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GH-422 Formalize Cloud Event conversion strategy to consistently handle binary-mode and structured-mode cloud events

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Moved CloudEvent related artifacts to ‘cloud events’ package with hopes to eventually donating it to CNCF SDK
Created CloudEventUtils identifying necessary constants and utility methods
This commit is contained in:
Oleg Zhurakousky
2020-11-12 15:13:35 +01:00
parent daa3c27226
commit a26ad928f6
14 changed files with 703 additions and 95 deletions
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126
spring-cloud-function-context/src/main/java/org/springframework/cloud/function/cloudevent/CloudEventDataContentTypeMessagePreProcessor.java Normal file
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@@ -0,0 +1,126 @@
/*
* Copyright 2020-2020 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.
*/
package org.springframework.cloud.function.cloudevent;
import java.util.Map;
import java.util.function.Function;
import org.springframework.cloud.function.context.config.SmartCompositeMessageConverter;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageHeaders;
import org.springframework.messaging.converter.CompositeMessageConverter;
import org.springframework.messaging.converter.ContentTypeResolver;
import org.springframework.messaging.converter.DefaultContentTypeResolver;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.util.Assert;
import org.springframework.util.MimeType;
import org.springframework.util.MimeTypeUtils;
/**
* A Cloud Events specific pre-processor that is added to {@link SmartCompositeMessageConverter}
* to potentially modify incoming message.
* <br><br>
* For Cloud Event coming in binary-mode such modification implies determining
* content type of the 'data' attribute (see {@link #getDataContentType(MessageHeaders)}
* of Cloud Event and creating a new {@link Message} with its `contentType` set to such
* content type while copying the rest of the headers.
* <br><br>
* Similar to Cloud Event coming in binary-mode, the Cloud Event coming in structured-mode
* such modification also implies determining content type of the 'data' attribute
* (see {@link #getDataContentType(MessageHeaders)}...
*
* @author Oleg Zhurakousky
* @since 3.1
*/
public class CloudEventDataContentTypeMessagePreProcessor implements Function<Message<?>, Message<?>> {
private final ContentTypeResolver contentTypeResolver = new DefaultContentTypeResolver();
private final MimeType cloudEventContentType = MimeTypeUtils.parseMimeType("application/cloudevents");
private final CompositeMessageConverter messageConverter;
public CloudEventDataContentTypeMessagePreProcessor(CompositeMessageConverter messageConverter) {
Assert.notNull(messageConverter, "'messageConverter' must not be null");
this.messageConverter = messageConverter;
}
@SuppressWarnings("unchecked")
@Override
public Message<?> apply(Message<?> inputMessage) {
if (CloudEventUtils.isBinary(inputMessage)) {
String dataContentType = this.getDataContentType(inputMessage.getHeaders());
Message<?> message = MessageBuilder.fromMessage(inputMessage)
.setHeader(MessageHeaders.CONTENT_TYPE, dataContentType)
// .setHeader("originalContentType", inputMessage.getHeaders().get(MessageHeaders.CONTENT_TYPE)) not sure about it
.build();
return message;
}
else if (this.isStructured(inputMessage)) {
MimeType contentType = this.contentTypeResolver.resolve(inputMessage.getHeaders());
String dataContentType = this.getDataContentType(inputMessage.getHeaders());
String suffix = contentType.getSubtypeSuffix();
MimeType cloudEventDeserializationContentType = MimeTypeUtils
.parseMimeType(contentType.getType() + "/" + suffix);
Message<?> cloudEventMessage = MessageBuilder.fromMessage(inputMessage)
.setHeader(MessageHeaders.CONTENT_TYPE, cloudEventDeserializationContentType)
.setHeader(CloudEventUtils.CE_DATACONTENTTYPE, dataContentType).build();
Map<String, Object> structuredCloudEvent = (Map<String, Object>) this.messageConverter
.fromMessage(cloudEventMessage, Map.class);
Message<?> binaryCeMessage = this.buildCeMessageFromStructured(structuredCloudEvent);
return binaryCeMessage;
}
else {
return inputMessage;
}
}
private Message<?> buildCeMessageFromStructured(Map<String, Object> structuredCloudEvent) {
MessageBuilder<?> builder = MessageBuilder.withPayload(structuredCloudEvent.get(CloudEventUtils.DATA));
structuredCloudEvent.remove(CloudEventUtils.DATA);
builder.copyHeaders(structuredCloudEvent);
return builder.build();
}
private String getDataContentType(MessageHeaders headers) {
if (headers.containsKey(CloudEventUtils.DATACONTENTTYPE)) {
return (String) headers.get(CloudEventUtils.DATACONTENTTYPE);
}
else if (headers.containsKey(CloudEventUtils.CE_DATACONTENTTYPE)) {
return (String) headers.get(CloudEventUtils.CE_DATACONTENTTYPE);
}
else if (headers.containsKey(MessageHeaders.CONTENT_TYPE)) {
return headers.get(MessageHeaders.CONTENT_TYPE).toString();
}
return "application/json";
}
private boolean isStructured(Message<?> message) {
if (!CloudEventUtils.isBinary(message)) {
Map<String, Object> headers = message.getHeaders();
if (headers.containsKey(MessageHeaders.CONTENT_TYPE)) {
MimeType contentType = this.contentTypeResolver.resolve(message.getHeaders());
if (contentType.getType().equals(this.cloudEventContentType.getType())
&& contentType.getSubtype().startsWith(this.cloudEventContentType.getSubtype())) {
return true;
}
}
}
return false;
}
}

