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Open Lane Changes

April 21, 2012 3 comments

My Open Lane application has undergone some significant changes. I’ve added:

  1. Entity classes for a swim meet and events within the meet.
  2. Enumerators for Gender and Stroke.
  3. An AgeGroup class to encapsulate an event’s age category.
  4. JSF DataModel subclasses for Meet and Event along with a refactored SignUp backing bean.
  5. JPA services for all data input and output.
  6. JSF Converter classes for Gender, Stroke, and AgeGroup.
  7. CSV file initialization functions to populate the Swimmer, Meet, Event, and User tables.

Gender and stroke each represent a fixed set of constants which can be objectified in Java as an enumerator. An enumerator provides a clean, self-documenting, and an efficient way of coding an object model. Java enumerators can also be used to encapsulated conversion functionality.

In the case of this application the meet, event, swimmer, and entry records are imported from a CSV file. Within the event record is a stroke (i.e. Freestyle, Backstroke) filed that is coded using a number.  A “1” represents Freestyle, a “2” represents Backstroke, and so on. Stroke has been coded so that each enumerator has its import field number code associated with it. During the import process a simple call to Stroke.parse(string) generates the correct enumerator.

Instead of putting parse into Stroke I could have created a distinct converter. That would have been a cleaner separation of the code. But I don’t anticipate the conversion changing or needing to be adaptable. This way the code is simpler and straight forward.

Stroke.java

package org.bwgz.swim.openlane.data.model;

public enum Stroke {
    FREE("1"),
    BACK("2"),
    BREAST("3"),
    FLY("4"),
    IM("5");

    private String code;

    Stroke(String code) {
    	this.code = code;
    }

     public String getCode() {
          return code;
     }

     public void setCode(String code) {
          this.code = code;
     }

    public static Stroke parse(String string) {
    	Stroke result = null;

    	for (Stroke stroke : Stroke.values() ) {
    		if (stroke.getCode().equalsIgnoreCase(string)) {
				result = stroke;
				break;
			}
		}

		return result;
    }
}

This is an example of using the Gender enumerator within a JPA query to abstract away the codes used in the database. I don’t have to concern myself with how the data is coded once it is imported into the database.

em.createQuery("select e from Event e where e.meet = :meet and (e.gender = :mixed or e.gender = :gender")
.setParameter("meet", meet)
.setParameter("mixed", Gender.MIXED)
.setParameter("gender", gender)
.getResultList();
 

Later in this article is an example of how the enumerator’s parse method is used.

Eventually the JSF tables will support sorting and paging. In preparation for that I’ve moved from List and Collection to JSF’s DataModel. DataModel is a wrapper that abstracts the underlying data. I’ve also used it to store which record (object) may have been selected by the user. Previously there was an independent bean to handle that. Putting it here keeps thing a bit tidier. I created DataModel’s for Event and Meet. Later I’ll reuse the pattern for a user’s open lane applications.

I’ve decided to build out services for each entity in the data model. This provides a level of encapsulation and organization that make the code more manageable. Using @Autowired I can also create services that are built upon other services. For example, the SignUpService uses the SwimmerService.

SignUpService.java snippet.

@Service("signupService")
@Repository
public class SignUpServiceImpl implements SignUpService, Serializable {

     private EntityManager em;
     @Autowired
     private SwimmerService swimmerService;

    @PersistenceContext
    public void setEntityManager(EntityManager em) {
    	this.em = em;
    }
….
    @Transactional
     public Boolean doSignUp(SignUp signUp) {
     Boolean result = Boolean.FALSE;

     Swimmer swimmer = swimmerService.findSwimmer(signUp.getUsasId());

As a general rule the code should have a clean separation between how data is represented internally and externally. JSF’s Converter class is one way to accomplish that. I needed a Converter for Gender, Stroke, and AgeGroup. Since Gender and Stroke were enumerators I create an abstract base class to simplify things. The Gender and Stroke converters need only supply the mappings between the internal representation (an enumerator) and string (display value).

