diff --git a/README.md b/README.md
index 61b3b57..3965041 100644
--- a/README.md
+++ b/README.md
@@ -23,20 +23,15 @@ Entity definition:
 public interface Timeline {
 
 	@PartitionKey
-	UUID getUserId();
-	
-	void setUserId(UUID uid);
+	UUID userId();
 	
 	@ClusteringColumn
 	@DataTypeName(Name.TIMEUUID)
-	Date getTimestamp();
-	
-	void setTimestamp(Date ts);
+	Date timestamp();
 	
 	@Column
-	String getText();
+	String text();
 	
-	void setText(String text);
 }
 ```
 
@@ -48,17 +43,17 @@ CasserSession session = Casser.init(getSession()).showCql().add(Timeline.class).
 
 Select information:
 ```
-session.select(timeline::getUserId, timeline::getTimestamp, timeline::getText)
-  .where(timeline::getUserId, "==", userId)
-  .orderBy(timeline::getTimestamp, "desc").limit(5).sync()
+session.select(timeline::userId, timeline::timestamp, timeline::text)
+  .where(timeline::userId, Operator.EQ, userId)
+  .orderBy(timeline::timestamp, "desc").limit(5).sync()
   .forEach(System.out::println);
 ```
 
 Insert information:
 ```
-Timeline post = Casser.pojo(Timeline.class);
-post.setUserId(userId);
-post.setTimestamp(new Date(postTime+1000L*i));
-post.setText("hello");
+TimelineImpl post = new TimelineImpl();
+post.userId=userId;
+post.timestamp=new Date(postTime+1000L*i);
+post.text="hello";
 session.upsert(post).sync();
 ```
diff --git a/src/main/java/casser/core/Filter.java b/src/main/java/casser/core/Filter.java
index f148dfa..30fa4ae 100644
--- a/src/main/java/casser/core/Filter.java
+++ b/src/main/java/casser/core/Filter.java
@@ -28,18 +28,18 @@ import com.datastax.driver.core.querybuilder.QueryBuilder;
 public final class Filter<V> {
 
 	private final CasserMappingProperty property;
-	private final FilterOperator operation;
+	private final Operator operation;
 	private final V value;
 	private final V[] values;
 	
-	private Filter(CasserMappingProperty prop, FilterOperator op, V value) {
+	private Filter(CasserMappingProperty prop, Operator op, V value) {
 		this.property = prop;
 		this.operation = op;
 		this.value = value;
 		this.values = null;
 	}
 
-	private Filter(CasserMappingProperty prop, FilterOperator op, V[] values) {
+	private Filter(CasserMappingProperty prop, Operator op, V[] values) {
 		this.property = prop;
 		this.operation = op;
 		this.value = null;
@@ -50,7 +50,7 @@ public final class Filter<V> {
 		return property;
 	}
 
-	public FilterOperator getOperation() {
+	public Operator getOperation() {
 		return operation;
 	}
 
@@ -62,7 +62,7 @@ public final class Filter<V> {
 		
 		switch(operation) {
 		
-		case EQUAL:
+		case EQ:
 			return QueryBuilder.eq(property.getColumnName(), 
 					valuePreparer.prepareColumnValue(value, property));
 		
@@ -73,16 +73,16 @@ public final class Filter<V> {
 			}
 			return QueryBuilder.in(property.getColumnName(), preparedValues);
 			
-		case LESSER:
+		case LT:
 			return QueryBuilder.lt(property.getColumnName(), valuePreparer.prepareColumnValue(value, property));
 
-		case LESSER_OR_EQUAL:
+		case LTE:
 			return QueryBuilder.lte(property.getColumnName(), valuePreparer.prepareColumnValue(value, property));
 
-		case GREATER:
+		case GT:
 			return QueryBuilder.gt(property.getColumnName(), valuePreparer.prepareColumnValue(value, property));
 
-		case GREATER_OR_EQUAL:
+		case GTE:
 			return QueryBuilder.gte(property.getColumnName(), valuePreparer.prepareColumnValue(value, property));
 
 		default:
@@ -92,7 +92,7 @@ public final class Filter<V> {
 	}
 	
 	public static <V> Filter<V> equal(Getter<V> getter, V val) {
-		return create(getter, FilterOperator.EQUAL, val);
