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24 files changed, 1720 insertions, 0 deletions

diff --git a/config-lib/src/main/java/com/yahoo/config/BooleanNode.java b/config-lib/src/main/java/com/yahoo/config/BooleanNode.java
new file mode 100644
index 00000000000..8347b800272
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/BooleanNode.java
@@ -0,0 +1,50 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+/**
+ * The BooleanNode class represents a boolean in a configuration tree.
+ */
+public class BooleanNode extends LeafNode<Boolean> {
+    public BooleanNode() {
+    }
+
+    public BooleanNode(boolean value) {
+        super(true);
+        this.value = value;
+    }
+
+    public Boolean value() {
+        return value;
+    }
+
+    @Override
+    public String getValue() {
+        return "" + value;
+    }
+
+    @Override
+    public String toString() {
+        return getValue();
+    }
+
+    @Override
+    protected boolean doSetValue(@NonNull String value) {
+        if (! value.equalsIgnoreCase("false") && ! value.equalsIgnoreCase("true")) {
+            return false;
+        }
+        this.value = Boolean.valueOf(value);
+        return true;
+    }
+
+    @Override
+    void serialize(String name, Serializer serializer) {
+        serializer.serialize(name, value);
+    }
+
+    @Override
+    void serialize(Serializer serializer) {
+        serializer.serialize(value);
+    }
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/ChangesRequiringRestart.java b/config-lib/src/main/java/com/yahoo/config/ChangesRequiringRestart.java
new file mode 100644
index 00000000000..6c17a21c649
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/ChangesRequiringRestart.java
@@ -0,0 +1,162 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+import static java.util.stream.Collectors.joining;
+
+/**
+ * @author <a href="mailto:magnarn@yahoo-inc.com">Magnar Nedland</a>
+ *
+ * This class aggregates information about config changes that causes a restart to be required.
+ */
+public class ChangesRequiringRestart {
+    static class ReportLine {
+        private String name;
+        private final Node from;
+        private final Node to;
+        private final String comment;
+
+        public ReportLine(String name, Node from, Node to, String comment) {
+            this.name = name;
+            this.from = from;
+            this.to = to;
+            this.comment = comment;
+        }
+
+        public void addNamePrefix(String prefix) {
+            if (!name.isEmpty()) {
+                name = prefix + "." + name;
+            } else {
+                name = prefix;
+            }
+        }
+
+        private String getCommentAndName(String indent, String namePrefix) {
+            return indent + (comment.isEmpty()? "" : "# " + comment.replace("\n", "\n" + indent + "# ") + "\n" + indent)
+                    + namePrefix + name;
+        }
+
+        private static String formatValue(String indent, Node n) {
+            String str = n.toString();
+            if (str.contains("\n")) {  // Struct
+                str = "\n" + indent + "  { " + str.replace("\n", "\n" + indent + "    ") + " }";
+            }
+            return str;
+        }
+
+        @Override
+        public String toString() {
+            return toString("", "");
+        }
+
+        public String toString(String indent, String namePrefix) {
+            if (from == null) {
+                return getCommentAndName(indent, namePrefix) + " was added with value " + formatValue(indent, to);
+            } else if (to == null) {
+                return getCommentAndName(indent, namePrefix) + " with value " + formatValue(indent, from) + " was removed";
+            }
+            return getCommentAndName(indent, namePrefix) + " has changed from " + formatValue(indent, from) + " to " + formatValue(indent, to);
+        }
+    }
+
+    private ArrayList<ReportLine> report = new ArrayList<>();
+    private String componentName;
+
+    public ChangesRequiringRestart(String componentName) {
+        this.componentName = componentName;
+    }
+
+    public String getName() {
+        return componentName;
+    }
+
+    public ChangesRequiringRestart compare(Node from, Node to, String name, String comment) {
+        if (!from.equals(to)) {
+            report.add(new ReportLine(name, from, to, comment));
+        }
+        return this;
+    }
+
+    public void mergeChanges(String prefix, ChangesRequiringRestart childReport) {
+        for (ReportLine line : childReport.getReportLines()) {
+            line.addNamePrefix(prefix);
+            report.add(line);
+        }
+    }
+
+    /**
+     * Interface used to pass lambda functions from generated code to compareArray/-Map functions.
+     */
+    public interface CompareFunc {
+        // Generates a report based on a config change.
+        ChangesRequiringRestart getChangesRequiringRestart(Node from, Node to);
+    }
+
+    public ChangesRequiringRestart compareArray(List<? extends Node> from,
+                                                List<? extends Node> to,
+                                                String name,
+                                                String comment,
+                                                CompareFunc func) {
+        if (!from.equals(to)) {
+            int commonElements = Math.min(from.size(), to.size());
+            for (int i = 0; i < commonElements; ++i) {
+                ChangesRequiringRestart childReport = func.getChangesRequiringRestart(from.get(i), to.get(i));
+                String prefix = childReport.componentName + "[" + Integer.toString(i) + "]";
+                mergeChanges(prefix, childReport);
+            }
+            for (int i = commonElements; i < from.size(); ++i) {
+                report.add(new ReportLine(name + "[" + Integer.toString(i) + "]", from.get(i), null, comment));
+            }
+            for (int i = commonElements; i < to.size(); ++i) {
+                report.add(new ReportLine(name + "[" + Integer.toString(i) + "]", null, to.get(i), comment));
+            }
+        }
+        return this;
+    }
+
+    public ChangesRequiringRestart compareMap(Map<String, ? extends Node> from,
+                                              Map<String, ? extends Node> to,
+                                              String name,
+                                              String comment,
+                                              CompareFunc func) {
+        if (!from.equals(to)) {
+            for (String key : from.keySet()) {
+                if (to.containsKey(key)) {
+                    ChangesRequiringRestart childReport = func.getChangesRequiringRestart(from.get(key), to.get(key));
+                    String prefix = childReport.componentName + "{" + key + "}";
+                    mergeChanges(prefix, childReport);
+                } else {
+                    report.add(new ReportLine(name + "{" + key + "}", from.get(key), null, comment));
+                }
+            }
+            for (String key : to.keySet()) {
+                if (!from.containsKey(key)) {
+                    report.add(new ReportLine(name + "{" + key + "}", null, to.get(key), comment));
+                }
+            }
+        }
+        return this;
+    }
+
+    List<ReportLine> getReportLines() {
+        return report;
+    }
+
+    @Override
+    public String toString() {
+        return toString("");
+    }
+
+    public String toString(String indent) {
+        return report.stream()
+                .map(line -> line.toString(indent, componentName + "."))
