JStream

faststream.nats.schemas.JStream

JStream(
    name,
    description=None,
    subjects=None,
    retention=None,
    max_consumers=None,
    max_msgs=None,
    max_bytes=None,
    discard=OLD,
    max_age=None,
    max_msgs_per_subject=-1,
    max_msg_size=-1,
    storage=None,
    num_replicas=None,
    no_ack=False,
    template_owner=None,
    duplicate_window=0,
    placement=None,
    mirror=None,
    sources=None,
    sealed=False,
    deny_delete=False,
    deny_purge=False,
    allow_rollup_hdrs=False,
    republish=None,
    allow_direct=None,
    mirror_direct=None,
    declare=True,
)

Bases: NameRequired

A class to represent a JetStream stream.

Initialized JSrream.

PARAMETER	DESCRIPTION
name	Stream name to work with. TYPE: str
description	Stream description if needed. TYPE: str | None DEFAULT: None
subjects	Subjects, used by stream to grab messages from them. Any message sent by NATS Core will be consumed by stream. Also, stream acknowledge message publisher with message, sent on reply subject of publisher. Can be single string or list of them. Dots separate tokens of subjects, every token may be matched with exact same token or wildcards. TYPE: list[str] | None DEFAULT: None
retention	Retention policy for stream to use. Default is Limits, which will delete messages only in case of resource depletion, if 'DiscardPolicy.OLD' used. In case of 'DiscardPolicy.NEW', stream will answer error for any write request. If 'RetentionPolicy.Interest' is used, message will be deleted as soon as all active consumers will consume that message. Note: consumers should be bounded to stream! If no consumers bound, all messages will be deleted, including new messages! If 'RetentionPolicy.WorkQueue' is used, you will be able to bound only one consumer to the stream, which guarantees message to be consumed only once. Since message acked, it will be deleted from the stream immediately. Note: Message will be deleted only if limit is reached or message acked successfully. Message that reached MaxDelivery limit will remain in the stream and should be manually deleted! Note: All policies will be responsive to Limits. TYPE: Optional[RetentionPolicy] DEFAULT: None
max_consumers	Max number of consumers to be bound with this stream. TYPE: int | None DEFAULT: None
max_msgs	Max number of messages to be stored in the stream. Stream can automatically delete old messages or stop receiving new messages, look for 'DiscardPolicy'. TYPE: int | None DEFAULT: None
max_bytes	Max bytes of all messages to be stored in the stream. Stream can automatically delete old messages or stop receiving new messages, look for 'DiscardPolicy'. TYPE: int | None DEFAULT: None
discard	Determines stream behavior on messages in case of retention exceeds. TYPE: Optional[DiscardPolicy] DEFAULT: OLD
max_age	TTL in seconds for messages. Since message arrive, TTL begun. As soon as TTL exceeds, message will be deleted. TYPE: float | None DEFAULT: None
max_msgs_per_subject	Limit message count per every unique subject. Stream index subjects to it's pretty fast tho. TYPE: int DEFAULT: -1
max_msg_size	Limit message size to be received. Note: the whole message can't be larger than NATS Core message limit. TYPE: int | None DEFAULT: -1
storage	Storage type, disk or memory. Disk is more durable, memory is faster. Memory can be better choice for systems, where new value overrides previous. TYPE: Optional[StorageType] DEFAULT: None
num_replicas	Replicas of stream to be used. All replicas create RAFT group with leader. In case of losing lesser than half, cluster will be available to reads and writes. In case of losing slightly more than half, cluster may be available but for reads only. TYPE: int | None DEFAULT: None
no_ack	Should stream acknowledge writes or not. Without acks publisher can't determine, does message received by stream or not. TYPE: bool DEFAULT: False
template_owner	A TTL for keys in implicit TTL-based hashmap of stream. That hashmap allows to early drop duplicate messages. Essential feature for idempotent writes. Note: disabled by default. Look for 'Nats-Msg-Id' in NATS documentation for more information. TYPE: str | None DEFAULT: None
duplicate_window	A TTL for keys in implicit TTL-based hashmap of stream. That hashmap allows to early drop duplicate messages. Essential feature for idempotent writes. Note: disabled by default. Look for 'Nats-Msg-Id' in NATS documentation for more information. TYPE: float DEFAULT: 0
placement	NATS Cluster for stream to be deployed in. Value is name of that cluster. TYPE: Optional[Placement] DEFAULT: None
mirror	Should stream be read-only replica of another stream, if so, value is name of that stream. TYPE: Optional[StreamSource] DEFAULT: None
sources	Should stream mux multiple streams into single one, if so, values is names of those streams. TYPE: list[StreamSource] | None DEFAULT: None
sealed	Is stream sealed, which means read-only locked. TYPE: bool DEFAULT: False
deny_delete	Should delete command be blocked. TYPE: bool DEFAULT: False
deny_purge	Should purge command be blocked. TYPE: bool DEFAULT: False
allow_rollup_hdrs	Should rollup headers be blocked. TYPE: bool DEFAULT: False
republish	Should be messages, received by stream, send to additional subject. TYPE: Optional[RePublish] DEFAULT: None
allow_direct	Should direct requests be allowed. Note: you can get stale data. TYPE: bool | None DEFAULT: None
mirror_direct	Should direct mirror requests be allowed TYPE: bool | None DEFAULT: None
declare	Whether to create stream automatically or just connect to it. TYPE: bool DEFAULT: True