+		return create(getter, Operator.EQ, val);
 	}
 
 	public static <V> Filter<V> in(Getter<V> getter, V[] vals) {
@@ -109,29 +109,29 @@ public final class Filter<V> {
 		
 		CasserMappingProperty prop = MappingUtil.resolveMappingProperty(getter);
 		
-		return new Filter<V>(prop, FilterOperator.IN, vals);
+		return new Filter<V>(prop, Operator.IN, vals);
 	}
 	
 	public static <V> Filter<V> greater(Getter<V> getter, V val) {
-		return create(getter, FilterOperator.GREATER, val);
+		return create(getter, Operator.GT, val);
 	}
 	
 	public static <V> Filter<V> less(Getter<V> getter, V val) {
-		return create(getter, FilterOperator.LESSER, val);
+		return create(getter, Operator.LT, val);
 	}
 
 	public static <V> Filter<V> greaterOrEqual(Getter<V> getter, V val) {
-		return create(getter, FilterOperator.GREATER_OR_EQUAL, val);
+		return create(getter, Operator.GTE, val);
 	}
 
 	public static <V> Filter<V> lessOrEqual(Getter<V> getter, V val) {
-		return create(getter, FilterOperator.LESSER_OR_EQUAL, val);
+		return create(getter, Operator.LTE, val);
 	}
 
 	public static <V> Filter<V> create(Getter<V> getter, String operator, V val) {
 		Objects.requireNonNull(operator, "empty operator");
 		
-		FilterOperator fo = FilterOperator.findByOperator(operator);
+		Operator fo = Operator.findByOperator(operator);
 		
 		if (fo == null) {
 			throw new CasserMappingException("invalid operator " + operator);
@@ -140,12 +140,12 @@ public final class Filter<V> {
 		return create(getter, fo, val);
 	}
 	
-	public static <V> Filter<V> create(Getter<V> getter, FilterOperator op, V val) {
+	public static <V> Filter<V> create(Getter<V> getter, Operator op, V val) {
 		Objects.requireNonNull(getter, "empty getter");
 		Objects.requireNonNull(op, "empty op");
 		Objects.requireNonNull(val, "empty value");
 		
-		if (op == FilterOperator.IN) {
+		if (op == Operator.IN) {
 			throw new IllegalArgumentException("invalid usage of the 'in' operator, use Filter.in() static method");
 		}
 		
diff --git a/src/main/java/casser/core/FilterOperator.java b/src/main/java/casser/core/Operator.java
similarity index 70%
rename from src/main/java/casser/core/FilterOperator.java
rename to src/main/java/casser/core/Operator.java
index c519c05..9f41dd4 100644
--- a/src/main/java/casser/core/FilterOperator.java
+++ b/src/main/java/casser/core/Operator.java
@@ -18,31 +18,31 @@ package casser.core;
 import java.util.HashMap;
 import java.util.Map;
 
-public enum FilterOperator {
+public enum Operator {
 
-	EQUAL("=="),
+	EQ("=="),
 	
 	IN("in"),
 
-	GREATER(">"),
+	GT(">"),
 
-	LESSER("<"),
+	LT("<"),
 
-	GREATER_OR_EQUAL(">="),
+	GTE(">="),
 
-	LESSER_OR_EQUAL("<=");
+	LTE("<=");
 	
 	private final String name;
 	
-	private final static Map<String, FilterOperator> indexByName = new HashMap<String, FilterOperator>();
+	private final static Map<String, Operator> indexByName = new HashMap<String, Operator>();
 	
 	static {
-		for (FilterOperator fo : FilterOperator.values()) {
+		for (Operator fo : Operator.values()) {
 			indexByName.put(fo.getName(), fo);
 		}
 	}
 	
-	private FilterOperator(String name) {
+	private Operator(String name) {
 		this.name = name;
 	}
 
@@ -50,7 +50,7 @@ public enum FilterOperator {
 		return name;
 	}
 	
-	public static FilterOperator findByOperator(String name) {
+	public static Operator findByOperator(String name) {
 		return indexByName.get(name);
 	}
 	
diff --git a/src/main/java/casser/core/operation/AbstractFilterOperation.java b/src/main/java/casser/core/operation/AbstractFilterOperation.java
