Friday, August 7, 2015

First Steps with jBPM and BPMN 2.0 Modelization Tools



In this post, I would like to share my initial experience with jBPM and BPMN 2.0 modelization tools in general. jBPM is an open-source workflow engine written in Java that can execute business processes described in BPMN 2.0.

Business Process Model and Notation (BPMN) is a graphical representation for specifying business processes in a business process model. As an architect, I have been using BPMN as a language for business process modeling (e.g. for the functional breakdown of complex processing pipelines for genomics systems).

They are different ways to install jBPM. The quickest installations options include:
  1. downloading a zip file and install it on a PC or
  2. downloading and using a docker image (particularly suitable for Mac OS)
In this post, I will describe option #1 (basic zip based install). In this case, what you obtain is a zip file - e.g. jbpm-6.2.0.Final-installer-full.zip - latest version as of 8/7/2015.

  • First make sure you have installed Apache Ant and it is on your Windows Path.
  • To install type the following command at the prompt in the jbpm-installer folder:
    • $ ant install.demo

After few minutes, all dependencies are fully downloaded and jBPM is installed.


     You are now ready to start the web-based Knowledge Is Everything KIE workbench (there is also an Eclipse IDE plugin available with the download that you can use).
  • $ ant start.demo
  • Alternatively you can also download and start the demo without eclipse
    • $ ant install.demo.noeclipse
    • $ ant start.demo.noeclipse

    Issues deploying jbpm-console.war
  • if jbpm-console.war cannot be deployed in JBoss wildfly application server (former JBoss AS).
  • see folder: ...\jBPM\jbpm-installer\wildfly-8.1.0.Final\standalone\deployments 
  • and check log file: ...\jBPM\jbpm-installer\wildfly-8.1.0.Final\standalone\log\server.log
  • You might have encounter an issue with your proxy!!!
  • There are several ways to fix this, including 
    • installing KIE outside your firewall/proxy server influence (not from our office!)
    • modify your file ...\jBPM\jbpm-installer\build.xml file:
                 <exec executable="${jboss.full.path.win}" spawn="yes" osfamily="windows">
                      <env key="JAVA_OPTS" value="-XX:MaxPermSize=256m -Xms256m -Xmx512m" />
                      <arg value="-b" />
                      <arg value="${jboss.bind.address}" />
                      <arg value="--server-config=standalone-full.xml" />
                      <arg value="-Dorg.kie.demo=true" />
                      <arg value="-Dorg.kie.example=false" />
                      <arg value="-Dhttp.proxyHost=...." />
                      <arg value="-Dhttp.proxyPort=8999" />
                      <arg value="c standalone-full.xml"/>

     Using KIE
  •  If successfully deployed, go to your browser (use Chrome for better experience!) and enter
    • http://localhost:8080/jbpm-console/kie-wb.html
       
     You should have access to the jBPM KIE console (see also video demo here and look at jBPM6 Developer Guide).

 


      The default user name and password are 'admin'.

      


To have access to the business process demos click Authoring/Project and choose async-examples.

Then Business Processes/check weather (one of the demos - this one is very simple and fun!).


 This displays a very simple business process where the user can enter a zip code and obtain the weather forecast associated to the zip code in question:



 
Open the properties pane  if not displayed by clicking the double arrow on the top right side of the application.

You can initially do a copy of the demo in case you want to make some modifications to the demo process. You will need to modify the ID and the Version of the business process and save a copy.






Enter a new name and optionally some comments for the new version of the process:


    The copy should now appear in the list of business processes:



Deployment of a Process is done by opening the Project and select Build/Build & Deploy:




 To run the demo process, select Process Management/Process Definitions then select your process and click on the start Action icon:

 

  Enter the user name ('admin') and a US zip code - Here I am using 94036 (Palo Alto, CA).



Thursday, April 2, 2015

Migrating Healthcare Applications to the Cloud through Containerization and Service Brokering



Organizations that are building their own cloud infrastructure from scratch or rely uniquely only on an infrastructure as a service (IaaS) from a provider, risk spending valuable resources and time building a specialized platform instead of focusing on their core business. On the other hand, organizations who adopt a turnkey proprietary cloud stack will lack flexibility and may end up locked into a specific technology or vendor.

Instead of designing the cloud architecture from the bottom up or the top down, a better strategy is to design from the inside out. By starting with the platform as a service (PaaS) as the central critical layer and creating ways to use various IaaS models and offerings in generic ways, it is possible to create a flexible and efficient lifecycle for the services and applications running on the platform.



In Healthcare, PaaS technology such as the one offered by Pivotal Cloud Foundry facilitates the rapid creation and migration of existing applications towards better user engagement, increasing collaboration between care givers and improving the lives of patients, while reducing the total cost of ownership (TCO).


