Theory of Constraints in Software Engineering - Revision history

Tkokotas at 12:58, 18 December 2018

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			''Developed by Iðunn Tara Ásgrímsdóttir''


	<span class="plainlinks">[https://en.wikipedia.org/wiki/Theory_of_constraints Theory of Constraints]</span> (TOC) is a methodology invented by [https://en.wikipedia.org/wiki/Eliyahu_M._Goldratt Dr. Eliyahu M. Goldratt] a scientist, physicist, author, educator and consultant<ref name="TOCMAN">McMullen, Jr., Thomas B. "Introduction to the Theory of Constraints (TOC) Management System", ''APICS'' Pub.1998</ref>. With the methodology the most important limiting factor, that hinders a goal to be achieved, is identified. Then that factor (i.e. constraint) is improved until it is no longer the limiting factor. Since Goldratt introduced the Theory of Constraints in his bestselling 1984 novel, ''[https://en.wikipedia.org/wiki/The_Goal_(novel) "The Goal"]'', the methodology has continued to evolve and develop into many different fields including [https://en.wikipedia.org/wiki/Software_engineering Software Engineering]. <ref name="Lean"></ref>		<span class="plainlinks">[https://en.wikipedia.org/wiki/Theory_of_constraints Theory of Constraints]</span> (TOC) is a methodology invented by [https://en.wikipedia.org/wiki/Eliyahu_M._Goldratt Dr. Eliyahu M. Goldratt] a scientist, physicist, author, educator and consultant<ref name="TOCMAN">McMullen, Jr., Thomas B. "Introduction to the Theory of Constraints (TOC) Management System", ''APICS'' Pub.1998</ref>. With the methodology the most important limiting factor, that hinders a goal to be achieved, is identified. Then that factor (i.e. constraint) is improved until it is no longer the limiting factor. Since Goldratt introduced the Theory of Constraints in his bestselling 1984 novel, ''[https://en.wikipedia.org/wiki/The_Goal_(novel) "The Goal"]'', the methodology has continued to evolve and develop into many different fields including [https://en.wikipedia.org/wiki/Software_engineering Software Engineering]. <ref name="Lean"></ref>

IdunnTara at 22:08, 25 September 2016

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	=== Throughput Accounting (TA) ===		=== Throughput Accounting (TA) ===
	In traditional accounting, inventory is an asset~~. That~~ often drives undesirable behavior at companies to manufacture items that are not truly needed because it generates a "paper profit" based on inventory that may or may not ever be sold. Since the Theory of Constraints considers inventory to be a liability, Throughput Accounting is used ~~because~~ it attempts to eliminate harmful distortions introduced in traditional accounting practices.<ref name="TOCSE"></ref>		In traditional accounting, inventory is an asset that often drives undesirable behavior at companies to manufacture items that are not truly needed. Those items are manufactured because it generates a "paper profit" based on inventory that may or may not ever be sold. Since the Theory of Constraints considers inventory to be a liability, Throughput Accounting is used as it attempts to eliminate harmful distortions introduced in traditional accounting practices.<ref name="TOCSE"></ref>

	Core measures in Throughput Accounting are the following		Core measures in Throughput Accounting are the following
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	== Limitations ==		== Limitations ==
	When applying the Theory of Constraints, one has to be aware of its limitations before implementing it.		When applying the Theory of Constraints, one has to be aware of its limitations before implementing it.
	First of all, the identification of the constraint is really important. The theory might work on a constraint that is caused by another constraining factor or it might focus on an irrelevant constraint. ~~That~~ could lead to waste of resources and time to limit some problem that is not critical to the success of the company. Another limitation of the theory is lack of consideration of variable factors. If the constraint is a demand for product, that varies independently from any action taken through the theory, resources invested in increasing the demand could have been more beneficial in expanding the production capacity. Theory of Constraints limits itself to short-term effects which is a limitation that can be overcome by ~~examine~~ the long-term effects of the work. If the short-term ~~effect remains~~ valid over a longer time-frame, the strategy indicated by the theory may be valid. If not, then other constraints have to be identified that result in long term benefits.<ref name="Limit"> Bert Markgraf. [http://yourbusiness.azcentral.com/limitations-theory-constraints-16352.html "Limitations of the Theory of Constraints"], ''studioD'', Date unknown. Retrieved on 25. September 2016. </ref>		First of all, the identification of the constraint is really important. The theory might work on a constraint that is caused by another constraining factor or it might focus on an irrelevant constraint. Focusing on irrelevant constraint could lead to waste of resources and time to limit some problem that is not critical to the success of the company. Another limitation of the theory is lack of consideration of variable factors. If the constraint is a demand for product, that varies independently from any action taken through the theory, resources invested in increasing the demand could have been more beneficial in expanding the production capacity. Theory of Constraints limits itself to short-term effects which is a limitation that can be overcome by examining the long-term effects of the work. If the short-term effects remain valid over a longer time-frame, the strategy indicated by the theory may be valid. If not, then other constraints have to be identified that result in long term benefits.<ref name="Limit"> Bert Markgraf. [http://yourbusiness.azcentral.com/limitations-theory-constraints-16352.html "Limitations of the Theory of Constraints"], ''studioD'', Date unknown. Retrieved on 25. September 2016. </ref>