AbstractEnumConverter.java

package org.bwgz.swim.openlane.faces.converter;

import java.util.Hashtable;
import java.util.Map;

import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;

public abstract class AbstractEnumConverter<T> implements Converter {
	private final static int ASSOCIATION_ENUM	= 0;
	private final static int ASSOCIATION_STRING	= 1;

	private Class<T> clazz;
	private final Map<T, String> toStringMap = new Hashtable<T, String>();
	private final Map<String, T> toEnumMap = new Hashtable<String, T>();

	@SuppressWarnings("unchecked")
	public AbstractEnumConverter(Class<T> clazz, Object[][] associations) {
		this.clazz = clazz;

		for (Object[] association : associations) {
			toEnumMap.put((String) association[ASSOCIATION_STRING], (T) association[ASSOCIATION_ENUM]);
			toStringMap.put((T) association[ASSOCIATION_ENUM], (String) association[ASSOCIATION_STRING]);
		}
	}

	public Object getAsObject(FacesContext context, UIComponent component, String value) {
		return toEnumMap.get(value);
	}

	@SuppressWarnings("unchecked")
	public String getAsString(FacesContext context, UIComponent component, Object value) {
            if (value.getClass() == clazz) {
        	 return toStringMap.get((T) value);
            }
            else
            {
                throw new IllegalArgumentException(String.format("Cannot convert object - not of type %s", clazz.getSimpleName()));
            }
	}
}

StrokeConverter.java

package org.bwgz.swim.openlane.faces.converter;

import javax.faces.convert.FacesConverter;
import org.bwgz.swim.openlane.data.model.Stroke;

@FacesConverter(value="strokeConverter")
public class StrokeConverter extends AbstractEnumConverter<Stroke> {
	private final static Object associations[][] = {
		{ Stroke.FREE,		"Free" },
		{ Stroke.BACK,		"Back" },
		{ Stroke.BREAST,	"Breast" },
		{ Stroke.FLY,		"Fly" },
		{ Stroke.IM,		"IM" },
	};

	public StrokeConverter() {
		super(Stroke.class, associations);
	}
}

The AgeGroup converter encapsulates the four rules used to describe an age category.

AgeGroupConverter.java

package org.bwgz.swim.openlane.faces.converter;

import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.FacesConverter;

import org.bwgz.swim.openlane.data.model.AgeGroup;

@FacesConverter(value="ageGroupConverter")
public class AgeGroupConverter implements Converter {
	private static final String SENIOR		= "Senior";
	private static final String UNDER		= "Under";
	private static final String OVER		= "Over";
	private static final String AMPERSAND	= "&";
	private static final String HYPHEN		= "-";

	private static final int LEFT	= 0;
	private static final int RIGHT	= 1;

	private Object getAsObject(String string) {
		long min = 0;
		long max = 0;

		if (string.equals(SENIOR)) {
			min = 0;
			max = 0;
		}
		else if (string.contains(AMPERSAND)) {
			String[] fields = string.split(AMPERSAND);

			if (fields[RIGHT].equals(UNDER)) {
				min = 0;
				max = Long.parseLong(fields[LEFT]);
			}
			else if (fields[RIGHT].equals(OVER)) {
				min = Long.parseLong(fields[LEFT]);
				max = 0;
			}
		}
		else if (string.contains(HYPHEN)) {
			String[] fields = string.split(HYPHEN);

			min = Long.parseLong(fields[LEFT]);
			max = Long.parseLong(fields[RIGHT]);
		}

		return new AgeGroup(min, max);
	}

	public Object getAsObject(FacesContext context, UIComponent component, String value) {
		return getAsObject(value);
	}

	private String getAsString(AgeGroup ageGroup) {
		String string;

		if (ageGroup.getMin() == 0 & ageGroup.getMax() == 0) {
			string = SENIOR;
		}
		else {
			String left;
			String seperator;
			String right;

