Node.js musings part I: node version management

I started programming at a very young age, when I was twelve. My first programming language was Basic. I wrote a program that would generate random calculation problems in different categories (under 10, under 100). If the answer given by the user was incorrect, a picture based on 10 x 10 squares would show the correct answer visually.
It was actually used by a remedial teacher (my mom 😉) on our home computer.

Since then I learned a language comparable to Pascal, I used LISP in university, took classes in C, C++, MFC, Visual Basic and Java.

The next software I wrote was after I graduated, for a marketing department. They showed calculations of how much water a water closet or shower would use in different languages. I wrote it in Visual Basic. That was the first time I learned about the hassle of versions in real life.
The program ran fine on my Windows machine (I think it was Windows 95). But on the sales persons machine it would not print. The library was incompatible with my compiled code. I was in 'DLL hell' 😱 as my professor used to call it.

I stayed away from procedural language and decided to focus on Java and JEE. I loved it! No issues with native libraries, object orientation to structure your code, automated builds, test frameworks etc etc.
Of course, I was involved in multiple projects. Some projects would support Java version 1.4 others 1.5 etc.  First I started having different versions on my machine and updating environment variables, but quickly I would need application servers etc as well, so I started creating Virtual Images for Virtual Box and have different versions of the JDK and application versions there.At least I had no issues with native libraries, like I remembered from Visual Basic! It was not ideal, but I managed and felt in control.

Today we are doing more and more projects in the (Oracle) Cloud. We are doing projects in Oracle SOA CS, Oracle Integration Cloud Service, Oracle API Platform Cloud Service and Oracle Mobile Cloud Service.
Oracle Mobile Cloud Service is expecting node.js code for the mobile backend functions that you write. This meant I had to learn JavaScript. Not everything was easy from the start: The asynchronous nature of Node was something I definitely had to get used to.  asynch/await to the rescue ;)
The beauty: no more application servers, no more multiple VMs for different versions: just code! So far so good. :)

Then, we moved to a different version of the cloud service and upgraded our node version to version 8.11.3. and happily start using the new version. I think right now we are on version 11. Of course this does not have a happy end: a week ago I started investigating Oracle BlockChain Cloud Service. It expects node version 6 😰. And now I am back in version hell: node.js uses specific native libraries under the covers, that of course are not the same between the different versions. I need to be able to switch between versions. Some projects expect the paths to be pointing to the right versions and of course constructs like await are not supported, so running my code in Netbeans becomes complicated...

nvm-win to the rescue

I was considering creating images for Virtual Box again (also because I still like bash better than windows Powershell), but I decided to research the topic a little bit. I stumbled upon this project: nvm-windows

It look really good: I can switch versions without having to fiddle around with the path or environments myself, it is all managed by this package that is written in go (another language I might want to learn, but one thing at the time ;) )

Here is how to install it on Windows:

1. Uninstall node from your local machine. Remove all folders related to it C:\Users\{username}\AppData\Roamding\npm and C:\Users\{username}\AppData\Roamding\npm-cache
2. Download nvm-setup.zip
3. Unzip it
4. Run nvm-setup and accept the defaults
5. Open a new Powershell window and type nvm
6. It will show the version (1.1.7 in my case)
7. Install the versions of node you need. In my case
1. nvm install 6
2. nvm install 8
3. nvm install latest

You can now list your versions, and use the one you would like to use by typing

• nvm list
• nvm use 6.15.1

I am not sure I love Node.js and javascript as much (yet) as I love Java, but it might happen in the future ....

Any comments and pointers on how you deal with versions of node are much appreciated, please feel free to comment on this blog or tweet them!

Happy coding 😏

Setting up fn on Kubernetes in the Oracle Cloud (OKE)

In this post I will briefly describe how you can install fn on Kubernetes in the Oracle Cloud (OKE).

