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Author: Troy Campano

Book Review: The Art of Scalability

TheArtOfScalabilityOverview

The Art of Scalability by Martin L. Abbott and Michael T. Fisher is a book about scaling IT Systems. Now, this isn’t a book just about the technical parts of scale; this book has split into three parts including:

– How to Staff for Scale
– What Processes Do You Need for Scale
– How to Architect Scalable Solutions

As you can see the technical architecture of developing scalable systems is only one part of this book. Instead this book takes a holistic view of scalability from the ground up building from the staff that supports the scalable system, to what they do, and then how the actual systems are put together.

This review will cover a handful of the topics/tips from the book, however this book is highly recommend for those working in systems that need to scale. Click here to purchase the book on Amazon.

Headroom

It is important to determine the headoom for your applications (the amount of free capacity in the application/system before you start to have problems. If you don’t start to analyze where your headroom is your system may be taken down by a surge in traffic to your application. In calculating headroom, make sure you’re looking at all components (firewalls, load balancers, database clusters, etc.

Architectural Principles

This book contains a short list of scalability related architectural principles including N+1 design (ensuring any component in the system has at least one additional component in case one of the components fails); designing for rollback, designing to be disable, designing to be monitored,designing for multiple live sites, asynchonous design (and how it is a superior type of design for scalable systems , stateless systems, and more.

JAD (Joint Application Design) and ARB (Architecture Review Board)

Here the book covers topics on what groups need to come together to take a collaborative approach to architecture and design, and who should be reviewing the architecture. The book also includes a JAD checking and a definition of JAD entry/exit criteria.

Performance and Stress Testing

There is decent coverage on the process of performance and stress testing.

TAD (Technology Agnostic Design)

Another acronym, TAD, describes designing architectures to be technology agnostic. Stay away from vendor terminology in your design, say “Load Balancer” instead of “F5 LTM” (even in your physical architectures!).

Fault Isolative Architectural Structures

Lots of good information on pods, shards, chunks, and other funky terminology.

Caching for Performance & Scale

How to utilize caching in your architectural strategy (especially important for web systems).

And much more…

And there’s much more this almost 600 page book covers including cloud and grid strategy, monitoring applications, multiple live data centers, etc.
I highly recommend this book for any architect or engineer that is working on large applications that need to scale (or may need to scale in the future).

Additional Resources

Passing the TOGAF Exam

Introduction

TOGAF (The Open Group Architecture Framework) is a framework and methodology for enterprise architecture.

Yesterday I took the Level 2 TOGAF v9 Certification Exam and passed! I will review the exam and some basic tips to help you study for the exam.

The Exam

TOGAF 9 Foundation

TOGAF has two certification levels, and two different exams (one for each of the levels). The first level is “TOGAF 9 Foundation”. The exam associated with this level of certification tests you on your knowledge of the core concepts of TOGAF. The test consists of 40 multiple choice questions. For each question there is only one correct answer. This exam is closed book.

TOGAF 9 Certified

The second level is “TOGAF 9 Certified”. This requires you to first pass the TOGAF 9 Foundation exam and then you will be able to take the certification exam. The certification exam is comprised of 8 questions and is open book. The questions are ‘Complex Multiple Choice Scenario-Based’ questions. For each question, you are presented with a case-study scenario and then are asked as an architect what would be the best way to approach the particular problem in the scenario. Multiple answers are presented to you and you must choose one. There are four answers, one of which is wrong and the other three are varying levels of correctness. You must choose the best answer. Different points are awarded based on the answer you choose (assuming you choose a correct answer). This exam is open book.

Additional Information

TOGAF has different paths to taking the certification. You can take the exams separately, all at once, or ‘upgrade’ your TOGAF v8 certification using a bridge exam. For details, go to http://www.togaf.info and download the “Information Sheet: TOGAF 9 People Certification” PDF for details on the exam.

 

Prepping for the Exam

Reading the TOGAF Book

First, read the TOGAF v9 book, available here:

http://www.opengroup.org/architecture/togaf9-doc/arch/. I read through the book and applied many of the principles and methodology in the book to my daily work as much as possible. This helped me gain a base understanding of the material.

