Creating Custom Modules

This guide explains how to create custom modules for the Tealium Prism SDK. Custom modules allow you to extend the SDK’s functionality with your own data collection, processing, or dispatching logic.

Overview

There are two main approaches to creating custom modules:

Using BasicModuleFactory - For simple modules with standard initialization patterns (only one module instance, no custom dependencies)
Implementing ModuleFactory - For modules requiring custom dependencies or multiple instances

Using BasicModuleFactory

The BasicModuleFactory is the recommended approach for most custom modules. It provides a standardized way to create modules that conform to the BasicModule protocol.

Step 1: Create Your Custom Module

Your custom module must conform to BasicModule:

class MyCustomModule: BasicModule {
    let version = "1.0.0"
    let id = Self.moduleType

    @StateSubject([:])
    var moduleConfiguration: ObservableState<DataObject>

    required init?(context: TealiumContext, moduleConfiguration: DataObject) {
        self._moduleConfiguration.value = moduleConfiguration

        // Validate required configuration
        guard let apiKey = moduleConfiguration.getDataItem(key: "apiKey")?.get(as: String.self),
              !apiKey.isEmpty else {
            return nil // Return nil if initialization fails
        }

        // Initialize your module with the provided configuration
    }

    static let moduleType: String = "MyCustomModule"
}

Step 2: Create a Settings Builder (Optional)

For type-safe configuration, create a custom settings builder:

public class MyCustomModuleSettingsBuilder: ModuleSettingsBuilder {
    enum Keys {
        static let apiKey = "apiKey"
        static let timeout = "timeout"
    }

    /// Sets the API key for the custom module.
    ///
    /// - Parameter apiKey: The API key to use
    /// - Returns: The builder instance for method chaining
    public func setApiKey(_ apiKey: String) -> Self {
        _configurationObject.set(apiKey, key: Keys.apiKey)
        return self
    }

     /// Sets the timeout for network requests.
     ///
     /// - Parameter timeout: The timeout in seconds
     /// - Returns: The builder instance for method chaining
    public func setTimeout(_ timeout: Int) -> Self {
        _configurationObject.set(timeout, key: Keys.timeout)
        return self
    }
}

Step 3: Add Factory Method to Modules Extension

Add a factory method to the Modules extension:

public extension Modules {
    static func myCustomModule(forcingSettings block: EnforcingSettings<MyCustomModuleSettingsBuilder>? = { $0 }) -> some ModuleFactory {
        BasicModuleFactory<MyCustomModule>(
            moduleType: Modules.Types.myCustomModule,
            enforcedSettings: block?(MyCustomModuleSettingsBuilder()).build()
        )
    }
}

Step 4: Register Your Module

Add your module to the Tealium configuration:

var config = TealiumConfig(
    account: "account",
    profile: "profile",
    environment: "dev"
)

// Add with default settings
config.addModule(Modules.myCustomModule())

// Or add with default settings 
// but require this module to be defined in the Local or Remote settings to be initialized
config.addModule(Modules.myCustomModule(forcingSettings: nil))

// Or configure with specific settings
config.addModule(Modules.myCustomModule(forcingSettings: { builder in
    builder.setApiKey("your-api-key")
           .setTimeout(30)
           .setEnabled(true)
}))

Custom ModuleFactory Implementation

For modules that need custom dependencies, multiple instances, or complex initialization logic, implement the ModuleFactory protocol directly:

public class CustomModuleFactory: ModuleFactory {
    public let allowsMultipleInstances: Bool
    public let moduleType: String

    private let customDependency: SomeDependency

    public init(customDependency: SomeDependency, allowsMultipleInstances: Bool = false) {
        self.customDependency = customDependency
        self.allowsMultipleInstances = allowsMultipleInstances
        self.moduleType = "CustomModule"
    }

    public func create(moduleId: String, context: TealiumContext, moduleConfiguration: DataObject) -> CustomModule? {
        CustomModule(context: context, 
                    moduleConfiguration: moduleConfiguration,
                    customDependency: customDependency)
    }

    public func getEnforcedSettings() -> [DataObject] {
        // Return enforced settings if needed
        []
    }
}

Best Practices

Module Type Constants: Define module type constants in Modules.Types for consistency
Validation: Always validate required configuration in your module’s initializer
Return nil: Return nil from the initializer if required configuration is missing or invalid
Settings Builders: Use ModuleSettingsBuilder subclasses for type-safe configuration
Documentation: Document your module’s configuration options and behavior

Limitations of BasicModuleFactory

Modules cannot be instantiated multiple times (allowsMultipleInstances is always false)
No support for custom dependencies beyond TealiumContext
Standard initialization pattern only

If you need these features, implement ModuleFactory directly.

CustomModules Reference