Source code in faststream/nats/schemas/js_stream.py

def __init__(
    self,
    name: str,
    description: str | None = None,
    subjects: list[str] | None = None,
    retention: Optional["RetentionPolicy"] = None,
    max_consumers: int | None = None,
    max_msgs: int | None = None,
    max_bytes: int | None = None,
    discard: Optional["DiscardPolicy"] = DiscardPolicy.OLD,
    max_age: float | None = None,  # in seconds
    max_msgs_per_subject: int = -1,
    max_msg_size: int | None = -1,
    storage: Optional["StorageType"] = None,
    num_replicas: int | None = None,
    no_ack: bool = False,
    template_owner: str | None = None,
    duplicate_window: float = 0,
    placement: Optional["Placement"] = None,
    mirror: Optional["StreamSource"] = None,
    sources: list["StreamSource"] | None = None,
    sealed: bool = False,
    deny_delete: bool = False,
    deny_purge: bool = False,
    allow_rollup_hdrs: bool = False,
    republish: Optional["RePublish"] = None,
    allow_direct: bool | None = None,
    mirror_direct: bool | None = None,
    declare: bool = True,
) -> None:
    """Initialized JSrream.

    Args:
        name:
            Stream name to work with.
        description:
            Stream description if needed.
        subjects:
            Subjects, used by stream to grab messages from them. Any message sent by NATS Core will be consumed
            by stream. Also, stream acknowledge message publisher with message, sent on reply subject of publisher.
            Can be single string or list of them. Dots separate tokens of subjects, every token may be matched with exact same
            token or wildcards.
        retention:
            Retention policy for stream to use. Default is Limits, which will delete messages only in case of resource depletion,
            if 'DiscardPolicy.OLD' used. In case of 'DiscardPolicy.NEW', stream will answer error for any write request.
            If 'RetentionPolicy.Interest' is used, message will be deleted as soon as all active consumers will consume that message.
            Note: consumers should be bounded to stream! If no consumers bound, all messages will be deleted, including new messages!
            If 'RetentionPolicy.WorkQueue' is used, you will be able to bound only one consumer to the stream, which guarantees
            message to be consumed only once. Since message acked, it will be deleted from the stream immediately.
            Note: Message will be deleted only if limit is reached or message acked successfully. Message that reached MaxDelivery limit will remain in the stream and should be manually deleted!
            Note: All policies will be responsive to Limits.
        max_consumers:
            Max number of consumers to be bound with this stream.
        max_msgs:
            Max number of messages to be stored in the stream. Stream can automatically delete old messages or stop receiving new messages, look for 'DiscardPolicy'.
        max_bytes:
            Max bytes of all messages to be stored in the stream. Stream can automatically delete old messages or stop receiving new messages, look for 'DiscardPolicy'.
        discard:
            Determines stream behavior on messages in case of retention exceeds.
        max_age:
            TTL in seconds for messages. Since message arrive, TTL begun. As soon as TTL exceeds, message will be deleted.
        max_msgs_per_subject:
            Limit message count per every unique subject. Stream index subjects to it's pretty fast tho.
        max_msg_size:
            Limit message size to be received. Note: the whole message can't be larger than NATS Core message limit.
        storage:
            Storage type, disk or memory. Disk is more durable, memory is faster. Memory can be better choice for systems,
            where new value overrides previous.
        num_replicas:
            Replicas of stream to be used. All replicas create RAFT group with leader. In case of losing lesser than half, cluster will be available to reads and writes.
            In case of losing slightly more than half, cluster may be available but for reads only.