			if (ageGroup.getMin() == 0) {
				left = String.valueOf(ageGroup.getMax());
				seperator = AMPERSAND;
				right = UNDER;
			}
			else if (ageGroup.getMax() == 0) {
				left = String.valueOf(ageGroup.getMin());
				seperator = AMPERSAND;
				right = OVER;
			}
			else {
				left = String.valueOf(ageGroup.getMin());
				seperator = HYPHEN;
				right = String.valueOf(ageGroup.getMax());
			}

			string = left + seperator + right;
		}

		return string;
	}

	public String getAsString(FacesContext context, UIComponent component, Object value) {
            if (value instanceof AgeGroup) {
                return getAsString((AgeGroup) value);
            }
            else
            {
                throw new IllegalArgumentException("Cannot convert object - not of type AgeGroup");
            }
	}
}

Meet, event, swimmer, and later entry records are imported from another system. Unfortunately the limitations of that system prevent the application from accessing them directly. Instead the data is exported to CSV files and then imported into the application.

Eventually I’ve incorporate a form of file upload within the application to provide live data import. For now some dummy (test) CSV files are included in the application and imported when the application is first accessed. Some services now have an initialize method. When called the method will read a CSV file and write the data to the database using JPA.

Using <on-start> within home-flow.xml I trigger the initializations. This is a hack for testing purposes only.

home-flow.xml snippet

<on-start>
        <evaluate expression="swimmerService.initialize()" />
        <evaluate expression="meetService.initialize()" />
        <evaluate expression="signupService.initialize()" />
</on-start>

I use FlatPack to process the CSV files. It’s a nice CSV library that I’ve used many times in the past. I particularly like that it allows you to create a map of the column names. On the other hand the map requires names for every column. This can be a bit tedious when you only need the first few columns. It can also choke when the file contains records with differing number of columns.

SwimmerServiceImpl.java snippet.

    @Transactional
    public void initialize() {
    if (!initialized) {
        DataSet dataSet;

        Parser parser;
        parser = DefaultParserFactory.getInstance().newDelimitedParser(
            new InputStreamReader(this.getClass().getClassLoader().getResourceAsStream("/test/data/athlete.pzmap.xml")), // xml column mapping
            new InputStreamReader(this.getClass().getClassLoader().getResourceAsStream("/test/data/athlete.csv")),  // csv file to parse
            ';', // delimiter
             '"', // text qualfier
             false); // ignore the first record (may need to be done if first record contain column names)

            dataSet = parser.parse();
            while (dataSet.next()) {
                Swimmer swimmer = new Swimmer();

                swimmer.setId(dataSet.getString("Reg_ID"));
                swimmer.setFirst(dataSet.getString("First_name"));
                swimmer.setLast(dataSet.getString("Last_name"));
                swimmer.setGender(Gender.parse(dataSet.getString("Ath_Sex")));
                swimmer.setId(dataSet.getString("Reg_ID"));
                swimmer.setBirthdate(stringToDate(dataSet.getString("Birth_date")));

                em.persist(swimmer);
                }

            initialized = true;
        }
     }
 

The code is available here on GitHub.

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Open Lane Sign Up

April 17, 2012 Leave a comment

Time for Open Lane to get more real with a user sign up feature. The application already has some user management along with authentication and authorization. Now it needs the ability for someone to sign up and create a user account. Here’s what needs to change.

Add a table and service for all eligible users (swimmers). It contains an unique identifier for each swimmer along with important name and demographic information. The data for this table is loaded from another system and should exist prior to a user attempting to sign up. The sign up process involves gathering some additional information and associating (linking) the user account with their pre-existing swimmer data.

I created entity and service classes to deal with this data. These classes cover the basics.

