Struct MessageBus

pub struct MessageBus {
    pub trader_id: TraderId,
    pub instance_id: UUID4,
    pub name: String,
    pub has_backing: bool,
    pub switchboard: MessagingSwitchboard,
    pub subscriptions: AHashSet<Subscription>,
    pub topics: IndexMap<MStr<Topic>, Vec<Subscription>>,
    pub endpoints: IndexMap<MStr<Endpoint>, ShareableMessageHandler>,
    pub correlation_index: AHashMap<UUID4, ShareableMessageHandler>,
}

A generic message bus to facilitate various messaging patterns.

The bus provides both a producer and consumer API for Pub/Sub, Req/Rep, as well as direct point-to-point messaging to registered endpoints.

Pub/Sub wildcard patterns for hierarchical topics are possible:

• * asterisk represents one or more characters in a pattern.
• ? question mark represents a single character in a pattern.

Given a topic and pattern potentially containing wildcard characters, i.e. * and ?, where ? can match any single character in the topic, and * can match any number of characters including zero characters.

The asterisk in a wildcard matches any character zero or more times. For example, comp* matches anything beginning with comp which means comp, complete, and computer are all matched.

A question mark matches a single character once. For example, c?mp matches camp and comp. The question mark can also be used more than once. For example, c??p would match both of the above examples and coop.

Fields

trader_id: TraderId

The trader ID associated with the message bus.

instance_id: UUID4

The instance ID associated with the message bus.

name: String

The name for the message bus.

has_backing: bool

If the message bus is backed by a database.

switchboard: MessagingSwitchboard

The switchboard for built-in endpoints.

subscriptions: AHashSet<Subscription>

Active subscriptions.

topics: IndexMap<MStr<Topic>, Vec<Subscription>>

Maps a topic to all the handlers registered for it this is updated whenever a new subscription is created.

endpoints: IndexMap<MStr<Endpoint>, ShareableMessageHandler>

Index of endpoint addresses and their handlers.

correlation_index: AHashMap<UUID4, ShareableMessageHandler>

Index of request correlation IDs and their response handlers.

Implementations

impl MessageBus

pub fn new( trader_id: TraderId, instance_id: UUID4, name: Option<String>, _config: Option<HashMap<String, Value>>, ) -> Self

Creates a new MessageBus instance.

pub fn memory_address(&self) -> String

Returns the message bus instances memory address.

pub fn endpoints(&self) -> Vec<&str>

Returns the registered endpoint addresses.

pub fn patterns(&self) -> Vec<&str>

Returns actively subscribed patterns.

pub fn has_subscribers<T: AsRef<str>>(&self, topic: T) -> bool

Returns whether there are subscribers for the topic.

pub fn subscriptions_count<T: AsRef<str>>(&self, topic: T) -> usize

Returns the count of subscribers for the topic.

Panics

Returns an error if the topic is not valid.

pub fn subscriptions(&self) -> Vec<&Subscription>

Returns active subscriptions.

pub fn subscription_handler_ids(&self) -> Vec<&str>

Returns the handler IDs for actively subscribed patterns.

pub fn is_registered<T: AsRef<str>>(&self, endpoint: T) -> bool

Returns whether the endpoint is registered.

Panics

Returns an error if the endpoint is not valid topic string.

pub fn is_subscribed<T: AsRef<str>>( &self, pattern: T, handler: ShareableMessageHandler, ) -> bool

Returns whether the handler is subscribed to the pattern.

pub const fn close(&self) -> Result<()>

Close the message bus which will close the sender channel and join the thread.

Errors

This function never returns an error (TBD once backing database added).

pub fn get_endpoint( &self, endpoint: MStr<Endpoint>, ) -> Option<&ShareableMessageHandler>

Returns the handler for the endpoint.

pub fn get_response_handler( &self, correlation_id: &UUID4, ) -> Option<&ShareableMessageHandler>

Returns the handler for the correlation_id.

pub fn matching_subscriptions<T: AsRef<str>>( &mut self, topic: T, ) -> Vec<Subscription>

Finds the subscriptions which match the topic and caches the results in the patterns map.

pub fn register_response_handler( &mut self, correlation_id: &UUID4, handler: ShareableMessageHandler, ) -> Result<()>

Registers a response handler for a specific correlation ID.

Errors

Returns an error if handler is already registered for the correlation_id.

impl MessageBus

Data specific functions.

pub fn register_message_bus(self) -> Rc<RefCell<MessageBus>>

Registers message bus for the current thread.

Trait Implementations

impl Debug for MessageBus

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

Formats the value using the given formatter.

impl Default for MessageBus

fn default() -> Self

Creates a new default MessageBus instance.