refactoring

* extracted FunctionGateway interface
* renamed current implementation to LocalFunctionGateway
* moved `compose` methods from FunctionGateway to FunctionRegistry

spring-cloud-function-core/src/main/java/org/springframework/cloud/function/gateway/FunctionGateway.java

@@ -17,91 +17,20 @@
 package org.springframework.cloud.function.gateway;
 
 import java.util.function.Consumer;
-import java.util.function.Function;
 import java.util.function.Supplier;
 
 import org.reactivestreams.Publisher;
-import org.reactivestreams.Subscriber;
-import org.reactivestreams.Subscription;
-
-import org.springframework.cloud.function.invoker.FunctionInvokingRunnable;
-import org.springframework.cloud.function.registry.FunctionRegistry;
-import org.springframework.scheduling.TaskScheduler;
 import org.springframework.scheduling.Trigger;
-import org.springframework.util.Assert;
 
 /**
  * @author Mark Fisher
  */
-public class FunctionGateway {
+public interface FunctionGateway {
 
-	private final FunctionRegistry registry;
+	<T, R> R invoke(String functionName, T request);
 
-	private final TaskScheduler scheduler;
+	<T, R> void schedule(String functionName, Trigger trigger, Supplier<T> supplier, Consumer<R> consumer);
 
-	public FunctionGateway(FunctionRegistry registry, TaskScheduler scheduler) {
+	<T, R> void subscribe(Publisher<T> publisher, String functionName, final Consumer<R> consumer);
-		Assert.notNull(registry, "FunctionRegistry must not be null");
-		Assert.notNull(scheduler, "TaskScheduler must not be null");
-		this.registry = registry;
-		this.scheduler = scheduler;
-	}
 
-	@SuppressWarnings("unchecked")
-	public void compose(String name, Function<?, ?>... functions) {
-		Assert.isTrue(functions != null && functions.length > 1, "more than one Function is required");
-		@SuppressWarnings("rawtypes")
-		Function function = functions[0];
-		for (int i = 1; i < functions.length; i++) {
-			function = function.andThen(functions[i]);
-		}
-		this.registry.register(name, function);
-	}
-
-	@SuppressWarnings("unchecked")
-	public void compose(String composedFunctionName, String... functionNames) {
-		Assert.isTrue(functionNames != null && functionNames.length > 1, "more than one Function is required");
-		@SuppressWarnings("rawtypes")
-		Function function = this.registry.lookup(functionNames[0]);
-		for (int i = 1; i < functionNames.length; i++) {
-			function = function.andThen(this.registry.lookup(functionNames[i]));
-		}
-		this.registry.register(composedFunctionName, function);
-	}
-
-	public <T, R> R invoke(String functionName, T request) {
-		Function<T, R> function = this.registry.lookup(functionName);
-		return function.apply(request);
-	}
-
-	public <T, R> void schedule(String functionName, Trigger trigger, Supplier<T> supplier, Consumer<R> consumer) {
-		Function<T, R> function = this.registry.lookup(functionName);
-		this.scheduler.schedule(new FunctionInvokingRunnable(supplier, function, consumer), trigger);
-	}
-
-	public <T, R> void subscribe(Publisher<T> publisher, String functionName, final Consumer<R> consumer) {
-		final Function<T, R> function = this.registry.lookup(functionName);
-		publisher.subscribe(new Subscriber<T>() {
-
-			@Override
-			public void onComplete() {}
-
-			@Override
-			public void onError(Throwable error) {}
-
-			@Override
-			public void onNext(T next) {
-				if (consumer != null) {
-					consumer.accept(function.apply(next));
-				}
-				else {
-					function.apply(next);
-				}
-			}
-
-			@Override
-			public void onSubscribe(Subscription subscription) {
-				subscription.request(Long.MAX_VALUE);
-			}
-		});
-	}
 }

