Debugging Azure Event Hubs and Stream Analytics Jobs

When you are dealing with millions of events per day (Json format). You need a debugging tool to deal with events that do no behave as expected.

Recently we had an issue where an Azure Streaming analytics job was in a degraded state. A colleague eventually found the issue to be the output of the Azure Streaming Analytics Job.

The error message was very misleading.

[11:36:35] Source 'EventHub' had 76 occurrences of kind 'InputDeserializerError.TypeConversionError' between processing times '2020-03-24T00:31:36.1109029Z' and '2020-03-24T00:36:35.9676583Z'. Could not deserialize the input event(s) from resource 'Partition: [11], Offset: [86672449297304], SequenceNumber: [137530194]' as Json. Some possible reasons: 1) Malformed events 2) Input source configured with incorrect serialization format\r\n"

The source of the issue was CosmosDB, we need to increase the RU’s. However the error seemed to indicate a serialization issue.

We developed a tool that could subscribe to events at exactly the same time of the error, using the sequence number and partition.

We also wanted to be able to use the tool for a large number of events +- 1 Million per hour.

Please click link to the EventHub .Net client. This tool is optimised to use as little memory as possible and leverage asynchronous file writes for the an optimal event subscription experience (Console app of course).

Have purposely avoided the newton soft library for the final file write to improve the performance.

The output will be a json array of events.

The next time you need to be able to subscribe to event hubs to diagnose an issue with a particular event, I would recommend using this tool to get the events you are interested in analysing.

Thank you.

Creating a Cloud Architecture Roadmap

Image result for cloud architecture jpg


When a product has been proved to be a success and has just come out of a MVP (Minimal Viable Product) or MMP (Minimal Marketable Product) state, usually a lot of corners would have been cut in order to get a product out and act on the valuable feedback. So inevitably there will be technical debt to take care of.

What is important is having a technical vision that will reduce costs and provide value/impact/scaleable/resilient/reliable which can then be communicated to all stakeholders.

A lot of cost savings can be made when scaling out by putting together a Cloud Architecture Roadmap. The roadmap can then be communicate with your stakeholders, development teams and most importantly finance. It will provide a high level “map” of where you are now and where you want to be at some point in the future.

A roadmap is every changing, just like when my wife and I go travelling around the world. We will have a roadmap of where want to go for a year but are open to making changes half way through the trip e.g. An earthquake hits a country we planned to visit etc. The same is true in IT, sometimes budgets are cut or a budget surplus needs to be consumed, such events can affect your roadmap.

It is something that you want to review on a regular schedule. Most importantly you want to communicate the roadmap and get feedback from others.

Feedback from other engineers and stakeholders is crucial – they may spot something that you did not or provide some better alternative solutions.


The first stage is to decompose your ideas. Below is a list that helps get me started in the right direction. This is by no means an exhausted list, it will differ based on your industry.

Component Description Example
Application Run-timeWhere apps are hostedAzure Kubernetes
Persistent StorageNon-Volatile DataFile Store
Block Store
Object Store
Backup/RecoveryBackup/Redundant SolutionsManaged Services
Azure OMS
Recovery Vaults
Volume Images
GEO Redundancy
Data/IOTConnected Devices / SensorsStreaming Analytics
Event Hubs
AI/Machine Learning
GatewayHow services are accessedAzure Front Door, NGIX, Application Gateway, WAF, Kubernetes Ingress Controllers
Hybrid ConnectivityOn-Premise Access
Cross Cloud
Express Route
Source ControlWhere code lives
Build – CI/CD
Github, Bitbucket
Azure Devops, Octopus Deploy, Jenkins
Certificate ManagementSSL CertificatesAzure Key Vault
SSL Offloading strategies
Secret ManagementStore sensitive configurationPuppet (Hiera), Azure Keyvault, Lastpass, 1Password
Mobile Device ManagementGoogle Play
G-Suite Enterprise MDM etc

Once you have an idea of all your components. The next step is to breakdown your road-map into milestones that will ultimately assist in reaching your final/target state. Which of course will not be final in a few years time 😉 or even months!

Sample Roadmap

Below is a link to a google slide presentation that you can use for your roadmap.

Architecture Decisions – Keep a record

Image result for decisions

There are several decision we make every day some conscious and many sub conscious. We have a bit more control over the conscious decisions we make in the work place from an Architecture perspective.

If you are into Development, Devops, Site reliability, Technical Product Owner, Architect or event a contract/consultant; you will be contributing to significant decision regarding engineering.

  1. What Database Technology should we use?
  2. What Search Technology will we use that can scale and do we leverage eventual consistency?
  3. What Container Orchestration or Micro-Service platform shall we use?

When making a decision in 2016, the decision may have been perfectly valid for the technology choices for that time. Fast forward to 2019 and if faced with the exact same decision your solution may be entirely different.

This is absolutely normal and this why it is important to have a “journal” where you outline the key reasons/rationale for a significant architecture decision.

It lays the foundation to effectively communicate with stakeholders and to “sell’ your decisions to others; even better to collaborate with others in a manner that is constructive to evaluating feedback and adjusting key decisions.

I keep a journal of decisions and use a powershell inspired naming convention of Verb-Noun. Secondly I will look at what is trending in the marketplace to use as a guide post. So for a logging/Tracking/Metrics stack, I might start off with reference materials. – Generalized Concepts around the stack – More specific towards the technology we will use

This allows me to keep on track with what the industry is doing and forces me to keep up to date with best practices.

Below is sample Decision Record that I use. I hope you may find it useful. I often use them when on-boarding consultants/contractors or new members of the team. It is a great way for them to gain insights into the past and where we going.

In the next blog post, I will discuss formulating an Architecture Roadmap and how to effectively communicate your vision with key stakeholders. Until then, happy decisions and do not be surprised when you sometimes convince yourself out of a bad decision that you made 😉

Now…How do I tell my wife we should do this at home when buying the next sofa?

TITLE (Verb-Description-# e.g. Choose-MetricsTracingLoggingStack)



<what is the issue that we’re seeing that is motivating this decision or change.>


<what boundaries are in place e.g. cost, technology knowledge/resources at hand>


<what is the change/transformation that we’re actually proposing or doing.>