DDevelopment & Design

Commitment in ScrumCommitment in Scrum

Short note taken long time ago from Henrik Kniberg’s slides about a few aspects of commitment in Scrum

This is a note to self. Note taken long ago from Scrum beyond trenches slides by Henrik Kniberg. Just for myself not to forget.

The sprint commitment – misconceptions

”We promise to achieve this goal”
“We promise to deliver all stories included in the sprint backlog”

I’ll repeat!. These are misconceptions!

 Team’s commitment to the product owner

We promise that:

“… we believe we can reach the sprint goal.”
“… we will do everything in our power to reach the sprint goal, and will let you know immediately if we no longer believe we can reach it.”
“… we believe that we can complete all stories included in the sprint backlog.”
“… we will demonstrate releasable code at the end of the sprint.”
“… if we fall behind schedule we will talk to you and, if necessary, remove the lowest priority stories first.”
“… if we get ahead of schedule, we will add stories to the sprint from the product backlog, in priority order.”
“… we will display our progress and status on a daily basis.”
“… every story that we do deliver is Done.”

Hmm, the opposite of misconceptions should be conceptions, right :D?

Your experience

Would you add any more to these lists? Do you have any experience being hit by wrongly understood commitment? Share!

Kiedyś programista, obecnie PM i ewangelista metod zwinnych.

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DDevelopment & Design

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DDevelopment & Design

Simple trick to DRY your Grails controller

Grails controllers are not very DRY. It's easy to find duplicated code fragments in default generated controller. Take a look at code sample below. It is duplicated four times in show, edit, update and delete actions:

class BookController {
def show() {
def bookInstance = Book.get(params.id)
if (!bookInstance) {
flash.message = message(code: 'default.not.found.message', args: [message(code: 'book.label', default: 'Book'), params.id])
redirect(action: "list")
return
        }
        [bookInstance: bookInstance]
    }
}

Why is it duplicated?

There is a reason for that duplication, though. If you move this snippet to a method, it can redirect to "list" action, but it can't prevent controller from further execution. After you call redirect, response status changes to 302, but after method exits, controller still runs subsequent code.

Solution

At TouK we've implemented a simple trick to resolve that situation:

  1. wrap everything with a simple withStoppingOnRender method,
  2. whenever you want to render or redirect AND stop controller execution - throw EndRenderingException.

We call it Big Return - return from a method and return from a controller at once. Here is how it works:

class BookController {
def show(Long id) {
withStoppingOnRender {
Book bookInstance = Book.get(id)
validateInstanceExists(bookInstance)
            [bookInstance: bookInstance]
        }
    }

protected Object withStoppingOnRender(Closure closure) {
try {
return closure.call()
        } catch (EndRenderingException e) {}
    }

private void validateInstanceExists(Book instance) {
if (!instance) {
flash.message = message(code: 'default.not.found.message', args: [message(code: 'book.label', default: 'Book'), params.id])
redirect(action: "list")
throw new EndRenderingException()
        }
    }
}

class EndRenderingException extends RuntimeException {}

Example usage

For simple CRUD controllers, you can use this solution and create some BaseController class for your controllers. We use withStoppingOnRender in every controller so code doesn't look like a spaghetti, we follow DRY principle and code is self-documented. Win-win-win! Here is a more complex example:

class DealerController {
@Transactional
def update() {
withStoppingOnRender {
Dealer dealerInstance = Dealer.get(params.id)
validateInstanceExists(dealerInstance)
validateAccountInExternalService(dealerInstance)
checkIfInstanceWasConcurrentlyModified(dealerInstance, params.version)
            dealerInstance.properties = params
saveUpdatedInstance(dealerInstance)
redirectToAfterUpdate(dealerInstance)
        }
    }
}