BloC Architecture in Flutter: a Modern Architectural Approach and How We Use it at Jimdo

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Flutter at Jimdo: Our Experience and Fun Moments

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Container Based Crons at Jimdo

When building a large-scale web service one of the things you come across sooner or later is automatically running tasks and Jimdo is no exception to this. For us these tasks can target multiple goals like renewing SSL certificates, processing payments, or calculating scaling information of our infrastructure. The way we execute and monitor them has been an ever changing topic for us and we iterated and evolved our ideas over the last years. In this blog post we are going to show you how we implemented our latest solution to this problem based on AWS CloudWatch Rules and ECS.

Setting expectations

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HTTPS at Jimdo

At Jimdo we are committed to providing our users with the easiest website builder on the web. Behind the scenes, of course, that includes security related topics - most notably HTTPS. But web security is actually not an easy topic and even though it could be considered natural these days (and things are definitely improving), still way too many websites are not secure. 


Recently, we tasked ourselves with doing our part to contribute to the HTTPS everywhere movement and built a solution to support HTTPS for every one of our users’ custom domains. The solution had to be as easy as possible by definition for our users, and the outcome ultimately requires no human interaction. 


Every Jimdo user today has HTTPS support by default on his website and this is the story of how we got there.

the journey begins

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From “Voice and Tone” Guidelines to UI Animations

In the one of the latest issues of the UI Animations Newsletter, Val Head proposed basing UI animations on the voice and tone guidelines your company uses for PR/Customer support etc.:


Voice and tone documents can be a helpful source to inform how you design your UI animation. They’re especially helpful for getting past that “blank page syndrome” for animation ideas because they define a direction to aim for.


So, I tried it a few weeks ago when I thought about how we could spruce up the animations within the Jimdo interface. Since I poured a lot of text into a GitHub issue about the whole topic, I figured I should publish these thoughts here for other people to get an idea of how this advice could work for them.


I used Material Design Motion (MDM) as a base to build upon since it is a great tool and has very good ideas on how to animate a user interface. The majority of their content can be applied to many use cases, including the Jimdo one.

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How to get rid of waste

In my last post I made the point that eliminating waste -- superfluous code, stale pull requests, unused cloud resources -- is a worthwhile investment every engineer should make on a regular basis. It minimizes complexity, which in turn lowers maintenance costs and reduces communication overhead. It also allows you to better focus your thinking and, assuming that you care about your work, makes you feel less guilty.


I promised you to write a follow-up post on strategies that can help to eliminate waste during software development. I stand by my word; here are five things that work great for my team at Jimdo.


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Put litter in its place

These days, at Jimdo, I'm part of a team that is responsible for the next-generation cloud infrastructure serving the 10+ million websites of our customers. Most of the time, we do pair programming -- a very efficient way to grasp complex topics and communicate about them. This is especially true when legacy systems are involved and your pairing partner (hey, Soenke!) happens to be one of the company's first engineers.

In our pairing sessions we automate, debug, and tune the pieces that make up our infrastructure. We write lots of code and tests. We fix bugs. We try to keep things as simple as possible, while knowing that a certain amount of complexity is necessary for our systems to do anything useful. Of course, we do enjoy creating new things from time to time; we're programmers, after all. On the other hand -- and this is the crucial point -- we also care a lot about doing the opposite:

  • Deleting code
  • Removing features
  • Deleting documentation
  • Throwing away Git branches
  • Destroying cloud resources
  • Decommissioning hardware servers
  • ...

We love to reduce complexity by getting rid of components that aren't needed. This is a rewarding investment of time -- an investment every developer should make on a regular basis.

Why bother?

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Simple service discovery using AWS Private Hosted Zones

A rather simple, but effective and easy-to-setup service discovery (SD) mechanism with near-zero maintenance costs can be build by utilizing the AWS Private Hosted Zone (PHZ) feature. PHZs allows you to connect a Route53 Hosted Zone to a VPC, which in turn means that DNS records in that zone are only visible to attached VPCs.