The main characteristics of this platform are:
  • Application containerization
  • Optimized application scaling
  • Application to service brokering
  • Abstraction of IaaS
  • Excellent application lifecycle management
  • Automatic middleware stack and operating system configuration
  • Advanced application monitoring

In this architecture, backing services (e.g., databases, caching systems, other data services (e.g., Amazon S3), messaging/queueing systems, SMTP services, various external APIs (Google Maps, terminology services, healthcare registry services) are just attached resources. For example, there is a distinction between a local digital imaging and communications in medicine (DICOM) local image store and a remote, 3rd party DICOM picture archiving and communication system (PACS) service hosted in the cloud.

The type of platform is especially suitable managing micro services, which allows better componentization, development and testing processes, decentralized governance, resilience and maintainability. These services, especially when they are based on a RESTful architecture, are extremely easy to build, integrate, test, extend, and maintain, and are extremely adapted for mobile applications integration.


Good and efficient lifecycle management is important to produce and maintain high quality software. This is particularly important in healthcare where the patient life is at risk or a breach of privacy could occur as a result of poor quality software.

The advantage of abstracting the IaaS layer access through a common API is that there no need to have multiple versions of application code for each deployment model. The same code will work and be monitored the same way for all cloud deployment models, including on premise and hybrid.





On top of the generic open PaaS infrastructure, we are adding generic and cross-cutting capabilities not part of the original platform including:
  • Identity management to allow customers, patients and consumers to be accurately and uniquely recognized by using an enterprise master patient index (eMPI) for patients and a lightweight directory access protocol (LDAP) based directory for healthcare providers and consumers.
  • Security/Identity Access Management: authentication, authorization, and single sign-on, all critical to secure provider, patient, and consumer applications and in certain cases, can be addressed by declarative proxification of these services.
  • Cloud-based, connected device management: device registration, discovery, routing, diagnostics, remote control, firmware provisioning, data collection, device-app-user pairing (we are currently supporting 6 million active consumer devices).
  • Open cloud based clinical workflow collaboration capabilities.
  • Secure cloud-based big data store and analytics capability (e.g., to store patient’s observations and genomic data.

  

We are also creating and exposing healthcare and wellness related services that applications can consume:

Our HealthSuite Digital platform also offers high availability, scalability, privacy and security compliance with regulations (e.g., HIPAA, HITECH) and standards (e.g., NIST SP800-53, ISO 27001) using multitenancy, redundancy, 24/7 monitoring and operations, and disaster recovery.



   More on:  F. Andry, R. Ridolfo, J. Huffman, Migrating Healthcare Applications to the Cloud through Containerization and Service Brokering, 8th International Conference on Health Informatics (HealthINF 2015), pp. 164-171, Lisbon, Portugal, January 2015.








Thursday, June 6, 2013

Java Code Refactoring





I recently browsed again the excellent book Code Complete from Steve McConnell while in the middle of several Java code reviews. Although the book is nor specifically dedicated to Java code, I still found it quite useful and inspiring.

The chapter on refactoring in particular offers a very practical perspective that all programmer should have in mind when it comes to infuse a dose of evolution in the life cycle of their software.

What I found particularly valuable are the checklists that the author has put together: reasons to refactor, specific re-factorings (data level, statement level, routine-level, class-implementation, class-interface, system-level), refactoring safely, strategies, summary.

In this post, I would like to illustrate some of these refactoring techniques with java code snippets.

Since I do not have time to comment every item in these checklists, I decided to pick-up those that are not trivial or obvious and might bring the best return on your refactoring investment. These items are high-lighted in green and developed in sections at the end of this article.

If you think that missing items are worth explaining, please add a comment to this post and I will be glad to add a specific paragraph for those as well.







Checklist: Reasons to Refactor

  • Code is duplicate
  • A routine is too long
  • A loop is too long or too deeply nested
  • A class/interface/method has poor cohesion
  • A class interface does not provide a consistent level of abstraction
  • A parameter list has too many parameters
  • Changes within a class tend to be compartmentalized
  • Changes require parallel modifications to multiple classes
  • Inheritance hierarchies have to be modified in parallel
  • Related data items that are used together are not organized into classes
  • A routine uses more features of another class than of its own class
  • A primitive data type is overloaded
  • A class doesn't do very much
  • A chain of routines passes tramp data
  • A middle man object isn't doing anything
  • One class is overly intimate with another
  • A routine has a poor name
  • Data members are public
  • A subclass uses only a small percentage of its parents' routines
  • Comments are used to explain difficult code
  • Global variables are used
  • A routine uses setup code before a routine call or takedown code after a routine call
  • A program contains code that seems like it might be needed someday

