YAML configuration: add support for items/metadata/channel links

bundles/org.openhab.core.io.rest.core/src/main/java/org/openhab/core/io/rest/core/internal/fileformat/FileFormatResource.java

@@ -160,7 +160,7 @@ public class FileFormatResource implements RESTResource {
               MyItem:
                 type: Switch
                 label: Label
-                category: icon
+                icon: icon
                 groups:
                   - Group1
                   - Group2

bundles/org.openhab.core.model.yaml/src/main/java/org/openhab/core/model/yaml/internal/YamlModelRepositoryImpl.java

@@ -41,6 +41,7 @@
 import org.openhab.core.model.yaml.YamlElementName;
 import org.openhab.core.model.yaml.YamlModelListener;
 import org.openhab.core.model.yaml.YamlModelRepository;
+import org.openhab.core.model.yaml.internal.items.YamlItemDTO;
 import org.openhab.core.model.yaml.internal.semantics.YamlSemanticTagDTO;
 import org.openhab.core.model.yaml.internal.things.YamlThingDTO;
 import org.openhab.core.service.WatchService;
@@ -88,7 +89,8 @@ public class YamlModelRepositoryImpl implements WatchService.WatchEventListener,
     private static final String READ_ONLY = "readOnly";
     private static final Set<String> KNOWN_ELEMENTS = Set.of( //
             getElementName(YamlSemanticTagDTO.class), // "tags"
-            getElementName(YamlThingDTO.class) // "things"
+            getElementName(YamlThingDTO.class), // "things"
+            getElementName(YamlItemDTO.class) // "items"
     );
 
     private static final String UNWANTED_EXCEPTION_TEXT = "at [Source: UNKNOWN; byte offset: #UNKNOWN] ";

bundles/org.openhab.core.model.yaml/src/main/java/org/openhab/core/model/yaml/internal/items/YamlChannelLinkProvider.java

@@ -0,0 +1,126 @@
+/*
+ * Copyright (c) 2010-2025 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.core.model.yaml.internal.items;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.openhab.core.common.registry.AbstractProvider;
+import org.openhab.core.config.core.Configuration;
+import org.openhab.core.items.ItemProvider;
+import org.openhab.core.model.yaml.internal.util.YamlElementUtils;
+import org.openhab.core.thing.ChannelUID;
+import org.openhab.core.thing.link.ItemChannelLink;
+import org.openhab.core.thing.link.ItemChannelLinkProvider;
+import org.openhab.core.thing.profiles.ProfileTypeUID;
+import org.osgi.service.component.annotations.Component;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * This class serves as a provider for all item channel links that is found within YAML files.
+ * It is filled with content by the {@link YamlItemProvider}, which cannot itself implement the
+ * {@link ItemChannelLinkProvider} interface as it already implements {@link ItemProvider},
+ * which would lead to duplicate methods.
+ *
+ * @author Laurent Garnier - Initial contribution
+ */
+@NonNullByDefault
+@Component(immediate = true, service = { ItemChannelLinkProvider.class, YamlChannelLinkProvider.class })
+public class YamlChannelLinkProvider extends AbstractProvider<ItemChannelLink> implements ItemChannelLinkProvider {
+
+    private final Logger logger = LoggerFactory.getLogger(YamlChannelLinkProvider.class);
+
+    // Map the channel links to each channel UID and then to each item name and finally to each model name
+    private Map<String, Map<String, Map<ChannelUID, ItemChannelLink>>> itemsChannelLinksMap = new ConcurrentHashMap<>();
+
+    @Override
+    public Collection<ItemChannelLink> getAll() {
+        return itemsChannelLinksMap.values().stream().flatMap(m -> m.values().stream())
+                .flatMap(m -> m.values().stream()).toList();
+    }
+
+    public Collection<ItemChannelLink> getAllFromModel(String modelName) {
+        return itemsChannelLinksMap.getOrDefault(modelName, Map.of()).values().stream()
+                .flatMap(m -> m.values().stream()).toList();
+    }
+
+    public void updateItemChannelLinks(String modelName, String itemName, Map<String, Configuration> channelLinks) {
+        Map<String, Map<ChannelUID, ItemChannelLink>> channelLinksMap = Objects
+                .requireNonNull(itemsChannelLinksMap.computeIfAbsent(modelName, k -> new ConcurrentHashMap<>()));
+        // Create a HashMap with an initial capacity of 2 (the default is 16) to save memory because most items have
+        // only one channel. A capacity of 2 is enough to avoid resizing the HashMap in most cases, whereas 1 would
+        // trigger a resize as soon as one element is added.
+        Map<ChannelUID, ItemChannelLink> links = Objects
+                .requireNonNull(channelLinksMap.computeIfAbsent(itemName, k -> new ConcurrentHashMap<>(2)));
+
+        Set<ChannelUID> linksToBeRemoved = new HashSet<>(links.keySet());
+
+        for (Map.Entry<String, Configuration> entry : channelLinks.entrySet()) {
+            String channelUID = entry.getKey();
+            Configuration configuration = entry.getValue();
+
+            ChannelUID channelUIDObject;
+            try {
+                channelUIDObject = new ChannelUID(channelUID);
+            } catch (IllegalArgumentException e) {
+                logger.warn("Invalid channel UID '{}' in channel link for item '{}'!", channelUID, itemName, e);
+                continue;
+            }
+
+            // Fix the configuration in case a profile is defined without any scope
+            if (configuration.containsKey("profile") && configuration.get("profile") instanceof String profile
+                    && profile.indexOf(":") == -1) {
+                String fullProfile = ProfileTypeUID.SYSTEM_SCOPE + ":" + profile;
+                configuration.put("profile", fullProfile);
+                logger.info(
+                        "Profile '{}' for channel '{}' is missing the scope prefix, assuming the correct UID is '{}'. Check your configuration.",
+                        profile, channelUID, fullProfile);
+            }
+
+            ItemChannelLink itemChannelLink = new ItemChannelLink(itemName, channelUIDObject, configuration);
+
+            linksToBeRemoved.remove(channelUIDObject);
+            ItemChannelLink oldLink = links.get(channelUIDObject);
+            if (oldLink == null) {
+                links.put(channelUIDObject, itemChannelLink);
+                logger.debug("notify added item channel link {}", itemChannelLink.getUID());
+                notifyListenersAboutAddedElement(itemChannelLink);
+            } else if (!YamlElementUtils.equalsConfig(configuration.getProperties(),
+                    oldLink.getConfiguration().getProperties())) {
+                links.put(channelUIDObject, itemChannelLink);
+                logger.debug("notify updated item channel link {}", itemChannelLink.getUID());
+                notifyListenersAboutUpdatedElement(oldLink, itemChannelLink);
+            }
+        }
+
+        linksToBeRemoved.forEach(uid -> {
+            ItemChannelLink link = links.remove(uid);
+            if (link != null) {
+                logger.debug("notify removed item channel link {}", link.getUID());
+                notifyListenersAboutRemovedElement(link);
+            }
+        });
+        if (links.isEmpty()) {
+            channelLinksMap.remove(itemName);
+        }
+        if (channelLinksMap.isEmpty()) {
+            itemsChannelLinksMap.remove(modelName);
+        }
+    }
+}