38
spring-cloud-function-context/src/main/java/org/springframework/cloud/function/cloudevent/CloudEventJsonMessageConverter.java Normal file
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@@ -0,0 +1,38 @@
/*
* Copyright 2020-2020 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.
*/
package org.springframework.cloud.function.cloudevent;
import org.springframework.cloud.function.context.config.JsonMessageConverter;
import org.springframework.cloud.function.json.JsonMapper;
import org.springframework.messaging.converter.MessageConverter;
import org.springframework.util.MimeType;
/**
* Implementation of {@link MessageConverter} which uses Jackson or Gson libraries to do the
* actual conversion via {@link JsonMapper} instance.
*
* @author Oleg Zhurakousky
*
* @since 3.1
*/
public class CloudEventJsonMessageConverter extends JsonMessageConverter {
public CloudEventJsonMessageConverter(JsonMapper jsonMapper) {
super(jsonMapper, new MimeType("application", "cloudevents+json"));
this.setStrictContentTypeMatch(true);
}
}

147
spring-cloud-function-context/src/main/java/org/springframework/cloud/function/cloudevent/CloudEventUtils.java Normal file
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@@ -0,0 +1,147 @@
/*
* Copyright 2020-2020 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.
*/
package org.springframework.cloud.function.cloudevent;
import java.util.Map;
import org.springframework.messaging.Message;
/**
* Miscellaneous utility methods to deal with Cloud Events - https://cloudevents.io/.
* <br>
* Mainly for internal use within the framework;
*
* @author Oleg Zhurakousky
* @since 3.1
*/
public final class CloudEventUtils {
private CloudEventUtils() {
}
/**
* Prefix for attributes.
*/
public static String ATTR_PREFIX = "ce_";
/**
* Value for 'data' attribute.
*/
public static String DATA = "data";
/**
* Value for 'data' attribute with prefix.
*/
public static String CE_DATA = ATTR_PREFIX + DATA;
/**
* Value for 'id' attribute.
*/
public static String ID = "id";
/**
* Value for 'id' attribute with prefix.
*/
public static String CE_ID = ATTR_PREFIX + ID;
/**
* Value for 'source' attribute.
*/
public static String SOURCE = "source";
/**
* Value for 'source' attribute with prefix.
*/
public static String CE_SOURCE = ATTR_PREFIX + SOURCE;
/**
* Value for 'specversion' attribute.
*/
public static String SPECVERSION = "specversion";
/**
* Value for 'specversion' attribute with prefix.
*/
public static String CE_SPECVERSION = ATTR_PREFIX + SPECVERSION;
/**
* Value for 'type' attribute.
*/
public static String TYPE = "type";
/**
* Value for 'type' attribute with prefix.
*/
public static String CE_TYPE = ATTR_PREFIX + TYPE;
/**
* Value for 'datacontenttype' attribute.
*/
public static String DATACONTENTTYPE = "datacontenttype";
/**
* Value for 'datacontenttype' attribute with prefix.
*/
public static String CE_DATACONTENTTYPE = ATTR_PREFIX + DATACONTENTTYPE;
/**
* Value for 'dataschema' attribute.
*/
public static String DATASCHEMA = "dataschema";
/**
* Value for 'dataschema' attribute with prefix.
*/
public static String CE_DATASCHEMA = ATTR_PREFIX + DATASCHEMA;
/**
* Value for 'subject' attribute.
*/
public static String SUBJECT = "subject";
/**
* Value for 'subject' attribute with prefix.
*/
public static String CE_SUBJECT = ATTR_PREFIX + SUBJECT;
/**
* Value for 'time' attribute.
*/
public static String TIME = "time";
/**
* Value for 'time' attribute with prefix.
*/
public static String CE_TIME = ATTR_PREFIX + TIME;
/**
* Checks if {@link Message} represents cloud event in binary-mode.
*/
public static boolean isBinary(Message<?> message) {
Map<String, Object> headers = message.getHeaders();
return (headers.containsKey("id")
&& headers.containsKey("source")
&& headers.containsKey("specversion")
&& headers.containsKey("type"))
||
(headers.containsKey("ce_id")
&& headers.containsKey("ce_source")
&& headers.containsKey("ce_specversion")
&& headers.containsKey("ce_type"));
}
}

