TCPMon is a tool which can be used to monitor the TCP based messages. Here I'm going to describe the steps to follow in order to monitor the messages using TCPMon.
I have two applications talking to each other.
One is WSO2 Identity Server, running on port 9443 in my local machine. The other is a web application deployed on Tomcat (port 8080).
The message exchange I want to monitor, happens in between the below endpoints.
You may have seen in some Java codes there are Java class names end with ...DTO and ...DAO. Why do we need this practice?
First of all let's look at what they stand for?
DTO : Data Transfer Object
DAO : Data Access Object
DTO objects are used to
transfer data between classes and modules of an application. DTO consists of only private fields, getters, setters and
constructors. It is not recommended to add business logic methods to
such classes. But they may contain some util methods.
DAO classes
encapsulate the logic for retrieving, saving and updating data in some data source or storage (a database, a file-system, etc.).
They abstract and encapsulate all access
to the data source. The DAO manages the connection with the data source
to obtain and store data.
A Mediator is simply a processing unit in the ESB. A mediator can do any modification to the messages.
In WSO2 ESB there are so many built-in mediators available. Also we can write custom mediators and add more to the available capabilities of the ESB.
Among those built in mediators Class Mediatoris capable of creating an instance of a custom-specified class and set it as a mediator. There are two approaches to create custom mediators.
Extend the org.apache.synapse.mediators.AbstractMediator class
Implement the org.apache.synapse.api.Mediator interface
In this post I'm going to show you how to implement a simple Class Mediator and using it in a proxy service.
Create a maven project with the name OrderServiceMediator.
You need to add the following dependency to your pom.xml
org.apache.synapsesynapse-core2.1.2-wso2v4
Also you will have to configure the required maven repository as follows. If this is not configured once you try mvn clean install it will give the following error.
[ERROR] Failed to execute goal on project OrderServiceMediator: Could not resolve dependencies for project
Next step is to write the Class Mediator Java code.
Create a new package called mediator (or any other package name you prefer). If you skip this step once you try to deploy the mediator in ESB Carbon will not make a bundle from it. So you will get the following error.
Add a new Java class CustomMediator which extends the AbstractMediator.
Now you will have override the public boolean mediate(MessageContext messageContext) method.
Implement the logic inside this method to do whatever modifications you need to do to the messages .
Here in my simple class mediator I am going to give a discount for the orders submit to the OrderProcessingService which is deployed in the Axis2 server. (This is the same OrderProcessingService described in my previous post).
package mediator;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.synapse.MessageContext;
import org.apache.synapse.mediators.AbstractMediator;
import javax.xml.namespace.QName;
/**
* Created with IntelliJ IDEA.
* User: manorama
* Date: 1/05/15
* Time: 10:25 AM
* To change this template use File | Settings | File Templates.
*/
public class CustomMediator extends AbstractMediator {
private static final Log log = LogFactory.getLog(CustomMediator.class);
private String discountFactor = "10";
private String bonusFor = "10";
private int bonusCount = 0;
@Override
public boolean mediate(MessageContext messageContext) {
// xs:schema targetNamespace given in the WSDL is "http://ws.apache.org/axis2"
String price = messageContext.getEnvelope().getBody().getFirstElement().
getFirstChildWithName(new QName("http://ws.apache.org/axis2","amount")).getText();
int discount = Integer.parseInt(discountFactor);
int bonusNo = Integer.parseInt(bonusFor);
double currentPrice = Double.parseDouble(price);
// Discounting factor is deducted from current price form every response
Double lastPrice = new Double(currentPrice - currentPrice * discount / 100);
// Special discount of 5% offers for the first responses as set in the bonusFor property
if (bonusCount <= bonusNo) {
lastPrice = new Double(lastPrice.doubleValue() - lastPrice.doubleValue() * 0.05);
bonusCount++;
}
String discountedPrice = lastPrice.toString();
messageContext.getEnvelope().getBody().getFirstElement().
getFirstChildWithName(new QName("http://ws.apache.org/axis2","amount")).setText(discountedPrice);
log.info("Order price discounted");
log.info("Original price: " + price);
log.info("Discounted price: " + discountedPrice);
return true;
}
public String getType() {
return null;
}
public void setTraceState(int traceState) {
traceState = 0;
}
public int getTraceState() {
return 0;
}
public void setDiscountFactor(String discount) {
discountFactor = discount;
}
public String getDiscountFactor() {
return discountFactor;
}
public void setBonusFor(String bonus) {
bonusFor = bonus;
}
public String getBonusFor() {
return bonusFor;
}
}
Note that the setter methods are implemented, to set the required property values through the mediator.
Next we will create the proxy service to the back-end service deployed in the Axis2 server. You can follow the steps mentioned in the WSO2 ESB user guide to create the proxy service. Here is my proxy service configuration.
scenario1
Now try to send a message to this proxy service and see the discounted price is assigned for to the amount. You can see the resulted value after going through the mediator using this url.
Logging is a kind of a recording mechanism of the activities occurred during the execution of a program. Further it can store exception and warnings as well as information which are mentioned as to log.
java.util.logging system facilitates logging functions. Logger is the java object used to log a message. Logger creates LogRecord object to store the relevant information to be logged and this object is passed to the handlers to be used for relevant formatting and printing.
Handler objects are assigned to the Logger. These are responsible for publishing the log messages to the external systems. The associated Filter objects do the relevant filtering.