        no_ack:
            Should stream acknowledge writes or not. Without acks publisher can't determine, does message received by stream or not.
        template_owner:
            A TTL for keys in implicit TTL-based hashmap of stream. That hashmap allows to early drop duplicate
            messages. Essential feature for idempotent writes. Note: disabled by default. Look for 'Nats-Msg-Id'
            in NATS documentation for more information.
        duplicate_window:
            A TTL for keys in implicit TTL-based hashmap of stream. That hashmap allows to early drop duplicate messages. Essential feature for idempotent writes.
            Note: disabled by default. Look for 'Nats-Msg-Id' in NATS documentation for more information.
        placement:
            NATS Cluster for stream to be deployed in. Value is name of that cluster.
        mirror:
            Should stream be read-only replica of another stream, if so, value is name of that stream.
        sources:
            Should stream mux multiple streams into single one, if so, values is names of those streams.
        sealed:
            Is stream sealed, which means read-only locked.
        deny_delete:
            Should delete command be blocked.
        deny_purge:
            Should purge command be blocked.
        allow_rollup_hdrs:
            Should rollup headers be blocked.
        republish:
            Should be messages, received by stream, send to additional subject.
        allow_direct:
            Should direct requests be allowed. Note: you can get stale data.
        mirror_direct:
            Should direct mirror requests be allowed
        declare:
            Whether to create stream automatically or just connect to it.
    """
    super().__init__(name)

    self.declare = declare
    self.subjects = SubjectsCollection(subjects)

    self.config = StreamConfig(
        name=name,
        description=description,
        retention=retention,
        max_consumers=max_consumers,
        max_msgs=max_msgs,
        max_bytes=max_bytes,
        discard=discard,
        max_age=max_age,
        max_msgs_per_subject=max_msgs_per_subject,
        max_msg_size=max_msg_size,
        storage=storage,
        num_replicas=num_replicas,
        no_ack=no_ack,
        template_owner=template_owner,
        duplicate_window=duplicate_window,
        placement=placement,
        mirror=mirror,
        sources=sources,
        sealed=sealed,
        deny_delete=deny_delete,
        deny_purge=deny_purge,
        allow_rollup_hdrs=allow_rollup_hdrs,
        republish=republish,
        allow_direct=allow_direct,
        mirror_direct=mirror_direct,
        subjects=[],  # use subjects from builder in declaration
    )

name instance-attribute

name = name

declare instance-attribute

declare = declare

subjects instance-attribute

subjects = SubjectsCollection(subjects)

config instance-attribute

config = StreamConfig(
    name=name,
    description=description,
    retention=retention,
    max_consumers=max_consumers,
    max_msgs=max_msgs,
    max_bytes=max_bytes,
    discard=discard,
    max_age=max_age,
    max_msgs_per_subject=max_msgs_per_subject,
    max_msg_size=max_msg_size,
    storage=storage,
    num_replicas=num_replicas,
    no_ack=no_ack,
    template_owner=template_owner,
    duplicate_window=duplicate_window,
    placement=placement,
    mirror=mirror,
    sources=sources,
    sealed=sealed,
    deny_delete=deny_delete,
    deny_purge=deny_purge,
    allow_rollup_hdrs=allow_rollup_hdrs,
    republish=republish,
    allow_direct=allow_direct,
    mirror_direct=mirror_direct,
    subjects=[],
)

validate classmethod

validate(value: str | Self, **kwargs: Any) -> Self

validate(value: None, **kwargs: Any) -> None

validate(value, **kwargs)

Factory to create object.

Source code in faststream/_internal/proto.py

@classmethod
def validate(cls, value: str | Self | None, **kwargs: Any) -> Self | None:
    """Factory to create object."""
    if value is not None and isinstance(value, str):
        value = cls(value, **kwargs)
    return value