+                .collect(joining("\n"));
+    }
+
+    public boolean needsRestart() {
+        return !report.isEmpty();
+    }
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/ConfigBuilder.java b/config-lib/src/main/java/com/yahoo/config/ConfigBuilder.java
new file mode 100644
index 00000000000..dc90df9b12f
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/ConfigBuilder.java
@@ -0,0 +1,11 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+/**
+ * Root interface for all config builders.
+ *
+ * @author gjoranv
+ * @since 5.1.6
+ */
+public interface ConfigBuilder {
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/ConfigInstance.java b/config-lib/src/main/java/com/yahoo/config/ConfigInstance.java
new file mode 100644
index 00000000000..bb091a6b4e1
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/ConfigInstance.java
@@ -0,0 +1,122 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Represents an instance of an application config with a specific configId.
+ * <p>
+ * An instance of this class contains all values (represented by Nodes) for the config object as it
+ * is the superclass of the generated config class used by the client.
+ */
+public abstract class ConfigInstance extends InnerNode {
+
+    public interface Builder extends ConfigBuilder {
+        /**
+         * Dispatches a getConfig() call if this instance's producer is of the right type
+         * @param producer a config producer
+         * @return true if this instance's producer was the correct type, and hence a getConfig call was dispatched
+         */
+        public boolean dispatchGetConfig(Producer producer);
+
+        public String getDefName();
+        public String getDefNamespace();
+        public String getDefMd5();
+    }
+
+    public interface Producer {}
+
+    private String configMd5 = "";
+
+    String configId;
+
+    /**
+     * Gets the name of the given config instance
+     */
+    public static String getDefName(Class<?> type) {
+        return getStaticStringField(type, "CONFIG_DEF_NAME");
+    }
+
+    /**
+     * Gets the namespace of the given config instance
+     */
+    public static String getDefNamespace(Class<?> type) {
+        return getStaticStringField(type, "CONFIG_DEF_NAMESPACE");
+    }
+
+    /**
+     * Returns the serialized representation of the given node.
+     * <p>
+     * Declared static, instead of InnerNode member, to avoid a public 0-arg method with a commonly used name.
+     *
+     * @param node The inner node
+     * @return a list of strings, containing the serialized representation of this config
+     */
+    public static List<String> serialize(InnerNode node) {
+        List<String> ret = new ArrayList<>();
+        for (Map.Entry<String, LeafNode<?>> entry : getAllDescendantLeafNodes(node).entrySet()) {
+            ret.add(entry.getKey() + " " + entry.getValue().toString());
+        }
+        return ret;
+    }
+
+    public static void serialize(InnerNode node, Serializer serializer) {
+        serializeMap(node.getChildren(), serializer);
+    }
+
+    @SuppressWarnings("unchecked")
+    private static void serializeObject(String name, Object child, Serializer serializer) {
+        if (child instanceof InnerNode) {
+            Serializer childSerializer = serializer.createInner(name);
+            serialize((InnerNode) child, childSerializer);
+        } else if (child instanceof Map) {
+            Serializer mapSerializer = serializer.createMap(name);
+            serializeMap((Map<String, Object>)child, mapSerializer);
+        } else if (child instanceof NodeVector) {
+            Serializer arraySerializer = serializer.createArray(name);
+            serializeArray((NodeVector) child, arraySerializer);
+        } else if (child instanceof LeafNode) {
+            ((LeafNode) child).serialize(name, serializer);
+        }
+    }
+
+    private static void serializeMap(Map<String, Object> childMap, Serializer serializer) {
+        for (Map.Entry<String, Object> entry : childMap.entrySet()) {
+            String name = entry.getKey();
+            Object child = entry.getValue();
+            serializeObject(name, child, serializer);
+        }
+    }
+
+    private static void serializeArray(NodeVector<?> nodeVector, Serializer arraySerializer) {
+        for (Object child : nodeVector.vector) {
+            if (child instanceof InnerNode) {
+                Serializer childSerializer = arraySerializer.createInner();
+                serialize((InnerNode) child, childSerializer);
+            } else if (child instanceof LeafNode) {
+                ((LeafNode) child).serialize(arraySerializer);
+            }
+        }
+    }
+
+
+    public String getConfigMd5() {
+        return configMd5;
+    }
+
+    public void setConfigMd5(String configMd5) {
+        this.configMd5 = configMd5;
+    }
+
+    private static String getStaticStringField(Class<?> type, String fieldName) {
+        try {
+            return (String) type.getField(fieldName).get(null);
+        } catch (Exception e) {
+            throw new RuntimeException
+                    (e.getMessage() + ": Static field " + fieldName + " not " + "accessible in " + type.getName());
+        }
+    }
+
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/ConfigurationRuntimeException.java b/config-lib/src/main/java/com/yahoo/config/ConfigurationRuntimeException.java
new file mode 100644
index 00000000000..56020906499
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/ConfigurationRuntimeException.java
@@ -0,0 +1,21 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+/**
+ * This exception is thrown on internal errors in the configuration system.
+ */
+@SuppressWarnings("serial")
+public class ConfigurationRuntimeException extends RuntimeException {
+    public ConfigurationRuntimeException(String message) {
+        super(message);
+    }
+
+    public ConfigurationRuntimeException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public ConfigurationRuntimeException(Throwable cause) {
+        super(cause);
+    }
+
+}
\ No newline at end of file
diff --git a/config-lib/src/main/java/com/yahoo/config/DoubleNode.java b/config-lib/src/main/java/com/yahoo/config/DoubleNode.java
new file mode 100644
index 00000000000..6ff97df579f
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/DoubleNode.java
@@ -0,0 +1,51 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+/**
+ * The DoubleNode class represents a double in a configuration tree.
+ */
+public class DoubleNode extends LeafNode<Double> {
+    public DoubleNode() {
+    }
+
+    public DoubleNode(double value) {
+        super(true);
+        this.value = value;
+    }
+
+    public Double value() {
+        return value;
+    }
+
+    @Override
+    public String getValue() {
+        return "" + value;
+    }
+
+    @Override
+    public String toString() {
+        return getValue();
+    }
+
+    @Override
+    protected boolean doSetValue(@NonNull String value) {
+        try {
+            this.value = Double.parseDouble(value);
+            return true;
+        } catch (NumberFormatException e) {
+            return false;
+        }
+    }
+
+    @Override
+    void serialize(String name, Serializer serializer) {
+        serializer.serialize(name, value);
+    }
+
+    @Override
+    void serialize(Serializer serializer) {
+        serializer.serialize(value);
+    }
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/EnumNode.java b/config-lib/src/main/java/com/yahoo/config/EnumNode.java
new file mode 100644
index 00000000000..5443d063bbd
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/EnumNode.java
@@ -0,0 +1,24 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+/**
+ * The EnumNode class is a superclass for Enumerations in a configuration tree.