bundles/org.openhab.core.model.yaml/src/main/java/org/openhab/core/model/yaml/internal/items/YamlGroupDTO.java

@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2010-2025 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.core.model.yaml.internal.items;
+
+import java.util.List;
+import java.util.Objects;
+import java.util.Set;
+
+import org.eclipse.jdt.annotation.NonNull;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.core.model.yaml.internal.util.YamlElementUtils;
+
+/**
+ * The {@link YamlGroupDTO} is a data transfer object used to serialize the details of a group item
+ * in a YAML configuration file.
+ *
+ * @author Laurent Garnier - Initial contribution
+ */
+public class YamlGroupDTO {
+
+    private static final String DEFAULT_FUNCTION = "EQUALITY";
+    private static final Set<String> VALID_FUNCTIONS = Set.of("AND", "OR", "NAND", "NOR", "XOR", "COUNT", "AVG",
+            "MEDIAN", "SUM", "MIN", "MAX", "LATEST", "EARLIEST", DEFAULT_FUNCTION);
+
+    public String type;
+    public String dimension;
+    public String function;
+    public List<@NonNull String> parameters;
+
+    public YamlGroupDTO() {
+    }
+
+    public boolean isValid(@NonNull List<@NonNull String> errors, @NonNull List<@NonNull String> warnings) {
+        boolean ok = true;
+        if (!YamlElementUtils.isValidItemType(type)) {
+            errors.add("invalid value \"%s\" for \"type\" field in group".formatted(type));
+            ok = false;
+        } else if (YamlElementUtils.isNumberItemType(type)) {
+            if (!YamlElementUtils.isValidItemDimension(dimension)) {
+                errors.add("invalid value \"%s\" for \"dimension\" field in group".formatted(dimension));
+                ok = false;
+            }
+        } else if (dimension != null) {
+            warnings.add("\"dimension\" field in group ignored as type is not Number");
+        }
+        if (!VALID_FUNCTIONS.contains(getFunction())) {
+            errors.add("invalid value \"%s\" for \"function\" field".formatted(function));
+            ok = false;
+        }
+        return ok;
+    }
+
+    public @Nullable String getBaseType() {
+        return YamlElementUtils.getItemTypeWithDimension(type, dimension);
+    }
+
+    public String getFunction() {
+        return function != null ? function.toUpperCase() : DEFAULT_FUNCTION;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(getBaseType(), getFunction());
+    }
+
+    @Override
+    public boolean equals(@Nullable Object obj) {
+        if (this == obj) {
+            return true;
+        } else if (obj == null || getClass() != obj.getClass()) {
+            return false;
+        }
+        YamlGroupDTO other = (YamlGroupDTO) obj;
+        return Objects.equals(getBaseType(), other.getBaseType()) && Objects.equals(getFunction(), other.getFunction())
+                && YamlElementUtils.equalsListStrings(parameters, other.parameters);
+    }
+}