camel-processor

Message processors for rust-camel (EIP implementations)

Overview

camel-processor provides implementations of Enterprise Integration Patterns (EIP) as processors that transform, filter, and route messages in rust-camel pipelines. These are the building blocks you use when defining routes.

Features

Filter: Conditional message routing based on predicates
Choice: Content-based routing with when/otherwise branches
Log: Logging processor for debugging and monitoring
SetHeader / DynamicSetHeader: Set message headers
SetBody / MapBody: Transform message bodies
Splitter: Split messages into multiple fragments
Aggregator: Aggregate multiple messages into one
Multicast: Send to multiple destinations in parallel
RecipientList: Dynamically resolve endpoints from expression at runtime
WireTap: Fire-and-forget message copying
Circuit Breaker: Resilience pattern implementation
Error Handler: Centralized error handling
Stop: Stop processing immediately
Script: Execute mutating expressions via ScriptMutator; changes to headers, properties, and body propagate back with atomic rollback on error
Delayer: Delay message processing with fixed or dynamic (header-based) duration
Stream Handling: Processors that consume streams replace the body with a JSON placeholder {"placeholder": true}
Marshal / Unmarshal: Serialize/deserialize message bodies using pluggable data formats (JSON, XML)

Installation

Add to your Cargo.toml:

[dependencies]
camel-processor = "0.2"

Usage

Using Processors Directly

use camel_processor::{
    FilterService, LogProcessor, LogLevel, SetHeader, SetBody,
    MapBody, SplitterService, MulticastService, DelayerService
};
use camel_api::{Exchange, Message, Body, Value, BoxProcessor, DelayConfig};

// Filter exchanges
let filter = FilterService::new(
    |ex: &Exchange| ex.input.body.as_text().map(|t| t.len() > 5).unwrap_or(false),
    my_processor
);

// Log messages
let logger = LogProcessor::new(LogLevel::Info, "Processing message".to_string());

// Set a header
let set_header = SetHeader::new(identity, "source", Value::String("api".into()));

// Map body
let upper = MapBody::new(identity, |body: Body| {
    body.as_text().map(|t| Body::Text(t.to_uppercase())).unwrap_or(body)
});

// Delay with fixed duration
let delayer = DelayerService::new(DelayConfig::new(500));

// Delay with dynamic header
let dynamic_delayer = DelayerService::new(
    DelayConfig::new(1000).with_dynamic_header("CamelDelayMs")
);

With RouteBuilder (Recommended)

use camel_builder::RouteBuilder;

let route = RouteBuilder::from("timer:tick")
    .set_header("processed", Value::Bool(true))
    .filter(|ex| ex.input.body.as_text().is_some())
        .log("Processing text message", LogLevel::Info)
        .map_body(|b| Body::Text(b.as_text().unwrap_or("").to_uppercase()))
    .end_filter()
    .to("mock:result")
    .build()
    .unwrap();

Available Processors

Processor	Purpose
`FilterService`	Route based on conditions
`ChoiceService`	Content-based routing (when/otherwise)
`LogProcessor`	Log exchange information
`SetHeader`	Set static header values
`DynamicSetHeader`	Set headers from expressions
`SetBody`	Replace message body
`MapBody`	Transform message body
`SplitterService`	Split messages
`AggregatorService`	Combine messages
`MulticastService`	Parallel routing
`WireTapService`	Side-channel routing
`CircuitBreakerLayer`	Fault tolerance
`ErrorHandlerLayer`	Error handling
`StopService`	Stop processing
`ScriptMutator`	Execute mutating scripts that modify Exchange headers, properties, or body
`MarshalService`	Marshal body using a DataFormat (e.g., Json → Text)
`UnmarshalService`	Unmarshal body using a DataFormat (e.g., Text → Json)
`DelayerService`	Delay message processing by a fixed or dynamic duration
`RecipientListService`	Dynamic recipient list — resolve endpoints from expression at runtime

Data Formats

The DataFormat trait defines serialization/deserialization for message bodies:

Format	Marshal (structured → wire)	Unmarshal (wire → structured)
`json`	`Body::Json` → `Body::Text`	`Body::Text`/`Body::Bytes` → `Body::Json`
`xml`	`Body::Xml` → `Body::Text`	`Body::Text`/`Body::Bytes` → `Body::Xml`

Usage with RouteBuilder

use camel_builder::RouteBuilder;

let route = RouteBuilder::from("direct:in")
    .unmarshal("json")
    .marshal("xml")
    .to("mock:out")
    .build()
    .unwrap();

YAML DSL

steps:
  - unmarshal: json
  - marshal: xml

camel-processor 0.6.3