+ */
+public abstract class EnumNode<ENUM extends Enum<?>> extends LeafNode<ENUM> {
+    public EnumNode() {
+    }
+
+    public EnumNode(boolean b) {
+        super(b);
+    }
+
+    @Override
+    public String toString() {
+        return (value == null) ? "(null)" : value.toString();
+    }
+
+    @Override
+    public String getValue() {
+        return (value == null) ? null : value.toString();
+    }
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/FileNode.java b/config-lib/src/main/java/com/yahoo/config/FileNode.java
new file mode 100644
index 00000000000..0d6bccb59a5
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/FileNode.java
@@ -0,0 +1,42 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+/**
+ * Represents a 'file' in a {@link ConfigInstance}, usually a filename.
+ *
+ * @author gjoranv
+ */
+public class FileNode extends LeafNode<FileReference> {
+
+    public FileNode() {
+    }
+
+    public FileNode(String stringVal) {
+        super(true);
+        this.value = new FileReference(ReferenceNode.stripQuotes(stringVal));
+    }
+
+    public FileReference value() {
+        return value;
+    }
+
+    @Override
+    public String getValue() {
+        return value.value();
+    }
+
+    @Override
+    public String toString() {
+        return (value == null) ? "(null)" : '"' + getValue() + '"';
+    }
+
+    @Override
+    protected boolean doSetValue(@NonNull String stringVal) {
+        value = new FileReference(ReferenceNode.stripQuotes(stringVal));
+        return true;
+    }
+
+
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/FileReference.java b/config-lib/src/main/java/com/yahoo/config/FileReference.java
new file mode 100755
index 00000000000..de86fc09be7
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/FileReference.java
@@ -0,0 +1,67 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import java.io.File;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * An immutable file reference that can only be created from classes within the same package.
+ * This is to prevent clients from creating arbitrary and invalid file references.
+ *
+ * @author tonytv
+ */
+public final class FileReference {
+
+    private final String value;
+
+    FileReference(String value) {
+        this.value = value;
+    }
+
+    public String value() {
+        return value;
+    }
+
+    @Override
+    public int hashCode() {
+        return value.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        return other instanceof FileReference &&
+                value.equals(((FileReference)other).value);
+    }
+
+    @Override
+    public String toString() {
+        return "file '" + value + "'";
+    }
+
+    public static List<String> toValues(Collection<FileReference> references) {
+        List<String> ret = new ArrayList<String>();
+        for (FileReference r: references) {
+            ret.add(r.value());
+        }
+        return ret;
+    }
+
+    public static Map<String, String> toValueMap(Map<String, FileReference> map) {
+        Map<String, String> ret = new LinkedHashMap<>();
+        for (Map.Entry<String, FileReference> e : map.entrySet()) {
+            ret.put(e.getKey(), e.getValue().value());
+        }
+        return ret;
+    }
+
+    public static FileReference mockFileReferenceForUnitTesting(File file) {
+        if (! file.exists())
+            throw new IllegalArgumentException("File '" + file.getAbsolutePath() + "' does not exist.");
+        return new FileReference(file.getPath());
+    }
+
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/InnerNode.java b/config-lib/src/main/java/com/yahoo/config/InnerNode.java
new file mode 100644
index 00000000000..eb7f36bbaea
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/InnerNode.java
@@ -0,0 +1,171 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import java.lang.reflect.Field;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.Iterator;
+import java.util.Map;
+
+/**
+ * Superclass for all inner nodes in a {@link ConfigInstance}.
+ * <p>
+ * This class cannot have non-private members because such members
+ * will interfere with the members in the generated subclass.
+ *
+ * @author gjoranv
+ */
+public abstract class InnerNode extends Node {
+
+    /**
+     * Creates a new InnerNode.
+     */
+    public InnerNode() {
+    }
+
+    @Override
+    public String toString() {
+        return mkString(ConfigInstance.serialize(this), "\n");
+    }
+
+    private static <T> String mkString(Collection<T> collection, String sep) {
+        StringBuilder sb = new StringBuilder();
+        boolean first = true;
+
+        for (T elem : collection) {
+            if (! first)
+                sb.append(sep);
+            first = false;
+            sb.append(elem);
+        }
+        return sb.toString();
+     }
+
+    /**
+     * Overrides {@link Node#postInitialize(String)}.
+     * Perform post initialization on this nodes children.
+     *
+     * @param configId The config id of this instance.
+     */
+    @Override
+    public void postInitialize(String configId) {
+        Map<String, Node> children = getChildrenWithVectorsFlattened();
+        for (Node node : children.values()) {
+            node.postInitialize(configId);
+        }
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        if (other == this)
+            return true;
+
+        if ( !(other instanceof InnerNode) || (other.getClass() != this.getClass()))
+            return false;
+
+        Collection<Object> children = getChildren().values();
+        Collection<Object> otherChildren = ((InnerNode)other).getChildren().values();
+
+        Iterator<Object> e1 = children.iterator();
+        Iterator<Object> e2 = otherChildren.iterator();
+        while(e1.hasNext() && e2.hasNext()) {
+            Object o1 = e1.next();
+            Object o2 = e2.next();
+            if (!(o1 == null ? o2 == null : o1.equals(o2)))
+                return false;
+        }
+        return !(e1.hasNext() || e2.hasNext());
+    }
+
+    @Override
+    public int hashCode() {
+        int res = 17;
+        for (Object child : getChildren().values())
+            res = 31 * res + child.hashCode();
+        return res;
+     }
+
+    protected Map<String, Object> getChildren() {
+        HashMap<String, Object> ret = new LinkedHashMap<String, Object>();
+        Field fields[] = getClass().getDeclaredFields();
+        for (Field field : fields) {
+            field.setAccessible(true);
+            Object fieldValue;
+            try {
+                fieldValue = field.get(this);
+            } catch (IllegalAccessException e) {
+                throw new ConfigurationRuntimeException(e);
+            }
+            if (fieldValue instanceof Node
+                    || fieldValue instanceof NodeVector<?>
+                    || fieldValue instanceof Map<?,?>)
+                ret.put(field.getName(), fieldValue);
+        }
+        return ret;
+    }
+
+    /**
+     * Returns a flat map of this node's direct children, including all NodeVectors' elements.
