Initial snapshot.

.gitignore

+**/*.history
+**/.DS_Store
\ No newline at end of file

README.md

+# Tentamen i EDAF20, 21 april 2020
+
+Detta repository innehåller följande:
+
++ Denna fil, [`README.md`](README.md) -- den innehåller bara lite
+  information, och du skall inte ändra i den.
+
++ En markdown-fil,
+  [`answers-and-comments.md`](answers-and-comments.md), med plats för
+  dina svar och kommentarer till frågorna. I denna fil skall du även
+  ange vid vilken/vilka tidpunkter som du kan ta den muntliga delen av
+  din tenta (en Zoom-intervju).
+
++ En fil `er-model.png`, som är en 'placeholder' för din ER-modell.
+  Meningen är att du skall rita din ER-modell i uppgift 1 i något
+  rit-program, och spara resultatet i en fil med namnet `er-model.png`
+  (din fil kommer att ersätta den gamla filen). Observera att vi
+  kräver att din ER-modell ritas med UML-notation, som i:
+  
+  ![](er-model.png)
+
+  Inscannade handritade figurer rättas inte.
+
++ En katalog `python-bottle` med ett skelett för en REST-service
+  implementerad med
+  [Python/Bottle](https://bottlepy.org/docs/stable/). Skelettet ligger
+  i filen `api.py`, och det använder en SQLite3-databas med namnet
+  `db.sqlite`, i samma katalog -- i filen `create-database.sql` skall
+  du skriva din SQL-kod för att skapa databasen.
+
++ En katalog `java-spark` med ett [gradle]()-projekt som använder
+  [Java/Spark](http://sparkjava.com/) för att implementera en
+  REST-service. Huvudprogrammet ligger i filen
+  `src/main/java/app/App.java`, och det använder en SQLite3-databas
+  med namnet `db.sqlite` i projektets rot-katalog (alltså
+  `java-spark/db.sqlite`) -- i filen `create-database.sql` skall du
+  skriva din SQL-kod för att skapa databasen.
+
+
+# Uppgifter
+
+Uppgifterna kommer att publiceras under tentans gång -- preliminärt
+kommer vi att ha följande tidsschema (uppgifterna nedan är exempel på
+hur det skulle kunna se ut, om vi hade haft ungefär samma uppgifter
+som på mars-tentan):
+
++ [Del 1](http://fileadmin.cs.lth.se/cs/Education/edaf75/58bbea62-5039-42fd-b271-fd8912dbdd7f/sample-exam/problem1.html) (uppgift 1): 14:00 - 15:30
++ [Del 2](http://fileadmin.cs.lth.se/cs/Education/edaf75/58bbea62-5039-42fd-b271-fd8912dbdd7f/sample-exam/problem2.html) (uppgift 2): 15:40 - 17:40
++ [Del 3](http://fileadmin.cs.lth.se/cs/Education/edaf75/58bbea62-5039-42fd-b271-fd8912dbdd7f/sample-exam/problem3-6.html) (uppgift 3-6): 17:50:00 - 19:00
+
+Om vi skulle få tekniska problem under tentan kommer vi att meddela
+eventuella förändringar i Zoom-mötet.

answers-and-comments.md

+# Svar och kommentarer
+
+Denna tentamen består av en skriftlig del och en muntlig del (ca 10-20
+minuter), då du i en Zoom-intervju får redogöra för hur du resonerat i
+dina lösningar, och lösa någon extrauppgift.
+
+För den muntliga delen kommer vi (eventuellt) att kontakta dig under
+någon av nedanstående alternativa tidsintervaller -- du måste ange
+minst ett intervall under vilket du kan ta din intervju, om du inte
+svarar när vi kontaktar dig under detta tidsintervall så kommer du att
+få din tentamen annullerad.
+
++ onsdag 22 april, 10-12
++ onsdag 22 april, 14-16
++ torsdag 23 april, 10-12
++ torsdag 23 april, 14-16
++ fredag 24 april, 10-12
++ fredag 24 april, 14-16
+
+Ange vilken/vilka tider du kan på här: ...
+
+Nedanför skall du skriva in dina svar till uppgift 3-5, och eventuella
+kommentarer till uppgift 1 och 2. Observera att vi tittar på hur ditt
+repository ser ut klockan 15:30 när vi rättar uppgift 1, så eventuella
+kommentarer till uppgift 1 som du lägger till efter det kommer vi inte
+att se när vi rättar. Motsvarande gäller uppgift 2, där vi bara ser
+sådant som du gör fram till klockan 17:40.
+
+## Uppgift 1
+
+![](er-model.png)
+
+## Uppgift 2
+
+Kommentarer: ...
+
+## Uppgift 3
+
+Här skall du skriva ditt svar på uppgift 3, enligt följande mall:
+
+a. Vi får nyckeln ... eftersom ...
+   och ...
+
+b. Relationen är inte i BCNF, eftersom ...
+
+c. Relationen är (inte) i BCNF, eftersom ...
+
+d. Vi kan bryta ner R till relationer som är i BNCF, och som har
+   egenskapen att de kan ...
+
+## Uppgift 4
+
+**Svar:**
+
+## Uppgift 5
+
+**Svar:**
+
+## Uppgift 6
+
+**Svar:**

java-spark/.gitattributes

+#
+# https://help.github.com/articles/dealing-with-line-endings/
+#
+# These are explicitly windows files and should use crlf
+*.bat           text eol=crlf
+

java-spark/.gitignore

+# Ignore Gradle project-specific cache directory
+.gradle
+
+# Ignore Gradle build output directory
+build

