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====== WildFly ======

===== Installation =====

Download from http://www.wildfly.org

Untar to ''/opt'' and create a symlink to ''/opt/wildfly''.

<code bash>
# separate user for running WildFly
sudo adduser --system wildfly
sudo addgroup --system wildfly
sudo usermod -g wildfly wildfly # set primary group of user wildfly to group wildfly

# set owner of symlink & all WildFly files to wildfly
sudo chown --no-dereference wildfly:wildfly /opt/wildfly
sudo chown -HR wildfly:wildfly /opt/wildfly
</code>

Start WildFly (optionally with [[https://docs.jboss.org/author/display/WFLY8/Command+line+parameters|command line parameters]])
<code bash>
sudo -u wildfly /opt/wildfly/bin/standalone.sh
</code>



===== Configuration =====

==== standalone.conf ====

''/opt/wildfly/bin/standalone.conf'':

Configure JVM arguments (e.g. ''-Xss'', ''-Xmx'') for standalone/server deployment. Note that when starting WildFly from Eclipse you need to configure these parameters in Eclipse!

It's also a good idea to explicitly set [[https://community.jboss.org/message/552982|UTF-8 as default]]:

<code>
JAVA_OPTS="$JAVA_OPTS -Dfile.encoding=UTF-8"
JAVA_OPTS="$JAVA_OPTS -Dsun.jnu.encoding=UTF-8"
</code>

==== System Service ====

=== systemd ===

Since Ubuntu 15.04 systemd replaced upstart as default init system.

Create the file ''/etc/systemd/system/wildfly.service'' and adapt the IP to the IP the service is publicly accessible with:

<code>
[Unit]
Description=WildFly
After=network.target

[Service]
Type=simple
User=wildfly
Group=wildfly
ExecStart=/opt/wildfly/bin/standalone.sh -b 127.0.0.1 -bmanagement 127.0.0.1

[Install]
WantedBy=multi-user.target
</code>

With ''WantedBy=multi-user.target'' we specify that we want to start WildFly after boot. For autostart to work we also have to enable the service:

<code bash>
sudo systemctl enable wildfly
</code>

Manually use / manage the service with:

<code bash>
sudo systemctl start wildfly
sudo systemctl stop wildfly
systemctl status wildfly
journalctl -f -u wildfly      # view log and follow it live
</code>

=== Upstart ===

Create ''/etc/init/wildfly.conf'' and adapt the IP to the IP the service is publicly accessible with:
<code>
start on (local-filesystems and net-device-up IFACE!=lo)

# stop on normal shutdown
stop on runlevel [016]

# -b binds the IP for port 8080, -bmanagement for port 9990
exec sudo -u wildfly /opt/wildfly/bin/standalone.sh -b 127.0.0.1 -bmanagement 127.0.0.1
</code>

The log ''/var/log/upstart/wildfly.log'' even includes system outs, messages printed from JNI code or crash / segfault information.

Optionally select a specific config, e.g. ''--server-config=standalone.xml'' or use port offset when running several instances of WildFly on one machine with ''-Djboss.socket.binding.port-offset=1''


Then start and stop WildFly with
<code bash>
sudo start wildfly
sudo stop wildfly
</code>


==== Enabling GZIP Compression ====

Go to the undertow subsystem configuration in ''/opt/wildfly/standalone/configuration/standalone.xml''.

Then add the gzip filter to the filter section and a filter-ref to host section under server, e.g.:

<code xml>
<subsystem xmlns="urn:jboss:domain:undertow:6.0" default-server="default-server" default-virtual-host="default-host" default-servlet-container="default" default-security-domain="other">
    <buffer-cache name="default"/>
    <server name="default-server">
        <http-listener name="default" socket-binding="http" redirect-socket="https" enable-http2="true"/>
        <https-listener name="https" socket-binding="https" security-realm="ApplicationRealm" enable-http2="true"/>
        <host name="default-host" alias="localhost">
            <location name="/" handler="welcome-content"/>
            <http-invoker security-realm="ApplicationRealm"/>
            <filter-ref name="gzipfilter" predicate="regex[pattern='text/html|text/css|application/javascript|application/json',value=%{o,Content-Type}] and max-content-size[value=1024]"/>
        </host>
    </server>
    <servlet-container name="default">
        <jsp-config/>
        <websockets/>
    </servlet-container>
    <handlers>
        <file name="welcome-content" path="${jboss.home.dir}/welcome-content"/>
    </handlers>
    <filters>
        <gzip name="gzipfilter"/>
    </filters>
</subsystem>
</code>

Source: http://mcaikovski.blogspot.com/2018/01/how-to-activate-gzip-compression-of.html

This will then work e.g. for welcome-content, which is static. For e.g. REST services look into http://docs.jboss.org/resteasy/docs/3.5.1.Final/userguide/html/gzip.html

==== Serving on Port 80/443 ====

Changing the default ports is easy. Look out for socket-binding in ''/opt/wildfly/standalone/configuration/standalone.xml'':

<code>
<socket-binding name="http" port="${jboss.http.port:80}"/>
<socket-binding name="https" port="${jboss.https.port:443}"/>
</code>

Note that serving on ports below 1024 requires root privileges. This means when manually starting WildFly you can start it with ''sudo'', but for a systemd service we need a different approach:

The safe way is to use ''setcap'' to allow ''java'' to bind ports but don't give it any more privileges. This must be done after every update of java!

