Support 2 types of expand - apoc & plain DFS

.gitignore

@@ -3,4 +3,7 @@
 target/
 logback/
 .DS_Store
+jetty-base/
+jetty-home-11.0.15/
 application.properties
+jetty-home-11.0.15.tar.gz

.lycheeignore

@@ -2,3 +2,4 @@ file:///*
 https://querydsl.com/*
 https://uel.java.net/
 https://www.openapis.org/
+https://api.paion-data.dev/*

README.md

@@ -2,19 +2,29 @@ Aristotle
 =========
 
 ![Java Version Badge][Java Version Badge]
-![HashiCorp Packer Badge][HashiCorp Packer Badge]
-![HashiCorp Terraform Badge][HashiCorp Terraform Badge]
 [![Apache License Badge]][Apache License, Version 2.0]
 
 Aristotle is a [JSR 370] [JAX-RS] webservice of CRUD operations against a graph database. It supports Neo4J now.
 
-Configuration
--------------
+Start Locally in Jetty
+----------------------
 
-- `NEO4J_URI`
-- `NEO4J_USERNAME`
-- `NEO4J_PASSWORD`
-- `NEO4J_DATABASE`
+Navigate to a dedicated directory; make sure port 8080 is not occupied and the following environment variables are set:
+
+```console
+export NEO4J_URI=
+export NEO4J_USERNAME=
+export NEO4J_PASSWORD=
+export NEO4J_DATABASE=
+```
+
+Then start webservice with:
+
+```bash
+./jetty-start.sh
+```
+
+Press `Ctr-C` to stop the webservice and delete generated directories if needed when done.
 
 Test
 ----
@@ -26,25 +36,31 @@ mvn clean verify
 Deployment
 ----------
 
-```bash
-mvn clean package
-```
+This is a one-person project. Agility outplays team scaling, so deployment is manual and pretty much follows
+[jetty-start.sh](./jetty-start.sh)
+
+### Sending Logs to ELK Cloud
+
+Simply add Logstash integration and install agent on the production server. The logs will be available on integration
+dashboard.
 
