Category Archives: java

JSF – RequestScoped CDI Beans and Imixs-Workflow

You can use Imixs-Workflow with a RequestScoped CDI Bean in JSF easily. The thing which is important is that you add two hidden fields into your form containing the $uniqueid and $version.

<!-- Workflow Events -->
 <ui:repeat var="event" value="#{workflowController.events}">
 <h:commandButton action="#{workflowController.process}"
 value="#{event.item['txtname']}">

 <f:setPropertyActionListener
 target="#{workflowController.workitem.item['$ActivityID']}"
 value="#{event.item['numactivityid']}" />

 </h:commandButton>
 </ui:repeat>
 <h:inputHidden value="#{workflowController.workitem.item['$uniqueid']}" />
 <h:inputHidden value="#{workflowController.workitem.item['$version']}" />

This mechanism ensures that the form can not be posted back to the server if the workitem was processed in the meantime. This situation can occur if the user opens the same workitem in multible browser tabs and tries to submit the same workitem form different tabs without refreshing the content. It also secures the situation when the user opens different worktiems in different tabs and tries to submit.

The Imixs-JSF project still uses ConversationScoped CDI Beans. The reason is an issue with the fileUploadController. But I think we will got back to RequestScoped also for the workflowController CID Bean in the future.

Deploy Gitbucket on Wildfly

When trying to deploy the Gitbucket project into wildfly I go tthe following error message:

WARN [org.jboss.modules] (ServerService Thread Pool -- 81) Failed to define class liquibase.serializer.core.yaml.YamlSerializer$LiquibaseRepresenter in Module "deployment.gitbucket.war:main" from Service Module Loader: java.lang.NoClassDefFoundError: Failed to link liquibase/serializer/core/yaml/YamlSerializer$LiquibaseRepresenter (Module "deployment.gitbucket.war:main" from Service Module Loader): org/yaml/snakeyaml/representer/Representer ...

This is a known issue and discussed here.

You can fix it if you add the file ‘jboss-deployment-structure.xml’ into the WEB-INF/ folder with the following content:

<jboss-deployment-structure>
  <deployment>
    <dependencies>
      <system export="true">
        <paths>
          <path name="com/sun/net/ssl/internal/ssl" />
          <path name="com/sun/net/ssl" />
        </paths>
      </system>
      <!-- add snakeyaml dependency -->
      <module name="org.yaml.snakeyaml"/>
    </dependencies>
  </deployment>
</jboss-deployment-structure>

How to install:

The following is a short install guide how to modify the gitbucket.war downloaded form the project release page:

1.) Download latest version from release page:

wget https://github.com/gitbucket/gitbucket/releases/download/4.7.1/gitbucket.war

change the version if needed

2.) unzip the war file

unzip gitbucket.war -d tmp/gitbucket.war

3.) create the ‘jboss-deployment-structure.xml’ file and add the content as explained above. Than copy the file into the WEB-INF folder

cp jboss-deployment-structure.xml /tmp/gitbucket.war/WEB-INF/

4.) create the doDeploy file

touch tmp/gitbucket.war/gitbucket.war.dodeploy

5.) start deployment by moving the folder to the wildfly deploy directory

cd tmp/
mv gitbucket.war /opt/wildfly/standalone/deployments/

Install Script

You can use also my install script from here to install gitbucket on Wildfly 9.x & 10.x under Linux.

/bin/bash wildfly-install.sh [INSTALLDIR] [GITBUCKET-VERSION]

You can specify the install directory of your wilfly installation and the gitbucket version.

Example:

/bin/bash wildfly-install.sh [INSTALLDIR] [GITBUCKET-VERSION]

Note: The script must be run as root. The script assumes that wildfly is running with the user ‘wildfly’. You can change this in your script if needed.

Why we should secure Business Objects?

Most applications deal with security in a functional way. This means that a business application typically defines different functional roles which are mapped to different users. For example let’s look on a simple Ordering System. In an Ordering System we will have roles like

  • Order-Creator‘ – creating the order
  • Order-Approver‘ – validating and approving
  • Order-Executor‘ – execution

These roles are typical for such an business application and mostly tightly coupled to the corresponding business methods – e.g. createOrder(), approveOrder() and executeOrder(). This works well in a monolithic business application where we can control the security layers as also the business logic. But as more complex the business application becomes, also the enclosed security becomes more complicated. For modern application design in addition we often have to deal with external web services and business logic which need to be adapted easily to changing requirements. So this static security model leads into a hell of hard coded business rules or, what is worse, can no longer guarantee the security. Continue reading

JPA and @OneToMany – How to Optimize?