index e8bbb6b..e6b65fb 100644
--- a/src/main/java/casser/core/operation/AbstractFilterOperation.java
+++ b/src/main/java/casser/core/operation/AbstractFilterOperation.java
@@ -20,7 +20,7 @@ import java.util.List;
 
 import casser.core.AbstractSessionOperations;
 import casser.core.Filter;
-import casser.core.FilterOperator;
+import casser.core.Operator;
 import casser.core.Getter;
 
 public abstract class AbstractFilterOperation<E, O extends AbstractFilterOperation<E, O>> extends AbstractEntityOperation<E, O> {
@@ -38,7 +38,7 @@ public abstract class AbstractFilterOperation<E, O extends AbstractFilterOperati
 		return (O) this;
 	}
 
-	public <V> O where(Getter<V> getter, FilterOperator operator, V val) {
+	public <V> O where(Getter<V> getter, Operator operator, V val) {
 		
 		addFilter(Filter.create(getter, operator, val));
 		
@@ -59,7 +59,7 @@ public abstract class AbstractFilterOperation<E, O extends AbstractFilterOperati
 		return (O) this;
 	}
 
-	public <V> O and(Getter<V> getter, FilterOperator operator, V val) {
+	public <V> O and(Getter<V> getter, Operator operator, V val) {
 		
 		addFilter(Filter.create(getter, operator, val));
 		
diff --git a/src/main/java/casser/core/operation/AbstractFilterStreamOperation.java b/src/main/java/casser/core/operation/AbstractFilterStreamOperation.java
index aa908f1..f4e2d96 100644
--- a/src/main/java/casser/core/operation/AbstractFilterStreamOperation.java
+++ b/src/main/java/casser/core/operation/AbstractFilterStreamOperation.java
@@ -20,7 +20,7 @@ import java.util.List;
 
 import casser.core.AbstractSessionOperations;
 import casser.core.Filter;
-import casser.core.FilterOperator;
+import casser.core.Operator;
 import casser.core.Getter;
 
 public abstract class AbstractFilterStreamOperation<E, O extends AbstractFilterStreamOperation<E, O>> extends AbstractStreamOperation<E, O> {
@@ -38,7 +38,7 @@ public abstract class AbstractFilterStreamOperation<E, O extends AbstractFilterS
 		return (O) this;
 	}
 
-	public <V> O where(Getter<V> getter, FilterOperator operator, V val) {
+	public <V> O where(Getter<V> getter, Operator operator, V val) {
 		
 		addFilter(Filter.create(getter, operator, val));
 		
@@ -59,7 +59,7 @@ public abstract class AbstractFilterStreamOperation<E, O extends AbstractFilterS
 		return (O) this;
 	}
 
-	public <V> O and(Getter<V> getter, FilterOperator operator, V val) {
+	public <V> O and(Getter<V> getter, Operator operator, V val) {
 		
 		addFilter(Filter.create(getter, operator, val));
 		
diff --git a/src/test/java/casser/test/integration/core/simple/SimpleUserTest.java b/src/test/java/casser/test/integration/core/simple/SimpleUserTest.java
index 6034121..e7cd3d9 100644
--- a/src/test/java/casser/test/integration/core/simple/SimpleUserTest.java
+++ b/src/test/java/casser/test/integration/core/simple/SimpleUserTest.java
@@ -22,7 +22,7 @@ import org.junit.Test;
 
 import casser.core.Casser;
 import casser.core.CasserSession;
-import casser.core.FilterOperator;
+import casser.core.Operator;
 import casser.test.integration.build.AbstractEmbeddedCassandraTest;
 
 public class SimpleUserTest extends AbstractEmbeddedCassandraTest {
@@ -73,7 +73,7 @@ public class SimpleUserTest extends AbstractEmbeddedCassandraTest {
 		session.update(user::name, "albert").set(user::age, 35)
 			.where(user::id, "==", 123L).sync();
 		
-		long cnt = session.count(user).where(user::id, FilterOperator.EQUAL, 123L).sync();
+		long cnt = session.count(user).where(user::id, Operator.EQ, 123L).sync();
 		Assert.assertEquals(1L, cnt);
 
 		String name = session.select(user::name)