java-spark/build.gradle

+
+plugins {
+    // Apply the java plugin to add support for Java
+    id 'java'
+
+    // Apply the application plugin to add support for building a CLI application.
+    id 'application'
+}
+
+repositories {
+    // Use jcenter for resolving dependencies.
+    // You can declare any Maven/Ivy/file repository here.
+    jcenter()
+}
+
+dependencies {
+    // This dependency is used by the application.
+    implementation 'com.google.guava:guava:28.2-jre'
+
+    // Use JUnit Jupiter API for testing.
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.6.0'
+
+    // Use JUnit Jupiter Engine for testing.
+    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.6.0'
+
+    // https://mvnrepository.com/artifact/org.xerial/sqlite-jdbc
+    implementation group: 'org.xerial', name: 'sqlite-jdbc', version: '3.30.1'
+
+    implementation "com.sparkjava:spark-core:2.8.0"
+}
+
+application {
+    // Define the main class for the application.
+    mainClassName = 'app.App'
+}
+
+test {
+    // Use junit platform for unit tests
+    useJUnitPlatform()
+}

java-spark/create-database.sql

+
+-- Du skall tabellen nedan med dina egna tabeller.
+
+DROP TABLE IF EXISTS some_table;
+CREATE TABLE some_table (
+  some_attribute     TEXT,
+  PRIMARY KEY (some_attribute)
+);
+
+
+-- Här kan du göra insättningar i dina tabeller, så att du kan testa
+-- din databas.
+
+INSERT
+INTO   some_table(some_attribute)
+VALUES ('Ett värde'),
+       ('Ett annat värde');

java-spark/gradle/wrapper/gradle-wrapper.properties

+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.3-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

java-spark/gradlew

+#!/usr/bin/env sh
+
+#
+# Copyright 2015 the original author or authors.
+#
+# 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
+#
+#      https://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.
+#
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=`expr $i + 1`
+    done
+    case $i in
+        0) set -- ;;
+        1) set -- "$args0" ;;
+        2) set -- "$args0" "$args1" ;;
+        3) set -- "$args0" "$args1" "$args2" ;;
+        4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=`save "$@"`
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+exec "$JAVACMD" "$@"

java-spark/gradlew.bat

+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windows variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

java-spark/settings.gradle

+/*
+ * This file was generated by the Gradle 'init' task.
+ *
+ * The settings file is used to specify which projects to include in your build.
+ *
+ * Detailed information about configuring a multi-project build in Gradle can be found
+ * in the user manual at https://docs.gradle.org/6.3/userguide/multi_project_builds.html
+ */
+
+rootProject.name = 'rest-service'

java-spark/src/main/java/app/App.java

+package app;
+
+import static spark.Spark.*;
+import java.sql.*;
+import java.util.*;
+import spark.*;
+
+public class App {
+
+    public static void main(String[] args) {
+        port(4567);
+        var db = new Database("db.sqlite");
+        get("/hello", (req, res) -> "get: hello, world!");
+        post("/hello", (req, res) -> "post: hello, world!");
+    }
+}
+
+class Database {
+
+    /**
+     * The database connection.
+     */
+    private Connection conn;
+
+    /**
+     * Creates the database interface object. Connection to the
+     * database is performed later.
+     */
+    public Database(String filename) {
+        openConnection(filename);
+    }
+
+    /**
+     * Opens a connection to the database, using the specified
+     * filename (if we'd used a traditional DBMS, such as PostgreSQL
+     * or MariaDB, we would have specified username and password
+     * instead).
+     */
+    public boolean openConnection(String filename) {
+        try {
+            Class.forName("org.sqlite.JDBC");
+            conn = DriverManager.getConnection("jdbc:sqlite:" + filename);
+        } catch (SQLException e) {
+            e.printStackTrace();
+            return false;
+        } catch (ClassNotFoundException e) {
+            e.printStackTrace();
+            return false;
+        }
+        return true;
+    }
+
+    /**
+     * Closes the connection to the database.
+     */
+    public void closeConnection() {
+        try {
+            if (conn != null) {
+                conn.close();
+            }
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+    }
+
+    /**
+     * Checks if the connection to the database has been established
+     *
+     * @return true if the connection has been established
+     */
+    public boolean isConnected() {
+        return conn != null;
+    }
+
+    /* ================================== */
+    /* --- insert your own code below --- */
+    /* ===============================*== */
+
+}
+
+
+/**
+ * Auxiliary class for automatically translating a ResultSet to JSON
+ */
+class JSONizer {
+
+    public static String toJSON(ResultSet rs, String name) throws SQLException {
+        StringBuilder sb = new StringBuilder();
+        ResultSetMetaData meta = rs.getMetaData();
+        boolean first = true;
+        sb.append("{\n");
+        sb.append("  \"" + name + "\": [\n");
+        while (rs.next()) {
+            if (!first) {
+                sb.append(",");
+                sb.append("\n");
+            }
+            first = false;
+            sb.append("    {");
+            for (int i = 1; i <= meta.getColumnCount(); i++) {
+                String label = meta.getColumnLabel(i);
+                String value = getValue(rs, i, meta.getColumnType(i));
+                sb.append("\"" + label + "\": " + value);
+                if (i < meta.getColumnCount()) {
+                    sb.append(", ");
+                }
+            }
+            sb.append("}");
+        }
+        sb.append("\n");
+        sb.append("  ]\n");
+        sb.append("}\n");
+        return sb.toString();
+    }
+
+    private static String getValue(ResultSet rs, int i, int columnType) throws SQLException {
+        switch (columnType) {
+        case java.sql.Types.INTEGER:
+            return String.valueOf(rs.getInt(i));