Clean up syntax

Author: Wes Biggs

README.md

@@ -6,16 +6,19 @@ This resolver should be used with one or more plugins for specific DSNP systems
 # Usage
 
 This package follows the conventions described in the [`did-resolver`](https://github.com/decentralized-identity/did-resolver) package and exposes a `getResolver()` function which returns a mapping from the `dsnp` DID method to a resolver function.
+Pass an array of plugins to the `getResolver()` method.
 
 ## Usage for DSNP DID method only
 
 ```
 import { Resolver } from "did-resolver";
-import dsnp from "@dsnp/did-resolver"; 
-import "dsnp-did-resolver-plugin-foo"; // See below for known plugins
+import dsnpResolver from "@dsnp/did-resolver"; 
+import { FooResolver} from "dsnp-did-resolver-plugin-foo"; // See below for known plugins
 // ... additional dsnp-did-resolver plugins if needed
 
-const resolver = new Resolver(dsnp.getResolver());
+const resolver = new Resolver(dsnpResolver.getResolver(
+  [ new FooResolver() ]
+));
 const myDid = "did:dsnp:123456";
 const result = await resolver.resolve(myDid);
 console.log(JSON.stringify(result, null, 2));
@@ -27,36 +30,46 @@ The Resolver constructor can combine resolvers for multiple DID methods as descr
 For example, if you also want to be able to resolve `did:ethr:*` DIDs, you would import and include the `ethr` resolver and pass its destructured resolver alongside the DSNP one to the constructor as follows:
 
 ```
-import ethr from "ethr-did-resolver";
+import ethrResolver from "ethr-did-resolver";
 // ... additional did-resolver packages; 
 
 const resolver = new Resolver({
-  ...dsnp.getResolver(),
-  ...ethr.getResolver()
+  ...dsnpResolver.getResolver([plugin]),
+  ...ethrResolver.getResolver()
 });
 // usage is same as in previous example
 ```
 
 # Plugins
 
-To resolve a DSNP User Id to a specific DSNP system, one or more system-specific plugins must be imported.
-Plugin import order defines the order in which this resolver will attempt to resolve a DSNP DID.
+To resolve a DSNP User Id to a specific DSNP system, one or more instances of system-specific plugins are required.
+Array ordering defines the order in which this resolver will attempt to resolve a DSNP DID.
 It will return the result from the first plugin that returns a DID document.
 
 ## Plugin development
 
-Plugins should implement a function with the `DSNPResolver` type (see `index.ts`):
+Plugins should implement the `DSNPResolver` interface, which includes a `resolve(bigint)` function (see `index.ts`):
 
 ```
-export type DSNPResolver = (dsnpUserId: BigInt) => Promise<DIDDocument | null>;
+export interface DSNPResolver {
+  resolve(dsnpUserId: bigint): Promise<DIDDocument | null>;
+}
 ```
 
 The `DIDDocument` type is defined in the `did-resolver` package.
 
-The DSNP resolver function should return `null` if the DSNP User Id cannot be resolved to a DID document for any reason.
+The `resolve()` function should return `null` if the DSNP User Id cannot be resolved to a DID document for any reason.
 Plugins should avoid throwing errors except in dire circumstances, as errors from one plugin will cause any further plugins that have been registered to *not* be called.
 
-Register the function by calling `registerDSNPResolver(myResolver)`.
+`DSNPResolver` instances are passed to the `getResolver()` function.
+
+## Known plugins
+
+| System | Plugin package
+|---|---|
+| Frequency | [`@dsnp/did-resolver-plugin-frequency`](https://github.com/AmplicaLabs/dsnp-did-resolver-plugin-frequency) | 
+
+Please submit a pull request with any additional plugins.
 
 # Development
 

index.test.ts

@@ -6,30 +6,31 @@ import {
   DIDResolutionOptions,
 } from "did-resolver";
 import { expect, jest, test } from "@jest/globals";
-import { DSNPResolver, getResolver, registerDSNPResolver } from "./index.js";
+import { DSNPResolver, getResolver } from "./index.js";
 
 const someDocument: DIDDocument = {
   id: "",
 };
 
-const plugin1: DSNPResolver = async (dsnpUserId: bigint) => {
-  if (dsnpUserId === 123456n) {
-    return someDocument;
-  } else {
-    return null;
+class Plugin1 implements DSNPResolver {
+  async resolve(dsnpUserId: bigint): Promise<DIDDocument | null> {
+    if (dsnpUserId === 123456n) {
+      return someDocument;
+    } else {
+      return null;
+    }
   }
-};
+}
 
-const plugin2: DSNPResolver = async (dsnpUserId: bigint) => {
-  if (dsnpUserId === 234567n) {
-    return someDocument;
-  } else {
-    return null;
+class Plugin2 implements DSNPResolver {
+  async resolve(dsnpUserId: bigint): Promise<DIDDocument | null> {
+    if (dsnpUserId === 234567n) {
+      return someDocument;
+    } else {
+      return null;
+    }
   }
-};
-
-registerDSNPResolver(plugin1);
-registerDSNPResolver(plugin2);
+}
 
 function errorResult(error: string): DIDResolutionResult {
   return {
@@ -61,7 +62,7 @@ describe("dsnp-did-resolver", () => {
   let resolver: GetResolverOutput;
 
   beforeAll(() => {
-    resolver = getResolver();
+    resolver = getResolver([new Plugin1(), new Plugin2()]);
   });
 
   async function doResolve(id: string) {

index.ts

@@ -7,12 +7,8 @@ import {
   DIDDocument,
 } from "did-resolver";
 
-const dsnpResolvers: DSNPResolver[] = [];
-
-export type DSNPResolver = (dsnpUserId: bigint) => Promise<DIDDocument | null>;
-
-export function registerDSNPResolver(resolver: DSNPResolver) {
-  dsnpResolvers.push(resolver);
+export interface DSNPResolver {
+  resolve(dsnpUserId: bigint): Promise<DIDDocument | null>;
 }
 
 const notFoundResult: DIDResolutionResult = {
@@ -21,7 +17,7 @@ const notFoundResult: DIDResolutionResult = {
   didResolutionMetadata: { error: "notFound" },
 };
 
-export function getResolver() {
+export function getResolver(dsnpResolvers: DSNPResolver[]) {
   async function resolve(
     did: string,
     parsed: ParsedDID,
@@ -54,7 +50,7 @@ export function getResolver() {
 
     for (const dsnpResolver of dsnpResolvers) {
       try {
-        const output = await dsnpResolver(dsnpUserId);
+        const output = await dsnpResolver.resolve(dsnpUserId);
         if (output)
           return {
             didResolutionMetadata: { contentType: "application/did+ld+json" },