+     * Keys are the node name, including index for vector elements, e.g. 'arr[0]'.
+     */
+    @SuppressWarnings("unchecked")
+    protected Map<String, Node> getChildrenWithVectorsFlattened() {
+        HashMap<String, Node> ret = new LinkedHashMap<String, Node>();
+
+        Map<String, Object> children = getChildren();
+        for (Map.Entry<String, Object> childEntry : children.entrySet()) {
+            String name = childEntry.getKey();
+            Object child = childEntry.getValue();
+            if (child instanceof NodeVector) {
+                addNodeVectorEntries(ret, name, (NodeVector<?>) child);
+            } else if (child instanceof Map<?,?>) {
+                addMapEntries(ret, name, (Map<String, Node>) child);
+            } else if (child instanceof Node) {
+                ret.put(name, (Node)child);
+            }
+        }
+        return ret;
+    }
+
+    private static void addMapEntries(HashMap<String, Node> ret, String name, Map<String, Node> map) {
+        for (Map.Entry<String, Node> entry : map.entrySet())
+            ret.put(name + "{" + entry.getKey() + "}", entry.getValue());
+    }
+
+
+    private static void addNodeVectorEntries(HashMap<String, Node> ret, String name, NodeVector<?> vector) {
+        for (int j = 0; j < vector.length(); j++)
+            ret.put(name + "[" + j + "]", (Node) vector.get(j));
+    }
+
+    protected static Map<String, LeafNode<?>> getAllDescendantLeafNodes(InnerNode node) {
+         return getAllDescendantLeafNodes("", node);
+     }
+
+     /**
+      * Generates a map of all leaf nodes, with full.paths[3] in key
+      *
+      * @param parentName Name of the parent node, can be empty.
+      * @param node The node to get leaf nodes for.
+      * @return map of leaf nodes
+      */
+     private static Map<String, LeafNode<?>> getAllDescendantLeafNodes(String parentName, InnerNode node) {
+         Map<String, LeafNode<?>> ret = new LinkedHashMap<String, LeafNode<?>>();
+         String prefix = parentName.isEmpty() ? "" : parentName + ".";
+         Map<String, Node> children = node.getChildrenWithVectorsFlattened();
+         for (Map.Entry<String, Node> childEntry : children.entrySet()) {
+             String name = childEntry.getKey();
+             String prefixedName = prefix + name;
+             name=name.replaceAll("\\[.*", "");
+             Node child = childEntry.getValue();
+             if (child instanceof LeafNode) {
+                 ret.put(prefixedName, (LeafNode<?>) child);
+             } else if (child instanceof InnerNode) {
+                 ret.putAll(getAllDescendantLeafNodes(prefixedName, (InnerNode) child));
+             }
+         }
+         return ret;
+     }
+
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/InnerNodeVector.java b/config-lib/src/main/java/com/yahoo/config/InnerNodeVector.java
new file mode 100644
index 00000000000..72ca0138a53
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/InnerNodeVector.java
@@ -0,0 +1,47 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import java.util.List;
+
+/**
+ * @author gjoranv
+ * @since 5.1.4
+ */
+public class InnerNodeVector<NODE extends InnerNode> extends NodeVector<NODE> {
+
+    NODE defaultNode;
+
+    /**
+     * Creates a new vector with the given default node.
+     */
+    // TODO: remove this ctor when the library uses reflection via builders, and resizing won't be necessary
+    public InnerNodeVector(NODE defaultNode) {
+        assert (defaultNode != null) : "The default node cannot be null";
+
+        this.defaultNode = defaultNode;
+        if (createNew() == null) {
+            throw new NullPointerException("Unable to duplicate the default node.");
+        }
+    }
+
+    public InnerNodeVector(List<NODE> nodes, NODE defaultNode) {
+        this(defaultNode);
+        for (NODE node : nodes) {
+            vector.add(node);
+        }
+    }
+
+    /**
+     * Creates a new Node by creating a new instance with the 0-argument constructor
+     */
+    // TODO: remove when the library uses reflection via builders
+    @SuppressWarnings("unchecked")
+    protected NODE createNew() {
+        try {
+            return (NODE) defaultNode.getClass().newInstance();
+        } catch (IllegalAccessException | InstantiationException ex) {
+            throw new ConfigurationRuntimeException(ex);
+        }
+    }
+
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/IntegerNode.java b/config-lib/src/main/java/com/yahoo/config/IntegerNode.java
new file mode 100644
index 00000000000..82db4cab030
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/IntegerNode.java
@@ -0,0 +1,52 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+/**
+ * The IntegerNode class represents an integer in a configuration tree.
+ */
+public class IntegerNode extends LeafNode<Integer> {
+
+    public IntegerNode() {
+    }
+
+    public IntegerNode(int value) {
+        super(true);
+        this.value = value;
+    }
+
+    public Integer value() {
+        return value;
+    }
+
+    @Override
+    public String getValue() {
+        return "" + value;
+    }
+
+    @Override
+    public String toString() {
+        return getValue();
+    }
+
+    @Override
+    protected boolean doSetValue(@NonNull String value) {
+        try {
+            this.value = Integer.parseInt(value);
+            return true;
+        } catch (NumberFormatException e) {
+            return false;
+        }
+    }
+
+    @Override
+    void serialize(String name, Serializer serializer) {
+        serializer.serialize(name, value);
+    }
+
+    @Override
+    void serialize(Serializer serializer) {
+        serializer.serialize(value);
+    }
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/LeafNode.java b/config-lib/src/main/java/com/yahoo/config/LeafNode.java
new file mode 100644
index 00000000000..24ec534e222
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/LeafNode.java
@@ -0,0 +1,120 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+/**
+ * Superclass for all leaf nodes in a {@link ConfigInstance}.
+ * <p>
+ * Subclasses represents leaf nodes with different types. These
+ * implementations should implement method value() with return-value
+ * corresponding to the actual type.
+ *
+ */
+public abstract class LeafNode<T> extends Node implements Cloneable {
+
+    protected boolean initialized;
+    protected T value;
+
+    /**
+     * Creates a new, uninitialized LeafNode
+     */
+    protected LeafNode() {
+        initialized = false;
+    }
+
+    /**
+     * Creates a new LeafNode.
