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(GAE-Standard+Java11) Sessions with multiple instances running

I have deployed my spring boot application on GAE, Java 11, Standard Environment. As per the documentation for Java11 we need to use app.yaml for configuring the instances.
I wanted to know as to how I can enable sharing of sessions between instances. As per my research, Earlier we could simply solve this problem by setting sessions-enabled and async-session-persistence in appengine-web.xml. With appengine-web.xml gone, what is the equivalent way of doing this in app.yaml.
Use case that i am trying to achieve is :
Using spring security (Unfortunately i get logged out when according to me the request of the same user goes to another instance.)
Storing the user retrieved from DB in a #SessionScoped variable so as to avoid multiple DB calls.
Any help here would be really appreciated. Thanks!

I went through a lot of documentation, but I believe that this is not inside the app.yaml configuration reference.
Alternatively, I could find that you could use session affinity in order to use a instance to reply always the requests of a same user, this can be enabled in your app you can use the next tag in your app.yaml according to this documentation.
network:
session_affinity: true
Hope this works for you.

Hazelcast Client Only Configuration

Is it possible to create a client only hazelcast node? We have hazelcast embedded in our Java Applications and they use a common hazelcast.xml. This works fine, however when one of our JVM's is distressed, it causes the other clustered JVM's to slow down and have issues. I want to run a hazelcast cluster outside of our application stack and update the common hazelcast.xml to point to the external cluster. I have tried various config options but the application JVM's always want to start a listener and become members. I realize I maybe asking for something that defeats the purpose of hazelcast, however I thought it may be possible to configure an instance to be a client only.
Thanks.

You can change your application to use Hazelcast client instances, but it requires a code change.
Instead of
HazelcastInstance hz = Hazelcast.newHazelcastInstance();
you'll need to initialize your instance by requesting a client one:
HazelcastInstance hz = HazelcastClient.newHazelcastClient();
Another option is to keep the code unchanged and configure your embedded members to be "lite" ones. So they don't own any partition (they don't store cluster data).
<hazelcast xmlns="http://www.hazelcast.com/schema/config"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.hazelcast.com/schema/config
http://www.hazelcast.com/schema/config/hazelcast-config-4.0.xsd">
<!--
===== HAZELCAST LITE MEMBER CONFIGURATION =====
Configuration element's name is <lite-member>. When you want to use a Hazelcast member as a lite member,
set this element's "enabled" attribute to true in that member's XML configuration. Lite members do not store
data and are used mainly to execute tasks and register listeners. They do not have partitions.
-->
<lite-member enabled="true"/>
</hazelcast>

Vertx Hazelcast: Cluster Problems

im working with Vertx and HazelCast to distribute my Verticles about the network.
No I have the problem, that my co-worker also uses clustered verticles with HazelCastManager.
Is there a possibility to avoid, that our verticles see each other to prevent by-effects?

You can define Hazelcast Cluster Groups in your cluster.xml file.
Here's the manual section related to it:
http://docs.hazelcast.org/docs/3.6/manual/html-single/index.html#creating-cluster-groups

If you use Multicast (default config) for discovery, you can redefine the groupname and password. Apart from that you can just choose any other option for discovery supported by the given Hazelcast version inside vert.x:
http://docs.hazelcast.org/docs/3.6/manual/html-single/index.html#discovering-cluster-members

Old question, but still valid, here's simple answer:
If you want to limit your vertx system to the single server, i.e. not have the eventbus leak out across your local network, the simplest thing to do is create a local copy of Hazelcast's cluster.xml on your classpath, i.e. copy/edit vertx source (see git):
vertx-hazelcast/src/main/resources/default-cluster.xml
into a new file in your vertx project
src/main/resources/cluster.xml
The required change is to the <multicast> stanza disabling that feature:
<hazelcast ...>
...
<network>
...
<join>
...
<multicast enabled="false">
...
</multicast>
<tcp-ip enabled="true">
<interface>127.0.0.1</interface>
</tcp-ip>

ActiveMQ Scheduler Failover with JDBC MasterSlave

I currently have a working two-broker JDBC MasterSlave configuration, and the next step for me is to implement a scheduler with failover. I've looked around and haven't seen any information about this, and was curious to see if this is possible or if I should try a different approach.
Currently, I have the two brokers using the same dataDirectory both within the broker tag and the JDBCPersistenceAdapter tag. However, within that data directory ActiveMQ creates two separate scheduler folders. I cannot seem to force it to use the same one, so failover with scheduling isn't working.
I've also tried the KahaDB approach with the same criteria, and that doesn't seem to work either.
Another option would be for the scheduler information to be pushed to the database (in this case, oracle) and be able to be picked up from there (not sure if possible).
Here is a basic overview of what I need:
Master and slave brokers up and running, using same dataDirectory (lets say, broker1 and broker2)
If I send a request to process messages through master at a certain time and master fails, slave should be able to pick up the scheduler information from master (this is where I'm stuck)
Slave should be processing these messages at the scheduled time
activemq.xml (relevant parts)
<broker xmlns="http://activemq.apache.org/schema/core" brokerName="b1" useJmx="true"
persistent="true" schedulerSupport="true">
<!-- kahaDB persistenceAdapter -->
<persistenceAdapter>
<kahaDB directory="{activemq.data}/kahadb" enableIndexWriteAsync="false"
ignoreMissingJournalfiles="true" checkForCorruptJournalFiles="true"
checksumJournalFiles="true"/>
</persistenceAdapter>
<!-- JDBC persistenceAdapter -->
<persistenceAdapter>
<jdbcPersistenceAdapter dataDirectory="{activemq.data}" dataSource="#oracle-ds"/>
</persistenceAdapter>
Can someone possibly point me in the right direction? I'm fairly new to ActiveMQ. Thanks in advance!

