Agile20x20

The Agile Practitioners group recently held a pecha-kucha event at Zuhlke Engineering. The talks were great! The content was intriguing and the Pecha Kucha format added an extra edge to the presentations.

We learned a few lessons that will help improve the next Agile20x20 event.

Here are the talks

Christian Heldstab does a great job of presenting Getting Things Done

Abid Quereshi exlapins the core values of Scrum

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The Buffering Law observed in Software Engineering

Railway buffer at the top of Pikes Peak, Colorado Springs CO

There is an informative slide deck on the FactoryPhysics website entitled A Fast Cycle Time Story. This slide deck was created by two Intel Products employees namely Tim Skowronski and Joan Tafoya.

The slides cover many aspects of lean manufacturing, one of the topics covered is The Buffering Law

Systems with variability must be buffered by some combination of:

  • Inventory
  • Capacity
  • Time

Tafoya and Skowronski explain the implication of this law

If you cannot pay to reduce variability, you will pay in terms of high WIP, under-utilized capacity, or reduced customer service i.e. lost sales, long lead times, and/or late deliveries.

The following variability buffering examples are provided:

  • Ballpoint Pens:
  • can’t buffer with time (who will backorder a cheap pen?)
  • can’t buffer with capacity (too expensive, and slow)
  • must buffer with inventory
  • Ambulance Service:
    • can’t buffer with inventory (an inventory of trips to hospitals?)
    • can’t buffer with time (response time is the key measure)
    • must buffer with capacity
  • Organ Transplants:
    • can’t buffer with WIP (perishable – very short usable life)
    • can’t buffer with capacity (we cannot ethically increase capacity)
    • must buffer with time

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    The X Penny Game

    The X Penny Game is a simulation game exploring the effects of WIP limits. It is a combination of Karen Greaves modified Scrum Penny game with Karl Scotland’s version of the Ball Flow Game.

    This game is geared to show the importance of limiting the work in progress and to explore the following formula (implied by Little’s Law)

    Flow Time = WIP/Throughput

    • Flow Time (Cycle Time, Lead Time) – average amount of time it takes to fully complete a unit of work
    • WIP (Work In Process) – is the average amount of units in the system
    • Throughput – average number of units being completed within a given time frame

    The game is designed to work with 6 to 12 people – we had 8 players and 1 facilitator

    The team divides into the following roles:

    • 1 – Customer
    • 5 – Workers
    • The rest are efficiency experts

    We had a total of 8 players (6 workers, 2 efficiency experts).

    The team organises themselves around a table. The image below shows how our team arranged themselves. Each worker has an empty area on the table directly in from of them referred to as a workspace.

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    Agile Practitioners

    It is important to mingle with other members from our industry. This keeps us up to date and stops us getting too caught up in a closed off world. If you would like to have face to face discussions with other professionals you may wish to join us at one of the  Agile Practitioners events. This London based group will be meeting at least once a month. We will be discussing a variety of topics. While we don’t plan to replace any of the existing Agile groups, we do intend to be intriguingly different.

    Avatars and not acting like a manager

    Recently we started using avatars on our Kanban board. We are certainly not the first to do this, however I was surprised by how excited and rejuvenated the team became. If you have never tried this I recommend you suggest it to your team and see if they go for it.

    Not only is it fun, but it is also practical. With one look at our board we can see exactly who is working on what and who they are working with. Each person has one avatar on the board, therefore they can only work on one task at a time. Occasionally someone will start work without updating the board, but this is very seldom.

    We went for the classic South Park characters, each team member got to draw themselves, here is the result:

    You may have noticed that my character (Daryn) is a bit stressed out. This is a reminder to myself, that as the ScrumMaster I should not get overly concerned about everything. I need to trust in the team and leave them alone to get the job done. I need to remember that a ScrumMaster is a facilitator and not a manager. For me, not acting like a manager is the most difficult part about being a ScrumMaster.

    Ajax Fundamentals – Part 4

    Index | Part 1 | Part 2 | Part 3 | Part 4 | Part 5

    5. Development and Debugging Tools

    5.1. Documenting JavaScript

    JSDoc is an open source tool used to add inline documentation to JavaScript source files.   JSDoc is based on the javadoc tool.   Many of the javadoc characteristics have been included in JSDoc.   An example of using JSDoc can be found here.

    5.2. Firefox Tools & Extensions

    DOM Inspector is included in the Mozilla Suite and Firefox browser.   This tool provides a graphical user interface that enables a user to brows the document object model of any site.   One can view, update and insert DOM attributes dynamically.   In order to assist JavaScript developers, DOM Inspector can be switched to JavaScript Object mode.   This shows all the properties and methods available to a JavaScript for a particular mode.   DOM Inspector provides a JavaScript evaluation window that allows the user to execute JavaScript against selected nodes.   There is the option to use CSS Style Rules and Computed Style information.   This allows a user to examine the CSS attributes associated with different page elements.

    Firefox JavaScript Console is a tool that logs JavaScript errors found on a page when the page is rendered.   The Firefox JavaScript Console gives ‘compiler-type’ messages.   It describes the error that occurred and the gives the line number.

    Firebug integrates with Firefox and provides many development tools.   Firebug has a version of a DOM inspector that enables a developer to find elements.   CSS support allows settings to be altered and viewed.   Firebug allows one to monitor the network activity in order to determine how long it takes for different sections of a page to download.      A JavaScript Debugger allows one to debug and step through the JavaScript at runtime.

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    Ajax Fundamentals – Part 3

    Index | Part 1 | Part 2 | Part 3 | Part 4 | Part 5

    3. Security Issues

    The XMLHttpRequest object is restricted to run within the browser’s security sandbox. Any resources requested by the XMLHttpRequest object must reside within the same domain from which the calling script originated. Therefore the XMLHttpRequest object is constrained to requesting resources that reside within the same domain from which the script was originally served. The W3C states, that in the future The XMLHttpRequest Object specification will define a way of doing cross-site requests.

    There is an overabundance of online documentation stating that Ajax introduces multiple security threats. These threats include fake requests, denial of service, cross-site scripting (XSS), reliance on client-side security, and more. Jeremiah Grossman’s article, Myth-Busting AJAX (In)security, maintains that these security issues existed before Ajax and the recommended security best practices remain unchanged. Part of internet security basics is to distrust the client. Ajax is a client side technology and requests need to be treaded with the same caution as all other calls.

    4. Disadvantages

    4.1. Usability Problems

    Web users have become familiar with using classic web pages. Users have become accustomed to using browser features such as the back and next buttons. Ajax calls are not loaded onto the browsers navigation stack. Therefore the back button will not undo the last ‘Ajax operation’. Developers need to explicitly cater for undo operations.

    Ajax enabled pages have a notion of state; this state is altered as the user navigates through the site. The browser is unaware of this state, and it is not reflected in the address bar. Therefore users are not always able to book mark a certain page state. Developers need to consider this when deciding on when to use Ajax.

    The asynchronous nature may make page updates difficult for the user to notice. The developer needs a way of drawing the user’s attention to the modified section of the page. The ‘yellow-fade technique’ has become common practice. In this technique the changes are highlighted with a yellow background, and the yellow fades gradually. These and other techniques are becoming familiar to web users.

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