+     *
+     * @param initialized true if this node is initialized.
+     */
+    protected LeafNode(boolean initialized) {
+        this.initialized = initialized;
+    }
+
+    public T value() {
+        return value;
+    }
+
+    /**
+     * Try to initialize this node with the given value. Returns true
+     * on success, false otherwise.
+     *
+     * @param value     the string represention of the desired node value.
+     * @return true on success, false otherwise.
+     */
+    final boolean initialize(String value) {
+        boolean success = setValue(value);
+        initialized |= success;
+        return success;
+    }
+
+    /**
+     * Subclasses must implement this, in compliance with the rules given in the return tag.
+     *
+     * @return the String representation of the node value, or the string "(null)" if the value is null.
+     */
+    public abstract String toString();
+
+    /**
+     * Subclasses must implement this, in compliance with the rules given in the return tag.
+     *
+     * @return the String representation of the node value, or the 'null' object if the node value is null.
+     */
+    public abstract String getValue();
+
+    /**
+     * Sets the value based on a string representation. Returns false if the value could
+     * not be set from the given string.
+     * TODO: return void (see doSetValue)
+     *
+     * @param value the value to set
+     * @return true on success, false otherwise
+     * @throws IllegalArgumentException when value is null
+     */
+    protected final boolean setValue(String value) {
+        if (value == null)
+            throw new IllegalArgumentException("Null value is not allowed");
+        return doSetValue(value);
+    }
+
+    // TODO: should throw exception instead of return false.
+    protected abstract boolean doSetValue(@NonNull String value);
+
+    /**
+     * This method is meant for internal use in the configuration
+     * system. Overrides Object.clone().
+     *
+     * @return a new instance similar to this object.
+     */
+    @Override
+    protected Object clone() {
+        try {
+            return super.clone();
+        } catch (CloneNotSupportedException e) {
+            throw new ConfigurationRuntimeException(e);
+        }
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (! (o instanceof LeafNode))
+            return false;
+
+        LeafNode<?> other = (LeafNode)o;
+        return value == null ? other.value == null :  value().equals(other.value);
+    }
+
+    @Override
+    public int hashCode() {
+        return (value == null) ? 0 : value.hashCode();
+    }
+
+    void serialize(String name, Serializer serializer) {
+        serializer.serialize(name, getValue());
+    }
+
+    void serialize(Serializer serializer) {
+        serializer.serialize(getValue());
+    }
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/LeafNodeMaps.java b/config-lib/src/main/java/com/yahoo/config/LeafNodeMaps.java
new file mode 100644
index 00000000000..789969662da
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/LeafNodeMaps.java
@@ -0,0 +1,65 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import java.nio.file.Path;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+/**
+ * @author gjoranv
+ * @since 5.1.17
+ */
+public class LeafNodeMaps {
+
+    /**
+     * Converts a map of String→NODE to String→REAL, where REAL is the underlying value type.
+     */
+    public static <NODE extends LeafNode<REAL>, REAL>
+    Map<String, REAL> asValueMap(Map<String, NODE> input)
+    {
+        Map<String, REAL> ret = new LinkedHashMap<>();
+        for(String key : input.keySet()) {
+            ret.put(key, input.get(key).value());
+        }
+        return Collections.unmodifiableMap(ret);
+    }
+
+    /**
+     * Converts a map of String→REAL to String→NODE, where REAL is the underlying value type.
+     */
+    @SuppressWarnings("unchecked")
+    public static <NODE extends LeafNode<REAL>, REAL>
+    Map<String, NODE> asNodeMap(Map<String, REAL> input, NODE defaultNode)
+    {
+        Map<String, NODE> ret = new LinkedHashMap<>();
+        for(String key : input.keySet()) {
+            NODE node = (NODE)defaultNode.clone();
+            node.value = input.get(key);
+            ret.put(key, node);
+        }
+        return Collections.unmodifiableMap(ret);
+    }
+
+
+    /**
+     * Special case for file type, since FileNode param type (FileReference) is not same as type (String) in config builder
+     */
+    public static Map<String, FileNode> asFileNodeMap(Map<String, String> stringMap) {
+        Map<String, FileNode> fileNodeMap = new LinkedHashMap<>();
+        for (Map.Entry<String, String> e : stringMap.entrySet()) {
+            fileNodeMap.put(e.getKey(), new FileNode(e.getValue()));
+        }
+        return Collections.unmodifiableMap(fileNodeMap);
+    }
+
+    public static Map<String, PathNode> asPathNodeMap(Map<String, FileReference> fileReferenceMap) {
+        Map<String, PathNode> pathNodeMap = new LinkedHashMap<>();
+        for (Map.Entry<String, FileReference> e : fileReferenceMap.entrySet()) {
+            pathNodeMap.put(e.getKey(), new PathNode(e.getValue()));
+        }
+        return Collections.unmodifiableMap(pathNodeMap);
+    }
+
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/LeafNodeVector.java b/config-lib/src/main/java/com/yahoo/config/LeafNodeVector.java
new file mode 100644
index 00000000000..59e070f1d56
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/LeafNodeVector.java
@@ -0,0 +1,79 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * A vector of leaf nodes.
+ *
+ * @author gjoranv
+ * @since 5.1.4
+ */
+public class LeafNodeVector<REAL, NODE extends LeafNode<REAL>> extends NodeVector<NODE> {
+
+    NODE defaultNode;
+
+    /**
+     * Creates a new vector with the given default node.
+     */
+    // TODO: remove this ctor when the library uses reflection via builders, and resizing won't be necessary
+    public LeafNodeVector(NODE defaultNode) {
+        assert (defaultNode != null) : "The default node cannot be null";
+
+        this.defaultNode = defaultNode;
+        if (createNew() == null) {
+            throw new NullPointerException("Unable to duplicate the default node.");
+        }
+    }
+
+    // TODO: take class instead of default node when the library uses reflection via builders
+    public LeafNodeVector(List<REAL> values, NODE defaultNode) {
+        this(defaultNode);
+        for (REAL value : values) {
+            NODE node = createNew();
+            node.value = value;
+            vector.add(node);
+        }
+    }
+
+    /**
+     * Creates a new Node by cloning the default node.