 ### Gateway Registration
 
 ```bash
 export GATEWAY_PUBLIC_IP=52.53.186.26
 
+# vocabulary paged & count
 curl -v -i -s -k -X POST https://api.paion-data.dev:8444/services \
   --data name=wilhelm-ws-languages \
-  --data url="http://${GATEWAY_PUBLIC_IP}:8080/v1/data/languages"
+  --data url="http://${GATEWAY_PUBLIC_IP}:8080/v1/neo4j/languages"
 curl -i -k -X POST https://api.paion-data.dev:8444/services/wilhelm-ws-languages/routes \
   --data "paths[]=/wilhelm/languages" \
   --data name=wilhelm-ws-languages
 
+# expand
 curl -v -i -s -k -X POST https://api.paion-data.dev:8444/services \
   --data name=wilhelm-ws-expand \
-  --data url="http://${GATEWAY_PUBLIC_IP}:8080/v1/data/expand"
+  --data url="http://${GATEWAY_PUBLIC_IP}:8080/v1/neo4j/expand"
 curl -i -k -X POST https://api.paion-data.dev:8444/services/wilhelm-ws-expand/routes \
   --data "paths[]=/wilhelm/expand" \
   --data name=wilhelm-ws-expand
@@ -54,8 +70,9 @@ We should see `HTTP/1.1 201 Created` as signs of success.
 
 #### Example requests:
 
-- https://api.paion-data.dev/wilhelm/languages/german?perPage=100&page=1
-- https://api.paion-data.dev/wilhelm/expand/nämlich
+- vocabulary count: https://api.paion-data.dev/wilhelm/languages/german?perPage=100&page=1
+- query vocabulary paged: https://api.paion-data.dev/wilhelm/languages/german/count
+- expand: https://api.paion-data.dev/wilhelm/expand/nämlich
 
 License
 -------
@@ -65,9 +82,6 @@ The use and distribution terms for [Aristotle]() are covered by the [Apache Lice
 [Apache License Badge]: https://img.shields.io/badge/Apache%202.0-F25910.svg?style=for-the-badge&logo=Apache&logoColor=white
 [Apache License, Version 2.0]: https://www.apache.org/licenses/LICENSE-2.0
 
-[HashiCorp Packer Badge]: https://img.shields.io/badge/Packer-02A8EF?style=for-the-badge&logo=Packer&logoColor=white
-[HashiCorp Terraform Badge]: https://img.shields.io/badge/Terraform-7B42BC?style=for-the-badge&logo=terraform&logoColor=white
-
 [Java Version Badge]: https://img.shields.io/badge/Java-17-brightgreen?style=for-the-badge&logo=OpenJDK&logoColor=white
 [JAX-RS]: https://jcp.org/en/jsr/detail?id=370
 [JSR 370]: https://jcp.org/en/jsr/detail?id=370

jetty-start.sh

@@ -0,0 +1,30 @@
+#!/bin/bash
+set -x
+set -e
+
+# Copyright Jiaqi Liu
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+mvn clean package -Dcheckstyle.skip -DskipTests
+
+wget -O jetty-home-11.0.15.tar.gz https://repo1.maven.org/maven2/org/eclipse/jetty/jetty-home/11.0.15/jetty-home-11.0.15.tar.gz
+tar -xzvf jetty-home-11.0.15.tar.gz
+export JETTY_HOME=$(pwd)/jetty-home-11.0.15
+
+mkdir -p jetty-base
+cd jetty-base
+java -jar $JETTY_HOME/start.jar --add-module=annotations,server,http,deploy,servlet,webapp,resources,jsp
+
+mv ../target/wilhelm-ws-1.0-SNAPSHOT.war webapps/ROOT.war
+java -jar $JETTY_HOME/start.jar

src/main/java/org/qubitpi/wilhelm/Graph.java

@@ -0,0 +1,155 @@
+/*
+ * Copyright Jiaqi Liu
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.qubitpi.wilhelm;
+
+import com.fasterxml.jackson.annotation.JsonIncludeProperties;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import jakarta.validation.constraints.NotNull;
+import net.jcip.annotations.Immutable;
+import net.jcip.annotations.ThreadSafe;
+
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Objects;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+/**
+ * A JSON-serializable object representation of a knowledge graph in wilhelm-ws.
+ */
+@Immutable
+@ThreadSafe
+@SuppressWarnings("ClassCanBeRecord")
+@JsonIncludeProperties({ "nodes", "links" })
+public class Graph {
+
+    private static final Logger LOG = LoggerFactory.getLogger(Graph.class);
+    private static final ObjectMapper JSON_MAPPER = new ObjectMapper();
+
+    private final Set<Node> nodes;
+    private final Set<Link> links;
+
+    /**
+     * All-args constructor.
+     *
+     * @param nodes  The set of all nodes contained in this Graph, cannot be {@code null}
+     * @param links  The set of all links contained in this Graph, cannot be {@code null}
+     */
+    public Graph(@NotNull final Set<Node> nodes, @NotNull final Set<Link> links) {
+        this.nodes = new HashSet<>(Objects.requireNonNull(nodes));
+        this.links = new HashSet<>(Objects.requireNonNull(links));
+    }
+
+    /**
+     * Creates a new {@link Graph} instance with no initial nodes or links in it.
+     *
+     * @return a new instance
+     */
+    public static Graph emptyGraph() {
+        return new Graph(new HashSet<>(), new HashSet<>());
+    }
+
+    /**
+     * Returns whether or not this {@link Graph} has neither nodes noe links.
+     *
+     * @return {@code true} if no nodes or links exist in this {@link Graph}, or {@code false} otherwise.
+     */
+    public boolean isEmpty() {
+        return getNodes().isEmpty() && getLinks().isEmpty();
+    }
+
+    /**
+     * Returns all weakly connected neighbors of a specified node.
+     * <p>
+     * If the node has no such neighrbors, this method returns an empty list
+     *
+     * @param node a node from this {@link Graph}
+     *
+     * @return all nodes each of which has a link between it and the provided node.
+     */
+    @NotNull
+    public Set<Node> getUndirectedNeighborsOf(final Node node) {
+        final Set<String> neighborIds = getLinks().stream()
+                .filter(link ->
+                        node.getId().equals(link.getSourceNodeId()) || node.getId().equals(link.getTargetNodeId())
