Struct McapSchema 

pub struct McapSchema {
    pub id: Option<SerializedComponentBatch>,
    pub name: Option<SerializedComponentBatch>,
    pub encoding: Option<SerializedComponentBatch>,
    pub data: Option<SerializedComponentBatch>,
}

Archetype: A schema definition that describes the structure of messages in an MCAP file.

Schemas define the data types and field structures used by messages in MCAP channels. They provide the blueprint for interpreting message payloads, specifying field names, types, and organization. Each schema is referenced by channels to indicate how their messages should be decoded and understood.

See also archetypes::McapChannel for channels that reference these schemas, archetypes::McapMessage for the messages that conform to these schemas, and the MCAP specification for complete format details.

⚠️ This type is unstable and may change significantly in a way that the data won’t be backwards compatible.

Fields

id: Option<SerializedComponentBatch>

Unique identifier for this schema within the MCAP file.

Schema IDs must be unique within an MCAP file and are referenced by channels to specify their message structure. A single schema can be shared across multiple channels.

name: Option<SerializedComponentBatch>

Human-readable name identifying this schema.

Schema names typically describe the message type or data structure (e.g., "geometry_msgs/msg/Twist", "sensor_msgs/msg/Image", "MyCustomMessage").

encoding: Option<SerializedComponentBatch>

The schema definition format used to describe the message structure.

Common schema encodings include:

• protobuf - Protocol Buffers schema definition
• ros1msg - ROS1 message definition format
• ros2msg - ROS2 message definition format
• jsonschema - JSON Schema specification
• flatbuffer - FlatBuffers schema definition

data: Option<SerializedComponentBatch>

The schema definition content as binary data.

This contains the actual schema specification in the format indicated by the encoding field. For text-based schemas (like ROS message definitions or JSON Schema), this is typically UTF-8 encoded text. For binary schema formats, this contains the serialized schema data.

Implementations

impl McapSchema

pub fn descriptor_id() -> ComponentDescriptor

Returns the ComponentDescriptor for Self::id.

The corresponding component is crate::components::SchemaId.

pub fn descriptor_name() -> ComponentDescriptor

Returns the ComponentDescriptor for Self::name.

The corresponding component is crate::components::Text.

pub fn descriptor_encoding() -> ComponentDescriptor

Returns the ComponentDescriptor for Self::encoding.

The corresponding component is crate::components::Text.

pub fn descriptor_data() -> ComponentDescriptor

Returns the ComponentDescriptor for Self::data.

The corresponding component is crate::components::Blob.

impl McapSchema

pub const NUM_COMPONENTS: usize = 4usize

The total number of components in the archetype: 4 required, 0 recommended, 0 optional

impl McapSchema

pub fn new( id: impl Into<SchemaId>, name: impl Into<Text>, encoding: impl Into<Text>, data: impl Into<Blob>, ) -> McapSchema

Create a new McapSchema.

pub fn update_fields() -> McapSchema

Update only some specific fields of a McapSchema.

pub fn clear_fields() -> McapSchema

Clear all the fields of a McapSchema.

pub fn columns<I>( self, _lengths: I, ) -> Result<impl Iterator<Item = SerializedComponentColumn>, SerializationError>

where I: IntoIterator<Item = usize> + Clone,

Partitions the component data into multiple sub-batches.

Specifically, this transforms the existing SerializedComponentBatches data into SerializedComponentColumns instead, via SerializedComponentBatch::partitioned.

This makes it possible to use RecordingStream::send_columns to send columnar data directly into Rerun.

The specified lengths must sum to the total length of the component batch.

pub fn columns_of_unit_batches( self, ) -> Result<impl Iterator<Item = SerializedComponentColumn>, SerializationError>

Helper to partition the component data into unit-length sub-batches.

This is semantically similar to calling Self::columns with std::iter::take(1).repeat(n), where n is automatically guessed.

pub fn with_id(self, id: impl Into<SchemaId>) -> McapSchema

Unique identifier for this schema within the MCAP file.

Schema IDs must be unique within an MCAP file and are referenced by channels to specify their message structure. A single schema can be shared across multiple channels.

pub fn with_many_id( self, id: impl IntoIterator<Item = impl Into<SchemaId>>, ) -> McapSchema

This method makes it possible to pack multiple crate::components::SchemaId in a single component batch.

This only makes sense when used in conjunction with Self::columns. Self::with_id should be used when logging a single row’s worth of data.

pub fn with_name(self, name: impl Into<Text>) -> McapSchema

Human-readable name identifying this schema.

