Make contentType optional in ExpectedResponse and AdditionalExpectedResponse classes

index.html

@@ -3685,7 +3685,7 @@ <h3><code>Form</code></h3>
                       ></cite
                     >].
                   </td>
-                  <td><a href="#sec-default-values">with default</a></td>
+                  <td>optional</td>
                   <td>
                     <a href="https://www.w3.org/TR/2012/REC-xmlschema11-2-20120405/#string"><code>string</code></a>
                   </td>
@@ -4068,7 +4068,7 @@ <h4>Response-related Terms Usage</h4>
 
               <p>
                 The optional <code>response</code> name-value pair can be used to provide metadata for the expected
-                response message. With the core vocabulary, it only includes content type information, but TD Context
+                response message. With the core vocabulary, it may only include content type information, but TD Context
                 Extensions could be applied.
                 <span class="rfc2119-assertion" id="td-expectedResponse-default-contentType"
                   >If no <code>response</code> name-value pair is provided, it MUST be assumed that the content type of
@@ -4077,9 +4077,7 @@ <h4>Response-related Terms Usage</h4>
                 Note that <code>contentType</code> within an
                 <code>ExpectedResponse</code>
                 <a href="#dfn-class" class="internalDFN" data-link-type="dfn">Class</a> does not have a
-                <a href="#dfn-default-value" class="internalDFN" data-link-type="dfn">Default Value</a>. For instance,
-                if the value of the content type of the form is <code>application/xml</code> the assumed value of the
-                content type of the response will be also <code>application/xml</code>.
+                <a href="#dfn-default-value" class="internalDFN" data-link-type="dfn">Default Value</a>.
               </p>
               <p>
                 In some cases additional responses might be possible. One example of this is error responses but in some
@@ -4094,28 +4092,26 @@ <h4>Response-related Terms Usage</h4>
               <p>
                 In some use cases, input and output data might be represented in a different form, for instance an
                 Action that accepts JSON, but returns an image. In such a case, the optional
-                <code>response</code> name-value pair can describe the content type of the expected response.
-                <span class="rfc2119-assertion" id="td-expectedResponse-contentType"
-                  >If the content type of the expected response differs from the content type of the form, the
-                  <code>Form</code> instance <em class="rfc2119" title="MUST">MUST</em> include a name-value pair with
-                  the name <code>response</code>.</span
-                >
-                For instance, an <code>ActionAffordance</code> could only accept <code>application/json</code> for its
-                input data, while it will respond with an <code>image/jpeg</code> content type for its output data. In
-                that case the content types differ and the <code>response</code>
-                name-value pair has to be used to provide response content type (<code>image/jpeg</code>) information to
-                the
-                <a href="#dfn-consumer" class="internalDFN" data-link-type="dfn">Consumer</a>.
+                <code>response</code> name-value pair can describe the content type of the expected response. As there
+                is no default value defined,
+                <span class="rfc2119-assertion" id="td-expectedResponse-missing-contentType">
+                  the lack of a <code>contentType</code> value in a <code>response</code> object within a form implies
+                  that the response <em class="rfc2119" title="MUST NOT">MUST NOT</em> contain any payload.
+                </span>
+                <span class="rfc2119-assertion" id="td-expectedResponse-defined-contentType">
+                  If a content type is defined in the <code>response</code> object within a form, a
+                  <a href="#dfn-consumer" class="internalDFN" data-link-type="dfn"> Consumer </a>
+                  MUST expect a response containing a payload in the respective format, e.g., an image in the case of
+                  <code>image/jpeg</code>.
+                </span>
               </p>
               <p>
-                Similar considerations apply to additional responses, although in this case the
-                <code>contentType</code> is optional if it is the same as the input content Type (e.g. JSON).
+                Similar considerations apply to additional responses.
                 <span class="rfc2119-assertion" id="td-additionalExpectedResponse-contentType"
                   >If the content type of an additional expected response differs from the content type of the form, the
                   <code>Form</code> instance <em class="rfc2119" title="MUST">MUST</em> include an entry in the array