<code bash>
sudo setcap cap_net_bind_service=+epi $JAVA_HOME/bin/java
sudo setcap cap_net_bind_service=+epi $JAVA_HOME/jre/bin/java
</code>

It is not recommended to simply use ''User=root'' in ''wildfly.service''.

==== Redirect HTTP to HTTPS =====

In ''/opt/wildfly/standalone/configuration/standalone.xml'' add the following configuration to automatically redirect e.g. from port 80 to https on port 443.

In subsystem (undertow) > filters add a redirect including your full domain name. The ''%U'' retains the rest of the URL.
<code>
<rewrite name="http-to-https" redirect="true" target="https://example.com:443%U"/>
</code>

..or if you do not need to retain the domain name you can replace it with the host ip (''%h'')

<code>
<rewrite name="http-to-https" redirect="true" target="https://%h:443%U"/>
</code>


In subsystem (undertow) > server > host add a reference to the filter. Adapt the predicate to your needs, the example only activates the filter when port 80 is accessed.
<code>
<filter-ref name="http-to-https" predicate="equals(%p,80)"/>
</code>

See the [[http://undertow.io/undertow-docs/undertow-docs-1.4.0/predicates-attributes-handlers.html|undertow documentation]] for more variables.

==== HTTPS & TLS Certificate ====

When using HTTPS you should most probably also provide a valid [[https://de.wikipedia.org/wiki/Transport_Layer_Security|TLS]] (aka SSL) certificate. Otherwise browsers tend to block access to your page or at least give a big warning that the page is not secure.

The certificate must be present in a Java Keystore file. Copy ''com.example.jks'' to ''/opt/wildfly/standalone/configuration''.

Then add the security-realm under management > security realms in ''/opt/wildfly/standalone/configuration/standalone.xml'':

<code>
<security-realm name="SslRealm">
    <server-identities>
        <ssl>
            <keystore path="com.example.jks" relative-to="jboss.server.config.dir" keystore-password="YOUR_PASSWORD"/>
        </ssl>
    </server-identities>
</security-realm>
</code>

 
And add this in subsystem (undertow) > server:

<code>
<https-listener name="default-ssl" socket-binding="https" security-realm="SslRealm" enable-http2="true"/>
</code>

Sources: http://reallifejava.com/configuring-ssl-in-wildfly-8, https://stackoverflow.com/questions/32008182/wildfly-9-http-to-https
==== Deployment / Management Website ====

By default port ''9990'' is used for deployment via the [[https://docs.jboss.org/wildfly/plugins/maven/latest|wildfly maven plugin]] and to access the web-based management interface.

For deployments to servers except ''localhost'' and to enter the management interface a 'Management User' in the 'ManagementRealm' is required:
<code bash>
sudo -u wildfly /opt/wildfly/bin/add-user.sh
</code>

This script creates an entry for each user in ''/opt/wildfly/standalone/configuration/mgmt-users.properties''.

Using Maven to deploy to WildFly/Jboss: [[maven#deploy_to_jboss]]

===== Database Connectivity (PostgreSQL) =====

To access a database, e.g. PostgreSQL, the driver dependency must not be included into the deployment itself but a data source must be configured within WildFly. Simply including the database dependency into your deployment opens a memory leak since they corresponding classes can not be removed by WildFly during un/redeploys of your project.


==== Configure a Datasource ====
An easy way configure the data source is to use the WildFly Managment web frontend (http://your-server:9990) to upload the [[https://mvnrepository.com/artifact/org.postgresql/postgresql|driver .jar]] and create a data source:
  - Deployments -> Add -> Upload a new deployment
  - Configuration -> Subsystems -> Datasources -> Non-XA

Then configure the data source:
  * make sure to use the full connection URL including the database name & that the user/password are correct
  * enable "validate-on-match" in "validation", which ensures the connection pool checks each connection and creates a new one if it is broken. This way we do not even notice restarts of the database server in our Java code. (see also http://stackoverflow.com/questions/28707650/wildfly-and-auto-reconnect-to-the-database)
  * limit the connection pool
  * test the connection in the "connection" tab

The data source configuration can also be found in ''/opt/wildfly/standalone/configuration/standalone.xml''.

More info in the [[https://docs.jboss.org/author/display/WFLY10/DataSource+configuration|official docs]]. 