 Checklist: Summary of Refactorings


Data Level Refactoring
  • Replace a magic number with a named constant
  • Rename a variable with a clearer or more informative name
  • Move an expression inline
  • Replace an expression with a routine
  • Introduce an intermediate variable
  • Convert a multi-use variable to a multiple single-use variables
  • Use a local variable for local purposes rather than a parameter
  • Convert a data primitive to a class
  • Convert a set of type codes to a class
  • Convert a set of type codes to a class with subclasses
  • Change an array to an object
  • Encapsulate a collection
  • Replace a traditional record with a data class
Statement Level Refactorings
  • Decompose a boolean expression
  • Move a complex boolean expression into a well-named boolean function
  • Consolidate fragments that are duplicated within different parts of a conditional
  • Use break or return instead of a loop control variable
  • Return as soon as you know the answer instead of assigning a return value within nested if-then-else statements
  • Replace conditionals with polymorphism (especially repeated case statements)
  • Create and use null objects instead of testing for null values
Routine Level Refactorings
  • Extract a routine
  • Move a routine's code inline
  • Convert a long routine to a class
  • Substitute a simple algorithm for a complex algorithm
  • Add a parameter
  • Remove a parameter
  • Separate query operations from modification operations
  • Combine similar routines by parameterizing them
  • Separate routines whose behavior depends on parameters passed in
  • Pass a whole object rather than specific fields
  • Pass specific fields rather than a whole object
  • Encapsulate downcasting ⇐ 

Class Implementation Refactorings
  • Change value objects to reference objects
  • Change reference objects to value objects
  • Replace virtual routines with data initialization
  • Change member routine or data placement
  • Extract specialized code into a subclass
  • Combine similar code into a superclass
Class Interface Refactorings
  • Move a routine to another class
  • Convert one class to two
  • Eliminate a class
  • Hide a delegate
  • Replace inheritance with delegation
  • Replace delegation with inheritance
  • Remove a middle man
  • Introduce a foreign routine
  • Introduce a class extension
  • Encapsulate an exposed member variable
  • Remove Set() routines for fields that cannot be changed
  • Hide routines that are not intended to be used outside the class
  • Encapsulate unused routines
  • Collapse a superclass and subclass if their implementations are very similar
System Level Refactorings
  • Duplicate data you can't control
  • Change unidirectional class association to bidirectional class association
  • Change bidirectional class association to unidirectional class association
  • Provide a factory routine rather than a simple constructor
  • Replace error codes with exceptions or vice versa

Selected items refactoring samples in java

  • A class/interface/method has poor cohesion
    • A class, interface or method should be only responsible for a precise and meaningful set of functionality and behavior. For example,the interface KitchenAppliance below lacks cohesion. A generic kitchen appliance should not allow to wash both clothes and dishes.
    •  
      public interface KitchenAppliance {
       public float waterConsumption = 0;
       public float energyConsumption = 0;
       void washClothes();
       void washDishes();
      }
      

              ⇒

      public interface WashingKitchenAppliance {
       public float waterConsumption = 0;
       public float energyConsumption = 0;
       void wash();
      } 
       
       
  • A class interface does not provide a consistent level of abstraction
    •  In Java, a consistent level of abstraction is usually obtained when the objects that represent abstract actors perform work, report on, change their state and communicate with other java objects in a a compatible and comparable way.
      The use of inheritance, encapsulation and polymorphism is usually the key to a consistent level of abstraction and is at the core of good design patterns. In the example below, an intermediary level of abstraction, e.g. DairyAnimal (cows, goats) and MeatAnimal (pigs, steers), could be created to avoid  specifying the type of food for each animal and focus on more specific features for the sub-classes.
    •  
      public class Animal extends LivingThing
      {
       private Location loc;
       private double energyReserves;
      
       public boolean isHungry() {
        return energyReserves < 2.5;
       }
       public void eat(Food food) {
        energyReserves += food.getCalories();
       }
       public void moveTo(Location location) {
        this.loc = location;
       }
      }
      
      thePig = new Animal();
      theCow = new Animal();
      if (thePig.isHungry()) {
          thePig.eat(tableScraps);
      }
      if (theCow.isHungry()) {
          theCow.eat(grass);
      }
      theCow.moveTo(theBarn);
       

       
      public class DairyAnimal extends Animal {
       private Double milkProduction;
      
       public Double getMilkProduction() {
        return milkProduction;
       }
              ...
      }
      
  • A parameter list has too many parameters
    • Methods with too many parameters is an indication that the code has either been badly designed initially (lack of abstraction) or has evolved over the months or years without proper refactoring. One elegant solution for creational methods/constructor requiring a large number of parameters is to use a builder pattern well define in Joshua Bloch's Effective Java and offers a way to use optional parameters:
    •  
      public NutritionFacts(int servingSize, int servings, int sodium, int iron, int fat, int carbs) {
           this.servingSize = servingSize;
           this.sodium = sodium;
           this.servingSize = servingSize;
           this.iron = iron;
           this.fat = fat;
           this.carbs = carbs;
      }
      