1
spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/catalog/SimpleFunctionRegistry.java
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@@ -16,7 +16,6 @@
package org.springframework.cloud.function.context.catalog;
import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

72
spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/config/CloudEventJsonMessageConverter.java
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@@ -1,72 +0,0 @@
/*
* Copyright 2020-2020 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.
*/
package org.springframework.cloud.function.context.config;
import java.lang.reflect.Type;
import java.nio.charset.StandardCharsets;
import java.util.Collection;
import java.util.Map;
import org.springframework.cloud.function.json.JsonMapper;
import org.springframework.lang.Nullable;
import org.springframework.messaging.Message;
import org.springframework.messaging.converter.MessageConverter;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.util.MimeType;
/**
* Implementation of {@link MessageConverter} which uses Jackson or Gson libraries to do the
* actual conversion via {@link JsonMapper} instance.
*
* @author Oleg Zhurakousky
*
* @since 3.1
*/
public class CloudEventJsonMessageConverter extends JsonMessageConverter {
private final JsonMapper mapper;
public CloudEventJsonMessageConverter(JsonMapper jsonMapper) {
super(jsonMapper, new MimeType("application", "cloudevents+json"));
this.mapper = jsonMapper;
}
@Override
protected Object convertFromInternal(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint) {
if (this.isBinary(message)) {
return super.convertFromInternal(message, targetClass, conversionHint);
}
else {
if (targetClass.isInstance(message.getPayload()) && !(message.getPayload() instanceof Collection<?>)) {
return message.getPayload();
}
Type convertToType = conversionHint == null ? targetClass : (Type) conversionHint;
String jsonString = message.getPayload() instanceof String
? (String) message.getPayload()
: new String((byte[]) message.getPayload(), StandardCharsets.UTF_8);
Map<String, Object> mapEvent = this.mapper.fromJson(jsonString, Map.class);
Object payload = this.mapper.fromJson(this.mapper.toJson(mapEvent.get("data")), convertToType);
mapEvent.remove("data");
return MessageBuilder.withPayload(payload).copyHeaders(mapEvent).build();
}
}
private boolean isBinary(Message<?> message) {
Map<String, Object> headers = message.getHeaders();
return headers.containsKey("source") && headers.containsKey("specversion") && headers.containsKey("type");
}
}