If anyone is curious, adding the schedulerDirectory property to the broker tag seems to be working fine. So my broker tag in activemq.xml now looks like this:
<broker xmlns="http://activemq.apache.org/schema/core" brokerName="broker1"
dataDirectory="{activemq.data}" useJmx="true" persistent="true"
schedulerSupport="true" schedulerDirectory="{activemq.data}/broker1/scheduler"/>

You have probably figured out what you need to do to make this work, but for the sake of other folks like me who was/is looking for the answer. if you're trying to make failover work for scheduled messages with the default kahaDb store (as of v 5.13.2) and a shared file system, you will need to do the following:
Have a folder in the shared file system defined as the dataDirectory attribute in the broker tag. /shared/folder in the example below
Use the same brokerName for all nodes in that master/slave cluster. myBroker1 in the example below.
Example:
<broker xmlns="http://activemq.apache.org/schema/core"
brokerName="myBroker1"
dataDirectory="/shared/folder"
schedulerSupport="true">

Commons configuration - JNDIConfiguration - How to?

I usually use Commons Configuration for manage my applications configs. I have used properties files configuration. Now I'm interested in using a JNDIConfiguration but I'm not able to understand how this works reading the documentation or googling it.
Contextualizing, I'm working in webapps running in an JBoss AS.
Where will be the properties stored? In a file? some tables in a database?
I will be grateful for any guidance at this level even if it comes in shape of links where I can read some valuable information about it.
As a final note my goal is to free me of linking a file with a hardcoded path for my properties, but also don't force me to have my config in database tables. If you have any suggestions on how to do that in some other way be free to share.

JNDIConfiguration looks up the configuration data on a JNDI server (in your case, the JBoss JNDI server). However, you still need a way of getting that data into the JNDI server in the first place, and Commons-Configuration won't help you with that.
It sounds to me that JNDI isn't what you want, it's just pushing the problem around a bit. JBoss still needs to store the configuration data somewhere, so you'll still have the same basic problem.
If you don't want hard-coded file paths, and you don't want a database, then I suggest you pass in the location of the properties file via a system property, e.g.
java -Dmy.config.path=/my/config.properties com.MyClass
Then pass that location to Commons Configuration and let it load your config that way. No hardcoded-paths, no database.

I don't know much about Commons Configuration and JNDIConfiguration, but if what you want is a set of key/value pairs, the standard way of doing this as per the Java EE specs, is to use env-entry in the web.xml or ejb.xml.
<env-entry>
<env-entry-name>maxExemptions</env-entry-name>
<env-entry-value>10</env-entry-value>
<env-entry-type>java.lang.Integer</env-entry-type>
</env-entry>
(example taken from JBoss web conf. reference.)
These values are bound in the JNDI so they can be looked up or injected.

Where will be the properties stored? In a file? some tables in a database?
As #ewernli mentioned, the Java EE way to add entries in the JNDI tree is to use env-entry in your deployment descriptor(s).
Now, if you don't want to repeat the same env-entry in several deployment descriptors, then there is a service for specifying global JNDI bindings: JNDIBindingServiceMgr.
Below, the provided jboss-service.xml example:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE server PUBLIC "-//JBoss//DTD MBean Service 4.0//EN"
"http://www.jboss.org/j2ee/dtd/jboss-service_4_0.dtd">
<server>
<mbean code="org.jboss.naming.JNDIBindingServiceMgr"
name="jboss.tests:service=JNDIBindingServiceMgr">
<attribute name="BindingsConfig" serialDataType="jbxb">
<jndi:bindings
xmlns:xs="http://www.w3.org/2001/XMLSchema-instance"
xmlns:jndi="urn:jboss:jndi-binding-service:1.0"
xs:schemaLocation="urn:jboss:jndi-binding-service:1.0 resource:jndi-binding-service_1_0.xsd"
>
<jndi:binding name="urls/jboss-home">
<jndi:value type="java.net.URL">http://www.jboss.org</jndi:value>
</jndi:binding>
<jndi:binding name="hosts/localhost">
<jndi:value editor="org.jboss.util.propertyeditor.InetAddressEditor">
127.0.0.1
</jndi:value>
</jndi:binding>
<jndi:binding name="maps/testProps">
<java:properties xmlns:java="urn:jboss:java-properties"
xmlns:xs="http://www.w3.org/2001/XMLSchema-instance"
xs:schemaLocation="urn:jboss:java-properties resource:java-properties_1_0.xsd">
<java:property>
<java:key>key1</java:key>
<java:value>value1</java:value>
</java:property>
<java:property>
<java:key>key2</java:key>
<java:value>value2</java:value>
</java:property>
</java:properties>
</jndi:binding>
</jndi:bindings>
</attribute>
<depends>jboss:service=Naming</depends>
</mbean>
</server>
If this is not what you are looking for, then I don't understand what you're looking for :) In that case, you should maybe clarify it.