diff --git a/config/demo.products-config.json b/config/demo.products-config.json
index 2aa9058..84a4f91 100644
--- a/config/demo.products-config.json
+++ b/config/demo.products-config.json
@@ -5,10 +5,10 @@
       "description": "Very epic GPU",
       "identifiers": [
         {
-          "Amazon": "B096Y2TYKV"
+          "AMAZON": "B096Y2TYKV"
         },
         {
-          "eBay": "Gigabyte GeForce RTX 3060"
+          "EBAY": "Gigabyte GeForce RTX 3060"
         }
       ]
     }
diff --git a/src/main/java/de/rwu/easydrop/api/client/AmazonProductDataSource.java b/src/main/java/de/rwu/easydrop/api/client/AmazonProductDataSource.java
index 06c806e..64d40ee 100644
--- a/src/main/java/de/rwu/easydrop/api/client/AmazonProductDataSource.java
+++ b/src/main/java/de/rwu/easydrop/api/client/AmazonProductDataSource.java
@@ -20,7 +20,7 @@ public final class AmazonProductDataSource extends AbstractDataSource {
     /**
      * Name of this data source.
      */
-    private static final Webshop DATA_ORIGIN = Webshop.Amazon;
+    private static final Webshop DATA_ORIGIN = Webshop.AMAZON;
     /**
      * Base URL to the Amazon data source.
      */
diff --git a/src/main/java/de/rwu/easydrop/api/client/AmazonPurchaser.java b/src/main/java/de/rwu/easydrop/api/client/AmazonPurchaser.java
index d1dc75c..af96ede 100644
--- a/src/main/java/de/rwu/easydrop/api/client/AmazonPurchaser.java
+++ b/src/main/java/de/rwu/easydrop/api/client/AmazonPurchaser.java
@@ -14,7 +14,7 @@ public final class AmazonPurchaser extends AbstractPurchaser {
     /**
      * Name of this data source.
      */
-    private static final Webshop DATA_TARGET = Webshop.Amazon;
+    private static final Webshop DATA_TARGET = Webshop.AMAZON;
     /**
      * Base URL to the Amazon Purchase API.
      */
diff --git a/src/main/java/de/rwu/easydrop/api/client/AmazonSeller.java b/src/main/java/de/rwu/easydrop/api/client/AmazonSeller.java
index 7b33138..42ab6c6 100644
--- a/src/main/java/de/rwu/easydrop/api/client/AmazonSeller.java
+++ b/src/main/java/de/rwu/easydrop/api/client/AmazonSeller.java
@@ -14,7 +14,7 @@ public final class AmazonSeller extends AbstractSeller {
     /**
      * Name of this data source.
      */
-    private static final Webshop DATA_TARGET = Webshop.Amazon;
+    private static final Webshop DATA_TARGET = Webshop.AMAZON;
     /**
      * Base URL to the Amazon Purchase API.
      */
diff --git a/src/main/java/de/rwu/easydrop/api/client/EbayItemDataSource.java b/src/main/java/de/rwu/easydrop/api/client/EbayItemDataSource.java
index 0b1ed40..f7a205a 100644
--- a/src/main/java/de/rwu/easydrop/api/client/EbayItemDataSource.java
+++ b/src/main/java/de/rwu/easydrop/api/client/EbayItemDataSource.java
@@ -20,7 +20,7 @@ public final class EbayItemDataSource extends AbstractDataSource {
     /**
      * Name of this data source.
      */
-    private static final Webshop DATA_ORIGIN = Webshop.eBay;
+    private static final Webshop DATA_ORIGIN = Webshop.EBAY;
     /**
      * Base URL to the eBay data source.
      */
diff --git a/src/main/java/de/rwu/easydrop/api/client/EbayPurchaser.java b/src/main/java/de/rwu/easydrop/api/client/EbayPurchaser.java
index ebaf121..67fc08e 100644
--- a/src/main/java/de/rwu/easydrop/api/client/EbayPurchaser.java
+++ b/src/main/java/de/rwu/easydrop/api/client/EbayPurchaser.java
@@ -14,7 +14,7 @@ public final class EbayPurchaser extends AbstractPurchaser {
     /**
      * Name of this data source.
      */
-    private static final Webshop DATA_TARGET = Webshop.eBay;
+    private static final Webshop DATA_TARGET = Webshop.EBAY;
     /**
      * Base URL to the eBay Purchase API.
      */
diff --git a/src/main/java/de/rwu/easydrop/api/client/EbaySeller.java b/src/main/java/de/rwu/easydrop/api/client/EbaySeller.java
index 55835ec..c09a852 100644
--- a/src/main/java/de/rwu/easydrop/api/client/EbaySeller.java
+++ b/src/main/java/de/rwu/easydrop/api/client/EbaySeller.java
@@ -14,7 +14,7 @@ public final class EbaySeller extends AbstractSeller {
     /**
      * Name of this data source.
      */
-    private static final Webshop DATA_TARGET = Webshop.eBay;
+    private static final Webshop DATA_TARGET = Webshop.EBAY;
     /**
      * Base URL to the eBay Purchase API.
      */
diff --git a/src/main/java/de/rwu/easydrop/core/Core.java b/src/main/java/de/rwu/easydrop/core/Core.java
index 3403b00..a33c14e 100644
--- a/src/main/java/de/rwu/easydrop/core/Core.java
+++ b/src/main/java/de/rwu/easydrop/core/Core.java
@@ -69,8 +69,8 @@ public final class Core {
         OfferProvisioner provis = new OfferProvisioner(odb);
         provis.runProvisioner(identifiedOffers);
 
