发布到已订阅的Lambda函数的AWS SNS记录空字段 [英] AWS SNS publishing to a subscribed Lambda function logs null fields
问题描述
试图将其发布到AWS论坛，但无论如何，看来我的帐户尚未准备就绪".
Tried to post this to the AWS Forums, but it seems my account is "not yet ready", whatever that means.
我已经设置了一个接受Lajo的AWS Lambda函数(用Java编写)，以允许对JSON进行自动反序列化.我正在使用的测试JSON在下面，它表示一旦一切正常运行，将从最终消息源发送的JSON字符串.
I've setup an AWS Lambda function (written in Java) that accepts a POJO in order to allow for automatic deserialization of JSON. The test JSON I am using is below and represents the JSON string that will be sent from the ultimate source of the message once everything is up and running.
{"sender":"Joe", "id":1, "event":"started", "ticks":2, "time":"20150623T214256Z", "version":"1.0"}
当我通过从Lambda测试"控制台将其发布进行测试时，此方法非常有效.
This worked perfectly when I tested it by publishing to it from the Lambda "test" console.
我现在正在尝试通过将Lambda函数订阅到主题来挂接SNS，并正在SNS控制台中对其进行测试.我尝试使用原始数据"(未显示任何结果)以及使用"JSON Generator"数据选项生成的JSON发送与上述相同的消息，但遇到了SNS出现问题将消息发送到Lambda函数，将实例化POJO，但是将使用所有空值调用默认构造函数或调用参数化构造函数.无论哪种方式，当Lambda函数通过在POJO中调用重写的toString()方法记录消息时，它都会为所有变量打印出null，而不会出现任何错误消息.同样，SNS主题配置为登录到Cloudwatch，并且也未报告任何错误.它的HTTP状态为202.
I'm now trying to hook in SNS by subscribing the Lambda function to a Topic and I am testing it from the SNS Console. I've tried sending the same exact message as above both with "raw data" (which didn't show any results) and the JSON generated using the "JSON Generator" data option and I am running into an issue where it seems when SNS sends the message to the Lambda function, the POJO is instantiated, but either the default constructor is called or the parameterized constructor is called with all null values. Either way, when the Lambda function logs the message via calling an overridden toString() method in the POJO, it prints out null for all of the variables without any error messages. Similarly, the SNS Topic is configured to log to Cloudwatch and it too is not reporting any errors. It gets an HTTP status 202.
这是新生成的JSON消息.
Here is the newly generated JSON message.
{
"default": "{\"sender\":\"Joe\", \"id\":1, \"event\":\"started\", \"ticks\":2, \"time\":\"20150623T214256Z\", \"version\":\"1.0\"}",
"lambda": "{\"sender\":\"Joe\", \"id\":1, \"event\":\"started\", \"ticks\":2, \"time\":\"20150623T214256Z\", \"version\":\"1.0\"}",
}
下面是日志消息.
Lambda的日志:
Lambda's logs:
START RequestId: 238a0546-627d-11e5-b228-817bf2a1219a
Received the following :: We have the following Message{sender=null, id=null, event=null, ticks=null, time=null, version=null}
END RequestId: 238a0546-627d-11e5-b228-817bf2a1219a
REPORT RequestId: 238a0546-627d-11e5-b228-817bf2a1219a Duration: 26.23 ms Billed Duration: 100 ms Memory Size: 1536 MB Max Memory Used: 69 MB
SNS日志:
{ "status": "SUCCESS", "notification": { "timestamp": "2015-09-24 05:28:51.079", "topicArn": "arn:aws:sns:us-east-1:256842276575:App", "messageId": "3f5c0fa1-8a50-5ce3-b7c9-41dc060212c8", "messageMD5Sum": "65a5cb6d53616bd385f72177fe98ecc2" }, "delivery": { "statusCode": 202, "dwellTimeMs": 92, "attempts": 1, "providerResponse": "{\"lambdaRequestId\":\"238a0546-627d-11e5-b228-817bf2a1219a\"}", "destination": "arn:aws:lambda:us-east-1:256842276575:function:App-Lambda-Trigger" } }
以下是适用的Lambda函数代码:
Below is the applicable Lambda function code:
package com.mycompany;
import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.LambdaLogger;
public class LambdaHandler {
public void Handler(Message msg, Context context) {
LambdaLogger logger = context.getLogger();
logger.log("Received the following :: " + msg.toString());
}
}
.