Take a Training Course

To prepare for the exam, I took a self-study training course through Architecting the Enterprise (http://www.architecting-the-enterprise.com/). With this program you receive a CD full of study materials, case studies, a workbook, and the official Open Group TOGAF v9 Practice Exam (though the practice exam is not on the CD but printed on paper). I found going through this course provided me a deeper understanding of the TOGAF materials. Each section of TOGAF is presented in a PowerPoint/PDF document; it walks you through each of the TOGAF sections step-by-step and it made it much more enjoyable than just reading the book. You are assigned an instructor who can answer any questions you may have over email and guide you through the process. After each section there is a series of questions that you answer in the workbook. The format is different than the exam since you are writing the answers in written text form (where the exam is multiple choice). At the end, you are asked to review a case study and then are asked to describe the process of implementing an enterprise architecture for the organization in the case study addressing the concerns presented in the case study. I found this to be much harder than the exam itself but it really helps you gain that deeper insight into TOGAF.

Taking a Practice Exam

Once you think you have enough knowledge to take the TOGAF exam, take a practice exam. Chris Eaton has put together a great set of practice questions that give you a gauge on the level of understanding needed for the exam. Check them out on his site artITecture here: http://chriseaton.wordpress.com/2009/08/24/togaf-9-certification-multiple-choice-questions/.

NOTE: Don’t take the practice exam until you’re ready and don’t look up the answers. If you want to know how much of the TOGAF material you really know, take the practice exam with a ‘closed book’. Otherwise you’re cheating yourself because once you know the answer there is no way to retake the exam and get an accurate picture of how much you really knew.

Also, if you took the Architecting the Enterprise course you were provided with the official TOGAF v9 practice exam. This exam is very much like the format of the real exam, but with different questions. If you didn’t take the training course I believe you can still purchase the practice exam through Prometric (http://ibt.prometric.com/AOGEA) and possibly through the Open Group Store: https://store.opengroup.org/catalog/.

 

Additional Tips

Here are some additional tips in studying for the exam.

Read the Book

The first exam is really about how much of the TOGAF materials you can memorize. The book is the best source for this information but you really must read the entire book, not just parts. The exam references specific pieces and examples from the different sections of the book. Ensure you’ve read through each section of the book (each link on the left-hand side of the online book).

Understand All ADM Phase Objectives

A lot of the questions on the exam had to do with choosing which of the answers was not included as an objective of a particular Phase of the ADM (Architecture Development Method). For example, “which of the following is NOT an objective of Phase E:”.

Become Familiar With ADM Phase Steps

Understanding the steps in each phase will help you spot the correct answers in some questions.

Understand the Artifacts

There were questions on the practice and real exam about, given a case study, which would be the best artifacts used to address the concerns of the stakeholders. This means really knowing chapter 35: http://www.opengroup.org/architecture/togaf9-doc/arch/chap35.html.

Additional Tips

Again, you need to read through and understand the book. You may focus on the following:

There were questions on all ADM phases; understand the differences between the Preliminary Phase and Phase A: Architecture Vision.

Understand the differences between Phase E: Opportunities & Solutions and Phase F: Migration Planning. They are similar (and in my opinion should be combined into the same phase).

As expected there were questions on Architecture Principles, Business Scenarios, Gap Analysis, Business Transformation Readiness Assessment, Risk Management, and other Guidelines and Techniques.

As expected there were questions on Reference Models and the Architecture Capability Framework.

Practice Exams

In addition to the Chris Eaton practice exams, you can get the official practice exams from the OpenGroup here:

TOGAF 9 Part 1 Practice Test

TOGAF 9 Part 2 Practice Test

 

The OpenGroup also has a free 10 question online practice exam here:

http://www.opengroup.org/togaf/cert/docs/examdemo.tpl?CALLER=about_the_exam.tpl.

And I’ve heard of other’s using this practice exam, through I haven’t used it myself:

http://www.bestpracticehelp.com/togafquiz.php.

As you can see the questions span the entire book, so reading the book is a must. Also getting a copy of the Chris Eaton AND Open Group TOGAF Practice Exams were VERY helpful. I wish you good luck in taking the exam!

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