Trivial examples of all the Immutant features
Clojure JavaScript HTML Shell CSS
Latest commit 302e8aa Oct 3, 2016 @tobias tobias committed on GitHub Merge pull request #8 from The-Alchemist/patch-1
Upgrade to clojure 1.8.0

README.md

Immutant Feature Demo

An app showing trivial examples of all the Immutant libraries. Most log something to stdout, but the demo.web examples are available at http://localhost:8080/.

You can view a running example here: https://immutant-feature-demo.herokuapp.com/index.html.

You need at least Java 8 and Leiningen 2.4.0

SSL and HTTP/2

By default, the web demo fires up only one HTTP listener on port 8080. But if you set the ssl-port option, it'll also fire up an HTTPS listener with a self-signed certificate. You can even enable HTTP 2.0 on that port by setting the http2? option. Doing so requires a version of ALPN to be available on the bootclasspath. We rely on a convenient Java agent to load one appropriate for your JVM. This agent is invoked, and the above options are set when the :http2 profile defined in project.clj is enabled, like so:

lein with-profile http2 run

You can run the app in several ways:

With lein run

The value of :main in project.clj is demo.core, which runs -main for all of the demo namespaces.

lein run

You can use the -m option to run specific namespaces, e.g.

lein run -m demo.web

And you can run an HTTP/2.0 listener on port 9999 like this:

lein with-profile http2 run -m demo.web ssl-port 9999

At a repl

You can fire up a repl and invoke each namespace directly

lein repl

Once at a prompt, try (demo.web/-main)

Or, for an HTTP/2.0 listener, try this:

`(demo.web/-main "ssl-port" 9999 "http2?" true)`

You'll note in the demo.web/-main function that the option keys are expected to be strings so that command line arguments can override them.

From a jar

Create an uberjar and run it

lein uberjar
java -jar target/demo-standalone.jar

To create an HTTP/2.0 listener from the uberjar, we'll need to do some work. Because we're no longer running the app from Leiningen, our :http2 profile does us no good, so we'll need to manually invoke the ALPN Java agent (described above). We'll also need to pass the necessary ssl-port and http2? command line options. Once you locate the agent jar in your local Maven repo, you may test HTTP/2 like so:

java -javaagent:{/path/to/jetty-alpn-agent.jar} -jar target/demo-standalone.jar ssl-port 8443 http2? true

This assumes you've activated the :http2 profile at some point. If you haven't, the agent jar won't be in your repo. To fetch it, try:

lein with-profile http2 check

In WildFly

WildFly is installed by downloading and unpacking an archive. For our purposes, we'll drop it in the project directory. For a list of available versions, see http://wildfly.org/downloads/

VERSION=10.0.0.Final

# Install WildFly
wget http://download.jboss.org/wildfly/$VERSION/wildfly-$VERSION.zip
unzip wildfly-$VERSION.zip

# Create the war file and deploy it to WildFly
lein immutant war -o wildfly-$VERSION

# Fire up WildFly
wildfly-$VERSION/bin/standalone.sh -c standalone-full.xml

Note the web examples will be deployed with a context path of /demo on WildFly so go to http://localhost:8080/demo/ to see the web examples. Alternatively, to mount the app at the root context, http://localhost:8080/, rename the war file beneath wildfly-$VERSION/standalone/deployments/ to ROOT.war.

In a WildFly cluster

We'll simulate a cluster by "installing" another WildFly instance:

cp -R wildfly-$VERSION wildfly-too
rm -rf wildfly-too/standalone/data/

Because we already deployed the war file, it gets copied over, too. And to avoid spurious errors, we remove the standalone/data directory where WildFly keeps some runtime state.

Now we'll start our first instance:

wildfly-$VERSION/bin/standalone.sh -c standalone-full-ha.xml -Djboss.node.name=one -Djboss.messaging.cluster.password=demo

Note the following:

  • We use the standalone-full-ha.xml file in which clustering is configured
  • Since both of our peers will be on the same host, we need to give each node a unique name
  • The cluster requires a password

In another shell, we fire up the second instance with similar options plus a system property to avoid port conflicts, since we're on the same host.

wildfly-too/bin/standalone.sh -c standalone-full-ha.xml -Djboss.node.name=two -Djboss.messaging.cluster.password=demo -Djboss.socket.binding.port-offset=100

You can correlate the output from both peers to the code beneath src/demo to observe HA singleton jobs, load-balanced messaging, and distributed caching. And you can observe session replication by reloading the following pages in your browser:

On Heroku

Press this button:

Deploy to Heroku

Or do it manually. Heroku requires a Procfile in the project root to bootstrap the app. With this in place, we simply create the heroku repo and push:

heroku create
git push heroku master

To see the log output:

heroku logs --tail

And to open the app in the browser:

heroku open

On OpenShift

The app includes start and stop action hooks beneath the .openshift/ directory that enable it to be deployed on OpenShift using the DIY cartridge.

We'll call our application demo:

rhc app-create demo diy --from-code https://github.com/immutant/feature-demo

To see the log output:

cd demo
rhc tail

Once the app is up, visit http://demo-<YOUR_DOMAIN>.rhcloud.com:8000/. The port, 8000, is optional for all but the WebSocket example, because OpenShift only supports WebSockets on port 8000.

In a WildFly cluster on OpenShift

We can use the WildFly cartridge to create a scaled application named wf. The pre_deploy_wildfly action hook will create our war file in a directory monitored by the app server.

rhc app-create wf wildfly --scaling --gear-size medium --from-code https://github.com/immutant/feature-demo

Note we set the --scaling option and a medium --gear-size. It will take a few minutes for the command to complete. Once it does, monitor the log output:

cd wf
rhc tail

View the web examples at http://wf-<YOUR_DOMAIN>.rhcloud.com:8000/

Try scaling the app up to 2 gears:

rhc cartridge-scale wildfly 2

View the gears for your app to obtain their ssh URL's:

rhc app-show --gears

Login to a gear to monitor/control it:

rhc ssh
help
gear restart
tail_all