Before digging deeper in the topic, let’s try to find a definition for 'simple service discovery'. I'd say in 99% of the cases service discovery is something like "I am an application called myapp, please give me (for example) my database and cache endpoints, and service Y which I rely on", so the service consumer and service announcer need to speak a common language, and we need no manual human interaction. This is at least how Wikipedia defines service discovery protocols:


Service discovery protocols (SDP) are network protocols which allow automatic detection of devices and services offered by these devices on a computer network. Service discovery requires a common language to allow software agents to make use of one another's services without the need for continuous user intervention.


So back to the topic. You might think: Why not use Consul, Etcd, SkyDNS etcpp? 


no software is better than no softwarertomayko


You are not done with installing the software. You might need to package, configure, monitor, upgrade and sometimes deeply understand and debug it as well. I for one just simply love it when my service providers are doing this for me (and Route53 has actually a very good uptime SLA, beat that!) and I can concentrate on adding value for my customers.


However, service discovery apps introduce more complexity, magic, and point of failures, so don't use them unless you absolutely need to.


This is another point. Keeping it simple is hard and an art. I learned the hard way that I should try to avoid more complex tools and processes as long as possible. Once you introduced complexity it’s hard to remove it again because you or other people might have built even more complex stuff upon it.


Ok, we are almost done with my ‘Total cost of ownership’ preaching. Another aspect for me of keeping it simple and lean is to use as much infrastructure as possible from my IaaS provider. For example databases (RDS), caches (ElastiCache), Queues and storage (e.g. S3). Those services usually don’t have a native interface to announce their services to Consul, Etcd etc. so one would need to write some glue which takes events from your IaaS provider, filters and then announces changes to the SD cluster.1

Ok, so how can we achieve a service discovery with the AWS building blocks and especially Private Hosted Zones?

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The Jimdo Burnout Game


  1. When you come to work, pay $1 for each person of your team who is already there 
  2. When you leave work, pay $1 for each person of your team who is still there
  3. First one with a diagnosed burnout wins!
  4. If you know the rules, you're part of the game


Optional rules

  • Once a month, buy blow for the whole team
  • Once a year, get a psychologist for the winner
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Fast feedback is everything

As software developers, we spend a lot of our time writing code. Whether we're implementing new features, fixing nasty bugs, or doing boring maintenance work, there's always some code we either create from scratch or try to modify for the better. When writing code, we need confidence in what we do. We need to know whether our changes work as intended. That's why we write tests after or, preferably, before touching any code. So, inevitably, a huge part of our daily work comes down to these two things: programming and testing.

Programming and testing are, of course, only vague terms, and their meaning depends on how exactly you approach software development. For example, when practicing test-driven development (TDD), you typically follow these steps:

  1. Write a test that defines the desired behavior.
  2. Run the test to see if it fails.
  3. Write some code to make the test pass.
  4. Run the test to see that it passes.
  5. Refactor the code (and re-run the test).

Even if you don't practice TDD (you totally should!), you're probably still going to:

  1. Write some code.
  2. Write a test after the fact.
  3. Run the test to see if it's successful.

In order to write an actual program, you have to run through these steps -- this loop -- again and again. The point is that no matter what development method you prefer, constantly jumping back and forth between programming and testing comes at a price: it doesn't just slow you down in terms of time spent (especially with long-running tests), the involved context switching also drains your mental energy, which might ultimately destroy your productivity. For this reason I believe that the following statement is so important -- and I'm not tired of repeating it whenever I get the chance:

When it comes to programming and testing, fast feedback is everything.

Here, fast feedback means that the time between changing code (or tests) and getting results from running the tests is reduced to a minimum. In other words, you end up with a fast edit-compile-test loop (the compile step is optional, of course). The great thing about this, as Joel Spolsky put it: "the faster the Edit-Compile-Test loop, the more productive you will be".

There are a couple things you can do to shorten the feedback loop. Certainly the first technique that comes to mind is isolated testing, which involves eliminating (slow) external dependencies like databases. This topic has received a lot of attention lately and I won't go into it here (by the way, TDD isn't dead). You should absolutely invest in your tests and make them faster. Besides trying to implement faster tests, however, you can also optimize the way you run them.


Running tests the fast way

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