      NutritionFacts soda = new NutritionFacts(240, 8, 35, 13, 0, 27);
      

      public class NutritionFacts {
       private int servingSize = 0;
       private int servings  = 0;
       private int sodium  = 0;
       private int iron  = 0;
       private int fat  = 0;
       private int carbs  = 0;
      
       public static class Builder {
        private int servingSize;
        private int servings;
        private int sodium;
        private int iron;
        private int fat;
        private int carbs;
      
        public Builder(int servingSize, int servings) {
         this.servingSize = servingSize;
         this.servings = servings;
        }
        
        public Builder sodium(int val) {
         this.sodium = val;
         return this;
        }
        
        public Builder iron(int val) {
         this.iron = val;
         return this;
        }
      
        public Builder fat(int val) {
         this.fat = val;
         return this;
        }
      
        public Builder carbs(int val) {
         this.carbs = val;
         return this;
        }
        
        public NutritionFacts build() {
         return new NutritionFacts(this);
        }
       }
       
       private NutritionFacts(Builder builder) {
        servingSize = builder.servingSize;
        servings = builder.servings;
        sodium = builder.sodium;
        iron = builder.iron;
        fat = builder.fat;
        carbs = builder.carbs;
       }
      }
      
      NutritionFacts soda = new NutritionFacts(240, 8).build();
      or
      NutritionFacts soda = new NutritionFacts(240, 8).sodium(35).iron(13).fat(0).carbs(27).build();
      or
      NutritionFacts soda = new NutritionFacts(240, 8).sodium(35).iron(13).carbs(27).build();
      
      
  • Changes require parallel modifications to multiple classes
    • If you regularly have to modify the same set of classes then try to refactor these classes with the correct level of abstraction and factorization so changes only affect one class.
  • Related data items that are used together are not organized into classes
    • Recurrent set of operations can be combined in its own class:
    • theCow = new DairyAnimal();
      theCow.brush();
      theCow.feed();
      theCow.milk();
      theCow.feed();
      

      public class DairyAnimalOperation {
       public void tend(DairyAnimal dairyAnimal) {
        dairyAnimal.brush();
        dairyAnimal.feed();
        dairyAnimal.milk();
        dairyAnimal.feed();
      };
      
      Even better, refactoring can include the use of a flexible strategy pattern, if the recurrent process needs to be dynamically.
  • A chain of routines passes tramp data
    • "Tramp data" refers to passing data to one method so it can be passed to another one (Page-Jones 1988). This can be solved by introducing a better level of abstraction in the interfaces in question
  • Replace a magic number with a named constant
    • The word magic refers to the use of numeric or string literal. Use constants or Enums instead.
    • public double areaOfCircle (double radius)  {  
          return Math.pow(radius * 3.14159, 2);  
      }  
      

      private static final double PI = 3.14159;
      
      public double areaOfCircle (double radius)  {  
          return Math.pow(radius * PI, 2);  
      } 
      
  • Convert a multi-use variable to a multiple single-use variables
    • Common offenders are variable names like i,j, temp. These need to be replaced by specific names (e.g. row, column).
    • for (int i=0;i&tl;N;i++) {
          for (int j=0;j&tl;M;j++) {
             matrix[i][j] = 0; 
          }
      }
      

      for (int row=0;row&tl;numRows;row++) {
          for (int colum=0;colum&tl;numColumns;colum++) {
              matrix[row][colum] = 0; 
          }
      }
      
  • Encapsulate a collection
    • Instead of returning the collection itself, encapsulate a read-only collection instance with specific methods to add or remove elements in the original collection. You can leverage unmodifiable view methods that are part of the collection class for this:
    • public static <T> Collection<T> unmodifiableCollection(Collection<? extends T> c)
      public static <T> Set<T> unmodifiableSet(Set<? extends T> s)
      public static <T> SortedSet<T> unmodifiableSortedSet(SortedSet<T> s)
      public static <T> List<T> unmodifiableList(List<? extends T> list)
      public static <K,V> Map<K,V> unmodifiableMap(Map<? extends K,? extends V> m)
      public static <K,V> SortedMap<K,V> unmodifiableSortedMap(SortedMap<K,? extends V> m)
      
  • Replace conditionals with polymorphism
    • With polymorphism, subclasses of a class possesses their own specific behaviors and share also some of the functionality of their parent class. Refactor conditionals, especially complex case statements with polymorphism design:
    • Bike myBike = new Bike();
      String bikeType = "default";
      witch(myBike.getTireWidth()) {
       case 23 : 
        if (myBike.getSuspension().compareToIgnoreCase("Simple") == 0) {
         bikeType = "Road bike";
        }
       break;
       default : 
        if (myBike.getSuspension().compareToIgnoreCase("Dual") == 0) {
         bikeType = "Mountain bike";
        }
       break;
      }

             ⇒

      public class MountainBike extends Bicycle {
          private String suspension;
      
          public MountainBike(
                     int startCadence,
                     int startSpeed,
                     int startGear,
                     String suspensionType){
              super(startCadence,
                    startSpeed,
                    startGear);
              this.setSuspension(suspensionType);
          }
      
          public String getSuspension(){
            return this.suspension;
          }
      
          public void setSuspension(String suspensionType) {
              this.suspension = suspensionType;
          }
      } 
      
      public class RoadBike extends Bicycle{
          private int tireWidth;
      
          public RoadBike(int startCadence,
                          int startSpeed,
                          int startGear,
                          int newTireWidth){
              super(startCadence,
                    startSpeed,
                    startGear);
              this.setTireWidth(newTireWidth);
          }
      
          public int getTireWidth(){
            return this.tireWidth;
          }
      
          public void setTireWidth(int newTireWidth){
              this.tireWidth = newTireWidth;
          }
      }
      