-                  associated with the name <code>additionalResponses</code> that includes a value for the name
-                  <code>contentType</code>.</span
-                >
+                  associated with the name <code>additionalResponses</code>.
+                </span>
                 <span class="rfc2119-assertion" id="td-additionalExpectedResponse-schema"
                   >If the data schema of an additional expected response differs from the output data schema of the
                   interaction, the <code>Form</code> instance <em class="rfc2119" title="MUST">MUST</em> include an
@@ -4159,7 +4155,7 @@ <h3><code>ExpectedResponse</code></h3>
                       ></cite
                     >].
                   </td>
-                  <td>mandatory</td>
+                  <td>optional</td>
                   <td>
                     <a href="https://www.w3.org/TR/2012/REC-xmlschema11-2-20120405/#string"><code>string</code></a>
                   </td>
@@ -4191,6 +4187,18 @@ <h3><code>AdditionalExpectedResponse</code></h3>
                     <a href="https://www.w3.org/TR/2012/REC-xmlschema11-2-20120405/#boolean"><code>boolean</code></a>
                   </td>
                 </tr>
+                <tr class="rfc2119-table-assertion" id="td-vocab-schema--AdditionalExpectedResponse">
+                  <td><code>schema</code></td>
+                  <td>
+                    Used to define the output data schema for an additional response if it differs from the default
+                    output data schema. Rather than a <code>DataSchema</code> object, the name of a previous definition
+                    given in a <code>schemaDefinitions</code> map must be used.
+                  </td>
+                  <td>optional</td>
+                  <td>
+                    <a href="https://www.w3.org/TR/2012/REC-xmlschema11-2-20120405/#string"><code>string</code></a>
+                  </td>
+                </tr>
                 <tr class="rfc2119-table-assertion" id="td-vocab-contentType--AdditionalExpectedResponse">
                   <td><code>contentType</code></td>
                   <td>
@@ -4205,18 +4213,6 @@ <h3><code>AdditionalExpectedResponse</code></h3>
                       ></cite
                     >].
                   </td>
-                  <td><a href="#sec-default-values">with default</a></td>
-                  <td>
-                    <a href="https://www.w3.org/TR/2012/REC-xmlschema11-2-20120405/#string"><code>string</code></a>
-                  </td>
-                </tr>
-                <tr class="rfc2119-table-assertion" id="td-vocab-schema--AdditionalExpectedResponse">
-                  <td><code>schema</code></td>
-                  <td>
-                    Used to define the output data schema for an additional response if it differs from the default
-                    output data schema. Rather than a <code>DataSchema</code> object, the name of a previous definition
-                    given in a <code>schemaDefinitions</code> map must be used.
-                  </td>
                   <td>optional</td>
                   <td>
                     <a href="https://www.w3.org/TR/2012/REC-xmlschema11-2-20120405/#string"><code>string</code></a>
@@ -4305,12 +4301,6 @@ <h3>Default Value Definitions</h3>
               <td><code>false</code></td>
               <td></td>
             </tr>
-            <tr class="rfc2119-default-assertion" id="td-default-AdditionalResponseContentType">
-              <td><code>AdditionalExpectedResponse</code></td>
-              <td><code>contentType</code></td>
-              <td>value of the <code>contentType</code> of the <code>Form</code> element it belongs to.</td>
-              <td></td>
-            </tr>
             <tr class="rfc2119-default-assertion" id="td-default-contentType">
               <td><code>Form</code></td>
               <td><code>contentType</code></td>
@@ -4563,14 +4553,16 @@ <h2>Omitting Default Values</h2>
         "status": {
             "type": "string",
             "forms": [{
-                "href": "https://mylamp.example.com/status"
+                "href": "https://mylamp.example.com/status",
+                "contentType": "application/json"
             }]
         }
     },
     "actions": {
         "toggle": {
             "forms": [{
-                "href": "https://mylamp.example.com/toggle"
+                "href": "https://mylamp.example.com/toggle",
+                "contentType": "application/json"
             }]
         }
     },
@@ -4581,6 +4573,7 @@ <h2>Omitting Default Values</h2>
             },
             "forms": [{
                 "href": "https://mylamp.example.com/oh",
+                "contentType": "application/json",
                 "subprotocol": "longpoll"
             }]
         }
@@ -6194,18 +6187,6 @@ <h3><code>response</code></h3>
               no <code>output</code> schema is required, as the content type fully specifies the representation format.
             </p>
 