-        // LOGGER.info("Creating transactions");
-        // TODO: Transactions
+        LOGGER.info("Creating transactions");
+        // Transaction logic!
 
         LOGGER.info("Done!");
     }
diff --git a/src/main/java/de/rwu/easydrop/data/connector/DatabaseConnector.java b/src/main/java/de/rwu/easydrop/data/connector/DatabaseConnector.java
deleted file mode 100644
index ce6360a..0000000
--- a/src/main/java/de/rwu/easydrop/data/connector/DatabaseConnector.java
+++ /dev/null
@@ -1,10 +0,0 @@
-package de.rwu.easydrop.data.connector;
-
-/**
- * Allows connecting to a SQLite Database.
- *
- * TODO implement
- */
-public class DatabaseConnector {
-
-}
diff --git a/src/main/java/de/rwu/easydrop/data/connector/SQLiteConnector.java b/src/main/java/de/rwu/easydrop/data/connector/SQLiteConnector.java
index ba43d53..4a9e492 100644
--- a/src/main/java/de/rwu/easydrop/data/connector/SQLiteConnector.java
+++ b/src/main/java/de/rwu/easydrop/data/connector/SQLiteConnector.java
@@ -36,6 +36,10 @@ public final class SQLiteConnector implements
      * Path to SQLite db file.
      */
     private static final String PERSISTENCE_PATH = "jdbc:sqlite:persistence.db";
+    /**
+     * Name of 'lastUpdate' column.
+     */
+    private static final String LAST_UPDATE_COL_NAME = "lastUpdate";
 
     /**
      * Creates instance.
@@ -123,13 +127,19 @@ public final class SQLiteConnector implements
         }
     }
 
-    @Override
+    /**
+     * Gets a ProductDTO by identifier.
+     *
+     * @param productId
+     * @return DTO
+     */
     public ProductDTO getProductDTOById(final String productId) {
         String query = "SELECT * FROM products WHERE productId = ?";
         ProductDTO dto = null;
 
-        try (Connection connection = db.getConnection();
-                PreparedStatement statement = connection.prepareStatement(query)) {
+        try {
+            Connection connection = db.getConnection();
+            PreparedStatement statement = connection.prepareStatement(query);
 
             statement.setString(1, productId);
 