  • Separate routines whose behavior depends on parameters passed in
    •  If you have a method which executes different statements based on a particular parameter value, figure out if you can break the method into separate ones without passing the parameter in question.
  • Encapsulate downcasting
    • Objects returned by a method should use the most specific type possible. 
    • public class A {
       public String doSomething() {
        return "Do something.";
       }
      }
      
      public class B extends A {
       public String doSomethingMoreSpecific() {
        return "Do something more specific.";
       }
      }
      
      public class DownCast {
      
       private List<A> list;
       
       public List<A> getList() {
        return list;
       }
      
       public List<B> getMostSpecificList() {
        return (List<B>) (List<?>) list;
       }
        
       public void setList(List<A> list) {
        this.list = list;
       }
      
       public DownCast() {
        list = new ArrayList<A>();
        for (int i=0;i<10;i++) {
         list.add(new B());
        }
       }
      
      }
      
      public static void main(String[] args) {
        
       DownCast obj = new DownCast();
       List<A> listOfA = obj.getList();
       System.out.println(listOfA.get(0).doSomething());
         
       List<B> listOfB = obj.getMostSpecificList();
       System.out.println(listOfB.get(0).doSomethingMoreSpecific());
          
      }
      
  •  Extract specialized code into a subclass
    • Refactor specialized code into specific own subclasses if the code in question is only used in a subset of initial classes.
  •  Hide a delegate
    •  If Class A calls B then C while A was supposed to only call B and B calls C, then dissociates C from A and have B calls C only.
  •  Remove a middle man
    • On the other hand, if you think that A should call C directly as long as the role of B is still clearly defines, does not have overlap with C and can be used independently of C.
  •  Encapsulate unused methods
    • Create new interfaces for the most common used set of methods
    • public class Bird {
       
       private String species;
       private String eggColor;
       private String food;
       private int flySpeed;
       private int flyHeight;
       private String dragType;
       private String wingType;
       
       public String getSpecies() {
        return species;
       }
       public void setSpecies(String species) {
        this.species = species;
       }
       public String getEggColor() {
        return eggColor;
       }
       public void setEggColor(String eggColor) {
        this.eggColor = eggColor;
       }
       public String getFood() {
        return food;
       }
       public void setFood(String food) {
        this.food = food;
       }
       public int getFlySpeed() {
        return flySpeed;
       }
       public void setFlySpeed(int flySpeed) {
        this.flySpeed = flySpeed;
       }
              ...
      }

             ⇒

       
      public interface BirdFlight {
       public int getFlySpeed();
       public void setFlySpeed(int flySpeed);
       public int getFlyHeight();
       public void setFlyHeight(int flyHeight);
       public String getDragType();
       public void setDragType(String dragType);
       public String getWingType() ;
       public void setWingType(String wingType);
      }
      
      public class Bird implements BirdFlight {
       
       private String species;
       private String eggColor;
       private String food;
       
       public String getSpecies() {
        return species;
       }
       public void setSpecies(String species) {
        this.species = species;
       }
       public String getEggColor() {
        return eggColor;
       }
       public void setEggColor(String eggColor) {
        this.eggColor = eggColor;
       }
       public String getFood() {
        return food;
       }
       public void setFood(String food) {
        this.food = food;
       }
       
       @Override
       public int getFlySpeed() {
        ...
       }
       @Override
       public void setFlySpeed(int flySpeed) {
        ...
       }
       @Override
       public int getFlyHeight() {
        ...
       }
       @Override
       public void setFlyHeight(int flyHeight) {
        ...
       }
       ...
        
      }
      
  •  Duplicate data you can't control
    • As long as layering principles are not violated, wrap or access data maintain by the system via a consistent way/interface/API. A typical examples is data shares in GUI control in the front-end layer. Try to find a way to copy/mirror the data in question and treat it as reference source of data.

Friday, May 17, 2013

Advanced UML Sequence Diagrams


A Sequence Diagram is a type of UML Interaction Diagram that is used to model objects that need to pass messages to accomplish a task.

The messages are usually defined in the order of the execution.

Objects interactions can include:
  • creation and termination
  • requests
  • invoke object operations
  • notifications
In the very simple sequence diagram below, a user sends a query to a health IT application that retrieve a clinical document to an XDS Repository. The clinical data is returned back to the user (an actor in this type of diagram).

Object colors can indicates a different scope between objects (e.g gray here indicate a component that is part of a different sub-system, or out-of-scope for the current document or release etc).
























Lifelines are vertical dashed lines with the object positioned at the top.  

Messages are horizontal lines with arrows pointing in the direction in which the message is sent with annotation (method, parameters, arguments, return value, type of control flow etc ...)










































UML 2.0 has two forms of messages:
  • operation call : the invocation of an operation of a receiving object (either synchronous or asynchronous)
  • signal : a message object sen out by one object and handle by another one (always asynchronous)




Synchronous messages usually have solid arrows (by the way, in the tool I use, return synchronous messages for not have a solid arrow). Asynchronous message use dashed arrows.


