==== Configure your Maven Build ====

Put the following configuration of the maven-war-plugin into the build/plugins section of your pom.xml:

<code>
<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-war-plugin</artifactId>
    <configuration>
        <archive>
            <manifestEntries>
                <!-- "The Dependencies manifest header is used to specify dependencies 
                    that a jar file has." (https://docs.jboss.org/author/display/MODULES/Manifest+module+information) 
                    Note that sql drivers must NOT be put in the war file (this is a source of 
                    memory leaks), so they are deployed directly to Wildfly, and they needed 
                    to be listed as application dependency here. -->
                <Dependencies>deployment.postgresql-9.4.1208.jar</Dependencies>
            </manifestEntries>
        </archive>
    </configuration>
</plugin>
</code>

==== Access the Datasource in Java ====

<code java>
@ApplicationScoped
public class DB {
    @Resource(mappedName = "java:/PostgresDS")
    private DataSource ds;

    boolean connectToDb(String userId) {
        try (Connection conn = ds.getConnection();
                Statement statement = conn.createStatement();
                ResultSet rs = statement.executeQuery("SELECT id FROM um_user WHERE id=" + userId)) {
            //...
        } catch (SQLException e) {
            //...
        }
    }
}
</code>

===== Logging =====
In jboss-cli you add new loggers and configure existing loggers using these commands

<code>
# create logger
/subsystem=logging/logger=at.ac.ait:add(level=DEBUG)

# set loglevel
/subsystem=logging/logger=at.ac.ait:write-attribute(name=level,value=ALL) 
# note that the "FINEST" level of java.util.logging maps only to level ALL (and not to TRACE)
</code>

To remove a logger:
<code>
/subsystem=logging/logger=at.ac.ait:remove
</code>


===== CDI =====
==== Alternatives ====
To specify an Alternative Implementation for a Bean and have it override the default implementation use: 

<code java>
import javax.annotation.Priority;
import javax.ejb.Stateless;
import javax.enterprise.inject.Alternative;


@Alternative
@Priority(1)
@Stateless
public class BetterMyBean  implements MyBean {
   ...
}

</code>


==== EventBus ====
CDI brings its own EventBus implementation. See https://docs.oracle.com/javaee/6/tutorial/doc/gkhic.html 

=== Simple Example ===


1. Define Dummy Event
<code java>
public class DummyEvent{}
</code>

2. Define Listener

<code java>
import javax.enterprise.context.ApplicationScoped;
import javax.enterprise.event.Observes;

@ApplicationScoped
public class DummyEventListener{
  public void myObserverMethod(@Observes DummyEvent e) { doSomethingWith(e);}
}
</code>

3. Fire Event
<code java>
import javax.inject.Inject;
import javax.enterprise.event.Event;
import javax.enterprise.context.ApplicationScoped;

@ApplicationScoped
public class Something {
  @Inject    
  private Event<DummyEvent> dummyEvent;

  public void someMethod() {
      dummyEvent.fire(new DummyEvent());
  }
}
</code>


Events seem to be processed syncronously. Asyncronous event processing can easily be enabled by defining an EventListener like this: 


<code java>
import javax.ejb.Asynchronous;
import javax.ejb.ConcurrencyManagement;
import javax.ejb.ConcurrencyManagementType;
import javax.ejb.Singleton;
import javax.enterprise.context.ApplicationScoped;
import javax.enterprise.event.Observes;

@ApplicationScoped
@Singleton
@ConcurrencyManagement(ConcurrencyManagementType.BEAN)
public class AsynchronousEventListener {

	@Asynchronous
	public void onEvent(@Observes DummyEvent e) {
		System.out.println("Got event and starting reeeeeally expensive computation ;) " );
		try {			
			Thread.sleep(10000);
			System.out.println("     DONE!" );
		} catch (InterruptedException e) {}	
	}
}

</code>



===== Gotchas =====

==== Managed Executor Service ====

The behaviour of executor services can be configured in (e.g.) ''/opt/wildfly/standalone/configuration/standalone.xml''.

The ''queue-length'' must be set explicitly:
<code>
<managed-executor-service name="default" jndi-name="java:jboss/ee/concurrency/executor/default" context-service="default" hung-task-threshold="60000" core-threads="2" max-threads="2" queue-length="1000" keepalive-time="5000"/>
</code>

Otherwise you will run into problems when submitting many tasks at once:
<code>
Caused by: javax.ejb.EJBException: java.util.concurrent.RejectedExecutionException: Task org.glassfish.enterprise.concurrent.internal.ManagedFutureTask@6e36d5b6 rejected from org.glassfish.enterprise.concurrent.internal.ManagedThreadPoolExecutor@6409b656[Running, pool size = 25, active threads = 25, queued tasks = 0, completed tasks = 12]
</code>
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