To me, its more like a technical new year. Last year the main plan was to get married. This year needs to improve more on application architecture side of software engineering. OK. Leave that with me.Lets get into the topic.
It took roughly 2 years to realize that we are using DSL in our project. I don’t know, why I didn't realize it in the first 2 years of project in which I was fixing DSL issues and adding more features to that. Reasons may be
- In the first 2 years I was / had to concentrating more on the deliverable and the technical (WPF,Silverlight,WCF,Linq etc…) aspects of project rather than its logical architecture design and now I am more focused on Architecture.
- The trainers (we had few in the beginning) didn’t tell us that we are using DSL in the project. Or nobody thought of the word DSL even though it is using in the project. (I had seen people using Singleton pattern without knowing the technical term ‘Singleton’)
- There are 2 types of developers in the project. I would say application creators. One group is hard core .Net developers who work on the framework using VB.Net and other team uses a tool to create business screens ,its validation and the business flow.If I spent some time on thinking what is the difference between these 2 groups, I would have realized that we are using DSL in the project.
Are we using DSL in our day to day projects?
- The framework you are created to solve the problems in your domain. The track components call the framework to fulfill business need.
- The business layer methods you are writing to meet specific business requirement.
- The configuration sections which are specific for business domain.
Importance of DSL in Application development
Software development v/s other Engineering_disciplines
If we take a civil engineering graduate, he learns how to construct a bridge in the class room and the same can be applied in real time when he works for a company project. I agree that there can be very slight variation. But majority are same. But take a look at software engineering graduate. He learns how to find out factorial of a given number during college days and he is assigned to create a site which needs to serve 1000hits/second. This is the case in almost all Indian institutions. No idea about foreign institutions.
The same applies to the business cases as well. The business of civil engineering will be same always or atleast engineer is familiar with the terms. But in case of software its is different. He needs to solve the issues of accounting, auditing or insurance and make their life easier without any prior knowledge in the business domains. Yes there are business analysts who are supposed to bridge the gap. But I don’t know how far they are good in bridging. May be I have never seen a real BA. All the BAs I have seen in may programming life are just requirement writers who write down requirements from users. They are not requirement creators. I strongly believe that only requirement creating BAs can bridge the gap between original domain expert users and pure programmers.
How to tackle the requirement change scenario in development
Solution – Convert your software users to programmers.
This sounds crazy.Are they going to write C# code?
No.They are going to write DSL programs
Is it practical ?
Yes. It is and we can see so many examples around. By introducing formulae and macros Microsoft excel made so many programmers. By writing cell formulae and macros aren’t the accountants and other general people became programmers? Yes they are.
May I go to users and tell them you need to learn programing?
It depends based on the level of your clients. In most of the scenarios you cannot tell them that they need to program. You need to use the words customization, configuration etc…When client reaches a mature state you may tell that there is a DSL which they can use to modify the application.
So what is the magic : Whenever you had to create / design software, model a domain language and program using it. Thanks to my former colleague Praseed Pai for the sentence.
Example - DSL in salary calculation scenarioLets look at a real time scenario for a normal developer other than taking scenarios like excel macro .
After some months Kochi became a metro and your client needs to add one more component into the salary called “Metro allowance”. Client again approached you to modify the software to add the new salary component. You modified the software and got payment for that too. Client was able to reduce (I don’t want to use the word fired) work load of 2 people in the administration department after introducing your software so that they were able to concentrate on growth aspects of company and it grown to a bigger size.
From here story can be diverted in 2 ways. You charged more by saying that, we introduced a configurable salary calculation technique so that you can enter the formulae in a particular text area and the system will calculate based on that. For example in the formulae you can refer the Basic pay using _BASIC_ . Obviously client became happy and as they are growing, they decided to create a web site and gave the contract to you. Your client is growing and also you. You will be contacted someday by other companies to purchase the same software. There is no best advertisement than your customer’s.
The other kind of the story can be like this. You charged same or little more and delivered the support for PF. Client is satisfied with the change. But they started thinking, how their competitors and other companies calculate salary. One day they will hear from others that “you know one thing we are using a salary calculation software which is configurable .There is no need to call software guys for formulae changes”. Obviously next time client will purchase that software or ask you to convert existing one in a configurable way. If you say no, that is the end. Your client will grow definitely but without you.
How was the configurable salary calculation happened? Its nothing but a DSL. You modeled / created it knowingly or unknowingly. _BASIC_ is part of that language.
Can I get a sample which uses DSL in C#
Hopefully you can expect a post which answer the same next week same day.With the salary calculation sample of course.