An interaction operand is a container that groups the interaction fragments and uses an optional guard expression or interaction constraint. When the guard condition is not present, the interaction is always executed.

Interaction operators include:
  • Alternative (alt) 
  • Option (opt) : 
  • Break (break) :
  • Parallel (par)
  • Loop (loop)  
  • Critical (critical) or (region)
  • Negative (neg)
  • Assertion (assert)
  • Strict Sequence (strict)
  • Weak Sequence (seq)
  • Ignore (ignore)
  • Consider (consider)
Lets consider a simple alternative (alt) operand.

Imagine that in the initial sequence diagram, that we want to request a document, we request a clinical document from an external source (CCD producer system).

In this case, the first thing is to add a combined fragment on top of the existing diagram, and choose the alt type:
































Then conditions are added (if and else equivalent):






























Then you can add the new alternative message (to the external CCD producer system) and re-organize the layout of the diagram : placing the combined fragment below the incoming message and moving the else clause separation (dotted line) below the first alternative (accessing the XDS repository). In my tool, you can use ALT-Left-Mouse click for this:









There are numerous UML modeling tools available (commercial or free). For his post, I used Enterprise Architect.

Thursday, March 28, 2013

Richfaces Ajax CDI Push and JBoss



You may not know it, but when you go to a restaurant, you most likely to be served via a method called service à la russe (service in the Russian Style). This is in contradiction to the much older traditional service à la française (service in the French Style).

In the original French Style, all the food was brought from the kitchen into the dining room of the aristocrats or high clergy and served all at once. Then the cooks who lost their jobs during the French revolution, end-up opening places call restaurants to make a living when common people could come to eat and relax (from the verb se restaurer in French), meaning "to restore itself".

French serving style remains in some high class restaurants where small tables or guéridons are moved close to the guest's table where the food preparation is completed and served.



The buffet is a variation of the French Style where the guests help themselves from the table (in French it is traditionally a piece of furniture that looks like a table with drawers called in fact buffet).











On the other hand, the Russian Style that comes from Russia was introduced in the French restaurants during the 19th century where courses are brought to the table sequentially by the waiter. This is now the style in which most modern western restaurants serve food (with some significant modifications).

The place setting (called a cover) for each guest includes a service plate, all the necessary cutlery except those required for dessert, and stemmed glasses for water, wines and champagne

Guests immediately remove their napkins and place them in their laps.

The rule is as such: a filled plate is always replaced with an empty one, and no place goes without a plate until just before the dessert course.

Directly before dessert everything is removed from the place settings but the wine and water glasses. Crumbs are cleared and dessert is served.

As you can see, both styles have very precise rules and mechanisms that must be followed to ensure the best service.




Richfaces itself offers several Ajax server-side push mechanisms to bring data from the server to the client.

Interesting to point-out by the way, that a waiter in french is called "un serveur" (someone who serves) and that the same word is used to design a server in computer science.

These three Ajax Push methods are:
  • TopicsContext - accesses a RichFaces message queue directly
  • Push CDI - uses the CDI Event mechanism to fire messages
  • Push JMS - the RichFaces Push consumes messages from an enterprise messaging system and exposes them to the client (tightly coupled with the JMS runtime) 
In a previous article I was explaining how RichFaces Extended Data Tables can be enhanced.

In this article, I will describe how Richfaces Ajax Push CDI can be implemented and deployed specifically on a JBoss container (I am using JBoss application server 7.0)



The Richfaces showcase describes well as usual the java and JSF code needed to implements the CDI Ajax Push.  One thing though, the Push JMS mechanism in not explicated in the show case, but described in the chapter 3 of the documentation.

First what does CDI means?

If you look at your project  facets (I am using Eclipse IDE), you will see that CDI stands for Context and Dependency Injection.

Container/Context Dependency Injection in Java EE 6 decouples the processing threads of  event producers and event consumers by using the Observer pattern in the form of event broadcasting.

An event in CDI is just a regular POJO that can be fired by any class through the use of the Event implementation injected automatically by the container via the @Inject annotation.







 

import java.io.Serializable;

import javax.enterprise.context.RequestScoped;
import javax.enterprise.event.Event;

import javax.inject.Inject;
import javax.inject.Named;

import org.richfaces.cdi.push.Push;

@Named
@RequestScoped
public class PushCdiBean implements Serializable {

 private static final long serialVersionUID = 6414191802542861042L;
 public static final String PUSH_CDI_TOPIC = "pushCdi";
 private String message = "";

 @Inject
 @Push(topic = PUSH_CDI_TOPIC)
 Event<string>pushEvent;
 
 
 public void sendMessage() throws Exception {
  if (pushEvent == null) {
  } else {
   pushEvent.fire(message);
  }
  message = "";
 }

 public String getMessage() {
  return message;
 }

 public void setMessage(String message) {
  this.message = message;
 }
}

If you download the source code of the Richfaces showcase (I am using richfaces-4.3.1.Final), you will see that the readme file located under .\richfaces-4.3.1.Final\examples\richfaces-showcase describes useful steps necessary to deploy the sample application on various containers, including JBoss.