@@ -142,10 +152,11 @@ public final class SQLiteConnector implements
                     dto.setMerchant(resultSet.getString("merchant"));
                     dto.setDeliveryPrice(resultSet.getDouble("deliveryPrice"));
                     dto.setAvailable(resultSet.getBoolean("available"));
+                    dto.setLastUpdate(resultSet.getString(LAST_UPDATE_COL_NAME));
                 }
             }
         } catch (SQLException e) {
-            throw new PersistenceException("Something went wrong while reading from SQLite", e);
+            throw new PersistenceException("Something went wrong while reading from SQLite");
         }
 
         return dto;
@@ -153,24 +164,33 @@ public final class SQLiteConnector implements
 
     /**
      * Deletes all data from persistence.
+     *
+     * @throws SQLException
      */
     public void clearData() {
         try (Connection connection = db.getConnection();
                 Statement statement = connection.createStatement()) {
-            String query = "DELETE FROM products; DELETE FROM offers;";
-            statement.executeUpdate(query);
+
+            String productsQuery = "DELETE FROM products;";
+            String offersQuery = "DELETE FROM offers;";
+            statement.executeUpdate(productsQuery);
+            statement.executeUpdate(offersQuery);
         } catch (SQLException e) {
             throw new PersistenceException("Something went wrong while clearing the database", e);
         }
     }
 
-    @Override
+    /**
+     * Writes an offer to persistence.
+     *
+     * @param dto OfferDTO
+     */
     public void writeOffer(final OfferDTO dto) {
         String query = "INSERT INTO offers ("
                 + "offerId, "
                 + "sourceWebshop, sourceId, sourcePrice, "
                 + "targetWebshop, targetId, targetPrice, "
-                + "lastUpdate"
+                + LAST_UPDATE_COL_NAME
                 + ") VALUES ("
                 + "?, ?, ?, ?, ?, ?, ?, ?"
                 + ")";
@@ -196,7 +216,12 @@ public final class SQLiteConnector implements
         }
     }
 
-    @Override
+    /**
+     * Gets an OfferDTO by identifier.
+     *
+     * @param offerId
+     * @return OfferDTO
+     */
     public OfferDTO getOfferDTOById(final String offerId) {
         String query = "SELECT * FROM offers WHERE offerId = ?";
         OfferDTO dto = null;
@@ -220,7 +245,7 @@ public final class SQLiteConnector implements
                     dto.setOfferId(resultSet.getString("offerId"));
                     dto.setSourceProduct(srcProduct);
                     dto.setTargetProduct(targetProduct);
-                    dto.setLastUpdate(resultSet.getString("lastUpdate"));
+                    dto.setLastUpdate(resultSet.getString(LAST_UPDATE_COL_NAME));
                 }
             }
         } catch (SQLException e) {
diff --git a/src/main/java/de/rwu/easydrop/model/ProductCatalogue.java b/src/main/java/de/rwu/easydrop/model/ProductCatalogue.java
index 2e91d1c..e907bcc 100644
--- a/src/main/java/de/rwu/easydrop/model/ProductCatalogue.java
+++ b/src/main/java/de/rwu/easydrop/model/ProductCatalogue.java
@@ -68,11 +68,11 @@ public class ProductCatalogue {
     @Override
     public String toString() {
         StringBuilder sb = new StringBuilder();
-        sb.append("Catalogue Name: ").append(productName).append("\n");
-        sb.append("Description: ").append(description).append("\n");
+        sb.append(String.format("Catalogue Name: %s%n", productName));
+        sb.append(String.format("Description: %s%n", description));
         sb.append("Products:\n");
         for (Product product : products) {
-            sb.append(product.toString()).append("\n");
+            sb.append(String.format("%s%n", product.toString()));
         }
         return sb.toString();
     }
diff --git a/src/main/java/de/rwu/easydrop/model/Webshop.java b/src/main/java/de/rwu/easydrop/model/Webshop.java
index c4852b6..bab281e 100644
--- a/src/main/java/de/rwu/easydrop/model/Webshop.java
+++ b/src/main/java/de/rwu/easydrop/model/Webshop.java
@@ -7,11 +7,11 @@ public enum Webshop {
     /**
      * Amazon Product API.
      */
-    Amazon,
+    AMAZON,
     /**
      * eBay Item API.
      */
-    eBay;
+    EBAY;
 
