Align value function to Scripting API

packages/binding-http/test/http-server-test.ts

@@ -160,7 +160,7 @@ class HttpServerTest {
         let test: DataSchemaValue;
         testThing.setPropertyReadHandler("test", (_) => Promise.resolve(test));
         testThing.setPropertyWriteHandler("test", async (value) => {
-            test = await value.value();
+            test = Buffer.from(await value.arrayBuffer()).toString("utf-8");
         });
 
         testThing.setActionHandler("try", async (input: WoT.InteractionOutput) => {

packages/binding-opcua/test/full-opcua-thing-test.ts

@@ -49,6 +49,7 @@ const thingDescription: WoT.ThingDescription = {
             observable: true,
             readOnly: true,
             unit: "°C",
+            type: "number",
             "opcua:nodeId": { root: "i=84", path: "/Objects/1:MySensor/2:ParameterSet/1:Temperature" },
             // Don't specifu type here as it could be multi form: type: [ "object", "number" ],
             forms: [
@@ -111,6 +112,7 @@ const thingDescription: WoT.ThingDescription = {
             description: "the temperature set point",
             observable: true,
             unit: "°C",
+            type: "number",
             // dont't
             forms: [
                 {
@@ -358,10 +360,25 @@ describe("Full OPCUA Thing Test", () => {
 
         return { thing, servient };
     }
-    async function doTest(thing: WoT.ConsumedThing, propertyName: string, localOptions: InteractionOptions) {
+    async function doTest(
+        thing: WoT.ConsumedThing,
+        propertyName: string,
+        localOptions: InteractionOptions,
+        forceParsing = false
+    ) {
         debug("------------------------------------------------------");
         try {
             const content = await thing.readProperty(propertyName, localOptions);
+            if (forceParsing) {
+                // In opcua binding it is possible to return a special response that contains
+                // reacher details than the bare value. However this make the returned value
+                // not complaint with its data schema. Therefore we have to fallback to
+                // custom parsing.
+                const raw = await content.arrayBuffer();
+                const json = JSON.parse(Buffer.from(raw).toString("utf-8"));
+                debug(json?.toString());
+                return json;
+            }
             const json = await content.value();
             debug(json?.toString());
             return json;
@@ -395,13 +412,13 @@ describe("Full OPCUA Thing Test", () => {
             const json1 = await doTest(thing, propertyName, { formIndex: 1 });
             expect(json1).to.eql(25);
 
-            const json2 = await doTest(thing, propertyName, { formIndex: 2 });
+            const json2 = await doTest(thing, propertyName, { formIndex: 2 }, true);
             expect(json2).to.eql({ Type: 11, Body: 25 });
 
             expect(thingDescription.properties?.temperature.forms[3].contentType).eql(
                 "application/opcua+json;type=DataValue"
             );
-            const json3 = await doTest(thing, propertyName, { formIndex: 3 });
+            const json3 = await doTest(thing, propertyName, { formIndex: 3 }, true);
             debug(json3?.toString());
             expect((json3 as Record<string, unknown>).Value).to.eql({ Type: 11, Body: 25 });
         } finally {

packages/core/src/interaction-output.ts

@@ -16,7 +16,7 @@
 import * as WoT from "wot-typescript-definitions";
 import { ContentSerdes } from "./content-serdes";
 import { ProtocolHelpers } from "./core";
-import { DataSchemaError, NotSupportedError } from "./errors";
+import { DataSchemaError, NotReadableError, NotSupportedError } from "./errors";
 import { Content } from "./content";
 import Ajv from "ajv";
 import { createLoggers } from "./logger";
@@ -33,7 +33,7 @@
 
 export class InteractionOutput implements WoT.InteractionOutput {
     private content: Content;
-    private parsedValue: unknown;
+    #value: unknown;
     private buffer?: ArrayBuffer;
     private _stream?: ReadableStream;
     dataUsed: boolean;
@@ -79,43 +79,46 @@
 
     async value<T extends WoT.DataSchemaValue>(): Promise<T> {
         // the value has been already read?
-        if (this.parsedValue !== undefined) {
-            return this.parsedValue as T;
+        if (this.#value !== undefined) {
+            return this.#value as T;
         }
 
         if (this.dataUsed) {
-            throw new Error("Can't read the stream once it has been already used");
+            throw new NotReadableError("Can't read the stream once it has been already used");
+        }
+
+        if (this.form == null) {
+            throw new NotReadableError("No form defined");
+        }
+
+        if (this.schema == null || this.schema.type == null) {
+            throw new NotReadableError("No schema defined");
         }
 