+     */
+    @SuppressWarnings("unchecked")
+    protected NODE createNew() {
+        return (NODE) (defaultNode).clone();
+    }
+
+    // TODO: create unmodifiable list in ctor when the library uses reflection via builders
+    @SuppressWarnings("unchecked")
+    public List<REAL> asList() {
+        List<REAL> ret = new ArrayList<REAL>();
+        for(NODE node : vector) {
+            ret.add(node.value());
+        }
+        return Collections.unmodifiableList(ret);
+    }
+
+    // TODO: Try to eliminate the need for this method when we have moved FileAcquirer to the config library
+    // It is needed now because the builder has a list of String, while REAL=FileReference.
+    public static LeafNodeVector<FileReference, FileNode> createFileNodeVector(Collection<String> values) {
+        List<FileReference> fileReferences = new ArrayList<FileReference>();
+         for (String s : values)
+             fileReferences.add(new FileReference(ReferenceNode.stripQuotes(s)));
+
+        return new LeafNodeVector<FileReference, FileNode>(fileReferences, new FileNode());
+    }
+
+    public static LeafNodeVector<Path, PathNode> createPathNodeVector(Collection<FileReference> values) {
+        List<Path> paths = new ArrayList<>();
+        for (FileReference fileReference : values)
+            paths.add(Paths.get(fileReference.value()));
+
+        return new LeafNodeVector<Path, PathNode>(paths, new PathNode());
+    }
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/LongNode.java b/config-lib/src/main/java/com/yahoo/config/LongNode.java
new file mode 100755
index 00000000000..7a3b29c1101
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/LongNode.java
@@ -0,0 +1,53 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+/**
+ * Represents a long in a configuration tree.
+ * @author gjoranv
+ */
+public class LongNode extends LeafNode<Long> {
+
+    public LongNode() {
+    }
+
+    public LongNode(long value) {
+        super(true);
+        this.value = value;
+    }
+
+    public Long value() {
+        return value;
+    }
+
+    @Override
+    public String getValue() {
+        return "" + value;
+    }
+
+    @Override
+    public String toString() {
+        return getValue();
+    }
+
+    @Override
+    protected boolean doSetValue(@NonNull String value) {
+        try {
+            this.value = Long.parseLong(value);
+            return true;
+        } catch (NumberFormatException e) {
+            return false;
+        }
+    }
+
+    @Override
+    void serialize(String name, Serializer serializer) {
+        serializer.serialize(name, value);
+    }
+
+    @Override
+    void serialize(Serializer serializer) {
+        serializer.serialize(value);
+    }
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/Node.java b/config-lib/src/main/java/com/yahoo/config/Node.java
new file mode 100644
index 00000000000..3dba5d083f4
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/Node.java
@@ -0,0 +1,29 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+/**
+ * The Node class is superclass for all nodes in a {@link
+ * ConfigInstance}.  Important subclasses of this node are {@link
+ * InnerNode} and {@link LeafNode}.
+ *
+ */
+public abstract class Node {
+
+    /**
+     * Postinitialize this node. Any node needing to process its values depending on the config
+     * id should override this method.
+     *
+     * @param configId  the configId of the ConfigInstance that owns (or is) this node
+     */
+    public void postInitialize(String configId) { return; }
+
+    /**
+     * This method is meant for internal use in the configuration system.
+     * Overrides Object.clone(), and is overriden by LeafNode.clone().
+     *
+     * @return a new instance similar to this object.
+     */
+    protected Object clone() throws CloneNotSupportedException {
+        return super.clone();
+    }
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/NodeVector.java b/config-lib/src/main/java/com/yahoo/config/NodeVector.java
new file mode 100644
index 00000000000..8ce5689937e
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/NodeVector.java
@@ -0,0 +1,151 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import java.util.*;
+
+
+/**
+ * A NodeVector represents an array declared with '[]' in a config definition file.
+ * It is a List that stores nodes with a given type. A given default node must
+ * be given, and this node will be cloned as the NodeVector size are increased.
+ *
+ */
+public abstract class NodeVector<NODE> implements java.util.List<NODE> {
+
+    protected final ArrayList<NODE> vector = new ArrayList<NODE>();
+
+    /**
+     * Creates a new Node.
+     */
+    protected abstract NODE createNew();
+
+    /**
+     * Returns the number of elements in this NodeVector.
+     * Alias for size().
+     *
+     * @return the number of elements in this NodeVector.
+     */
+    public int length() {
+        return size();
+    }
+
+    /**
+     * Resizes this NodeVector. Removes or adds new nodes as needed.
+     *
+     * @param n the new size of this NodeVector
+     */
+    // TODO: remove when the library uses reflection via builders, and resizing won't be necessary
+    public void setSize(int n) {
+        while (size() > n) vector.remove(n);
+        while (size() < n) vector.add(createNew());
+    }
+
+    @SuppressWarnings("serial")
+    public static class ReadOnlyException extends RuntimeException {
+    }
+
+    private static final ReadOnlyException e = new ReadOnlyException();
+
+    public void add(int index, NODE element) {
+        throw e;
+    }
+
+    public boolean add(NODE o) {
+        throw e;
+    }
+
+    public boolean addAll(Collection<? extends NODE> c) {
+        throw e;
+    }
+
+    public boolean addAll(int index, Collection<? extends NODE> c) {
+        throw e;
+    }
+
+    public void clear() {
+        throw e;
+    }
+
+    public NODE remove(int index) {
+        throw e;
+    }
+
+    public boolean remove(Object o) {
+        throw e;
+    }
+
+    public boolean removeAll(Collection<?> c) {
+        throw e;
+    }
+
+    public boolean retainAll(Collection<?> c) {
+        throw e;
+    }
+
+    public NODE set(int index, NODE element) {
+        throw e;
+    }
+
+    public boolean contains(Object o) {
+        return vector.contains(o);
+    }
+
+    public boolean containsAll(Collection<?> c) {
+        return vector.containsAll(c);
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        return o instanceof NodeVector && vector.equals(((NodeVector) o).vector);
+    }
+
+    @Override
+    public int hashCode() {
+        return vector.hashCode();
+    }
+
+    @SuppressWarnings("unchecked")
+    public NODE get(int index) {
+        return vector.get(index);
+    }
+
+    public int indexOf(Object o) {
+        return vector.indexOf(o);
+    }
+
+    public boolean isEmpty() {
+        return vector.isEmpty();
+    }
+
+    public Iterator<NODE> iterator() {
+        return vector.iterator();
+    }
+
+    public int lastIndexOf(Object o) {
+        return vector.lastIndexOf(o);
+    }
+
+    public ListIterator<NODE> listIterator() {
+        return vector.listIterator();
+    }
+
+    public ListIterator<NODE> listIterator(int index) {
+        return vector.listIterator(index);
+    }
+
+    public int size() {
+        return vector.size();
+    }
+
+    public List<NODE> subList(int fromIndex, int toIndex) {
+        return vector.subList(fromIndex, toIndex);
+    }
+
+    public Object[] toArray() {
+        return vector.toArray();
+    }
+
+    public <T> T[] toArray(T[] a) {
+        return vector.toArray(a);
+    }
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/PathNode.java b/config-lib/src/main/java/com/yahoo/config/PathNode.java
new file mode 100644
index 00000000000..91676137214
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/PathNode.java
@@ -0,0 +1,71 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+import java.io.File;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Represents a 'path' in a {@link ConfigInstance}, usually a filename.
