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By Date: June 2015

Random insights in Bluemix development (a.k.a Die Leiden des Jungen W)


Each platform comes with it's own little challenges, things that work differently than you expect. Those little things can easily steal a few hours. This post collects some of my random insights:
  • Development cycle

    I'm a big fan of offline development. My preferred way is to use a local git repository and push my code to Bluemix DevOps service to handle compilation and deployment. It comes with a few caveats
    • When you do anything beyond basic Java, you want to use Apache Maven. The dependency management is worth the learning curve. If you started with the Java boilerplate, you end up with an ANT project. Take some time, to not only mavenize it, but adjust the directories to follow the maven standards. This involves shuffling a few files around (/src vs. /src/main/java and /bin vs. /target/main/java for starters) and edit the pom.xml to remove the custom path
    • Make sure you clear out the path in the build job on Devops, maven already deploys to target. If you have specified target in Devops, you end with the code in target/target and the deploy task won't find anything
    • Learn about the liberty profile and its available feature, so you can properly specify <scope>provided</scope> in the POM.xml
    • In node.js, when you manually install a module in node_modules, that isn't pulled from a repository through an entry in package.json, that module will not be visible to standard build and deploy, since (surprise surprise) node_modules are excluded from version control and build checkout.
      Now there are a bunch of workarounds described, but I'll sum it up: don't bother. Either you move your module into a repository DevOps can reach or you build the application locally and use cf push
    • manifest.yml is your friend. Learn about it. Especially the path command. When deploying a maven build your path will be /target/[name-of-app]-[maven-version].war
    • You can specify a buildpack and environment parameters in a manifest. Works like a charm. However removing them from the manifest has no effect. You have to manually unset the values using the cf tool. Also the buildpack needs to be reset manually, so be careful there!
  • Services

    The automagical configuration of services is one of the things to love in Bluemix. This especially holds true for Java
    • The samples suggest to use the VCAP_SERVICES environment variable to get credentials and urls for your services. In short: don't. The Java Liberty build pack does a nice job making the values available though JNDI or Spring. So simply use those. To make sure that Java:comp/env can see them properly, don't forget to reference them in web.xml
    • In diversion from this: I found the mqLite Java classes less stressful that configuring JMS via JNDI. The developers did a good job making that library too work automagical on Bluemix.
    • For some services (e.g. JAX-RS 2.0 client; BlueMix SSO) you do have to touch the server.xml.
      The two methods are a packaged server or a server directory. The former requires a local liberty profile installed, so I prefer the later. It is actually easier than it sounds. In your (Maven) project, you create new directories DefaultServer and DefaultServer/apps (case sensitive!). You create/edit the server.xml in the DefaultServer directory. Then check for your maven plugin in pom.xml and change the output directory (in bold):
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-war-plugin</artifactId>
        <version>2.3</version>
        <configuration>
          <failOnMissingWebXml>false</failOnMissingWebXml>
          <warName>${artifactId}</warName>
          <outputDirectory>${basedir}/defaultServer/apps</outputDirectory>
        </configuration>
      </plugin>
      

      Then you can deploy your application using mvn install and cf push [appname] -p defaultServer. These two commands work in DevOps too!
    • The SSO service is "Single Sign On", there is no real "Single Sign Out". That's not an issue specific to Bluemix, but something all SSO solutions struggle with, just to be clear what to expect. The login dialog is ugly, but fully customizable. The nature of SSO (Corporate and/or a public provider) makes it a minimal provider: identity only, no roles, attributes or groups. In the spirit of micro services: build a rest based service for that
  • Node-RED

    While it is advertised as IoT tool, there is much more to this little gem
    • Node-RED runs on Bluemix, your local PC or even a Rasberry Pi. For the later head over to The Thingbox to get your ready OS image
    • Node-RED can be easily expanded, there are tons of ready modules at Node-RED flows. Not all are suitable for Bluemix (e.g. the ones talking Bluetooth), but a local Node-RED can easily talk to a Bluemix Node-RED making it easy for applications to run distributed
    • My little favourite: connect a HTTP post input directly to a Cloudant output. Node-RED converts the encoded form into a JSON object you can drop into the database as is. You might want to add a small filter (a compute node) to avoid data contamination
As usual YMMV