-            <p>
-              <span class="rfc2119-assertion" id="td-form-response-object">
-                If present, the value assigned to <code>response</code> in an instance of <code>Form</code> MUST be a
-                JSON object.
-              </span>
-              <span class="rfc2119-assertion" id="td-forms-response">
-                If present, the response object MUST contain a <code>contentType</code> member as defined in the
-                <a>Class</a> definition of <a href="#expectedresponse" class="sec-ref"><code>ExpectedResponse</code></a
-                >.
-              </span>
-            </p>
-
             <p>
               A <code>form</code> snippet with the <code>response</code> member is shown below based on the
               <code>takePhoto</code> Action described above:
@@ -6229,6 +6210,30 @@ <h3><code>response</code></h3>
     },
     // ...
 }
+</pre
+            >
+
+            <p>
+              In cases where responses are not expected to contain a payload and therefore no `contentType` as well, an
+              empty `response` object can be used to convey this information.
+            </p>
+            <pre class="example">
+{
+    // ...
+    "actions": {
+        "brewCoffee": {
+            "describe": "Invoking this action does not return a payload.",           
+            // ...
+            "forms": [{
+                "op": "invokeaction",
+                "href": "http://coffee-maker.example.com/brew-coffee",
+                "contentType": "application/json",
+                "response": {}
+            }]
+        }
+    },
+    // ...
+}
 </pre
             >
           </section>

index.template.html

@@ -1310,12 +1310,6 @@ <h3>Default Value Definitions</h3>
               <td><code>false</code></td>
               <td></td>
             </tr>
-            <tr class="rfc2119-default-assertion" id="td-default-AdditionalResponseContentType">
-              <td><code>AdditionalExpectedResponse</code></td>
-              <td><code>contentType</code></td>
-              <td>value of the <code>contentType</code> of the <code>Form</code> element it belongs to.</td>
-              <td></td>
-            </tr>
             <tr class="rfc2119-default-assertion" id="td-default-contentType">
               <td><code>Form</code></td>
               <td><code>contentType</code></td>
@@ -1568,14 +1562,16 @@ <h2>Omitting Default Values</h2>
         "status": {
             "type": "string",
             "forms": [{
-                "href": "https://mylamp.example.com/status"
+                "href": "https://mylamp.example.com/status",
+                "contentType": "application/json"
             }]
         }
     },
     "actions": {
         "toggle": {
             "forms": [{
-                "href": "https://mylamp.example.com/toggle"
+                "href": "https://mylamp.example.com/toggle",
+                "contentType": "application/json"
             }]
         }
     },
@@ -1586,6 +1582,7 @@ <h2>Omitting Default Values</h2>
             },
             "forms": [{
                 "href": "https://mylamp.example.com/oh",
+                "contentType": "application/json",
                 "subprotocol": "longpoll"
             }]
         }
@@ -3199,18 +3196,6 @@ <h3><code>response</code></h3>
               no <code>output</code> schema is required, as the content type fully specifies the representation format.
             </p>
 
-            <p>
-              <span class="rfc2119-assertion" id="td-form-response-object">
-                If present, the value assigned to <code>response</code> in an instance of <code>Form</code> MUST be a
-                JSON object.
-              </span>
-              <span class="rfc2119-assertion" id="td-forms-response">
-                If present, the response object MUST contain a <code>contentType</code> member as defined in the
-                <a>Class</a> definition of <a href="#expectedresponse" class="sec-ref"><code>ExpectedResponse</code></a
-                >.
-              </span>
-            </p>
-
             <p>
               A <code>form</code> snippet with the <code>response</code> member is shown below based on the
               <code>takePhoto</code> Action described above:
@@ -3234,6 +3219,30 @@ <h3><code>response</code></h3>
     },
     // ...
 }
+</pre
+            >
+
+            <p>
+              In cases where responses are not expected to contain a payload and therefore no `contentType` as well, an
+              empty `response` object can be used to convey this information.
+            </p>
+            <pre class="example">
+{
+    // ...
+    "actions": {
+        "brewCoffee": {
+            "describe": "Invoking this action does not return a payload.",           
+            // ...
+            "forms": [{
+                "op": "invokeaction",
+                "href": "http://coffee-maker.example.com/brew-coffee",
+                "contentType": "application/json",
+                "response": {}
+            }]
+        }
+    },
+    // ...
+}
 </pre
             >
           </section>