         // is content type valid?
-        if (!this.form || !ContentSerdes.get().isSupported(this.content.type)) {
-            const message = !this.form ? "Missing form" : `Content type ${this.content.type} not supported`;
+        if (!ContentSerdes.get().isSupported(this.content.type)) {
+            const message = `Content type ${this.content.type} not supported`;
             throw new NotSupportedError(message);
         }
 
         // read fully the stream
-        const data = await this.content.toBuffer();
+        const bytes = await this.content.toBuffer();
         this.dataUsed = true;
-        this.buffer = data;
+        this.buffer = bytes;
+
+        const json = ContentSerdes.get().contentToValue({ type: this.content.type, body: bytes }, this.schema);
+
+        // validate the schema
+        const validate = ajv.compile<T>(this.schema);
 
-        // call the contentToValue
-        // TODO: should be fixed contentToValue MUST define schema as nullable
-        const value = ContentSerdes.get().contentToValue({ type: this.content.type, body: data }, this.schema ?? {});
-
-        // any data (schema)?
-        if (this.schema) {
-            // validate the schema
-            const validate = ajv.compile<T>(this.schema);
-
-            if (!validate(value)) {
-                debug(`schema = ${util.inspect(this.schema, { depth: 10, colors: true })}`);
-                debug(`value: ${value}`);
-                debug(`Errror: ${validate.errors}`);
-                throw new DataSchemaError("Invalid value according to DataSchema", value as WoT.DataSchemaValue);
-            }
+        if (!validate(json)) {
+            debug(`schema = ${util.inspect(this.schema, { depth: 10, colors: true })}`);
+            debug(`value: ${json}`);
+            debug(`Errror: ${validate.errors}`);
+            throw new DataSchemaError("Invalid value according to DataSchema", json as WoT.DataSchemaValue);
         }
 
-        this.parsedValue = value;
-        return this.parsedValue as T;
+        this.#value = json;
+        return json;
     }
 }

packages/core/src/wot-impl.ts

@@ -22,33 +22,34 @@ import Helpers from "./helpers";
 import { createLoggers } from "./logger";
 import ContentManager from "./content-serdes";
 import { getLastValidationErrors, isThingDescription } from "./validation";
+import { inspect } from "util";
 
 const { debug } = createLoggers("core", "wot-impl");
 
 class ThingDiscoveryProcess implements WoT.ThingDiscoveryProcess {
-    constructor(rawThingDescriptions: WoT.DataSchemaValue, filter?: WoT.ThingFilter) {
+    constructor(private directory: ConsumedThing, public filter?: WoT.ThingFilter) {
         this.filter = filter;
         this.done = false;
-        this.rawThingDescriptions = rawThingDescriptions;
     }
 
-    rawThingDescriptions: WoT.DataSchemaValue;
-
-    filter?: WoT.ThingFilter | undefined;
     done: boolean;
     error?: Error | undefined;
     async stop(): Promise<void> {
         this.done = true;
     }
 
     async *[Symbol.asyncIterator](): AsyncIterator<WoT.ThingDescription> {
-        if (!(this.rawThingDescriptions instanceof Array)) {
-            this.error = new Error("Encountered an invalid output value.");
+        let rawThingDescriptions: WoT.ThingDescription[];
+        try {
+            const thingsPropertyOutput = await this.directory.readProperty("things");
+            rawThingDescriptions = (await thingsPropertyOutput.value()) as WoT.ThingDescription[];
+        } catch (error) {
+            this.error = error instanceof Error ? error : new Error(inspect(error));
             this.done = true;
             return;
         }
 
-        for (const outputValue of this.rawThingDescriptions) {
+        for (const outputValue of rawThingDescriptions) {
             if (this.done) {
                 return;
             }
@@ -81,10 +82,7 @@ export default class WoTImpl {
         const directoyThingDescription = await this.requestThingDescription(url);
         const consumedDirectoy = await this.consume(directoyThingDescription);
 
-        const thingsPropertyOutput = await consumedDirectoy.readProperty("things");
-        const rawThingDescriptions = await thingsPropertyOutput.value();
-
-        return new ThingDiscoveryProcess(rawThingDescriptions, filter);
+        return new ThingDiscoveryProcess(consumedDirectoy, filter);
     }
 
     /** @inheritDoc */

packages/core/test/DiscoveryTest.ts

@@ -36,6 +36,7 @@ function createDirectoryTestTd(title: string, thingsPropertyHref: string) {
         },
         properties: {
             things: {
+                type: "array",
                 forms: [
                     {
                         href: thingsPropertyHref,