Posted by on 29 June 2015 | Comments (1) | categories: Bluemix

Investigating JNDI


When developing Java, locally or for Bluemix a best practise is to use JNDI to access resources and services you use. In Cloud Foundry all services are listed in the VCAP_SERVICES environment variable and could be parsed as JSON string. However this would make the application platform dependent, which is something you want to avoid.
Typically a JNDI service requires to edit the server.xml to point to the right service. However editing the server.xml in Bluemix is something you do want to avoid as much as possible. Luckily the Websphere Java Liberty Buildpack, which is the one Bluemix uses for Java by default, does handle that for you automagic and all Bluemix services turn into discoverable JNDI objects. So far in theory. I found myself in the tricky situation to check what services are actually there. So I wrote some code that turns the available JNDI objects into a JSON string.
    @GET
    @Path("/jndi")
    @Produces(MediaType.APPLICATION_JSON)
    public Response getJndi() {
        StringBuilder b = new StringBuilder();
        b.append("{ \"java:comp\" : [");
        this.renderJndi("java:comp", b);
        b.append("]}");

        return Response.status(Status.OK).entity(b.toString()).build();
    }

    private void renderJndi(String prefix, StringBuilder b) {
        boolean isFirst = true;

        try {
            InitialContext ic = new InitialContext();
            NamingEnumerationlt;NameClassPairgt; list = ic.list(prefix);
            while (list.hasMore()) {
                if (!isFirst) {
                    b.append(", \n");
                }

                NameClassPair ncp = list.next();
                String theName = ncp.getName();
                String className = ncp.getClassName();

                b.append("{\"name\" : \"");
                b.append(theName);
                b.append("\",");
                b.append("\"javaClass\" : \"");

                b.append(className);
                b.append("\"");
                if ("javax.naming.Context".equals(className)) {
                    b.append(", \"children\" : [");
                    this.renderJndi(prefix + (prefix.endsWith(":") ? "" : "/") + theName, b);
                    b.append("]");
                }
                b.append("}");
                isFirst = false;
            }
        } catch (Exception e) {
            e.printStackTrace();
            b.append("\"");
            b.append(e.getMessage());
            b.append("\"");
        }

    }

Enjoy - As usual you YMMV

Posted by on 18 June 2015 | Comments (0) | categories: Bluemix Java

Adventures with Node-RED


Node-RED is a project that succesfully escaped "ET" - not the alien but IBM's Emerging Technology group. Build on top of node.js, Node-RED runs in many places, including the Rasberry PI and IBM Bluemix.
In Node-RED the flow between nodes is graphically represented by lines you drag between them, requiring just a little scripting to get them going.
The interesting part are the nodes that are available (unless you fancy to write your own): A large array of ready made flows with nodes and sample applications makes Node-RED extremly flexible (I wonder if it would make sense to build a workflow engine with it). In case you don't find a node you fancy, you can build your own. Not all nodes are created equal, so you need to check what works. When you run Node-RED on Bluemix, you won't get access to hardware like serial port or Bluetooth, but you gain a DNS addressable IP endpoint (you are not limited to http(s)). Furthermore, IBM provides direct access to the IBM IoT cloud, that takes the headache out of device configuration by providing an extensive library of device libraries.
So how to get additional nodes, own or others, onto Bluemix? Here are the steps:
  1. create a new application with the IoT Boilerplate
  2. link that application to version control on hub.jazz.net
  3. clone the repository locally git clone ...
  4. edit the package.json and add the item you would like to add
  5. commit and push the changes back to jazzhub and let "build and deploy" sort it out

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Posted by on 02 June 2015 | Comments (0) | categories: Bluemix