Prerequisites

1. You need to have access to Oracle Cloud Infrastructure (OCI) with a unique account. If you have a federated account, you should create another one to be able to create a kubernetes cluster. This account must have either Administrator privileges or belong to a group to which a policy grants the appropriate Container Engine for Kubernetes permissions. Since my example is for R&D purposes, I will be using an account with Administrator privileges.
2. Install and configure the OCI CLI, generate an API signing key pair and add that public key to your username. 
3. Create a separate compartment for the cluster and make sure your compartment has the necessary resources and your root compartments needs the policy Allow service OKE to manage all-resources in tenancy 
4. Install and setup kubectl on Windowns (tip: use Chocolatey)
5. Install helm

Create the Kubernetes cluster

1. Navigate to your console
2. Under Developer Services, select "clusters"
3. Pick the compartment that you created or want to use
4. Click on "Create Cluster" and accept all the defaults
5. Click "Create"
6. Inspect the details 
7. Download the kubeconfig file and store it in your .kube directory

If it fails because of service limits, raise an SR with Oracle support to get your limits increased.

Install fn 

1. Make sure your server version of helm is up to date (helm init --upgrade)
2. Create a directory fnhelm
3. Clone the git repo: git clone https://github.com/fnproject/fn-helm.git
4. Install the chart dependencies: helm dep build fn
5. Install it in your cluster: helm install --name my-release fn

Deploy your function to the cluster

1. Make sure you are logged in to your dockerhub account
2. Set the fn context to the right value
3. Deploy the function to the cluster

The fn context

When you use fn deploy, it uses a context to determine where to deploy to, and what registry to use. The URL for the fnserver you deployed to the kubernetes cluster  can be found by issuing the following command

• $(kubectl get svc --namespace default my-release-fn-api -o jsonpath='{.status.loadBalancer.ingress[0].ip}'):80

However, you can also look it up using a kubectl proxy: 

• kubectl proxy 
• Navigate to a browser: https://localhost:8001/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy/#
• Select "Services" in the navigation menu at the left

• Click on the External Endpoint of the my-release-fn-api 
• You should see the following:

Now we can create the context by running the following commands:

• fn list contexts
• fn create context ociLonneke --api-url [your url] --provider default --registry [your_dockerhub_username]
• fn list contexts

Deploy the function to the cluster

Finally! We are ready to deploy our first function to our cluster. In this case I use the Java tutorial example. 

• fn init --runtime java --trigger http javafn
• fn build
• fn deploy --app java-app

This will result in the following output (or something similar)

Successfully created app:  java-app

Successfully created function: javafn with lonneke/javafn:0.0.2

Successfully created trigger: javafn-trigger

Trigger Endpoint: http://xxx.xx.xx.xx:80/t/java-app/javafn-trigger

Test the function

Open a browser and type the url as stated by the trigger endpoint. You should see the following result:

Next steps

Now you have your kubernetes cluster up and running, you can move your functions from your local installation to the cluster and start using them in production!

Happy coding 😊

Even Aces make mistakes: Reuse

Every year Debrah Lilley is kind enough to round up a couple of Oracle Aces to talk about projects, and/or new features at Oracle Open World.
This year we present a session with 9(!) people about our 'favorite' mistake we made and what we learned from it.

From the summary:

"A quick diversion from our now traditional featured short talks, this year our EMEA ACE Directors will share their biggest errors and what they learned from it. A fast, fun session that will energize you on your Oracle OpenWorld 2018 experience."

I have five minutes to talk about my favorite mistake, so this blog post elaborates on the topic a bit more.

Reuse

In software, we like to reuse code. This enhances productivity, it minimizes the chance of introducing new mistakes and gives us a chance to focus on the new things we are trying to accomplish, instead of reinventing the wheel. This has been a very strong driver of Service Oriented Architecture (SOA). 

There are multiple ways of implementing or realizing reuse:

• create a runtime component that you call from your code to do the job ('a service')
• create a library or code that you share from a central location and import in your code ('a common artifact in SOA Suite in MDS, or a library in Java or Node.js)
• a pattern ('template') that you apply as a best practice 
• a copy (!?) of the code you want to reuse and adapt. 

One of the downsides of reuse, is flexibility loss. If you are reusing something, a change to it will impact all the consumer or users of that piece of code. service etc. This is why micro services architecture is all about bounded contexts and decoupling using events. 

