Categories
functional model-driven testing

How to use OCL

#ocl #expression #modeling #language

OCL, the Object Constraint Language, is a powerful expression language for UML, SysML, and other languages based on UML. Unfortunately, there is no good documentation around for using OCL inside tools like MagicDraw and such. But, at least we have some input from which we can extract most important aspects.

Here is my link collection on OCL. The bad news are, this stuff is pretty old and it also varies in its statements. Either nobody is really working on it as a core module anymore or we just cannot find fresh insights here. Feel free to write me if you find any better resources.

Definition

Quick Reference

Tutorial

Standard

API Reference

MagicDraw

Categories
architecture business feature functional model-driven

Feature Lifecycle in Architecture

#feature #lifecycle #tracing

When changing your application landscape on a bigger scale you might have to worry about a target architecture that you can only reach with intermediate steps like per year or release. Even a high-level roadmap may be rather complex due to necessary plan changes. The following reduced example shows the core problem:

Feature Roadmap

As you see, applications are repeated in different time windows and so are the features they provide. Moreover, feature provisioning may change like “Duplicate Check” might move from “LegacyCRM” to “BrandnewCMR”. In addition, features themselves may change like “Search Customer” and “Search Partner” being merged into “Search Account”.

I see people doing these things in Excel and Visio or, even worse, in Powerpoint. And everytime my hair stands up expecting a lot of waste or worse like lost COVID-19 results. Excel is a powerful thing, no doubt, but it has its limits. The right way to do such an exercise is using a proper method with a proper tool set. There are many options like application lifecycle tools, enterprise architecture management tools, and modeling tools. I will explain the core concept using a modeling tool, but it can easily be translated to other tools.

The core concept is based on adding the notion of lifecycle or time in general to your plan elements. Each gets a begin and end date between which it is valid. Consequently, showing an application being valid from 2018 to 2022 in a plan scenario for 2025 is not valid because it is long gone. But, since applications and also features typically live for many years, we can save a lot of redundancy by reusing the same elements wherever valid which also drastically improves consistency of your plan.

Now, you can understand much better how we build the diagram from above. In fact, our database contains less elements and relations than you count on the diagram since we simply reuse them where valid.

Plan Elements

You may already guess the drastic improvement you can achieve in your very probably much larger scenario. It’s getting even better because we are now able to improve data quality with data validation as well as Powerpoint slides and Excel sheets by simply getting those as results of reports. We can even transfer plan data from and to other tools if necessary like for requirements management or budget planning.

Categories
architecture business data feature functional model-driven

The Power of Feature Models

#feature #modeling #tracing #portfolio

In the following, we will have a look where feature models can help improving management of software development.

Example for mapping features to apps

Definition

In software development, a feature model is a compact representation of all the products of the Software Product Line (SPL) in terms of “features”.

source: Wikipedia

There are many more sources on the subject, but this simple one will suffice here.

Manage Development using Feature Models

In software development features are mostly implemented by code. Your development process like e.g. Scrum typically focuses on people, communication, self-organizing teams, and a running system among other things. A Scrum team sprints its own way from stories to running code. A typical question popping up looking at the big picture is:

“How can development be managed across teams and products?”

Cascaded agile working models like SAFe and LeSS (Scrum of Scrums) argue that architecture plays an important role and at the same time needs to be aligned with the code. How can you scale architecture from product code to product portfolio?

Scaling Architecture from Products to Portfolio

Imagine you need to report a KPI for sales YTD based on weekly and daily sales data from various sales apps having different sales models. Three different app teams might be involved probably using different technologies and documentation. How do we get to a common denominator helping to organize development?

First, let’s understand the business logic regardless of technologies. The feature “KPI sales YTD” itself is agnostic of sources delivering the raw data. It provides a unified concept into which some magic transforms the feature “Timeline of sales numbers” from sources B2C and B2B.

Having identified those features we can now organize development. The app “Sales Information System” is responsible for calculating the KPI sales YTD while the apps “Sales System B2C” and “Sales System B2B” each manage timelines of sales numbers. Development effort can now be partitioned for the teams and dependencies are known too.

The central idea here is to find a common concept for both products and portfolio. For those managing across products and teams features are used as basic units while app teams refine those to their specific needs.

If you need more precision e.g. in the case that the aggregation of the timelines needs to be done in several steps like export timeline, enrich timeline, and sum up timeline you can cascade features. There are good approaches refining a feature model using e.g. business functions or business data or a combination of both.

Conclusion

Breaking products down into features has a lot of benefits

  • Speak a common language (portfolio and products)
  • Avoid double work (deduplicate feature implementation)
  • Avoid overall waste (streamlined feature catalogue)
  • Make progress transparent (plan per feature)
  • Ease analysis (impact per feature)
  • Clearly specify changes (story per feature change)

Feature models support improvement of software development especially in case of self-organizing product teams.