In this article I want to explain an issue concerning the JPA OneToMany relationship which I was faced with in one of my own projects. Working with object -orientated languages like java we often model relationships between object in various cases. One of such relationships is the OnToMany relationship. For example an object ‘Server’ may have a relationship to an object ‘Configuration’. To make the ‘Configuration’ object generic we can model the JPA object in Java like this:

@javax.persistence.Entity
public class Configuration implements java.io.Serializable {
 private static final long serialVersionUID = 1L;

 @Id
 @GeneratedValue
 private BigInteger id;

 public String itemValue;
 public String itemName;

 @SuppressWarnings("unused")
 private Configuration() {
 }

 public Configuration(String name, String value) {
 itemValue = value;
 itemName = name;
 }
}

Continue reading

Microservices, Verticals and Business Process Management?

If you think about modern architecture, you will possibly find that one of the best solution (for the moment) seems to be a microservice architecture. Microservices are a quite different approach as we followed in the past, where we often designed monolithic enterprise applications. In a monolithic application context a single software system is encapsulating the business-logic, the database-layer and the UI components. The Java EE architecture provides a perfect framework to build such kind of applications to be deployed and executed in a scalable and transactional application server environment.

microservices_verticals_bpm-00

But monolithic enterprise applications are sometimes difficult to maintain, even if only little changes need to be made to one of its components. This is one reason why the idea came up to split a monolithic application block into several microservices.

One of the question is, how to change the architecture from a monolith approach to a modern service based architecture? A good overview what this means can be read in Christians Posta’s Blog.

Vertical Services

At the first look it seems to be easy to separate business logic into isolated services. But often this approach ends with a closely spaced set of microservices, which are not really loose coupled. One of the reasons can be the database layer which survives as a monolithic block behind all the new microservices. This happens when we think that database objects are related to each other. And this is only a very realistic picture of our real business world. But this creates complex synchronization points between all of our services and teams and you have to coordinate all of the changes in the database layer. Often a database change caused by one service affects also other services.

microservices_verticals_bpm-01

One solution to solve this problem can be, dividing the functionality into cohesive “verticals”, which are not driven by technical or organizational aspects. Each vertical will have its own “business logic”, “database” and an optional “UI component”. With  this approach, we don’t need to re-deploy the entire monolithic business-service tier, if we made changes to a single database object or a functionality of one of these verticals. Ideally, a single team can own and operate on each vertical as well.

microservices_verticals_bpm-02

 

Usually, it is recommended to control the synchronization between the services by sending events. The approach behind this idea is the “Reactive Programming” style. The communication between the services is realized in an asynchronous way . So the business logic of one service layer did not depend on the result of another service layer. A service may or may not react on a specific event. And this is the idea of loose coupling.

But does this fit your business requirements?

The “Business Process Service Architecture”

One problem with decoupling the business logic into separate services is the fact, that there still exists an “Over-All-Business-Logic” behind all these services. This is known as the “Business Process.” If, in our example above, the Order-Service, Invoice-Service and Logistic-Service are implemented as separate building blocks, there is still the general bussiness process of the “Ordering-Management” in the background defining states and business rules. For example if a product is ordered by a customer (Order-Service) the product may not be shipped (Logistic-Service) before an invoice was sent to the customer (Invoice-Service). So it is not sufficient, if the Invoice-Service and the Logistic-Service react asynchronously on a new event, triggered by the Order-Service, without reflecting the business process.

What we can do now, is defining separate events indicating each phase in the Order-Management-Process. For example the Order-Service can send an “Order-Ready-For-Invoice-Event” to signal that the invoice need to be send. And a new “Order-Ready-For-Shipment-Event” can be triggered by the Invoice-Service to indicate that the invoice for the order was sent to the customer and the product can be shipped. But now we have again created the same problem as we had before with the common database. We couple our services via specific event types which are reflecting our business process. The business process is now spread across various services.

To avoid this effect of tightly coupled services we can separate the business process itself as a service. This means that we move the Over-All-Business-Logic out of our services and provide a separate new service layer reflecting only the business process.

