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https://issues.apache.org/jira/browse/ARTEMIS-4327?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Justin Bertram resolved ARTEMIS-4327.
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Resolution: Not A Problem
> AMQBuffer.readNullableString() is returning null when the buffer is not empty
> ------------------------------------------------------------------------------
>
> Key: ARTEMIS-4327
> URL: https://issues.apache.org/jira/browse/ARTEMIS-4327
> Project: ActiveMQ Artemis
> Issue Type: Bug
> Affects Versions: 2.19.1
> Environment: Artemis client is
> org.apache.activemq:artemis-core-client:2.19.1, Java code is using the
> Artemis Core API.
> Artemis server appears to be 2.28.0, and is running in a Docker container.
> Reporter: Chelsea Salyards
> Priority: Major
>
> *The Issue*
> Either I do not understand the intended functionality of
> {{AMQBuffer.readNullableString()}}, or it is not functioning correctly. Based
> on the name, I assumed that it would return {{null}} if the buffer was empty,
> and if it was not, it would return a {{String}}.
> In my client code, I have the following:
> {code:java}
> ServerLocator locator = ActiveMQClient.createServerLocator(AMQ_BROKER_URL);
> ClientSessionFactory sessionFactory = locator.createSessionFactory();
> ClientSession session = sessionFactory.createSession();
> session.start();
> Client message = session.createMessage(true);
> message.getBodyBuffer().writeString("test string");
> logger.debug("Regular string: " + message.getDataBuffer().readString());
> logger.debug("Nullable string: " +
> message.getDataBuffer().readNullableString());
> ClientProducer producer = session.createProducer("test-queue");
> producer.send(message);{code}
> The first debug output, using {{readString()}} prints out the string "test
> string" like I expect. However, the second debug output prints {{null}}, but
> I expected it to print "test string".
> *Potential Cause*
> I took a look at the message in the queue via the Artemis web console, and I
> can see the bytes for the message body are as follows:
> {noformat}
> 00 00 00 0b 00 0b 74 65 73 74 20 73 74 72 69 6e 67{noformat}
> Looking at the Artemis client source code, particularly the code for
> {{ChannelBufferWrapper}}, an implementation of the {{ActiveMQBuffer}} class,
> I see that {{readNullableString()}} is defined as the following:
> activemq-artemis/artemis-commons/src/main/java/org/apache/activemq/artemis/core/buffers/impl/ChannelBufferWrapper.java
> {code:java}
> public String readNullableString() {
> int b = buffer.readByte();
> if (b == DataConstants.NULL) {
> return null;
> }
> return readStringInternal();
> }{code}
> So if I am reading this correctly, this seems to be saying that if the buffer
> starts with the byte {{00}}, it will return {{null}}, even if the buffer is
> not empty. Am I reading this correctly? As shown in my example above, the
> message body starts with byte {{00}}.
> Other details about the message, if it helps:
> * durable: true
> * protocol: CORE
> * type: default
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