/*
* Copyright 2010 Google Inc.
*
* 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 com.google.gwt.requestfactory.server;
import com.google.gwt.autobean.server.AutoBeanFactoryMagic;
import com.google.gwt.autobean.server.Configuration;
import com.google.gwt.autobean.server.impl.TypeUtils;
import com.google.gwt.autobean.shared.AutoBean;
import com.google.gwt.autobean.shared.AutoBeanCodex;
import com.google.gwt.autobean.shared.AutoBeanUtils;
import com.google.gwt.autobean.shared.AutoBeanVisitor;
import com.google.gwt.autobean.shared.Splittable;
import com.google.gwt.autobean.shared.ValueCodex;
import com.google.gwt.requestfactory.shared.BaseProxy;
import com.google.gwt.requestfactory.shared.EntityProxyId;
import com.google.gwt.requestfactory.shared.InstanceRequest;
import com.google.gwt.requestfactory.shared.Request;
import com.google.gwt.requestfactory.shared.ServerFailure;
import com.google.gwt.requestfactory.shared.WriteOperation;
import com.google.gwt.requestfactory.shared.impl.BaseProxyCategory;
import com.google.gwt.requestfactory.shared.impl.Constants;
import com.google.gwt.requestfactory.shared.impl.EntityCodex;
import com.google.gwt.requestfactory.shared.impl.EntityProxyCategory;
import com.google.gwt.requestfactory.shared.impl.SimpleProxyId;
import com.google.gwt.requestfactory.shared.impl.ValueProxyCategory;
import com.google.gwt.requestfactory.shared.messages.IdMessage.Strength;
import com.google.gwt.requestfactory.shared.messages.InvocationMessage;
import com.google.gwt.requestfactory.shared.messages.MessageFactory;
import com.google.gwt.requestfactory.shared.messages.OperationMessage;
import com.google.gwt.requestfactory.shared.messages.RequestMessage;
import com.google.gwt.requestfactory.shared.messages.ResponseMessage;
import com.google.gwt.requestfactory.shared.messages.ServerFailureMessage;
import com.google.gwt.requestfactory.shared.messages.ViolationMessage;
import com.google.gwt.user.server.Base64Utils;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.validation.ConstraintViolation;
/**
* Processes request payloads from a RequestFactory client. This implementation
* is stateless. A single instance may be reused and is thread-safe.
*/
public class SimpleRequestProcessor {
/**
* This parameterization is so long, it improves readability to have a
* specific type.
*/
@SuppressWarnings("serial")
static class IdToEntityMap extends
HashMap<SimpleProxyId<?>, AutoBean<? extends BaseProxy>> {
}
/**
* Allows the creation of properly-configured AutoBeans without having to
* create an AutoBeanFactory with the desired annotations.
*/
static final Configuration CONFIGURATION = new Configuration.Builder().setCategories(
EntityProxyCategory.class, ValueProxyCategory.class,
BaseProxyCategory.class).setNoWrap(EntityProxyId.class).build();
/**
* Vends message objects.
*/
static final MessageFactory FACTORY = AutoBeanFactoryMagic.create(MessageFactory.class);
static String fromBase64(String encoded) {
try {
return new String(Base64Utils.fromBase64(encoded), "UTF-8");
} catch (UnsupportedEncodingException e) {
throw new UnexpectedException(e);
}
}
static String toBase64(String data) {
try {
return Base64Utils.toBase64(data.getBytes("UTF-8"));
} catch (UnsupportedEncodingException e) {
throw new UnexpectedException(e);
}
}
private ExceptionHandler exceptionHandler = new DefaultExceptionHandler();
private final ServiceLayer service;
public SimpleRequestProcessor(ServiceLayer serviceLayer) {
this.service = serviceLayer;
}
/**
* Process a payload sent by a RequestFactory client.
*
* @param payload the payload sent by the client
* @return a payload to return to the client
*/
public String process(String payload) {
RequestMessage req = AutoBeanCodex.decode(FACTORY, RequestMessage.class,
payload).as();
AutoBean<ResponseMessage> responseBean = FACTORY.response();
try {
process(req, responseBean.as());
} catch (ReportableException e) {
e.printStackTrace();
// Create a new response envelope, since the state is unknown
responseBean = FACTORY.response();
responseBean.as().setGeneralFailure(createFailureMessage(e).as());
}
// Return a JSON-formatted payload
return AutoBeanCodex.encode(responseBean).getPayload();
}
public void setExceptionHandler(ExceptionHandler exceptionHandler) {
this.exceptionHandler = exceptionHandler;
}
/**
* Encode a list of objects into a self-contained message that can be used for
* out-of-band communication.