ontology/hctl.html

@@ -159,7 +159,7 @@ <h2>Terminology</h2>
                 <code>schemaDefinitions</code> map must be used.</span><table class="def numbered"><tbody><tr><td>Domain includes</td><td><code><a href="#AdditionalExpectedResponse">hctl:AdditionalExpectedResponse</a></code></td></tr></tbody></table></section>
 <section id="hasOperationType"><h4>hasOperationType</h4><p>IRI: <code>https://www.w3.org/2019/wot/hypermedia#hasOperationType</code></p><span>Indicates the semantic intention of performing the operation(s) described by the form.</span><table class="def numbered"><tbody><tr><td>Domain includes</td><td><code><a href="#Form">hctl:Form</a></code></td></tr></tbody></table></section>
 <section id="returns"><h4>returns</h4><p>IRI: <code>https://www.w3.org/2019/wot/hypermedia#returns</code></p><span>This optional term can be used if, e.g., the output communication metadata differ from input metadata (e.g., output contentType differ from the
-     input contentType). The response name contains metadata that is only valid for the reponse messages.</span><table class="def numbered"><tbody><tr><td>Domain includes</td><td><code><a href="#Form">hctl:Form</a></code></td></tr><tr><td>Range includes</td><td><code><a href="#ExpectedResponse">hctl:ExpectedResponse</a></code></td></tr></tbody></table></section></section><section><h3>Datatype Properties</h3><section id="forContentCoding"><h4>forContentCoding</h4><p>IRI: <code>https://www.w3.org/2019/wot/hypermedia#forContentCoding</code></p><span>Content coding values indicate an encoding transformation that has been or can be applied to a representation. Content codings are primarily used to allow a representation to be compressed or otherwise usefully transformed without losing the identity of its underlying media type and without loss of information. Examples of content coding include "gzip", "deflate", etc. </span><table class="def numbered"><tbody><tr><td>Domain includes</td><td><code><a href="#Form">hctl:Form</a></code></td></tr><tr><td>Range includes</td><td><code><a href="http://schema.org/Text">schema:Text</a></code></td></tr></tbody></table></section>
+     input contentType). The response name contains metadata that is only valid for the response messages.</span><table class="def numbered"><tbody><tr><td>Domain includes</td><td><code><a href="#Form">hctl:Form</a></code></td></tr><tr><td>Range includes</td><td><code><a href="#ExpectedResponse">hctl:ExpectedResponse</a></code></td></tr></tbody></table></section></section><section><h3>Datatype Properties</h3><section id="forContentCoding"><h4>forContentCoding</h4><p>IRI: <code>https://www.w3.org/2019/wot/hypermedia#forContentCoding</code></p><span>Content coding values indicate an encoding transformation that has been or can be applied to a representation. Content codings are primarily used to allow a representation to be compressed or otherwise usefully transformed without losing the identity of its underlying media type and without loss of information. Examples of content coding include "gzip", "deflate", etc. </span><table class="def numbered"><tbody><tr><td>Domain includes</td><td><code><a href="#Form">hctl:Form</a></code></td></tr><tr><td>Range includes</td><td><code><a href="http://schema.org/Text">schema:Text</a></code></td></tr></tbody></table></section>
 <section id="forContentType"><h4>forContentType</h4><p>IRI: <code>https://www.w3.org/2019/wot/hypermedia#forContentType</code></p><span>Assign a content type based on a media type [[IANA-MEDIA-TYPES]] (e.g., 'text/plain') and potential parameters (e.g., 'charset=utf-8') for the media type.</span><table class="def numbered"><tbody><tr><td>Domain includes</td><td><code><a href="#Form">hctl:Form</a></code></td></tr><tr><td>Range includes</td><td><code><a href="http://schema.org/Text">schema:Text</a></code></td></tr></tbody></table></section>
 <section id="forSubProtocol"><h4>forSubProtocol</h4><p>IRI: <code>https://www.w3.org/2019/wot/hypermedia#forSubProtocol</code></p><span>Indicates the exact mechanism by which an interaction will be accomplished for a given protocol when there are multiple options.
 

ontology/hctl.ttl

@@ -44,7 +44,7 @@ For example, for HTTP and Events, it indicates which of several available mechan
 :returns rdf:type owl:ObjectProperty ;
     rdfs:label "returns" ;
     rdfs:comment """This optional term can be used if, e.g., the output communication metadata differ from input metadata (e.g., output contentType differ from the
-     input contentType). The response name contains metadata that is only valid for the reponse messages."""@en ;
+     input contentType). The response name contains metadata that is only valid for the response messages."""@en ;
     schema:domainIncludes :Form ;
     schema:rangeIncludes :ExpectedResponse .
 

validation/td-json-schema-validation.json

@@ -318,8 +318,7 @@
         "contentType": {
           "type": "string"
         }
-      },
-      "required": ["contentType"]
+      }
     },
     "form_element_base": {
       "type": "object",