What is this?

Are you using an Application Server (AS)--such as JBoss/WildFly--that has modules coupled to other layered modules running on the same AS? If you've tried to make microservices out of a monolith it's quite possible you've got code that does exactly this.

This Maven project generates a WAR with a bunch of endpoints to excercise some architectural approaches of the above.

This module is a demo/teaching tool as to how resources are possibly wasted. It has endpoints to enable comparisson of alternate architectures:

synchronous loopback callbacks (problem, runs out of request threads)
asynchronous loopback callbacks (problem, runs out of client connections unless async APIs shared among modules)
akka (nice but needs to be pervasive)
queueing (nice, maybe use Apache Camel?)

The purpose of this is to convey how the application server interacts between request connections/threads, client connections (outgoing connections)

Haystack JARs (Demo 1)

Configuration

Kick off queueing 'sticks of hay' (lines of text) onto a farily hardcoded message queue.

JMS queue reads/writes using netty for Hornet:

192.168.0.118;port=5445

Sample Wildfly standalone.xml:

      <subsystem xmlns="urn:jboss:domain:messaging:3.0">
        <hornetq-server>
          ...
          <paging-directory path="/paging"/>
          ...
          <address-settings>
              <address-setting match="#">
                  <max-size-bytes>104857600</max-size-bytes>
                  <page-size-bytes>10485760</page-size-bytes>
                  <address-full-policy>BLOCK</address-full-policy>
              </address-setting>
          </address-settings>
          ...
          <jms-connection-factories>
              ...
              <connection-factory name="RemoteConnectionFactory">
                   ...
                   <consumer-window-size>0</consumer-window-size>
              </connection-factory>
              ...
          <jms-connection-factories>
          ...
          <jms-destinations>
            ...
            <jms-queue name="HaystackQueue">
                <entry name="/queue/HaystackQueue"/>
                <entry name="java:jboss/exported/jms/queues/HaystackQueue"/>
            </jms-queue>
            <jms-queue name="HaystackBackchannelQueue">
                <entry name="/queue/HaystackBackchannelQueue"/>
                <entry name="java:jboss/exported/jms/queues/HaystackBackchannelQueue"/>
            </jms-queue>
          </jms-destinations>
          ...
        </hornetq-server>
     </subsystem>
      ...
      <socket-binding-group name="standard-sockets" default-interface="public" port-offset="${jboss.socket.binding.port-offset:0}">
        ...
        <socket-binding name="messaging" port="5445"/>
        ...
      </socket-binding-group>

Also make sure the following user is configured for 'guest' role:

User: jms
Password: jms

Demo Endpoints (Demo 2)

localhost:8080\limits\rest\config?bodyDelayMillis=0&leafDelayMillis=100&numAsyncRequests=3&numWorkers=3&useThreadForAsync=true

Configuration for endpoints below.

bodyDelayMillis
- millis to Thread.sleep on each recusrive call into 'sync'/'async'/'queued' that is not a leaf/end call of tree of calls
leafDelayMillis
- millis to Thread.sleep on each recusrive call into 'sync'/'async'/'queued' that is a leaf/end call of tree of calls
numAsyncRequests
- number of threads to use for JAX-RS client calling async HTTP ('async' endpoint)
numWorkers
- number of worker threads for 'queued' endpoint
useThreadForAsync
- for 'async' endpoint should the request thread be used to make async calls [false] or should a separate thread be used [true]

http://localhost:8080/limits/rest/sync?conns=2&iter=2

Each recusive connection is a synchronous HTTP call using JAX-RS: starting from request thread.

conns
- connections to children (down tree) to make for each connection not a leaf
iter
- iterations to recurse (e.g. '1' means 'conns' recursive leaf calls made).

http://localhost:8080/limits/rest/async?conns=2&iter=2

Each recursive connection is an asynchronous HTTP call using JAX-RS.

conns
- see 'sync' above
iter
- see 'sync' above

http://localhost:8080/limits/rest/queued?conns=2&iter=2

Each recursion is handled through a queue configured in the WAR.

conns
- see 'sync' above
iter
- see 'sync' above

http://localhost:8080/limits/rest/akka?conns=2&iter=2

Like 'queued' except Akka is used with a nicer backchannel.

conns
- see 'sync' above
iter
- see 'sync' above

JakubNer/javaasperftest