Sphereon-Opensource
Presentation Exchange v1 and v2
Typescript models
Table of Contents
Background
The Presentation Exchange OpenAPI (PEX-OpenAPI) is an OpenAPI specification based upon the DIF Presentation Exchange v2.0.0 and DIF Presentation Exchange v1.0.0 specifications.
A standardised Presentation Exchange is crucial for interoperability between different systems that are used by verifiers and holders (e.g. wallets). It enables the verifiers- and holder-systems to interpret models used by each other consistently. The PEX-OpenAPI specification and Models Generator will allow for use-cases with the need to implement a Presentation Exchange, possibly using different programming languages.
The PEX-Models Typescript library is a pre-generated and published library, ready to be used in typescript/javascript projects that can directly be used from a package manager using npmjs.com. This library can be used in any JavaScript project, providing a consistent structure of the models required in presentation exchange between verifiers and holders of verifiable credentials.
Additionally, the PEX-Models library can be used to create libraries for verification of presentation definition and submission objects themselves. In this fashion, the PEX-Models library is used in Sphereon's PEX library to validate the model objects.
Usage
Step 1 : Create a project using the models
The provided example will create a new NPM project using typescript as language. It will import and use JwtObject, similarly you can import and use other objects.
cd '<workspace>'
mkdir my-pex-models-consumer-prj
cd my-pex-models-consumer-prj
npm initnpm init will ask a few questions, the default answer to those questions can be selected.
Step 2 : Add script & Import models
To use the models generated as a result of step 1
npm install
npm install --save @sphereon/pex-models
npm install --save ts-nodeCreate a folder named scripts
mkdir scriptsCreate a file in 'scripts' named consumer-script.ts with following content.
import {JwtObject} from '@sphereon/pex-models'
var jwtObject : JwtObject = {
alg : ['someAlgorithm']
};
console.log(jwtObject);In package.json add a script "my-pex-models-consumer-script": "ts-node scripts/consumer-script.ts" in the scripts section. The resulting Package.json should look like following.
{
"name": "my-pex-models-consumer-prj",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"my-pex-models-consumer-script": "ts-node scripts/consumer-script.ts"
},
"author": "",
"license": "ISC",
"dependencies": {
"@sphereon/pex-models": "2.0.0",
"ts-node": "^9.1.1"
}
}Step 3 : Check if everything went correctly
In the terminal run the following command from the <workspace>/my-pex-models-consumer-prj
cd '<workspace>/my-pex-models-consumer-prj'
npm run my-pex-models-consumer-scriptYou should expect this to be printed on the console.
{ alg: [ 'someAlgorithm' ] }