+ *
+ * @author gjoranv
+ * @since 5.1.30
+ */
+public class PathNode extends LeafNode<Path> {
+
+    private final FileReference fileReference;
+
+    public PathNode() {
+        fileReference = null;
+    }
+
+    public PathNode(FileReference fileReference) {
+        super(true);
+        this.value = new File(fileReference.value()).toPath();
+        this.fileReference = fileReference;
+    }
+
+    public Path value() {
+        return value;
+    }
+
+    @Override
+    public String getValue() {
+        return value.toString();
+    }
+
+    @Override
+    public String toString() {
+        return (value == null) ? "(null)" : '"' + getValue() + '"';
+    }
+
+    @Override
+    protected boolean doSetValue(@NonNull String stringVal) {
+        throw new UnsupportedOperationException("doSetValue should not be necessary since the library anymore!");
+    }
+
+    public FileReference getFileReference() {
+        return fileReference;
+    }
+
+    public static List<FileReference> toFileReferences(List<PathNode> pathNodes) {
+        List<FileReference> fileReferences = new ArrayList<>();
+        for (PathNode pathNode : pathNodes)
+            fileReferences.add(pathNode.getFileReference());
+        return fileReferences;
+    }
+
+    public static Map<String, FileReference> toFileReferenceMap(Map<String, PathNode> map) {
+        Map<String, FileReference> ret = new LinkedHashMap<>();
+        for (Map.Entry<String, PathNode> e : map.entrySet()) {
+            ret.put(e.getKey(), e.getValue().getFileReference());
+        }
+        return ret;
+    }
+
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/ReferenceNode.java b/config-lib/src/main/java/com/yahoo/config/ReferenceNode.java
new file mode 100644
index 00000000000..a5e6400f456
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/ReferenceNode.java
@@ -0,0 +1,83 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+/**
+ * A ReferenceNode class represents a reference (that is a config-id)
+ * in a {@link ConfigInstance}.
+ */
+public class ReferenceNode extends LeafNode<String> {
+
+    public ReferenceNode() {
+    }
+
+    /**
+     * Creates a new ReferenceNode with the given value.
+     *
+     * @param value the value of this ReferenceNode
+     */
+    public ReferenceNode(String value) {
+        super(true);
+        this.value = stripQuotes(value);
+    }
+
+    /**
+     * Returns the value of this reference node. Same as {@link
+     * #toString()} since the value of a ReferenceNode is a String (but
+     * implementations in other {@link LeafNode} sub-classes differ).
+     *
+     * @return the string representation of this ReferenceNode.
+     */
+    public String value() {
+        return value;
+    }
+
+    @Override
+    public String getValue() {
+        return value();
+    }
+
+    @Override
+    public String toString() {
+        return (value == null) ? "(null)" : getValue();
+    }
+
+    @Override
+    protected boolean doSetValue(@NonNull String value) {
+        this.value = stripQuotes(value);
+        return true;
+    }
+
+    /**
+     * Overrides {@link Node#postInitialize(String)}
+     * Checks for ":parent:" values, which will be replaced by the configId.
+     *
+     * @param configId  the configId of the ConfigInstance that owns (or is) this node
+     */
+    @Override
+    public void postInitialize(String configId) {
+        super.postInitialize(configId);
+        if (":parent:".equals(value()))  {
+            doSetValue(configId);
+        }
+    }
+
+    /**
+     * Strips the quotes before or after the value, if present.
+     */
+    static String stripQuotes(String value) {
+        if (value == null) {
+            return value;
+        }
+        StringBuffer buffer = new StringBuffer(value.trim());
+        if (buffer.length() > 0 && buffer.charAt(0) == '"') {
+            buffer.deleteCharAt(0);
+        }
+        if (buffer.length() > 0 && buffer.charAt(buffer.length() - 1) == '"') {
+            buffer.setLength(buffer.length() - 1);
+        }
+        return buffer.toString();
+    }
+
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/Serializer.java b/config-lib/src/main/java/com/yahoo/config/Serializer.java
new file mode 100644
index 00000000000..95d20011f2c
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/Serializer.java
@@ -0,0 +1,31 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+/**
+* @author lulf
+* @since 5.1
+*/
+public interface Serializer {
+    Serializer createInner(String name);
+    Serializer createArray(String name);
+    Serializer createInner();
+    Serializer createMap(String name);
+
+    /**
+     * Serialize leaf values.
+     */
+    void serialize(String name, boolean value);
+    void serialize(String name, double value);
+    void serialize(String name, long value);
+    void serialize(String name, int value);
+    void serialize(String name, String value);
+
+    /**
+     * Serialize array values.
+     */
+    void serialize(boolean value);
+    void serialize(double value);
+    void serialize(long value);
+    void serialize(int value);
+    void serialize(String value);
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/StringNode.java b/config-lib/src/main/java/com/yahoo/config/StringNode.java
new file mode 100644
index 00000000000..344a7e2dd40
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/StringNode.java
@@ -0,0 +1,123 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import com.yahoo.config.text.StringUtilities;
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+/**
+ * A StringNode class represents a string in a {@link ConfigInstance}.
+ *
+ * @author larschr
+ */
+public class StringNode extends LeafNode<String> {
+
+    /**
+     * Creates a new un-initialized StringNode.
+     */
+    public StringNode() {
+    }
+
+    /**
+     * Creates a new StringNode, initialized to <code>value</code>.
+     *
+     * @param value the value of this StringNode.
+     */
+    public StringNode(String value) {
+        super(true);
+        this.value = value;
+    }
+
+    /**
+     * Returns the value of this string. Same as {@link #getValue()}
+     * since the value of this node is a String (but implementations
+     * in other {@link LeafNode} sub-classes differ).
