This skill guides you through creating custom processors to extend Transmissions functionality, helping you choose between core and remote development.

Quick Start Decision Tree

First check for an existing processor that can be used in src/processors. If the name is a reasonable match for the required functionality, check the processor's signature in comments in the code.

Choose your development path:

Core Development (Recommended for reusable processors)

✅ Processors available to all apps
✅ Registered in framework factory
✅ Easy to test and debug
✅ Can be contributed to framework
❌ Requires framework modification

Use when: Building reusable processors, contributing to framework

Remote Development (For app-specific processors)

✅ Keeps app self-contained
✅ Independent from framework
⚠️ Requires manual import paths
⚠️ Factory registration challenges
❌ More complex setup

Use when: Processor is app-specific, maintaining separation

Workflow

1. Gather Information

Ask the user:

Processor name: What should it be called? (e.g., MyProcessor)
Group name: What category? (e.g., my-group, or use existing like util, text, flow)
Development location: Core (src/processors/) or Remote (app-specific)?
Processor purpose: What transformation does it perform?

2. Create Processor Structure

Execute based on chosen path:

For Core Development (New Group):

# Copy example group
cp -r src/processors/example-group src/processors/{GROUP_NAME}

# Rename processor file
mv src/processors/{GROUP_NAME}/Example.js src/processors/{GROUP_NAME}/{PROCESSOR_NAME}.js

# Rename factory
mv src/processors/{GROUP_NAME}/ExampleProcessorsFactory.js src/processors/{GROUP_NAME}/{GROUP_NAME}ProcessorsFactory.js

# List created files
ls -la src/processors/{GROUP_NAME}/

For Core Development (Existing Group):

# Just create new processor in existing group
# Example: adding to util/
touch src/processors/util/{PROCESSOR_NAME}.js

For Remote Development:

# Create in app's processor directory
mkdir -p ~/hyperdata/trans-apps/apps/{APP_NAME}/processors

# Copy example
cp src/processors/example-group/Example.js ~/hyperdata/trans-apps/apps/{APP_NAME}/processors/{PROCESSOR_NAME}.js

# Copy factory
cp src/processors/example-group/ExampleProcessorsFactory.js ~/hyperdata/trans-apps/apps/{APP_NAME}/processors/{PROCESSOR_NAME}Factory.js

3. Implement Processor

Edit the processor file:

Basic structure:

// src/processors/{GROUP}/{ PROCESSOR_NAME}.js

import logger from '../../utils/Logger.js'
import ns from '../../utils/ns.js'
import Processor from '../../model/Processor.js'

/**
 * @class {PROCESSOR_NAME}
 * @extends Processor
 * @classdesc
 * {PROCESSOR_DESCRIPTION}
 *
 * ### Processor Signature
 * #### __*Settings*__
 * * **`ns.trn.settingName`** - Description
 *
 * #### __*Input*__
 * * **`message.field`** - Expected input
 *
 * #### __*Output*__
 * * **`message.result`** - Output field
 */
class {PROCESSOR_NAME} extends Processor {
    constructor(config) {
        super(config)
    }

    async process(message) {
        logger.debug(`{PROCESSOR_NAME}.process`)

        // Skip if spawning completion
        if (message.done) {
            return this.emit('message', message)
        }

        // Get configuration
        const setting = super.getProperty(ns.trn.settingName, 'default')

        // Process message
        // YOUR LOGIC HERE

        // Emit result
        return this.emit('message', message)
    }
}

export default {PROCESSOR_NAME}

4. Update Factory

Edit factory file to register processor:

For new group:

// src/processors/{GROUP}/{GROUP}ProcessorsFactory.js

import logger from '../../utils/Logger.js'
import ns from '../../utils/ns.js'
import {PROCESSOR_NAME} from './{PROCESSOR_NAME}.js'

class {GROUP}ProcessorsFactory {
    static createProcessor(type, config) {
        if (type.equals(ns.trn.{PROCESSOR_NAME})) {
            return new {PROCESSOR_NAME}(config)
        }
        // Add more processors here
        return false
    }
}

export default {GROUP}ProcessorsFactory

For existing group: Add to existing factory file:

import {PROCESSOR_NAME} from './{PROCESSOR_NAME}.js'

// In createProcessor method:
if (type.equals(ns.trn.{PROCESSOR_NAME})) {
    return new {PROCESSOR_NAME}(config)
}

5. Register in AbstractProcessorFactory

For core processors only:

Edit src/engine/AbstractProcessorFactory.js:

// Add import at top
import {GROUP}ProcessorsFactory from '../processors/{GROUP}/{GROUP}ProcessorsFactory.js'

// Add to createProcessor method
static createProcessor(type, app) {
    // ... existing processors ...

    var processor = {GROUP}ProcessorsFactory.createProcessor(type, app)
    if (processor) return processor

    // ... rest of factories ...
}

6. Test Processor

Create test app:

# Create test app
mkdir -p src/apps/test/{PROCESSOR_NAME}-test

# Create transmissions.ttl
cat > src/apps/test/{PROCESSOR_NAME}-test/transmissions.ttl << 'EOF'
@prefix : <http://purl.org/stuff/transmissions/> .

:test a :EntryTransmission ;
    :pipe (:setup :test-processor :verify) .

:setup a :SetField ;
    :settings [
        :field "testInput" ;
        :value "test-value"
    ] .

:test-processor a :{PROCESSOR_NAME} ;
    :settings [
        :settingName "test-setting"
    ] .

:verify a :ShowMessage .
EOF

Run test:

./trans test.{PROCESSOR_NAME}-test -v

Quick Reference

Common Processor Patterns

See templates/processor-template.md for:

Simple transformation
Property manipulation
Async operations
Error handling
State management

Factory Registration

See templates/factory-guide.md for:

Factory structure
Type checking
Multiple processors
Error handling

Testing Strategies

See templates/testing.md for:

Unit testing
Integration testing
Test app creation
Debugging techniques

Common Issues

Processor not found:

Check factory registration
Verify import paths
Check AbstractProcessorFactory.js includes your factory

Type mismatch:

Verify ns.trn.{PROCESSOR_NAME} matches transmissions.ttl
Check factory uses type.equals() not ===

Import errors:

Check relative paths in imports
For remote: paths may be very long (../../../../../../)

Next Steps

After basic processor creation:

Implement core logic in process() method
Add comprehensive JSDoc comments
Create test apps
Add to integration tests
Document in processor's about.md
Consider contributing to core if reusable

Reference

Example processor: src/processors/example-group/Example.js
Processor base class: src/model/Processor.js
Factory pattern: src/engine/AbstractProcessorFactory.js
Manual: docs/manual/dev/processors.md