*/
<T> Splittable createOobMessage(List<T> domainValues) {
RequestState state = new RequestState(service);
List<Splittable> encodedValues = new ArrayList<Splittable>(
domainValues.size());
for (T domainValue : domainValues) {
Object clientValue;
if (domainValue == null) {
clientValue = null;
} else {
Class<?> clientType = service.resolveClientType(domainValue.getClass(),
BaseProxy.class, true);
clientValue = state.getResolver().resolveClientValue(domainValue,
clientType, Collections.<String> emptySet());
}
encodedValues.add(EntityCodex.encode(state, clientValue));
}
IdToEntityMap map = new IdToEntityMap();
map.putAll(state.beans);
List<OperationMessage> operations = new ArrayList<OperationMessage>();
createReturnOperations(operations, state, map);
InvocationMessage invocation = FACTORY.invocation().as();
invocation.setParameters(encodedValues);
AutoBean<RequestMessage> bean = FACTORY.request();
RequestMessage resp = bean.as();
resp.setInvocations(Collections.singletonList(invocation));
resp.setOperations(operations);
return AutoBeanCodex.encode(bean);
}
/**
* Decode an out-of-band message.
*/
<T> List<T> decodeOobMessage(Class<T> domainClass, Splittable payload) {
Class<?> proxyType = service.resolveClientType(domainClass,
BaseProxy.class, true);
RequestState state = new RequestState(service);
RequestMessage message = AutoBeanCodex.decode(FACTORY,
RequestMessage.class, payload).as();
processOperationMessages(state, message);
List<Object> decoded = decodeInvocationArguments(state,
message.getInvocations().get(0).getParameters(),
new Class<?>[] {proxyType}, new Type[] {domainClass});
@SuppressWarnings("unchecked")
List<T> toReturn = (List<T>) decoded;
return toReturn;
}
/**
* Main processing method.
*/
void process(RequestMessage req, ResponseMessage resp) {
final RequestState source = new RequestState(service);
// Apply operations
processOperationMessages(source, req);
// Validate entities
List<ViolationMessage> errorMessages = validateEntities(source);
if (!errorMessages.isEmpty()) {
resp.setViolations(errorMessages);
return;
}
RequestState returnState = new RequestState(source);
// Invoke methods
List<Splittable> invocationResults = new ArrayList<Splittable>();
List<Boolean> invocationSuccess = new ArrayList<Boolean>();
List<InvocationMessage> invlist = req.getInvocations();
processInvocationMessages(source, invlist, invocationResults,
invocationSuccess, returnState);
// Store return objects
List<OperationMessage> operations = new ArrayList<OperationMessage>();
IdToEntityMap toProcess = new IdToEntityMap();
toProcess.putAll(source.beans);
toProcess.putAll(returnState.beans);
createReturnOperations(operations, returnState, toProcess);
resp.setInvocationResults(invocationResults);
resp.setStatusCodes(invocationSuccess);
if (!operations.isEmpty()) {
resp.setOperations(operations);
}
}
private AutoBean<ServerFailureMessage> createFailureMessage(
ReportableException e) {
ServerFailure failure = exceptionHandler.createServerFailure(e.getCause() == null
? e : e.getCause());
AutoBean<ServerFailureMessage> bean = FACTORY.failure();
ServerFailureMessage msg = bean.as();
msg.setExceptionType(failure.getExceptionType());
msg.setMessage(failure.getMessage());
msg.setStackTrace(failure.getStackTraceString());
msg.setFatal(failure.isFatal());
return bean;
}
private void createReturnOperations(List<OperationMessage> operations,
RequestState returnState, IdToEntityMap toProcess) {
for (Map.Entry<SimpleProxyId<?>, AutoBean<? extends BaseProxy>> entry : toProcess.entrySet()) {
SimpleProxyId<?> id = entry.getKey();
AutoBean<? extends BaseProxy> bean = entry.getValue();
Object domainObject = bean.getTag(Constants.DOMAIN_OBJECT);
WriteOperation writeOperation;
if (id.isEphemeral()) {
// See if the entity has been persisted in the meantime
returnState.getResolver().resolveClientValue(domainObject,
id.getProxyClass(), Collections.<String> emptySet());
}
if (id.isEphemeral() || id.isSynthetic() || domainObject == null) {
// If the object isn't persistent, there's no reason to send an update
writeOperation = null;
} else if (!service.isLive(domainObject)) {
writeOperation = WriteOperation.DELETE;
} else if (id.wasEphemeral()) {
writeOperation = WriteOperation.PERSIST;
} else {
writeOperation = WriteOperation.UPDATE;
}
Splittable version = null;
if (writeOperation == WriteOperation.PERSIST
|| writeOperation == WriteOperation.UPDATE) {
/*
* If we're sending an operation, the domain object must be persistent.