+     *
+     * @return the string representation of this StringNode, or null if
+     *         the vlaue is explicitly set to null
+     */
+    public String value() {
+        return value;
+    }
+
+    @Override
+    public String getValue() {
+        return value();
+    }
+
+    @Override
+    public String toString() {
+        return (value == null) ? "(null)" : '"' + StringUtilities.escape(getValue()) + '"';
+    }
+
+    /**
+     * Remove character escape codes.
+     *
+     * @param string escaped string
+     * @return unescaped string
+     */
+    public static String unescapeQuotedString(String string) {
+        StringBuilder sb = new StringBuilder(string);
+        for (int i = 0; i < sb.length(); i++) {
+            if (sb.charAt(i) == '\\') {
+                sb.deleteCharAt(i);
+                if (i == sb.length()) {
+                    throw new IllegalArgumentException("Parse error" + string);
+                }
+                switch (sb.charAt(i)) {
+                    case'n':
+                        sb.setCharAt(i, '\n');
+                        break;
+                    case'r':
+                        sb.setCharAt(i, '\r');
+                        break;
+                    case't':
+                        sb.setCharAt(i, '\t');
+                        break;
+                    case'f':
+                        sb.setCharAt(i, '\f');
+                        break;
+                    case'x':
+                        if (i + 2 >= sb.length()) {
+                            throw new IllegalArgumentException
+                                    ("Could not parse hex value " + string);
+                        }
+                        sb.setCharAt(i, (char) Integer.parseInt
+                                (sb.substring(i + 1, i + 3), 16));
+                        sb.delete(i + 1, i + 3);
+                        break;
+                    case'\\':
+                        sb.setCharAt(i, '\\');
+                        break;
+                }
+            }
+        }
+
+        if (sb.length() > 0 && (sb.charAt(0) == '"') && sb.charAt(sb.length() - 1) == '"') {
+            sb.deleteCharAt(sb.length() - 1);//remove last quote
+            if (sb.length() > 0) {
+                sb.deleteCharAt(0);  //remove first quote
+            }
+        }
+        return sb.toString();
+    }
+
+    /**
+     * Sets the value of this string from a the string representation
+     * of this value in the (escaped) input configuration. The value
+     * supplied to this method needs un-escaping and will be
+     * un-escaped.
+     *
+     * @param value the new value of this node.
+     */
+    @Override
+    protected boolean doSetValue(@NonNull String value) {
+        if (value.startsWith("\"") && value.endsWith("\""))
+            this.value = unescapeQuotedString(value);
+        else {
+            //TODO: unquoted strings can be probably be prohibited now.(?) -gv
+            this.value = value;
+        }
+        return true;
+    }
+
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/package-info.java b/config-lib/src/main/java/com/yahoo/config/package-info.java
new file mode 100644
index 00000000000..c1069b6649a
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/package-info.java
@@ -0,0 +1,7 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+@ExportPackage
+@PublicApi
+package com.yahoo.config;
+
+import com.yahoo.api.annotations.PublicApi;
+import com.yahoo.osgi.annotation.ExportPackage;
diff --git a/config-lib/src/main/java/com/yahoo/config/text/StringUtilities.java b/config-lib/src/main/java/com/yahoo/config/text/StringUtilities.java
new file mode 100644
index 00000000000..1b05ae779bf
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/text/StringUtilities.java
@@ -0,0 +1,88 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config.text;
+
+import java.nio.charset.Charset;
+import java.io.ByteArrayOutputStream;
+
+/**
+ * Escapes strings into and out of a format where they only contain printable characters.
+ *
+ * Need to duplicate escape / unescape of strings as we have in C++ for java version of system states.
+ *
+ * @author <a href="mailto:humbe@yahoo-inc.com">Haakon Humberset</a>
+ */
+public class StringUtilities {
+    private static Charset UTF8 = Charset.forName("utf8");
+
+    private static byte toHex(int val) { return (byte) (val < 10 ? '0' + val : 'a' + (val - 10)); }
+
+    private static class ReplacementCharacters {
+        public byte needEscape[] = new byte[256];
+        public byte replacement1[] = new byte[256];
+        public byte replacement2[] = new byte[256];
+
+        public ReplacementCharacters() {
+            for (int i=0; i<256; ++i) {
+                if (i >= 32 && i <= 126) {
+                    needEscape[i] = 0;
+                } else if (i > 127) {
+                    needEscape[i] = 0;
+                } else {
+                    needEscape[i] = 3;
+                    replacement1[i] = toHex((i >> 4) & 0xF);
+                    replacement2[i] = toHex(i & 0xF);
+                }
+            }
+            makeSimpleEscape('"', '"');
+            makeSimpleEscape('\\', '\\');
+            makeSimpleEscape('\t', 't');
+            makeSimpleEscape('\n', 'n');
+            makeSimpleEscape('\r', 'r');
+            makeSimpleEscape('\f', 'f');
+        }
+
+        private void makeSimpleEscape(char source, char dest) {
+            needEscape[source] = 1;
+            replacement1[source] = '\\';
+            replacement2[source] = (byte) dest;
+        }
+    }
+
+    private final static ReplacementCharacters replacementCharacters = new ReplacementCharacters();
+
+    public static String escape(String source) { return escape(source, '\0'); }
+
+    /**
+     * Escapes strings into a format with only printable ASCII characters.
+     *
+     * @param source The string to escape
+     * @param delimiter Escape this character too, even if it is printable.
+     * @return The escaped string
+     */
+    public static String escape(String source, char delimiter) {
+        byte bytes[] = source.getBytes(UTF8);
+        ByteArrayOutputStream result = new ByteArrayOutputStream();
+        for (byte b : bytes) {
+            int val = b;
+            if (val < 0) val += 256;
+            if (b == delimiter) {
+                result.write('\\');
+                result.write('x');
+                result.write(toHex((val >> 4) & 0xF));
+                result.write(toHex(val & 0xF));
+            } else if (replacementCharacters.needEscape[val] == 0) {
+                result.write(b);
+            } else {
+                if (replacementCharacters.needEscape[val] == 3) {
+                    result.write('\\');
+                    result.write('x');
+                }
+                result.write(replacementCharacters.replacement1[val]);
+                result.write(replacementCharacters.replacement2[val]);
+            }
+        }
+        return new String(result.toByteArray(), UTF8);
+    }
+
+
+}