I have a few lambdas working together through SNS. One lambda receives a request and send data to SNS. Another lambda is subscribed to SNS. It was easy to do in JavaScript as the incoming message just an JS object. Now I am rewriting the lambda to Java. I am looking for the type to use in the handler.
Here's what the lambda looks like. SNSMessage is the placeholder for the type.
public class ArchiveRequestHandler implements RequestHandler<SNSMessage?, Void> {
@Override public Void handleRequest(SNSMessage? input, Context context) {
// do something with the message
return null;
}
}
This is how an example message looks like:
{
"Records": [
{
"EventVersion": "1.0",
"EventSubscriptionArn": "arn:aws:sns:EXAMPLE",
"EventSource": "aws:sns",
"Sns": {
"SignatureVersion": "1",
"Timestamp": "1970-01-01T00:00:00.000Z",
"Signature": "EXAMPLE",
"SigningCertUrl": "EXAMPLE",
"MessageId": "1234567-ee98-5cb9-9903-4c221d41eb5e",
"Message": "Hello from SNS!",
"MessageAttributes": {
"Test": {
"Type": "String",
"Value": "TestString"
},
"TestBinary": {
"Type": "Binary",
"Value": "TestBinary"
}
},
"Type": "Notification",
"UnsubscribeUrl": "EXAMPLE",
"TopicArn": "arn:aws:sns:EXAMPLE",
"Subject": "TestInvoke"
}
}
]
}
Now I am sure I can create my own type to parse this, but I was hoping there is a more standard way of doing this. However I haven't found anything in the lambda nor SNS SDK dependencies that looks like this object.
Thanks to the comments by @dnault and @notionquest I found that this object is part of the aws-lambda-java-events
library. I added the dependency:
compile 'com.amazonaws:aws-lambda-java-events:1.3.0'
And now I can do:
public class ArchiveRequestHandler implements RequestHandler<SNSEvent, Void> {
@Override public Void handleRequest(SNSEvent input, Context context) {
// do something with the message
return null;
}
}
The following Lambda code processes the SNS input message/s:
import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.LambdaLogger;
import com.amazonaws.services.lambda.runtime.RequestHandler;
import com.amazonaws.services.lambda.runtime.events.SNSEvent;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
public class LogEvent implements RequestHandler<SNSEvent, Object> {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd_HH:mm:ss");
public Object handleRequest(SNSEvent request, Context context){
String timeStamp = sdf.format(new Date());
LambdaLogger logger = context.getLogger();
logger.log("-------------------------Invocation started: --------------" + timeStamp);
List<SNSEvent.SNSRecord> snsRecordList = request.getRecords();
if ( snsRecordList != null ){
SNSEvent.SNS recordSNS = null;
for ( SNSEvent.SNSRecord snsRecord : snsRecordList ) {
recordSNS = snsRecord.getSNS();
logger.log(
"Subject:[" + recordSNS.getSubject() + "]" +
"Arn:[" + recordSNS.getTopicArn() + "]" +
"attribs:[" + recordSNS.getMessageAttributes() + "]" +
"message:[" + recordSNS.getMessage() + "]" );
}//for
}
timeStamp = sdf.format(new Date());
logger.log("-------------------------Invocation completed: -------------" + timeStamp);
return null;
}
}
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