@jargon/sdk-core

@jargon/sdk-core

Jargon's SDK core package contains functionality common to multiple voice platforms and frameworks.

Core concepts

Content resources and resource files

Content resources define the text that may vary across user locales.

Resource files are JSON, with a single top-level object (similar to package.json). The keys within that object are the identifiers you'll use to refer to specific resources within your source code. Nested objects are supported to help you organize your resources.

{
  "key1":"Text for key 1",
  "key2":"Text for key 2",
  "nestedObjects":{
    "are":{
      "supported":"Use the key 'nestedObjects.are.supported' to refer to this resource"
    }
  }
}

Resource value format

Resource values are in ICU MessageFormat. This format supports constructing text at runtime based on parameters passed in from your code, and selecting alternative forms to handle things like pluralization and gender.

Named parameters

{
  "sayHello":"Hello {name}"
}

Plural forms

{
  "itemCount":"{count, plural, =0 {You have zero items} =1 {You have one item} other {You have # items}}"
}

Gendered forms

{
  "pronounSelection":"{gender, select, female {She did it!} male {He did it!} other {It did it!}"
}

Variations

Resources can have multiple variations. Variations are defined using nested objects:

{
  "resourceWithVariations":{
    "v1":"First variation",
    "v2":"Second variation",
    "v3":"Third variation"
  }
}

When rendering the key resourceWithVariations the ResourceManager will choose a variation at random (with other more complex methods coming in future versions). If you render the same resource multiple times within a single request (e.g., for spoken content and for card or screen content) the ResourceManager will by default consistently choose the same variation.

Note that you can always select a specific variation using its fully-qualified key (e.g., resourceWithVariations.v1)

You can determine which variation the was choses via the ResourceManager's selectedVariation(s) routines.

Functionality

Resource management and runtime rendering

ResourceManager allows clients to access content resources stored in locale-specifc files, and to render those resources at runtime, substituting parameters.

A ResourceManager instance is meant to live only for the lifetime of a single request, and is bound to a specific locale. Instances are created via a ResourceManagerFactory instance, normally DefaultResourceManagerFactory.

Resource files live in "resources" subdirectory of the process's runtime directory; this will soon be customizeable via ResourceManagerOptions.

Runtime Interface

RenderItem

A RenderItem specifies a resource key, optional parameters, and options to control details of the rendering (which are themselves optional).

interface RenderItem {
  /** The resource key to render */
  key: string
  /** Params to use during rendering (optional) */
  params?: RenderParams
  /** Render options (optional) */
  options?: RenderOptions
}

RenderParams are a map from parameter name to a string, number, or RenderItem instance.

interface RenderParams {
  [param: string]: string | number | RenderItem
}

The use of a RenderItem instance as a parameter value makes it easy to compose multiple resource together at runtime. This is useful when a parameter value varies across locales, or when you want the SDK to select across multiple variations for a parameter value, and reduces the need to chain together multiple calls into the ResourceManager.

The ri helper function simplifies constructing a RenderItem:

function ri (key: string, params?: RenderParams, options?: RenderOptions): RenderItem

rm.render(ri('sayHello', { 'name': 'World' }))

RenderOptions allows fine-grained control of rendering behavior for a specific call, overriding the configuration set at the ResourceManager level.

interface RenderOptions {
  /** When true, forces the use of a new random value for selecting variations,
   * overriding consistentRandom
   */
  readonly forceNewRandom?: boolean
}

ResourceManager

ResourceManager is the core interface for rendering locale-specific content at runtime.

export interface ResourceManager {
  /** Renders a string in the current locale
   * @param {RenderItem} item The item to render
   * @returns {Promise<string>} A promise to the rendered string
   */
  render (item: RenderItem): Promise<string>

  /** Renders multiple item
   * @param {RenderItem[]} items The items to render
   * @returns {Promise<string[]} A promise to the rendered strings
   */
  renderBatch (items: RenderItem[]): Promise<string[]>

  /** Renders an object in the current locale. This also supports returning
   * strings, numbers, or booleans
   * @param {RenderItem} item The item to render
   * @returns {Promise<T>} A promise to the rendered object
   */
  renderObject<T> (item: RenderItem): Promise<T>

  /** Retrieves information about the selected variant for a rendered item. This
   * will only return a result when rendering the item required a variation
   * selection. If item has been used for multiple calls to a render routine
   * the result of the first operation will be returned; use selectedVariations
   * to see all results.
   * @param {RenderItem} item The item to retrieve the selected variant for
   * @return {Promise<SelectedVariation>} A promise to the selected variation
   */
  selectedVariation (item: RenderItem): Promise<SelectedVariation>

  /** Retrieves information about all selected variations for rendered item. This
   * will only return a result for items that required a variation selection
   * during rendering. Results are ordered by the ordering of the calls to render
   * routines.
   * @return {Promise<SelectedVariation[]>} A promise to the selected variations
   */
  selectedVariations (): Promise<SelectedVariation[]>

  /** The locale the resource manager uses */
  readonly locale: string
}

Note that the render routines return Promises to the rendered content, not the content directly.

ResourceManagerFactory

A ResourceManagerFactory construct locale-specific ResourceManager instance.

export interface ResourceManagerFactory {
  /** Constructs a ResourceManager for the specified locale
   * @param {string} locale
   */
  forLocale (locale: string): ResourceManager
}

Locales name use the standard BCP-47 tags, such as 'en-US' or 'de-DE'.

ResourceManagerOptions

Options for controlling resource manager functionality. Defaults are specified in DefaultResourceManagerOptions.

export interface ResourceManagerOptions {
  /** When true (default), the resource manager will use the same random value
   * when randomly selecting among variations; this ensures that calls to different routines
   * (speak, reprompt, etc.) with identical RenderItem inputs will render the same output.
   * When false, each render call will use a different random value, leading to possible
   * inconsistencies in the final response. Note that this option can be overridden via
   * a RenderItem option.
   */
  consistentRandom?: boolean

  /** Resource files for the provided locales will be loaded during initialization instead
   * of on first use; default is none.
   */
  localesToPreload?: string[]

  /** When true (default), the resource manager will keep track of which variation it selected,
   * allowing clients to view those selections through a call to selectedVariation(s)
   */
  trackSelectedVariations?: boolean
}

export const DefaultResourceManagerOptions: Required<ResourceManagerOptions> = {
  consistentRandom: true,
  localesToPreload: [],
  trackSelectedVariations: true
}

RenderOptions

Options for controlling rendering behavior, overriding the ResourceManagers configuration. Defaults are specified in DefaultRenderOptions.

/**
 * Options control additional rendering behavior, overridding the
 * settings configured at the ResourceManager level.
 */
export interface RenderOptions {
  /** When true, forces the use of a new random value for selecting variations,
   * overriding consistentRandom
   */
  readonly forceNewRandom?: boolean
}

export const DefaultRenderOptions: RenderOptions = {
  forceNewRandom: false
}

Usage

const sdkCore = require('@jargon/sdk-core');
const options = {}
const resourceManagerFactory = new sdkCore.DefaultResourceManagerFactory(options)
const resourceManager = resourceManagerFactory.forLocale('en-US')
const contentPromise = resourceManager.render(sdkCore.ri('sayHello', { 'name': 'World' }))