6
spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/config/ContextFunctionCatalogAutoConfiguration.java
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@@ -30,6 +30,8 @@ import com.google.gson.Gson;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.cloud.function.cloudevent.CloudEventDataContentTypeMessagePreProcessor;
import org.springframework.cloud.function.cloudevent.CloudEventJsonMessageConverter;
import org.springframework.cloud.function.context.FunctionCatalog;
import org.springframework.cloud.function.context.FunctionProperties;
import org.springframework.cloud.function.context.FunctionRegistry;
@@ -78,7 +80,7 @@ public class ContextFunctionCatalogAutoConfiguration {
conversionService.addConverter(converter);
}
CompositeMessageConverter messageConverter = null;
SmartCompositeMessageConverter messageConverter = null;
List<MessageConverter> mcList = new ArrayList<>();
if (!CollectionUtils.isEmpty(messageConverters)) {
@@ -104,6 +106,8 @@ public class ContextFunctionCatalogAutoConfiguration {
if (!CollectionUtils.isEmpty(mcList)) {
messageConverter = new SmartCompositeMessageConverter(mcList);
CloudEventDataContentTypeMessagePreProcessor messagePreProcessor = new CloudEventDataContentTypeMessagePreProcessor(messageConverter);
messageConverter.setMessagePreProcessor(messagePreProcessor);
}
return new BeanFactoryAwareFunctionRegistry(conversionService, messageConverter, jsonMapper);

13
spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/config/SmartCompositeMessageConverter.java
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@@ -18,6 +18,7 @@ package org.springframework.cloud.function.context.config;
import java.util.Collection;
import java.util.List;
import java.util.function.Function;
import org.springframework.lang.Nullable;
import org.springframework.messaging.Message;
@@ -37,6 +38,8 @@ import org.springframework.util.StringUtils;
*/
public class SmartCompositeMessageConverter extends CompositeMessageConverter {
private Function<Message<?>, Message<?>> preProcessor;
public SmartCompositeMessageConverter(Collection<MessageConverter> converters) {
super(converters);
}
@@ -44,6 +47,9 @@ public class SmartCompositeMessageConverter extends CompositeMessageConverter {
@Override
@Nullable
public Object fromMessage(Message<?> message, Class<?> targetClass) {
if (this.preProcessor != null) {
message = this.preProcessor.apply(message);
}
for (MessageConverter converter : getConverters()) {
Object result = converter.fromMessage(message, targetClass);
if (result != null) {
@@ -56,6 +62,9 @@ public class SmartCompositeMessageConverter extends CompositeMessageConverter {
@Override
@Nullable
public Object fromMessage(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint) {
if (this.preProcessor != null) {
message = this.preProcessor.apply(message);
}
for (MessageConverter converter : getConverters()) {
Object result = (converter instanceof SmartMessageConverter ?
((SmartMessageConverter) converter).fromMessage(message, targetClass, conversionHint) :
@@ -133,4 +142,8 @@ public class SmartCompositeMessageConverter extends CompositeMessageConverter {
}
return null;
}
public void setMessagePreProcessor(Function<Message<?>, Message<?>> preProcessor) {
this.preProcessor = preProcessor;
}
}

4
spring-cloud-function-context/src/main/java/org/springframework/cloud/function/json/JacksonMapper.java
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@@ -18,6 +18,7 @@ package org.springframework.cloud.function.json;
import java.io.Reader;
import java.lang.reflect.Type;
import java.util.Map;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JavaType;
@@ -56,6 +57,9 @@ public class JacksonMapper extends JsonMapper {
else if (json instanceof Reader) {
convertedValue = this.mapper.readValue((Reader) json, constructType);
}
else if (json instanceof Map) {
convertedValue = this.mapper.convertValue(json, constructType);
}
}
catch (Exception e) {
throw new IllegalStateException("Failed to convert. Possible bug as the conversion probably shouldn't have been attampted here", e);

10
spring-cloud-function-context/src/main/java/org/springframework/cloud/function/json/JsonMapper.java
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@@ -16,6 +16,7 @@
package org.springframework.cloud.function.json;
import java.io.Reader;
import java.lang.reflect.Type;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
@@ -77,6 +78,15 @@ public abstract class JsonMapper {
return (T) results;
}
else {
if (!(json instanceof String) && !(json instanceof byte[]) && !(json instanceof Reader)) {
json = this.toJson(json);
if (FunctionTypeUtils.getRawType(type) == String.class) {
return (T) new String((byte[]) json, StandardCharsets.UTF_8);
}
else if (FunctionTypeUtils.getRawType(type) == byte[].class) {
return (T) json;
}
}
return this.doFromJson(json, type);
}
}