* This means that it must also have a non-null version.
*/
Object domainVersion = service.getVersion(domainObject);
if (domainVersion == null) {
throw new UnexpectedException("The persisted entity with id "
+ service.getId(domainObject) + " has a null version", null);
}
version = returnState.flatten(domainVersion);
}
boolean inResponse = bean.getTag(Constants.IN_RESPONSE) != null;
/*
* Don't send any data back to the client for an update on an object that
* isn't part of the response payload when the client's version matches
* the domain version.
*/
if (WriteOperation.UPDATE.equals(writeOperation) && !inResponse) {
String previousVersion = bean.<String> getTag(Constants.VERSION_PROPERTY_B64);
if (version != null && previousVersion != null
&& version.equals(fromBase64(previousVersion))) {
continue;
}
}
OperationMessage op = FACTORY.operation().as();
/*
* Send a client id if the id is ephemeral or was previously associated
* with a client id.
*/
if (id.wasEphemeral()) {
op.setClientId(id.getClientId());
}
op.setOperation(writeOperation);
// Only send properties for entities that are part of the return graph
if (inResponse) {
Map<String, Splittable> propertyMap = new LinkedHashMap<String, Splittable>();
// Add all non-null properties to the serialized form
Map<String, Object> diff = AutoBeanUtils.getAllProperties(bean);
for (Map.Entry<String, Object> d : diff.entrySet()) {
Object value = d.getValue();
if (value != null) {
propertyMap.put(d.getKey(), EntityCodex.encode(returnState, value));
}
}
op.setPropertyMap(propertyMap);
}
if (!id.isEphemeral() && !id.isSynthetic()) {
// Send the server address only for persistent objects
op.setServerId(toBase64(id.getServerId()));
}
if (id.isSynthetic()) {
op.setStrength(Strength.SYNTHETIC);
op.setSyntheticId(id.getSyntheticId());
} else if (id.isEphemeral()) {
op.setStrength(Strength.EPHEMERAL);
}
op.setTypeToken(service.resolveTypeToken(id.getProxyClass()));
if (version != null) {
op.setVersion(toBase64(version.getPayload()));
}
operations.add(op);
}
}
/**
* Decode the arguments to pass into the domain method. If the domain method
* is not static, the instance object will be in the 0th position.
*/
private List<Object> decodeInvocationArguments(RequestState source,
InvocationMessage invocation, Method contextMethod) {
boolean isStatic = Request.class.isAssignableFrom(contextMethod.getReturnType());
int baseLength = contextMethod.getParameterTypes().length;
int length = baseLength + (isStatic ? 0 : 1);
int offset = isStatic ? 0 : 1;
Class<?>[] contextArgs = new Class<?>[length];
Type[] genericArgs = new Type[length];
if (!isStatic) {
genericArgs[0] = TypeUtils.getSingleParameterization(
InstanceRequest.class, contextMethod.getGenericReturnType());
contextArgs[0] = TypeUtils.ensureBaseType(genericArgs[0]);
}
System.arraycopy(contextMethod.getParameterTypes(), 0, contextArgs, offset,
baseLength);
System.arraycopy(contextMethod.getGenericParameterTypes(), 0, genericArgs,
offset, baseLength);
List<Object> args = decodeInvocationArguments(source,
invocation.getParameters(), contextArgs, genericArgs);
return args;
}
/**
* Handles instance invocations as the instance at the 0th parameter.
