HEAD; _OTHER Always
server.address string Host identifier of the "URI origin" HTTP request is sent to. example.com; 10.1.2.80 Always
server.port int Port identifier of the "URI origin" HTTP request is sent to. 80; 8080; 443 Always
url.full string Absolute URL describing a network resource according to RFC3986 [2] https://www.foo.bar/search?q=* Always
error.type string Request failure reason: one of the HTTP request errors in snake_case, or a full exception type, or an HTTP 4xx/5xx status code. System.OperationCanceledException; name_resolution_error; secure_connection_error ; 404 If the request has failed.
http.request.method_original string Original HTTP method sent by the client in the request line. ACL; foo If http.request.method is not a well-known method.
http.response.status_code int HTTP response status code. 200 If response was received.
network.protocol.version string Version of the HTTP protocol used. 1.1; 2 If response was received.

[1] http.request.method: The value contains the method name, if the method is one of the well-known methods listed in RFC9110; otherwise the value is _OTHER. The user-provided method names are mapped to known names in a case-insensitive manner. For example, if the user provides the name GeT, it will be mapped to GET, and http.request.method_original will not be populated.

[2] url.full: To avoid leaking secrets the value is redacted by default: the entire query is replaced with a * character and the user info & fragment are removed. For more information and opt-out switches, see the URI redaction breaking change docs.

HTTP client request: wait for connection (experimental)

This activity is a child of an HTTP client request activity. It represents the time interval the corresponding request is waiting for an available connection in the request queue. If a free connection is available in the pool when the request comes in, no wait for connection activity will be created. Note that wait for connection does not represent the actual connection establishment; that is modeled by the HTTP connection setup activity. SocketsHttpHandler may retry requests, for example, on connection failures or HTTP version downgrades. Retries are not reported as separate HTTP client request activities; however, each new connection attempt will result in a new wait for connection activity under the parent request activity.

Availability ActivitySource name OperationName DisplayName
.NET 9+ Experimental.System.Net.Http.Connections Experimental.System.Net.Http.Connections.WaitForConnection HTTP wait_for_connection {address}:{port}

Tip

The time it takes to get a connection from the pool is also reported by the http.client.request.time_in_queue metric.

Warning

This activity is experimental. It might be altered or deleted in a future version.

Attributes (tags)

Attribute Type Description Examples Presence
error.type string The connection failure reason: one of the HTTP request errors in snake_case, or a full exception type. System.OperationCanceledException; name_resolution_error; secure_connection_error If the connection attempt fails.

HTTP connection setup (experimental)

This activity describes the establishment of an HTTP connection. Typically, this includes the the time it takes to resolve the DNS, establish the socket connection, and perform the TLS handshake.

Availability ActivitySource name OperationName DisplayName
.NET 9+ Experimental.System.Net.Http.Connections Experimental.System.Net.Http.Connections.ConnectionSetup HTTP connection_setup {address}:{port}

There is no parent-child relationship between the HTTP client request and the HTTP connection setup activities; the latter will always be a root activity, living in a separate trace. However, if the connection attempt represented by HTTP connection setup results in a succesful HTTP connection, and that connection is picked up by a request to serve it, the instrumentation adds an ActivityLink to the HTTP client request activity pointing to the HTTP connection setup activity. That is, each request is linked to the connection that served the request.

Note

If HTTP connection setup fails, it won't be linked to any HTTP client request.

Warning

This activity is experimental. It might be altered or deleted in a future version.

Attributes (tags)

Attribute Type Description Examples Presence
error.type string Connection failure reason: one of the HTTP request errors in snake_case, or a full exception type. System.Net.Sockets.SocketException; name_resolution_error; secure_connection_error If the connection attempt fails.
network.peer.address string Peer IP address of the socket connection. 10.5.3.2 If the connection attempt succeeds.
server.address string Host identifier of the "URI origin" the initial HTTP request is sent to. example.com Always
server.port int Port identifier of the "URI origin" the initial HTTP request is sent to. Always
url.scheme string The URI scheme component identifying the used protocol. http; https Always

DNS lookup (experimental)

This activity describes DNS lookups performed via Dns calls. It corresponds to the managed call and not the physical DNS lookup(s) done by the underlying OS resolver. When the DNS lookup activity is reported along with a HTTP connection setup activity, DNS lookup becomes a child of HTTP connection setup.

Availability ActivitySource name OperationName DisplayName
.NET 9+ Experimental.System.Net.NameResolution Experimental.System.Net.NameResolution.DnsLookup DNS [reverse] lookup {question}

Tip

The DNS lookup duration is also reported by the dns.lookup.duration metric.

Warning

This activity is experimental. It might be altered or deleted in a future version.

Attributes (tags)

Attribute Type Description Examples Presence
error.type string The error code or exception name. [1] host_not_found If the lookup fails.
dns.answers string[] List of resolved IP addresses (for DNS lookup) or a single element containing domain name (for reverse lookup). ["10.0.0.1", "2001:0db8:85a3:0000:0000:8a2e:0370:7334"] If the lookup succeeds.
dns.question.name string The domain name or an IP address being queried. example.com Always

[1]: The value is either a DNS-related SocketError in snake_case (host_not_found, try_again, no_recovery, address_family_not_supported), or a full exception name.

Socket connect (experimental)

This activity describes the establishment of a Socket connection via Connect or ConnectAsync. When the socket connect activity is reported along with an HTTP connection setup activity, socket connect becomes a child of HTTP connection setup.

Availability ActivitySource name OperationName DisplayName
.NET 9+ Experimental.System.Net.Sockets Experimental.System.Net.Sockets.Connect socket connect {address}[:{port}]

Warning

This activity is experimental. It might be altered or deleted in a future version.

Attributes (tags)

Attribute Type Description Examples Presence
error.type string The SocketError in snake_case. address_already_in_use; connection_refused If the socket connection attempt fails.
network.peer.address string Peer address of the network connection - IP address or Unix domain socket name. 10.5.3.2; /tmp/my.sock IP and UDS sockets.
network.peer.port int Peer port number of the IP connection. 65123 IP sockets.
network.transport string OSI transport layer or inter-process communication method. tcp; udp; unix IP and UDS sockets.
network.type string OSI network layer or non-OSI equivalent. ipv4; ipv6 IP sockets.

TLS handshake (experimental)

This activity describes the TLS client or server handshake performed via SslStream's authentication methods. When the TLS handshake activity is reported for client-side authentication along with the HTTP connection setup activity, TLS handshake becomes a child of HTTP connection setup.

Availability ActivitySource name OperationName DisplayName
.NET 9+ Experimental.System.Net.Security Experimental.System.Net.Security.TlsHandshake TLS client handshake {host} -or- TLS server handshake

Warning

This activity is experimental. It might be altered or deleted in future versions.

Attributes (tags)

Attribute Type Description Examples Presence
error.type string Describes a class of error the operation ended with. System.Net.Security.Authentication.AuthenticationException; System.OperationCanceledException If the handshake fails.
server.address string The server name indication (SNI) used in the 'Client Hello' message during TLS handshake. example.com When authenticating as client.
tls.protocol.name string Normalized lowercase protocol name parsed from original string of the negotiated SSL/TLS protocol version ssl; tls When the protocol info is available.
tls.protocol.version string Numeric part of the version parsed from the original string of the negotiated SSL/TLS protocol version 1.2; 1.3 When the protocol info is available.