+                )
+                .flatMap(link -> Stream.of(link.getSourceNodeId(), link.getTargetNodeId()))
+                .filter(id -> !node.getId().equals(id))
+                .collect(Collectors.toUnmodifiableSet());
+
+        return getNodes().stream()
+                .filter(it -> neighborIds.contains(it.getId()))
+                .collect(Collectors.toUnmodifiableSet());
+    }
+
+    /**
+     * Combines the nodes and links from this {@link Graph} instance and the other one and returns a new {@link Graph}.
+     *
+     * @param that the other {@link Graph} instance to be merged with this {@link Graph}
+     *
+     * @return a new instance
+     */
+    public Graph merge(@NotNull final Graph that) {
+        return new Graph(
+                Stream.of(this.getNodes(), that.getNodes()).flatMap(Set::stream).collect(Collectors.toSet()),
+                Stream.of(this.getLinks(), that.getLinks()).flatMap(Set::stream).collect(Collectors.toSet())
+        );
+    }
+
+    /**
+     * Returns an unmodifiable view of all the nodes in this Graph instance.
+     *
+     * @return an immutable list of nodes
+     */
+    @NotNull
+    public Set<Node> getNodes() {
+        return Collections.unmodifiableSet(nodes);
+    }
+
+    /**
+     * Returns an unmodifiable view of all the links in this Graph instance.
+     *
+     * @return an immutable list of links
+     */
+    @NotNull
+    public Set<Link> getLinks() {
+        return Collections.unmodifiableSet(links);
+    }
+
+    /**
+     * Returns a JSON serialization of this Graph instance. It contains 2 fields: nodes and links, each of which is a
+     * list of nodes and links respectively. Each list element is itself a JSON object whose structure are defined by
+     * Jackson's serialization on {@link Node} and {@link Link}.
+     *
+     * @return a JSON string
+     */
+    @NotNull
+    @Override
+    public String toString() {
+        try {
+            return JSON_MAPPER.writeValueAsString(this);
+        } catch (final JsonProcessingException exception) {
+            LOG.error(exception.getMessage());
+            throw new IllegalStateException(exception);
+        }
+    }
+}

src/main/java/org/qubitpi/wilhelm/Language.java

@@ -20,6 +20,7 @@
 import net.jcip.annotations.ThreadSafe;
 
 import java.util.Arrays;
+import java.util.function.Function;
 import java.util.stream.Collectors;
 
 /**
@@ -59,25 +60,61 @@ public enum Language {
     }
 
     /**
-     * Constructs a {@link Language} from its client-side name.
+     * Constructs a {@link Language} from its {@link #getDatabaseName() database name}.
      *
      * @param language  The client-side requested language name
      *
      * @return a new instance
      *
      * @throws IllegalArgumentException if the language name is not a valid one
      */
+    @NotNull
+    public static Language ofDatabaseName(@NotNull final String language) {
+        return valueOf(language, Language::getDatabaseName);
+    }
+
+    /**
+     * Constructs a {@link Language} from its {@link #getPathName() client-side name}.
+     *
+     * @param language  The client-side requested language name
+     *
+     * @return a new instance
+     *
+     * @throws IllegalArgumentException if the language name is not a valid one
+     */
+    @NotNull
     public static Language ofClientValue(@NotNull final String language) throws IllegalArgumentException {
+        return valueOf(language, Language::getPathName);
+    }
+
+    /**
+     * Converts a string value to a {@link Language} object.
+     * <p>
+     * The string value must match one of the {@link #getDatabaseName() database name} or
+     * {@link #getPathName() client API name}.
+     *
+     * @param language  A string whose value is equal to either {@link #getDatabaseName() database name} or
+     * {@link #getPathName() client API name}
+     * @param nameExtractor  If {@code language} matches {@link #getDatabaseName()}, use {@link #getDatabaseName()};
+     * otherwise use {@link #getPathName()}
+     *
+     * @return a new instance
+     *
+     * @throws IllegalArgumentException if the language name is not a valid one
+     */
+    private static Language valueOf(@NotNull final String language, final Function<Language, String> nameExtractor) {
         return Arrays.stream(values())
-                .filter(value -> value.pathName.equals(language))
+                .filter(value -> nameExtractor.apply(value).equals(language))
                 .findFirst()
                 .orElseThrow(() -> new IllegalArgumentException(
                         String.format(
                                 "'%s' is not a recognized language. Acceptable ones are %s",
                                 language,
-                                Arrays.stream(values()).map(Language::getPathName).collect(Collectors.joining(", ")
-                                )
-                        )));
+                                Arrays.stream(values())
+                                        .map(nameExtractor)
+                                        .collect(Collectors.joining(", "))
+                        )
+                ));
     }
 
     @NotNull
@@ -89,4 +126,9 @@ public String getPathName() {
     public String getDatabaseName() {
         return databaseName;
     }
+
+    @Override
+    public String toString() {
+        return getDatabaseName();
+    }
 }