Swimmer.java

package org.bwgz.swim.openlane.model;

import java.io.Serializable;
import java.util.Date;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "Swimmers")
public class Swimmer implements Serializable {
	private static final long serialVersionUID = 1816256078842365678L;

	private String id;
	private String first;
	private String last;
	private String middle;
	private String gender;
	private Date birthdate;

	public Swimmer() {
	}

	public Swimmer(String id) {
		this.id = id;
	}

	@Id
	public String getId() {
		return id;
	}

	public void setId(String id) {
		this.id = id;
	}

	public String getFirst() {
		return first;
	}

	public void setFirst(String first) {
		this.first = first;
	}

	public String getLast() {
		return last;
	}

	public void setLast(String last) {
		this.last = last;
	}

	public String getMiddle() {
		return middle;
	}

	public void setMiddle(String middle) {
		this.middle = middle;
	}

	public String getGender() {
		return gender;
	}

	public void setGender(String gender) {
		this.gender = gender;
	}

	public Date getBirthdate() {
		return birthdate;
	}

	public void setBirthdate(Date birthdate) {
		this.birthdate = birthdate;
	}

	public static long getSerialversionuid() {
		return serialVersionUID;
	}

	@Override
        public String toString() {
              return String.format("%s@%x; Id: %s; First: %s; Middle: %s; Last: %s; Gender: %s; Birthdate: %s;",
              this.getClass().getName(), this.hashCode(),
              getId(), getFirst(), getMiddle(), getLast(), getGender(), getBirthdate());
}

}

SwimmerService.java

package org.bwgz.swim.openlane.service;

import java.util.List;

import org.bwgz.swim.openlane.model.Swimmer;

public interface SwimmerService {
public List<Swimmer> findSwimmers(String id);
public Swimmer findSwimmer(String id);
}

SwimmerServiceImpl.java

package org.bwgz.swim.openlane.service;

import java.io.Serializable;
import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;

import org.bwgz.swim.openlane.model.Swimmer;
import org.springframework.stereotype.Repository;
import org.springframework.stereotype.Service;

@Service("swimmerService")
@Repository
public class SwimmerServiceImpl implements SwimmerService, Serializable {
	private static final long serialVersionUID = -7264545602862288436L;

	private EntityManager em;

	@PersistenceContext
	public void setEntityManager(EntityManager em) {
		this.em = em;
	}

	private Query findSwimmerQuery(String id) {
		return em.createQuery("select u from Swimmer u where u.id = :id")
				.setParameter("id", id);
	}

	@SuppressWarnings("unchecked")
	public List<Swimmer> findSwimmers(String id) {
		List<Swimmer> list = null;

		if (id != null) {
			list = (List<Swimmer>) findSwimmerQuery(id).getResultList();
		}

		return list;
	}

	public Swimmer findSwimmer(String id) {
		Swimmer swimmer = null;

		if (id != null) {
			try {
				swimmer = (Swimmer) findSwimmerQuery(id).getSingleResult();
			} catch (Exception e) {
			}
		}

		return swimmer;
	}

}

Not just anyone can sign up for a user account. Only someone who’s eligible to participate in a swim meet can apply for an open lane. The process has to account for this when a prospective user signs up. I created an JSF Validator to check if the id given during sign-up matches an existing swimmer. If it does not then the Validator will throw an exception and the JSF form will catch it.

USwimmerValidator.java

package org.bwgz.swim.openlane.faces.validator;

import javax.faces.application.FacesMessage;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.validator.Validator;
import javax.faces.validator.ValidatorException;

import org.bwgz.swim.openlane.model.Swimmer;
import org.bwgz.swim.openlane.service.SwimmerService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component
public class USwimmerValidator implements Validator {

	@Autowired
	private SwimmerService service;

	public void setService(SwimmerService service) {
		this.service = service;
	}

	public void validate(FacesContext context, UIComponent component,
			Object value) throws ValidatorException {
		System.out.printf("USwimmerValidator.validate(%s, %s, %s)\n", context,
				component, value);
		System.out.printf("\t component.getId: %s\n", component.getId());
		System.out.printf("\t component.getClientId: %s\n",
				component.getClientId(context));
		System.out.printf("\t component.getContainerClientId: %s\n",
				component.getContainerClientId(context));
		System.out.printf("\t service: %s\n", service);

		Swimmer membership = service.findSwimmer((String) value);
		if (membership == null) {
			FacesMessage message = new FacesMessage();
			message.setSeverity(FacesMessage.SEVERITY_ERROR);
			message.setSummary("Swimmer not found.");
			message.setDetail("Swimmer not found.");
			context.addMessage(component.getClientId(context), message);
			throw new ValidatorException(message);
		}
	}
}

I decided to create a sub-flow to handle the sign up process. I also needed a backing bean for the sign up form. The heart of the flow involves capturing the username, email, password, and swimmer id in a JSF form, validating the input, and then creating the user account.