*/
private List<Object> decodeInvocationArguments(RequestState source,
List<Splittable> parameters, Class<?>[] contextArgs, Type[] genericArgs) {
if (parameters == null) {
// Can't return Collections.emptyList() because this must be mutable
return new ArrayList<Object>();
}
assert parameters.size() == contextArgs.length;
List<Object> args = new ArrayList<Object>(contextArgs.length);
for (int i = 0, j = contextArgs.length; i < j; i++) {
Class<?> type = contextArgs[i];
Class<?> elementType = null;
Splittable split;
if (Collection.class.isAssignableFrom(type)) {
elementType = TypeUtils.ensureBaseType(TypeUtils.getSingleParameterization(
Collection.class, genericArgs[i]));
split = parameters.get(i);
} else {
split = parameters.get(i);
}
Object arg = EntityCodex.decode(source, type, elementType, split);
arg = source.getResolver().resolveDomainValue(arg,
!EntityProxyId.class.equals(contextArgs[i]));
args.add(arg);
}
return args;
}
private void processInvocationMessages(RequestState state,
List<InvocationMessage> invlist, List<Splittable> results,
List<Boolean> success, RequestState returnState) {
for (InvocationMessage invocation : invlist) {
try {
// Find the Method
String[] operation = invocation.getOperation().split("::");
Method contextMethod = service.resolveRequestContextMethod(
operation[0], operation[1]);
if (contextMethod == null) {
throw new UnexpectedException("Cannot resolve operation "
+ invocation.getOperation(), null);
}
Method domainMethod = service.resolveDomainMethod(contextMethod);
if (domainMethod == null) {
throw new UnexpectedException("Cannot resolve domain method "
+ invocation.getOperation(), null);
}
// Compute the arguments
List<Object> args = decodeInvocationArguments(state, invocation,
contextMethod);
// Possibly use a ServiceLocator
if (service.requiresServiceLocator(contextMethod, domainMethod)) {
Object serviceInstance = service.createServiceInstance(contextMethod,
domainMethod);
args.add(0, serviceInstance);
}
// Invoke it
Object returnValue = service.invoke(domainMethod, args.toArray());
// Convert domain object to client object
Type requestReturnType = service.getRequestReturnType(contextMethod);
returnValue = state.getResolver().resolveClientValue(returnValue,
requestReturnType, invocation.getPropertyRefs());
// Convert the client object to a string
results.add(EntityCodex.encode(returnState, returnValue));
success.add(true);
} catch (ReportableException e) {
results.add(AutoBeanCodex.encode(createFailureMessage(e)));
success.add(false);
}
}
}
private void processOperationMessages(final RequestState state,
RequestMessage req) {
List<OperationMessage> operations = req.getOperations();
if (operations == null) {
return;
}
List<AutoBean<? extends BaseProxy>> beans = state.getBeansForPayload(operations);
assert operations.size() == beans.size();
Iterator<OperationMessage> itOp = operations.iterator();
for (AutoBean<? extends BaseProxy> bean : beans) {
OperationMessage operation = itOp.next();
// Save the client's version information to reduce payload size later
bean.setTag(Constants.VERSION_PROPERTY_B64, operation.getVersion());
// Load the domain object with properties, if it exists
final Object domain = bean.getTag(Constants.DOMAIN_OBJECT);
if (domain != null) {
// Apply any property updates
final Map<String, Splittable> flatValueMap = operation.getPropertyMap();
if (flatValueMap != null) {
bean.accept(new AutoBeanVisitor() {
@Override
public boolean visitReferenceProperty(String propertyName,
AutoBean<?> value, PropertyContext ctx) {
// containsKey to distinguish null from unknown
if (flatValueMap.containsKey(propertyName)) {
Class<?> elementType = ctx instanceof CollectionPropertyContext
? ((CollectionPropertyContext) ctx).getElementType() : null;
Object newValue = EntityCodex.decode(state, ctx.getType(),
elementType, flatValueMap.get(propertyName));
Object resolved = state.getResolver().resolveDomainValue(
newValue, false);
service.setProperty(domain, propertyName,
service.resolveDomainClass(ctx.getType()), resolved);
}
return false;
}
@Override
public boolean visitValueProperty(String propertyName,
Object value, PropertyContext ctx) {
if (flatValueMap.containsKey(propertyName)) {
Splittable split = flatValueMap.get(propertyName);
Object newValue = ValueCodex.decode(ctx.getType(), split);
Object resolved = state.getResolver().resolveDomainValue(
newValue, false);
service.setProperty(domain, propertyName, ctx.getType(),
resolved);
}
return false;
}
});
}
}
}
}
/**
* Validate all of the entities referenced in a RequestState.
*/
private List<ViolationMessage> validateEntities(RequestState source) {
List<ViolationMessage> errorMessages = new ArrayList<ViolationMessage>();
for (Map.Entry<SimpleProxyId<?>, AutoBean<? extends BaseProxy>> entry : source.beans.entrySet()) {
AutoBean<? extends BaseProxy> bean = entry.getValue();
Object domainObject = bean.getTag(Constants.DOMAIN_OBJECT);
// The object could have been deleted
if (domainObject != null) {
Set<ConstraintViolation<Object>> errors = service.validate(domainObject);
if (errors != null && !errors.isEmpty()) {
SimpleProxyId<?> id = entry.getKey();
for (ConstraintViolation<Object> error : errors) {
ViolationMessage message = FACTORY.violation().as();
message.setClientId(id.getClientId());
message.setMessage(error.getMessage());
message.setPath(error.getPropertyPath().toString());
if (id.isEphemeral()) {
message.setClientId(id.getClientId());
message.setStrength(Strength.EPHEMERAL);
} else {
message.setServerId(toBase64(id.getServerId()));
}
message.setTypeToken(service.resolveTypeToken(id.getProxyClass()));
errorMessages.add(message);
}
}
}
}
return errorMessages;
}
}