Issue
I need some advise to implement the best protocol (not http, tcp, ...) te send messages.
- Should I send Serialized Objects? (POJO's)
- Should I send technology independent XML messages?
- What would be recommended? Both will work, but what is best practice. Sharing a library is not what I prefer, but is it easy to work with XML? Are there better alternatives? Thanks in advance!
I have one server, with a 1000 clients connected. The server delivers task to the clients. The clients send information back after executing different tasks.
How should I send a task to a JMS client with some parameters?
A task is nothing more than an action and some parameters.
- Example: "action=measure; parameters: duration=100sec; samples=100" --> collect 100 samples during 100 seconds.
- Example: "action=config; parameters: set of configuration parameters" --> to change the client configuration
- Example: "action=stop" --> Stop the client (the system wil restart after a daily reboot)
A report is nothing more than data.
- Example: "list of 100 values from measurement"
- Example: "the content of a log-file"
I have read many articles, but couldn't find an answer for this question. Thanks in advance.
Solution
This is our current implementation.
We define a protocol with an XSD and let this generate classes (POJO's). This allows us to marshal/unmarshal the objects and send them as XML objects.
Our XSD:
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:jaxb="http://java.sun.com/xml/ns/jaxb"
jaxb:version="2.0">
<!-- Ping
The server will send a ping to a client and waits for a pong.
****************************************************************** -->
<xs:element name="Ping">
<xs:complexType>
<xs:sequence>
<xs:element name="client" type="xs:string"/>
<xs:element name="message" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<!-- Pong
The client will send a pong back to the server.
****************************************************************** -->
<xs:element name="Pong">
<xs:complexType>
<xs:sequence>
<xs:element name="client" type="xs:string"/>
<xs:element name="message" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<!-- Alive
The client will send an alive message when it starts up.
The time is local client time.
****************************************************************** -->
<xs:element name="Alive">
<xs:complexType>
<xs:sequence>
<xs:element name="client" type="xs:string"/>
<xs:element name="time" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<!-- ... Many more message definitions ...
****************************************************************** -->
</xs:schema>
Our test class:
public class JaxbFacadeTest {
@Test
public void testPing() throws JAXBException, SAXException, UnsupportedEncodingException {
System.out.println("testPing");
Ping ping = new Ping();
ping.setClient("guid-client");
ping.setMessage("Ping Message");
String marshalToString = JaxbFacade.getInstance().marshalToString(ping);
System.out.println(marshalToString);
}
@Test
public void testPong() throws JAXBException, SAXException, UnsupportedEncodingException {
System.out.println("testPong");
Pong pong = new Pong();
pong.setClient("guid-client");
pong.setMessage("Ping Message");
String marshalToString = JaxbFacade.getInstance().marshalToString(pong);
System.out.println(marshalToString);
}
@Test
public void testAlive() throws JAXBException, SAXException, UnsupportedEncodingException {
System.out.println("testAlive");
Date now = new Date();
Alive alive = new Alive();
alive.setClient("guid-client");
alive.setTime(now.toString());
String marshalToString = JaxbFacade.getInstance().marshalToString(alive);
System.out.println(marshalToString);
}
//Many more
}
The classes are generated with maven:
<build>
<resources>
<resource>
<directory>${project.basedir}/src/main/xsd</directory>
<targetPath>com/test/package/client/jaxb</targetPath>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.jvnet.jaxb2.maven2</groupId>
<artifactId>maven-jaxb2-plugin</artifactId>
<executions>
<execution>
<id>jaxb</id>
<goals>
<goal>generate</goal>
</goals>
</execution>
</executions>
<configuration>
<generatePackage>com.test.package.client.jaxb</generatePackage>
<schemaDirectory>${project.basedir}/src/main/xsd</schemaDirectory>
</configuration>
</plugin>
</plugins>
</build>
Answered By - Dimitri Dewaele Answer Checked By - Clifford M. (PHPFixing Volunteer)
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