On start up the sub-flow instantiates a backing bean (signupBean) which will be used throughout the sub-flow and then discarded. A sign up page (signup.xhtml) is called by the view state and when the form on that page is submitted the flow will execute the action state adduser. adduser calls the User service to create a user record in the the database. If that succeeds the sub flow exits. If not, it takes the user back to the sign up form for another attempt. At anytime during the sub flow the user can exit by selecting a home link.

signup-flow.xml

<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns="http://www.springframework.org/schema/webflow"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/webflow
		http://www.springframework.org/schema/webflow/spring-webflow-2.0.xsd">

	<on-start>
            <evaluate expression="signupBean" result="flowScope.signup" />
	</on-start>

	<view-state id="signup">
		<transition on="submit" to="adduser"/>
		<transition on="home" to="home"/>
	</view-state>

	<action-state id="adduser">
		<evaluate expression="userService.addUser(signup, swimmerService.findSwimmer(signup.usasId))" />
                <transition on="yes" to="success" />
                <transition on="no" to="signup" />
	</action-state>

	<end-state id="home"/>
	<end-state id="success"/>

</flow>

All the of input fields on the sign up page are validated. That validation is defined using annotations in Setup.java. There’s also the JSF Validator mentioned above. The user can’t get past the sign-up page unless they enter legitimate answers.

Setup.java

package org.bwgz.swim.openlane.model;

import java.io.Serializable;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.RequestScoped;
import javax.validation.constraints.Pattern;
import javax.validation.constraints.Size;

@ManagedBean
@RequestScoped
public class SignUp implements Serializable {
	private static final long serialVersionUID = 4957886416619036377L;

	@Size(min = 5, max=20, message = "Please enter a valid username (5-20 characters)")
	private String username;

	@Size(min = 5, max=20, message = "Please enter a valid password (5-20 characters)")
	private String password;

	@Size(min = 1, message = "Please enter the Email")
	@Pattern(regexp = "[a-zA-Z0-9]+@[a-zA-Z0-9]+\\.[a-zA-Z0-9]+", message = "Email format is invalid.")
	private String email;

	@Size(min = 14, max=14, message = "Please enter a valid USA Swimming ID (14 characters)")
	@Pattern(regexp = "[a-zA-Z0-9]+", message = "USA Swimming ID format is invalid.")
	private String usasId;

	public SignUp() {
	}

	public String getUsername() {
		return username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public String getEmail() {
		return email;
	}

	public void setEmail(String email) {
		this.email = email;
	}

	public String getUsasId() {
		return usasId;
	}

	public void setUsasId(String usasId) {
		this.usasId = usasId;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

    @Override
    public String toString() {
    	return String.format("%s@%x; Username: %s; Password: %s; Email: %s; UsasId: %s;",
    			this.getClass().getName(), this.hashCode(),
    			getUsername(), getPassword(), getEmail(), getUsasId());
    }
}

Here’s the the JSF form code from signup.xhtml.

<h:form id="signup">
	<h:outputLabel>User Name: </h:outputLabel>
	<h:inputText id="username" value="${signup.username}"/>
	<br/>
	<h:outputLabel>Password: </h:outputLabel>
	<h:inputText id="password" value="${signup.password}"/>
	<br/>
	<h:outputLabel>Your Email: </h:outputLabel>
	<h:inputText id="email" value="${signup.email}"/>
	<br/>
	<h:outputLabel>Your USA Swimming Id: </h:outputLabel>
	<h:inputText id="usasId" value="${signup.usasId}">
	    <f:validator binding="${USwimmerValidator}"/>
	</h:inputText>

	<br/>
	<h:commandButton id="submit" action="submit" value="Sign Up" update="@form" />
</h:form>

Note the validator tag on the Id inputText tag. I took me quite some time to get this to work correctly.