Schema names typically describe the message type or data structure (e.g., "geometry_msgs/msg/Twist", "sensor_msgs/msg/Image", "MyCustomMessage").

pub fn with_many_name( self, name: impl IntoIterator<Item = impl Into<Text>>, ) -> McapSchema

This method makes it possible to pack multiple crate::components::Text in a single component batch.

This only makes sense when used in conjunction with Self::columns. Self::with_name should be used when logging a single row’s worth of data.

pub fn with_encoding(self, encoding: impl Into<Text>) -> McapSchema

The schema definition format used to describe the message structure.

Common schema encodings include:

• protobuf - Protocol Buffers schema definition
• ros1msg - ROS1 message definition format
• ros2msg - ROS2 message definition format
• jsonschema - JSON Schema specification
• flatbuffer - FlatBuffers schema definition

pub fn with_many_encoding( self, encoding: impl IntoIterator<Item = impl Into<Text>>, ) -> McapSchema

This method makes it possible to pack multiple crate::components::Text in a single component batch.

This only makes sense when used in conjunction with Self::columns. Self::with_encoding should be used when logging a single row’s worth of data.

pub fn with_data(self, data: impl Into<Blob>) -> McapSchema

The schema definition content as binary data.

This contains the actual schema specification in the format indicated by the encoding field. For text-based schemas (like ROS message definitions or JSON Schema), this is typically UTF-8 encoded text. For binary schema formats, this contains the serialized schema data.

pub fn with_many_data( self, data: impl IntoIterator<Item = impl Into<Blob>>, ) -> McapSchema

This method makes it possible to pack multiple crate::components::Blob in a single component batch.

This only makes sense when used in conjunction with Self::columns. Self::with_data should be used when logging a single row’s worth of data.

Trait Implementations

impl Archetype for McapSchema

fn name() -> ArchetypeName

The fully-qualified name of this archetype, e.g. rerun.archetypes.Points2D.

fn display_name() -> &'static str

Readable name for displaying in UI.

fn required_components() -> Cow<'static, [ComponentDescriptor]>

Returns all component descriptors that must be provided by the user when constructing this archetype.

fn recommended_components() -> Cow<'static, [ComponentDescriptor]>

Returns all component descriptors that should be provided by the user when constructing this archetype.

fn optional_components() -> Cow<'static, [ComponentDescriptor]>

Returns all component descriptors that may be provided by the user when constructing this archetype.

fn all_components() -> Cow<'static, [ComponentDescriptor]>

Returns all component descriptors that must, should and may be provided by the user when constructing this archetype.

fn from_arrow_components( arrow_data: impl IntoIterator<Item = (ComponentDescriptor, Arc<dyn Array>)>, ) -> Result<McapSchema, DeserializationError>

Given an iterator of Arrow arrays and their respective ComponentDescriptors, deserializes them into this archetype.

fn all_component_identifiers() -> impl Iterator<Item = ComponentIdentifier>

Utility method based on Self::all_components to return all component identifiers.

fn from_arrow( data: impl IntoIterator<Item = (Field, Arc<dyn Array>)>, ) -> Result<Self, DeserializationError>

where Self: Sized,

Given an iterator of Arrow arrays and their respective field metadata, deserializes them into this archetype.

impl AsComponents for McapSchema

fn as_serialized_batches(&self) -> Vec<SerializedComponentBatch>

Exposes the object’s contents as a set of SerializedComponentBatches.

fn to_arrow(&self) -> Result<Vec<(Field, Arc<dyn Array>)>, SerializationError>

Serializes all non-null Components of this bundle into Arrow arrays.

impl Clone for McapSchema

fn clone(&self) -> McapSchema

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for McapSchema

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for McapSchema

fn default() -> McapSchema

Returns the “default value” for a type.

impl PartialEq for McapSchema

fn eq(&self, other: &McapSchema) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl SizeBytes for McapSchema

fn heap_size_bytes(&self) -> u64

Returns how many bytes self uses on the heap.

fn total_size_bytes(&self) -> u64

Returns the total size of self in bytes, accounting for both stack and heap space.

fn stack_size_bytes(&self) -> u64

Returns the total size of self on the stack, in bytes.

fn is_pod() -> bool

Is Self just plain old data?

impl ArchetypeReflectionMarker for McapSchema

impl StructuralPartialEq for McapSchema