First, you need your Maven pom file to have both the Java API CDI and the atmosphere dependencies:
<dependency>
 <groupId>javax.enterprise</groupId>
 <artifactId>cdi-api</artifactId>
 <version>1.1-20130222</version> 
</dependency>
<dependency>
 <groupId>org.atmosphere</groupId>
        <artifactId>atmosphere-runtime</artifactId>
        <version>1.0.10</version>
</dependency>

To be able to inject your CDI bean, your WEB-INF folder needs to contain a bean.xml file:

<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:weld="http://jboss.org/schema/weld/beans" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://docs.jboss.org/cdi/beans_1_0.xsd http://jboss.org/schema/weld/beans http://jboss.org/schema/weld/beans_1_1.xsd"> </beans>

On your deployment platform, you need JBoss standalone configuration located in .\standalone\configuration\standalone-full.xml to have a JMS topic that match your Push CDI topic:


<jms-destinations>
 <jms-queue name="testQueue">       
  <entry name="queue/test"/>  
  <entry name="java:jboss/exported/jms/queue/test"/>
        </jms-queue>  
 <jms-topic name="pushCdi">
         <entry name="topic/pushCdi"/>  
 </jms-topic>     
</jms-destinations>


You also need to start the JBoss server in full configuration:























Another necessary step is  to create the JMS user account/password:

























From there, you should be able to test your Ajax CDI push application. In my case, the consumer is a popup window that I launch by clicking a button (see code below):

Producer code:

<ui:define name="body">
 <h:form id ="from">
  <a4j:commandButton value="Message Consumer"
   oncomplete="#{rich:component('cdi_message_consumer_popup')}.show();" />
  <h:panelGrid columns="4">
   <h:outputLabel value="Message:" />
   <h:inputText id="messageInput" value="#{pushCdiBean.message}"/>
   <a4j:commandButton value="Send" 
    action="#{pushCdiBean.sendMessage}"
    execute="@form" 
    render="messageInput" 
    oncomplete="#{rich:element('messageInput')}.value=''"/>
  </h:panelGrid>
 </h:form>
 <ui:include src="rf_ajax_push_consumer_popup.xhtml" />
</ui:define>

Consumer code:

<rich:popupPanel 
 id="cdi_message_consumer_popup" 
 modal="false"
 resizeable="false" top="100" 
 left="300" 
 autosized="true"
 domElementAttachment="parent">
 <f:facet name="header">
  <h:outputText value="Ajax Push/CDI Message Consumer    " />
 </f:facet>
 <f:facet name="controls">
  <h:outputLink value="#"
   onclick="#{rich:component('cdi_message_consumer_popup')}.hide(); return false;">
   <h:outputText value="X" styleClass="textHeader" />
  </h:outputLink>
 </f:facet>
 <h:form>
  <h:panelGrid columns="3">
   <a4j:push address="pushCdi" 
    onerror="alert('error: ' + event.rf.data)"
    ondataavailable="jQuery('<li />').prependTo('#messages').text(event.rf.data)">
   </a4j:push>
   <ul id="messages" />
  </h:panelGrid>
 </h:form>
</rich:popupPanel>















The message (simple string) is send to the server and pushed back to the browser. The original message is then cleaned:
















A big thank to my colleague Asha Ambikavijayakumaran for figuring out all the tricky details for the JBoss deployment for this Richfaces showcase!


All ingredients and open source code related to this recipe can be found at YummyCode on the JSF Plate project.





Saturday, February 9, 2013

Advanced RichFaces Extended Data Tables

 
With Mardi Gras and Carnival around the corner, this is crêpe season!

This post is the first of a set of recipes that describe useful tips and reusable code and patterns related to Java, JSF 2.0 and RichFaces 4.0.  In this article I am describing practical integration code when using advanced Richfaces Extended Data Tables.

The RichFaces showcase describes well how to start creating your own extendedDataTable. However, here are some additional personal ingredients that can be very handy when preparing an appealing stack of JSF based web pages.





1) Setting your Table

The first time your try to put together a RichFaces extendedDataTable, you might encounter the following behavior: your table does not look like as you expected it: columns have a default size (the length of the label) and the whole size is the size of your whole window, so you end up with a large white space where they are no columns:


 One reason could be that no column or table size has been specified:


 <rich:extendedDataTable id="table" value="#{countries.countryItems} var="country" >
    <f:facet name="header">
        <h:outputText value="Countries" />
    </f:facet>
    <rich:column>
        <f:facet name="header">
            <h:outputText value="Name" />
        </f:facet>
        <h:outputText value="#{country.name}" />
    </rich:column>
    <rich:column>
        <f:facet name="header">
            <h:outputText value="Capital" />
        </f:facet>
        <h:outputText value="#{country.capital}" />
    </rich:column>
    <rich:column>
        <f:facet name="header">
            <h:outputText value="Language(s)" />
        </f:facet>
        <h:outputText value="#{country.languages}" />
    </rich:column>
</rich:extendedDataTable>