First, I created the Validator using @FacesValidator and  then added  @Autowired to the SwimmerService variable is needed during validation. It looked something like this.

@FacesValidator("swimmerValidator")
public class USwimmerValidator implements Validator {

    @Autowired
    private SwimmerService service;

This only half worked. The JSF form was able to execute the validator but SwimmerService was not set. After scouring the Internet I learned that the validator was know to JSF but not Spring. I had to drop @FacesValidator and go with @Component inside. This meant in the JSF form I needed to use binding instead of validatorId.

Second, my code original used a different Validator class name called USASMemberValidator. When I refactored it to SwimmerValidator the auto-wiring stopped working. I don’t know why. When I renamed it to USwimmerValidator everything worked fine. Something like this shouldn’t happen. This isn’t the first time in my career that I’ve seen something as flaky as this but it surprised me that I’d see it here.

While investigating all this I came across javax.inject (@Inject). I’m going to looking into this as an alternative.

Finally, I re-factored User by adding a Swimmer variable and annotating it with a one to one relationship. Here’s a snippet from User.java.

	@OneToOne(fetch=FetchType.EAGER)
	public Swimmer getSwimmer() {
		return swimmer;
	}

This is a unidirectional relationship and sufficient for now. I’ll probably re-factor it to a bidirectional relationship to provide some referential capabilities. I also need to ensure that when when a user record is deleted the associated swimmer record is not.

Next step is to get down to the business of an open lane application submission. More on that in my next Open Lane post.

As always, the code is available here on GitHub.

Open Lane – Sunday Housekeeping

April 16, 2012 Leave a comment

Up to now I’ve been focused on get Open Lane up and running. Today I went back and made it more manageable. I don’t want to get too far down the road without being able to build it from a shell using Maven. Also I don’t want to keep committing Eclipse specific files to my version code system Git. I want to be able to:

  • Download the latest version from github.
  • Build a war package using Maven.
  • Deploy that package to a Tomcat server and bring up Open Lane in a browser.
  • Generate an Eclipse project using Maven.

There’s plenty of  good Maven and Git documentation on the Internet. So I won’t get into the details on how to much to technologies work. With that in mind, I will highlight a few things.

The Maven pom file that comes with Spring Web Flow’s booking-faces sample was a good place to start. It very vanilla and doesn’t invoke exotic or highly customized commands or dependenicies. It expects the source tree to follow Maven defaults such as src/main/java. The only significant change was to add my application id’s and fix some the version in some Spring dependencies that were sharing the version.

	<groupId>org.bwgz.swim.openlane</groupId>
	<artifactId>open-lane</artifactId>
	<name>Open Lane</name>
	<version>0.0.1.RELEASE</version>

This results in a pom file that can be found here. After modifying my source tree the new pom could generate a war file and Eclipse project.

Command Description
mvn package Creates a war file in the target directory.
mvn eclipse:eclipse Creates an Eclipse project.

When creating the Eclipse project I found that I needed to ensure I didn’t have any old Eclipse directories hanging around. If I did then things didn’t go well when running the project in Eclipse.

The generated Eclipse project also defaults to Java 1.5 and Web 2.5. I’d prefer it to Java 1.6 or event 1.7 and Web 3.0. Those changes will come later.

During all of this I found a bug in home-flow.xml. The problem was with the evaluation expression …

expression="userService.findUser(currentUser.name)" result="viewScope.user"

Spring Web Flow (SWF) sets currentUser only if a user has been authenticated. Starting up the application on a clean install meant that no one was authenticated and in turn currentUser was not initialized (null). That caused my home flow to blow up because I was attempting to access a member of a null object. I fixed this by changing the expression to …

expression="currentUser != null ? userService.findUser(currentUser.name) : null"

This bug still perplexes me a bit because with the old code, if I logged out the user, there wasn’t a problem. I was as if currentUser was an empty (vs. null) object.