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1 Masaryk University Faculty of Informatics }w!"#$%&'()+,-./012345<ya Information System in Go Language Master Thesis Slavomír Polák Brno, Spring 2017

2 Declaration Hereby I declare, that this paper is my original authorial work, which I have worked out by my own. All sources, references and literature used or excerpted during elaboration of this work are properly cited and listed in complete reference to the due source. Slavomír Polák Advisor: doc. RNDr. Tomáš Pitner, Ph.D. ii

3 Acknowledgement I would like to thank to my supervisor doc. RNDr. Tomáš Pitner, Ph.D. for his professional guidance, methodical support, which he provided me during my work on this thesis. Also, I would like to thank to my family and friends for their support. iii

4 Abstract The aim of the master thesis, is creating of a design and implementation of information system in Go language. At first, frameworks that are used in this work are described. In the next steps we analyze customer s requirements and create design, that we implement. In implementation we use Revel framework for creating a web application and Gorp framework for database implementation. iv

5 Keywords golang, framework, Revel, Gorp, information system, design of information system, web application v

6 Contents 1 Introduction Web app with Revel How to work with Revel Routing Storing data in Revel How does Revel works Database in Go Competition Analysis Current situation facebook blablacar.cz Software lifecycle Requirements Non-functional requirements Functional requirements Design Use case Implementation Verification Maintenance Conclusion Appendix vi

7 1 Introduction In modern information world, every company, even the small ones have to work with data. They store data about their customers, employees, trades and others. Then we analyses the data for increasing of our profit. We need to know which product is best seller or which one is problem to sell. Also in these days, connection with the rest of the world is essential. We need to know our competition, what they can offer and their prices for similar goods to ours. Customers mostly find their goods on the Internet. So it s important to have web page, so we can be online. Every company has it s own business processes. It is not really hard to maintain business processes if we are in a small company. But if we are in a larger company, or if we are a part of bigger concern, it s easier for us to maintain processes and communication by computer. Solution for these three points is Information System (IS). Every one of us heard of it and even worked with some kind of IS. IS are often created for special user (certain company or enterprise). In this work, we create IS for certain customer. Our customer share his car with other people that have the same journey. Customer shares ride only with people that he knows, or the passenger who knows some of his friends. For creating IS, we use Golang (Go). Go was created by Google and it s strongly typed and has a garbage collector. Go has good support for use of concurrent porgramming, which we can use in our application (request processing). Due to the fact that we need to find customers (passengers) on the internet, even if we know them, we have to create web application. For this kind of web application is pure HTML 1 pages with a bit of styling with CSS 2 not enough and that s another reason for using Go. It is possible to create web application by using only Go, but if we already have invented wheel, why to try it invent again? So rather than making app form scratch, we use framework named Revel. Revel is framework for creating web app with Go, 1. HyperText Markup Languages 2. Cascading Style Sheets - changes presentation of data in markup languages 1

8 1. Introduction but it lacks support for database. We need to use another framework for creating and working with database, which is Gorp. With help of Gorp, we can build our application at the top of the SQLite 3 database. 3. open source, embeded relational database 2

9 2 Web app with Revel If we want to create a web based application in Go, we can do this on our own from scratch, or we can use framework. Revel[1] is framework for creating a web based application in Go. It is based on Model-View-Controller Software architecture, which splits application into three layers. Model that describes data, View that presents data from Model and Controller which processes requests and then makes changes in view or model. Its main advantages are steep learning curve (it s easy to learn) and hot code reaload. Every time, when you change something in your project in /app directory, Revel watchers will notice that changes have been made, and then Revel recompile your code and you can see changes immediately. Because of that, all views, controllers and models, needs to be stored under this directory. For a web developer, it is really time saving if you don t have to restart your server or recompile the whole source code. 2.1 How to work with Revel If you want to create application in Revel, you need three things[1]: Go version at least 1.4 Git or Mercurial, because you will need to get various dependencies for Revel Revel framework. For installing Revel, you just run go get github.com/revel/revel from command line in unix based Operation Systems. It clones Revel framework to your $GOPATH repository and get all of the dependencies and packages that s needed for running applications under Revel. Now you can create Revel application by revel new [name] in command line. Application will be created in your \$GOPATH/src directory. 3

10 2. Web app with Revel For running the application, you need to do revel run [name] and then go to in your web browser. With basic knowledge of common web based applications you can create your own application really fast. You need to follow these steps: Define Model[1] that can be used in your application. In case of Go and Revel, you need to create struct with attributes of Model[3]. If you look at the code below, we have struct User with string atribute Name. If we want, we can add there some validation control. In our example, we had parameter Name that is required and needs to have at least 3 characters and maximum count of characters is 6. Because of Validation function, we need to import github.com/revel/revel. Revel provides good validation facility. All functions used for Validation are native and each of them return ValidationResult, if one of them will fail, function Validate returns Error. We can also add our own error message as you can see in our example at line 12. package models import ( " github. com/ r e v e l / r e v e l " ) type User s t r u c t { Name s t r i n g } func ( user *User ) Validate ( v * r e v e l. Validation ) { v. Required ( user.name). Message ( "A User Name i s required! " ) v. MinSize ( user. Name, 4). Message ( " At l e a s t 4 c h a r a c t e r s i s needed " ) v. MaxSize ( user. Name, 6). Message ( ) } Native validation in Revel also supports Match case, where you can compare given parameter with regexp. All models need to be stored in /app directory, because of Revel hot code reaload. Now we Define controller[1][2]. Controller is any type, that embeds 4

11 Bibliography [1] Revel framework [online]. May [2] SAENZ JEREMY, Building Web Apps with Go. GitBook 2015 [3] ANONYMOUS, Build web application with Golang. GitBook 2017 [4] Gorp framework [online]. November [5] Revel, GORP, and MySQL Building a classic 3-tier web application controller in Golang. [online]. November