When creating Loggers it is recommended to provide a name based on the package and the class name in which the logger is created.
import java.io.IOException;
import java.util.logging.Logger;
public class LoggerExample {
private static final Logger LOGGER = Logger.getLogger(LoggerExample.class.getName());
// Code goes here..........
}
Handler is responsible for publishing the log message at the target destination. It can be a file or the Standard output.
StreamHandler : Publishes all the log messages to an OutputStream FileHandler : Records all the log messages to a specific file SocketHandler : Publishes all the log messages to a network stream connection. MemoryHandler : Keeps the log messages in a memory buffer
We can configure the handlers, formatters, filters and levels through the methods provided for the Logger class.
Also we can configure those using a properties file inside which the relevant configuration information are defined.
WSO2 ESB supports securing unsecured web services. In this post I'm going to explain how you can secure a web service with WSO2 ESB, using it as an integration layer.
You may have heard of proxy services. A proxy service is a virtual service hosted within an ESB. Simply a proxy service wraps a back-end web service hosted in an application server. A proxy service receives messages that have been sent to a specific endpoint (back-end service) defined in the proxy service configuration. Before forwarding the messages to the relevant endpoint the proxy service can process them if needed, using mediators.
These back-end services may no be secured always. In such a case those unsecured services can be made secured by using the ESB as integration layer. To do that what we need to do is creating a secure proxy service with WS-Security enabled with a specified security policy.
Here are the simple steps to follow to secure a web service.
Open the ESB Management Console.
Create a Proxy Service by clicking on the Services -> Add -> Proxy Service ->Pass Through Proxy in the Main tab. (Here I've selected Pass Through Proxy since I just need to forward messages to the endpoint without performing any processing on them)
Give a name for the Proxy Service and specify the target endpoint. Here I've given the web service URL which is hosted within the Axis2 server.
Then you will be redirected to the List of Services.
You will see the proxy service is shown as 'Unsecured'. Click on 'Unsecured'.
You will be prompted to Enable Security. Select Yes. Then select the UsernameToken as the Basic Scenario.
Click Next. Select user group and Finish.
Now the proxy service is security enabled. You can see the endpoint starting with https:// service dashboard of the proxy service.
Now let's see how to access this web service using a secure client.
REST is an architectural style that used to write a web
service in a certain way. It is based on web-standards and the HTTP protocol. This style was defined by Roy
Fielding in 2000.
In REST architecture the main concept is the Resource which can be uniquely identified by an Uniform Resource Identifier or URI. Every resource supports the HTTP operations.
In this post I'm going to describe how to implement a RESTfull web service which I am going to create as a standalone service with an embedded Jetty server. So you do not need to deploy it in a web container.
This is a simple web service to store and retrieve music track details.
Here is the pom.xml file which contains the relevant dependencies. You can see how the embedded Jetty server is configured through the maven-jetty-plugin and the port being set to 9090.
This web service accepts requests in JSON format and responds with the same format.
Here is the data model Track.java
package com.wso2.training.manorama.model;
/**
* Created with IntelliJ IDEA.
* User: manorama
* Date: 12/4/14
* Time: 10:24 PM
* To change this template use File | Settings | File Templates.
*/
public class Track {
String title;
String singer;
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getSinger() {
return singer;
}
public void setSinger(String singer) {
this.singer = singer;
}
@Override
public String toString() {
return "Track [title=" + title + ", singer=" + singer + "]";
}
}
Now I will describe you how to implement the RESTfull web service for this. Here is the web service implementation class.
package com.wso2.training.manorama;
import com.wso2.training.manorama.model.Track;
import javax.ws.rs.*;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
/**
* Created with IntelliJ IDEA.
* User: manorama
* Date: 12/4/14
* Time: 10:23 PM
* To change this template use File | Settings | File Templates.
*/
@Path("/musicservice")
public class JSONService {
@GET
@Path("/randomtracks")
@Produces(MediaType.APPLICATION_JSON)
public Track getTrackInJSON() {
// Here you can modify this code to get a random track from the available music tracks
Track track = new Track();
track.setTitle("Enter Sandman");
track.setSinger("Metallica");
return track;
}
@POST
@Path("/tracks")
@Consumes(MediaType.APPLICATION_JSON)
public Response createTrackInJSON(Track track) {
String result = "Track saved : " + track;
return Response.status(201).entity(result).build();
}
}
To map the incoming requests, we configure the web.xml (webapp/WEB-INF/web.xml)
When looking at the web service implementation java code, you can see the GET requests with the pattern /randomtracks come to the getTrackInJSON() method. It will respond with a Track object in json format. Note the @Produces(MediaType.APPLICATION_JSON) annotation.
The POST requests comes with the pattern /tracks will create a new Track object and responds with the HTTP 201 OK.The Track object should be in the json format. Note the @Consumes(MediaType.APPLICATION_JSON) annotation
com.sun.jersey.api.json.POJOMappingFeaturetrue
This will map the POJO class to json. Thus the posted json string will be converted into “Track” object automatically.
To deploy this you will need several libraries to be included in the webapp/WEB-INF/lib folder
asm-3.1.jar
jersey-client-1.18.jar
jersey-core-1.18.jar
jersey-json-1.18.jar
jersey-server-1.18.jar
jersey-servlet-1.18.jar
jsr311-api-1.1.1.jar
Since this is a standalone service you do not need to deploy it in a web container. Simply run, $ mvn jetty:run
