Create a target

Intro

libmodulor provides targets that are commonly used.

But depending on your needs, you might want to create your own targets as there is a high probability that the provided ones do not fit your criteria, especially the GUI ones since they are very basic.

Yet, they are good examples to take inspiration from in order to understand how apps, use cases and products are instrumented.

CLI

A CLI target exposes a product so it can be used in a Terminal Emulator :

node index.js SignIn --email dexter@caramail.com
> Password : *******************

node index.js --help
node index.js --version

To create a CLI target, you need to implement the CLIManager interface. See node-core-cli as an example.

Important aspects to take into account (non-exhaustive list) :

• the command must be mounted at uc.def.ext.cmd.mountAt ?? ucMountingPoint(uc)
• the command must execute uc.def.lifecycle.client.main according to the policy
• each input field must be mapped to a dedicated flag (e.g. email => --email)
• handle the fields type when parsing the command (e.g. number, boolean)
• handle the field cardinality when parsing the command (e.g. --tag Work --tag Boss => tag: ['Work', 'Boss'])
• handle the field "sensitivity" (see isSensitive()) by prompting for them instead of providing a flag to avoid leaking secrets in your history
• expose common commands usually provided by a CLI program (e.g. --help, --version, etc.) (these are usually not use cases)
• build the help based on uc.def.io and WordingManager
• build the version based on your package.json
• handle unknown commands by whether failing or displaying the help section

Here is a great list of solutions to build your own.

Server

A server target exposes a product so it can be called as a REST-like API :

curl \
    -X POST \
    -H "Content-Type: application/json" \
    -H "X-API-Key: PublicApiKeyToBeChangedWhenDeploying" \
    -d '{"email":"dexter@caramail.com","password":"thedarkpassenger305"}' \
    http://localhost:7443/api/v1/SignIn

To create a server target, you need to implement the ServerManager interface. See node-express-server as an example.

Important aspects to take into account (non-exhaustive list) :

• the use case must be mounted at the path and pathAliases provided by ucHTTPContract
• the request handler must execute uc.def.lifecycle.server.main according to the policy
• the request handler must handle the uc.def.io.o.sideEffects
• the request handler must return a 204 when there is no uc.def.io.o
• the request handler must handle the output transformation based on ext.http.transform
• the appropriate middleware must be mounted to handle uc.def.sec.publicApiKeyCheckType
• the appropriate middleware must be mounted to handle uc.def.sec.authType
• cookies must be implemented to handle authentication

GUI

A GUI target exposes a product as a user interface. See react-native-pure and react-web-pure as examples.

Typically, it provides "components" to :

• access a use case (e.g. a button or a link)
• interact with a use case (e.g. a button or a form)

Important aspects to take into account (non-exhaustive list) :

• the "access" component must handle the uc.def.lifecycle.client.policy
• the "interact" component must display a form when the use case needs input filling
• the form fields must handle the input fields type, cardinality, etc.
• the "interact" component must display a control (e.g. a button) when the use case does not need input filling
• the button submitting a use case must handle the different statuses (idle, changing, submitting, etc.)
• the wording must rely on WordingManager

MCP Server

A MCP server target exposes a product as a MCP server. See node-mcp-server as an example.

Like a regular server, it exposes the use cases as MCP tools.

Others

The list above corresponds to the current state of human interfaces in Software. We can bet that new ones will arrive pretty soon. So the only limit is your imagination.

We're looking forward to working on AR/VR targets, Voice targets, Haptic targets, etc...