Business-Process-Service-Architecture

I will call this a “Business-Process-Service-Architecture”. In this architecture style each service layer depends on the business-process-service.  Events are sent only between a vertical and the Business-Process-Service layer. Our Order-Service, Invoice-Service and Logistic-Service may or may not react on those process events. The advantage of this architecture is, that we now have one service which controls the ordering management process and is reflecting the state for each process instance. Each vertical can call the business-service layer to query the status of the Over-All-Business-Process and also use these workflow information for further processing. Also we can change our business process independent from our vertical service layers.

BPMN 2.0 and Workflow Engines

One of the most common technologies to describe a business process is the ‘Business Process Model and Notation’ – BPMN 2.0 standard. BPMN was initially designed to describe a business process without all the technical details of a software system. A BPMN diagram is easy to understand and a good starting point to talk about a business process with technician as also with management people. Beside the general description of a business process, a BPMN model can also be executed by a process or workflow engine. The Workflow Management System controls each task from the starting point until it is finished. So based on the model description the workflow engine controls the life-cycle of a business process. An example of a workflow engine which can be integrated into a Business Process Service Architecture is the Open Source project Imixs-Workflow.

Beside the general control of the business process, our new service can also collect any kind of meta information from our verticals. The service becomes the central information point in our microservice architecture. We can now change our business process model and integrate new verticals without affecting existing implementations. We have finally decoupled our services. This is one of the most important effects you can achieve with this architecture style.  In a future article I will show an example how to integrate a Business Process Service based on a RESTfull service interface.

WildFly Undertow – How to Configure a Request Dump

If you need to debug the request headers send to Wildfly application server you can configure a Request-Dumper. There for change the standalone.xml file and add a filter-ref and filter configuration into the subsystem section of undertow. See the following example:

... 
<subsystem xmlns="urn:jboss:domain:undertow:2.0">
....
 <server name="default-server">
       ...
      <host name="default-host" alias="localhost">
          .....
          <filter-ref name="request-dumper"/>
      </host>
 </server>
....
<filters>
    .....
    <filter name="request-dumper" class-name="io.undertow.server.handlers.RequestDumpingHandler" module="io.undertow.core" />
</filters

This will print out all the request information send by a browser.

Wildfly and MVC 1.0 Ozark

I just started to build a new Java EE Web Application based on the new MVC 1.0 Framework which will become part of Java EE8. I tried to run the application on Wildfly 9.0.2.

Setup a Maven Project

To setup a MVC 1.0 Web Application with maven seems to be quite simple. I Just added the following dependencies into my pom.xm :

 <!-- MVC 1.0 dependencies -->
 <dependency>
   <groupId>org.glassfish.ozark</groupId>
   <artifactId>ozark</artifactId>
   <version>1.0.0-m02</version>
   <scope>compile</scope>
 </dependency>
 <dependency>
   <groupId>org.glassfish.jersey.containers</groupId>
   <artifactId>jersey-container-servlet</artifactId>
   <version>2.22</version>
 </dependency>

As ozark is based on jersey we need the jersey-container-servlet. As ozark is based on Java 8 it is also necessary to start Wildfly with JDK 8. Otherwise the war file can not be deployed.

The application class

Next I added an application class with a resurce mapping /api/

@ApplicationPath("api")
public class MyApplication extends Application {
}

This class is necessary to call the application URL like

/myapp/api/hello?name=xx

Here is my controller class:

@Path("hello")
public class HelloController {
 @Inject 
 private Greeting greeting; 
 private static Logger logger = Logger.getLogger(HelloController.class.getName());

 @GET
 @Controller
 @View("/pages/hello.xhtml")
 public void hello(@QueryParam("name") String name) {
 logger.info("set new message: "+name);
 greeting.setMessage("Hello "+name);
 }
}

On the first look the conroller is triggered. But currently I am not able to return the target page (in my example /pages/hello.xhtml)

The reason seems to be that the jersey servlet container will not replace the resteasy implementation for the application.

Maybe someone knows how to solve this problem?

Wildfly – HeapSize

The default memory setting for Wildfly are not very high and can be to less for deployed applications. The default VM settings are typically:

  • -Xms64m
  • -Xmx512m
  • -XX:MaxPermSize=256m

For production mode this can be increased by editing the “bin/standalone.conf” file. To increase the memory size from 512MB to 2GB change the following line from:

JAVA_OPTS="-Xms64m -Xmx512m -XX:MaxPermSize=256m -Djava.net.preferIPv4Stack=true"

into

JAVA_OPTS="-Xms2048m -Xmx2048m -XX:MaxPermSize=256m -Djava.net.preferIPv4Stack=true"

The settings depend on the applications deployed on wildfly.