public class Message {
private String sender;
private Integer id;
private String event;
private Integer ticks;
private String time;
private Double version;
public Message(String sender, Integer id, String event, Integer ticks, String time, Double version) {
this.sender = sender;
this.id = id;
this.event = event;
this.ticks = ticks;
this.time = time;
this.version = version;
}
... getters/setters ...
public Message() {
}
@Override
public String toString() {
return "We have the following Message{" + "sender=" + getSender() + ", id=" + id + ", event=" + event + ", ticks=" + ticks + ", time=" + time + ", version=" + version + '}';
}
在进行了一些挖掘并查看了一些JavaScript示例之后(我似乎无法找到预订SNS的函数的任何Java示例)，似乎它们都收到了事件".我在AWS的Github存储库中找到了Java类SNSEvent(
After doing some digging and looking at some javascript examples (I can't seem to find any Java examples of functions subscribed to SNS), it seems they all receive "event". I've found on AWS' Github repository a Java class SNSEvent (https://github.com/aws/aws-lambda-java-libs/blob/master/aws-lambda-java-events/src/main/java/com/amazonaws/services/lambda/runtime/events/SNSEvent.java), however it's not in the official Javadoc. None of the AWS documentation I have been able to find document a Java Lambda function setup to receive a POJO deserialized (which I can't believe is all that uncommon) and I can't find anything that specifies what object type is sent by the SNS Topic to the Lambda function, if infact I should not expect the POJO type.
有人可以澄清一下，我的Lambda函数应该接收哪种对象类型?有人可以提供一些示例代码吗?
Can someone please clarify, what object type should I have my Lambda function expect to receive? Can someone provide some sample code?
任何帮助将不胜感激.
编辑1
我根据建议修改了函数以接受SNSEvent和Context对象，并且函数抛出以下异常:
I modified my function to accept SNSEvent and Context objects, per a suggestion and my function throws the following exception:
Error loading method handler on class com.app.LambdaHandler: class java.lang.NoClassDefFoundError java.lang.NoClassDefFoundError: com/amazonaws/services/lambda/runtime/events/SNSEvent
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
at java.lang.Class.privateGetPublicMethods(Class.java:2902)
at java.lang.Class.getMethods(Class.java:1615) Caused by: java.lang.ClassNotFoundException: com.amazonaws.services.lambda.runtime.events.SNSEvent
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
好像运行时环境不能识别SNSEvent吗?
As if the runtime environment does not recognize SNSEvent?
推荐答案
我认为您应该更改两件事:
There are two things I think you should change:
- 您的Message类未遵循预期的配置示例事件"下，查看Lambda中的SNS事件模板.
- Your Message class does not follow the expected Lambda POJO format of getX/setX accessors that Lambda will use to deserialize the event object.
- If your event is from SNS, it will follow the generic SNS object format rather than your custom format. You will have to inspect the SNS event to extract your custom data in the
Message, then parse that separately. Take a look at the SNS event template in Lambda under Actions > Configure sample event.
以下是使用 AWS Lambda的示例Lambda函数，用于处理Java中的SNS事件. Java支持库.
package example;
import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.LambdaLogger;
import com.amazonaws.services.lambda.runtime.events.SNSEvent;
public class SNSEventHandler {
public String handleSNSEvent(SNSEvent event, Context context) {
LambdaLogger logger = context.getLogger();
for (SNSEvent.SNSRecord record : event.getRecords()) {
SNSEvent.SNS sns = record.getSNS();
logger.log("handleSNSEvent received SNS message " + sns.getMessage());
}
return "handleSNSEvent finished";
}
}
The SNSEvent data model suggests that multiple events might arrive to the handler at the same time, so the sample shows iterating over them rather than just assuming one. I haven't seen that in practice yet, but my usage has been low-volume.
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