spring-cloud-function-core/src/main/java/org/springframework/cloud/function/gateway/LocalFunctionGateway.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright 2016 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
+ *
+ * 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.springframework.cloud.function.gateway;
+
+import java.util.function.Consumer;
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+import org.reactivestreams.Publisher;
+import org.reactivestreams.Subscriber;
+import org.reactivestreams.Subscription;
+
+import org.springframework.cloud.function.invoker.FunctionInvokingRunnable;
+import org.springframework.cloud.function.registry.FunctionRegistry;
+import org.springframework.scheduling.TaskScheduler;
+import org.springframework.scheduling.Trigger;
+import org.springframework.util.Assert;
+
+/**
+ * @author Mark Fisher
+ */
+public class LocalFunctionGateway implements FunctionGateway {
+
+	private final FunctionRegistry registry;
+
+	private final TaskScheduler scheduler;
+
+	public LocalFunctionGateway(FunctionRegistry registry, TaskScheduler scheduler) {
+		Assert.notNull(registry, "FunctionRegistry must not be null");
+		Assert.notNull(scheduler, "TaskScheduler must not be null");
+		this.registry = registry;
+		this.scheduler = scheduler;
+	}
+
+	@Override
+	public <T, R> R invoke(String functionName, T request) {
+		Function<T, R> function = this.registry.lookup(functionName);
+		return function.apply(request);
+	}
+
+	@Override
+	public <T, R> void schedule(String functionName, Trigger trigger, Supplier<T> supplier, Consumer<R> consumer) {
+		Function<T, R> function = this.registry.lookup(functionName);
+		this.scheduler.schedule(new FunctionInvokingRunnable(supplier, function, consumer), trigger);
+	}
+
+	@Override
+	public <T, R> void subscribe(Publisher<T> publisher, String functionName, final Consumer<R> consumer) {
+		final Function<T, R> function = this.registry.lookup(functionName);
+		publisher.subscribe(new Subscriber<T>() {
+
+			@Override
+			public void onComplete() {}
+
+			@Override
+			public void onError(Throwable error) {}
+
+			@Override
+			public void onNext(T next) {
+				if (consumer != null) {
+					consumer.accept(function.apply(next));
+				}
+				else {
+					function.apply(next);
+				}
+			}
+
+			@Override
+			public void onSubscribe(Subscription subscription) {
+				subscription.request(Long.MAX_VALUE);
+			}
+		});
+	}
+}

spring-cloud-function-core/src/main/java/org/springframework/cloud/function/registry/FunctionRegistry.java

@@ -29,4 +29,8 @@ public interface FunctionRegistry {
 
 	void register(String name, String function);
 
+	void compose(String composedFunctionName, Function<?, ?>... functions);
+
+	void compose(String composedFunctionName, String... functionNames);
+
 }

spring-cloud-function-core/src/main/java/org/springframework/cloud/function/registry/FunctionRegistrySupport.java

@@ -19,6 +19,7 @@ package org.springframework.cloud.function.registry;
 import java.util.function.Function;
 
 import org.springframework.cloud.function.compiler.FunctionCompiler;
+import org.springframework.util.Assert;
 
 /**
  * @author Mark Fisher
@@ -32,4 +33,26 @@ public abstract class FunctionRegistrySupport implements FunctionRegistry {
 		Function<?, ?> function = compiler.compile(code);
 		this.register(name, function);
 	}
+
+	@SuppressWarnings("unchecked")
+	public void compose(String name, Function<?, ?>... functions) {
+		Assert.isTrue(functions != null && functions.length > 1, "more than one Function is required");
+		@SuppressWarnings("rawtypes")
+		Function function = functions[0];
+		for (int i = 1; i < functions.length; i++) {
+			function = function.andThen(functions[i]);
+		}
+		this.register(name, function);
+	}
+
+	@SuppressWarnings("unchecked")
+	public void compose(String composedFunctionName, String... functionNames) {
+		Assert.isTrue(functionNames != null && functionNames.length > 1, "more than one Function is required");
+		@SuppressWarnings("rawtypes")
+		Function function = this.lookup(functionNames[0]);
+		for (int i = 1; i < functionNames.length; i++) {
+			function = function.andThen(this.lookup(functionNames[i]));
+		}
+		this.register(composedFunctionName, function);
+	}
 }