One way to quickly fix this is to assign specific sizes to your columns and headers (in my case these are absolute values in pixels and have adjusted the values to take into account the height of a row and the presence of a vertical scroller).  I have also added single selection mode so I can click on a row to retrieve more information about a certain item:

<rich:extendedDataTable id="table" value="#{countries.countryItems}"
    var="country" selection="#{countries.selection}" 
    style="height:190px; width:503px;"
    selectionMode="single">
    <a4j:ajax execute="@form" event="selectionchange" listener="#{countries.selectionListener}"/>
        <f:facet name="header">
            <h:outputText value="Countries" />
        </f:facet>
        <rich:column width="100px">
            <f:facet name="header">
                <h:outputText value="Name" />
            </f:facet>
            <h:outputText value="#{country.name}" />
        </rich:column>
        <rich:column width="100px">
            <f:facet name="header">
                 <h:outputText value="Capital" />
            </f:facet>
            <h:outputText value="#{country.capital}" />
        </rich:column>
        <rich:column width="300px">
            <f:facet name="header">
                <h:outputText value="Language(s)" />
            </f:facet>
            <h:outputText value="#{country.languages}" />
        </rich:column>
</rich:extendedDataTable>
















2) Interaction improvements

Let say now that you want to add a button to load or refresh the information in the table and that this takes some time because you are connected to a remote service. You may want to show to the end-user an indicator that some processing or data retrieval is happening (for this example, I added a waiting function in the iem list bean to simulate a few seconds wait).

I propose to use an animated GIF and take advantage of the RichFaces a4j:status (an indicator of an Ajax request. It has two states: start and stop. The start state indicates that an Ajax request is in progress. When an Ajax response is returned, the component switches to the stop state).

In this case, I refer to a4j:status every time I click on the refresh button to download the countries statistics. I have also added an animated GIF file called processing.gif in my webapp/img folder and top aligned both the button and the ajax indicator into a JSF panel grid:


<h:panelGroup>
    <h:panelGrid columns="2" columnClasses="alignTop, alignTop">
        <a4j:commandButton value="Refresh" status="refreshTable"
     oncomplete="#{countries.refresh()}" />
        <a4j:status name="someProcessing">
            <f:facet name="start">
         <h:graphicImage value="/img/processing.gif" />
     </f:facet>
        </a4j:status>
    </h:panelGrid>
</h:panelGroup>

As a result, the processing indicator appears next to the button when it is clicked and disappear after the table has been refreshed.


















In fact, you can use the same indicator when selecting a row to display detailed information about an item if the retrieval of the additional information takes too long for the user (e.g. more than a couple of seconds):


<a4j:ajax execute="@form" event="selectionchange" status="someProcessing" listener="#{countries.selectionListener}" />


3) Adding some coloring and flavor

If you don't have a predefine look and feel (e.g. a reusable template or UI toolkit), you can easily use the themes and skins that come with RichFaces.  A skin can be quickly added to the web.xml file as follow:


<context-param>
    <param-name>org.richfaces.skin</param-name>
    <param-value>wine</param-value>
</context-param>

Some of my favorites predefined skins are deepMarine and wine:

 
















4) The missing ingredients

Even though the RichFaces Extended Data Tables have a lot of features such as filtering, sorting, scrolling, frozen columns, here are always missing ingredients that you would like to use to offer a better experience to the end user. One that you will not find in the ExtendedDataTable is the wrapping of text in a column or a robust column horizontal scrolling. Hopefully this feature will be added in future release.


5) Always give a tip if you can

Offering tips is generally a good practice. It makes feel everybody happy: the person who provides it knowing that he/she has done a good job, and the end-user who enjoys it and saves time using them.

In this example, I have added a column to to indicate which countries have a GDP above one Trillion US Dollars. When the use hovers the mouse above the checkbox or the name of the country, a tooltip appears and shows the GDP number for the selected country.

















Tooltips can be easily added as follow:

<rich:column styleClass="#{msg.status}" width="35px">
    <f:facet name="header">
        <h:outputText value="GDP > $1T" />
    </f:facet>
    <rich:tooltip mode="client" target="largeGDPCountry">
        <h:outputText value="#{country.name} - 2011 GDP: #{country.gdp} > $1T" />
    </rich:tooltip>
    <h:graphicImage id="largeGDPCountry" value="/img/checkmark.png" rendered="#{country.largeGdp}" alt="GDP" />
</rich:column>
<rich:column width="100px">
    <f:facet name="header">
        <h:outputText value="Name" />
    </f:facet>
    <h:outputText id="countryName" value="#{country.name}" />
    <rich:tooltip mode="client" target="countryName">
        <h:outputText value="#{country.name} - 2011 GDP: #{country.gdp} $M" />
    </rich:tooltip>
</rich:column>


Ingredients and open source code related to this recipe can be found at YummyCode on the JSF Plate project.