     /**
      * Attempts to derive a webshop value from a string.
@@ -26,6 +26,6 @@ public enum Webshop {
                 return shop;
             }
         }
-        throw new IllegalArgumentException(String.format("No webshop called {} found", str));
+        throw new IllegalArgumentException(String.format("No webshop called %s found", str));
     }
 }
diff --git a/src/main/java/de/rwu/easydrop/service/processing/OfferProvisioner.java b/src/main/java/de/rwu/easydrop/service/processing/OfferProvisioner.java
index d6801c7..5c1847e 100644
--- a/src/main/java/de/rwu/easydrop/service/processing/OfferProvisioner.java
+++ b/src/main/java/de/rwu/easydrop/service/processing/OfferProvisioner.java
@@ -32,10 +32,10 @@ public class OfferProvisioner {
     private EbaySeller ebaySeller;
 
     private void toSeller(final Offer offer) throws IllegalArgumentException {
-        if (offer.getTargetProduct().getDataOrigin() == Webshop.eBay) {
+        if (offer.getTargetProduct().getDataOrigin() == Webshop.EBAY) {
             this.ebaySeller.sellProduct(ProductMapper.mapProductToDTO(offer.getTargetProduct()));
 
-        } else if (offer.getTargetProduct().getDataOrigin().equals(Webshop.Amazon)) {
+        } else if (offer.getTargetProduct().getDataOrigin().equals(Webshop.AMAZON)) {
             this.amazonSeller.sellProduct(ProductMapper.mapProductToDTO(offer.getTargetProduct()));
         } else {
             throw new IllegalArgumentException("Unsupported target plattform");
diff --git a/src/main/java/de/rwu/easydrop/service/retriever/CatalogueRetriever.java b/src/main/java/de/rwu/easydrop/service/retriever/CatalogueRetriever.java
index 9af6436..44c32a3 100644
--- a/src/main/java/de/rwu/easydrop/service/retriever/CatalogueRetriever.java
+++ b/src/main/java/de/rwu/easydrop/service/retriever/CatalogueRetriever.java
@@ -71,7 +71,9 @@ public class CatalogueRetriever {
             }
 
             productCatalogues.add(newProductCatalogue);
-            LOGGER.info("\nLoaded Catalogue: \n" + newProductCatalogue.toString());
+            String catString = String.format(
+                    "%nLoaded Catalogue: %n%s", newProductCatalogue.toString());
+            LOGGER.info(catString);
         }
     }
 }
diff --git a/src/main/java/de/rwu/easydrop/service/retriever/ProductRetriever.java b/src/main/java/de/rwu/easydrop/service/retriever/ProductRetriever.java
index cd5cb30..8e42ea3 100644
--- a/src/main/java/de/rwu/easydrop/service/retriever/ProductRetriever.java
+++ b/src/main/java/de/rwu/easydrop/service/retriever/ProductRetriever.java
@@ -94,9 +94,9 @@ public class ProductRetriever {
      */
     public Product getProductFromWebshop(final Webshop shop, final String productIdentifier) {
         switch (shop) {
-            case Amazon:
+            case AMAZON:
                 return getProductFromAmazon(productIdentifier);
-            case eBay:
+            case EBAY:
                 return getProductFromEbay(productIdentifier);
             default:
                 return null;
diff --git a/src/main/java/de/rwu/easydrop/util/Timestamp.java b/src/main/java/de/rwu/easydrop/util/Timestamp.java
index a087982..1532c96 100644
--- a/src/main/java/de/rwu/easydrop/util/Timestamp.java
+++ b/src/main/java/de/rwu/easydrop/util/Timestamp.java
@@ -8,7 +8,7 @@ import java.time.format.DateTimeFormatter;
  *
  * @since 0.3.0
  */
-public abstract class Timestamp {
+public final class Timestamp {
     /**
      * Hidden constructor.
      */