In SOA there has been a very common misconception: the fact that reuse is good, no matter what, resulting in inflexible very complex code that is expensive to change and, in the end, hard to reuse (!)

This particularly happens a lot with canonical models, and yes, I made that mistake too.

Let's go back in time, to a project where we created an application for the province of Overijssel for permits and grants, using Oracle SOA Suite 11g, a content management. The solution basically consisted of 4 different composites (Apply, Process, Decide, Notify), the Oracle Servicebus, a content management system, SAP ERP, a permit application and a.NET user interface.

For the integration between the .NET interface and the BPEL process support, we designed a canonical model.

Canonical model side note

The picture below shows what a canonical mode is supposed to do: make sure that in the servicebus and between applications, a canonical model is used.

End of side note

However, we decided to use the canonical model inside of our BPELs as well. This had several advantages:

1. we did not have to design the WSDL and XML Schemas for the BPEL
2. we could assign the entire message to the BPEL input and output variables

Change

We were done very fast, but we found we needed a number of changes in the canonical model to facilitate the .NET application. They wanted different structures and different fields. None of these had any functional impact on process flow, since the BPEL was mostly driving the process, adding approvals, enrichments and fetching and storing data in the correct backend system.
However, because we used the canonical model in all of our BPELs, we had to redo all of our assignments and xslts to pick up this new version, making sure nothing changed in the flow and functionality of the component.
The change cost the same amount of time as the inital realization, because the work in BPEL is not in clicking together the scopes, but in building the logic in the assignments and xslts.

Lessons learned

We learned a number of things from this particular approach:

1. Separation of concerns matters. This has been a long standing IT and computer science principle. See for example (https://en.wikipedia.org/wiki/Separation_of_concerns). There is a reason you put different groups in your electrical wiring in your house: if one of the groups fails, the other parts of the house are unaffected. When you have to make a change for a specific purpose, you should have to make that change in one place only. In case of the canonical model, in the servicebus and the components that are calling the servicebus.
2. Reuse has an impact on changeability and maintainability. To make sure things can be changed, apply the tolerant reader pattern ((https://martinfowler.com/bliki/TolerantReader.html)
3. Pick your reuse pattern carefully: a pattern you want to reuse (or a template), a library that you will apply, a service that you want to call, or creating a copy to be quick, but that you will be able to change independently.
4. Don't send data to systems that don't care about it. In this case were were sending data and dragging it along in the BPEL that were not needed in the BPEL. Typically all you need in the BPEL are identifiers and dates. Then, when you need more data in a specific scope, you can fetch it from the appropriate source. 

We refactored the code and made specific WSDLs and XSDs for all BPELs and used the canonical model in the OSB, where it belongs. 

It became a lot easier to work with the messages in the BPEL and changes in the UI had no or little impact on the process, as they should!

Code smells

So how do you know if you are reusing the canonical model too much. These are some tell tales that point in that direction:

SOA Suite

1. You have to redeploy 'MDS' everytime a new feature is defined
2. All your artefacts (WSDLs, XSDs, DVMs) are in MDS, there are no 'local composite' artefact
3. You have a lot of data in your messages in BPEL that are in none of the assigns or in only one of the assigns
4. You have a lot of merge conflicts with other teams that are working on completely different topics
5. You have a if statements in your BPEL that never merge back into 1 common flow, based on something in your canonical model

Java, Javascript

1. Your ORM library gets updated all the time and your code needs to change because of it.
2. You filter out values and fields in most of your code
3. You are extending the common objects to add your own behavior and attributes and filter out the common behavior. 

Conclusion

Reuse is a powerful and important topic to be productive and to avoid mistakes. However, reuse is not a goal, it is a means to an end.  Modern systems need to be changeable in the first place. Reuse should be carried out within the context as appropriate. Global models should be treated carefully and be minimized to where they add value and are needed. 

We can all learn from domain driven design principles and microservices architectures in our other architectures as well to make sure we don't paint ourselves into a corner!

Happy coding 😎