	== Annoted Bibliography ==		== Annoted Bibliography ==
	*<ref name="Lean"> Unknown. [http://www.leanproduction.com/theory-of-constraints.html "Theory of Constraints"], ''Lean Production'', Date unknown. Retrieved on 10 September 2016. </ref> '''Vorne, Theory of Constraints''' This guide describes Theory of Constraints in comprehensible terms. It focuses on the basic terms of the theory and gets right to the point in each matter. The guide is made by an organization that specializes in manufacturing systems and follows the latest trends in Lean Manufacturing. The guide contains a helpful tables about the subject which are used through the article. The guide is used through the article to get a better and simpler ~~under standing~~ of TOC.		*<ref name="Lean"> Unknown. [http://www.leanproduction.com/theory-of-constraints.html "Theory of Constraints"], ''Lean Production'', Date unknown. Retrieved on 10 September 2016. </ref> '''Vorne, Theory of Constraints''' This guide describes Theory of Constraints in comprehensible terms. It focuses on the basic terms of the theory and gets right to the point in each matter. The guide is made by an organization that specializes in manufacturing systems and follows the latest trends in Lean Manufacturing. The guide contains helpful tables about the subject which are used through the article. The guide is used through-out the article to get a better and simpler understanding of TOC.

	* <ref name="SoftwareBOK"> Braude, Eric J. & Bernstein, Michael E. "SOFTWARE ENGINEERING Modern Approaches", ''Waveland press, INC''United States of America 2016.</ref> '''Eric J. Braude and Michael E. Bernstein, 2016, Software Engineering Modern Approaches.''' This book is designed to accommodate multiple approaches to the learning and teaching of Software Engineering. It is good to understand the basic thinking behind Software Engineering. The book was used in the article to get explain Software Engineering and its concept.		* <ref name="SoftwareBOK"> Braude, Eric J. & Bernstein, Michael E. "SOFTWARE ENGINEERING Modern Approaches", ''Waveland press, INC''United States of America 2016.</ref> '''Eric J. Braude and Michael E. Bernstein, 2016, Software Engineering Modern Approaches.''' This book is designed to accommodate multiple approaches to the learning and teaching of Software Engineering. It is good to understand the basic thinking behind Software Engineering. The book was used in the article to get explain Software Engineering and its concept.
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	*<ref name="Anderson"> Anderson, David J. "AGILE MANAGEMENT FOR SOFTWARE ENGINEERING: Applying the Theory of Constraints for Business Results", ''Prentice Hall PTR'' United States of America, September 17 2003. Retrieved on 10 September 2016</ref> '''David J. Anderson, 2003, Agile Management For Software Engineering: Applying the Theory of Constraints for Business Results''' This book is about software engineering management and explains how agile software development is used to make a business better. The author shows managers how to apply management science to gain the full business benefits of agility through application of the Theory of Constraints.		*<ref name="Anderson"> Anderson, David J. "AGILE MANAGEMENT FOR SOFTWARE ENGINEERING: Applying the Theory of Constraints for Business Results", ''Prentice Hall PTR'' United States of America, September 17 2003. Retrieved on 10 September 2016</ref> '''David J. Anderson, 2003, Agile Management For Software Engineering: Applying the Theory of Constraints for Business Results''' This book is about software engineering management and explains how agile software development is used to make a business better. The author shows managers how to apply management science to gain the full business benefits of agility through application of the Theory of Constraints.

	*<ref name="TOCBOK"> Goldratt, Eliyahu M. "What is this thing called THEORY OF CONSTRAINTS and how should it be implemented?", '''', Croton-on-Hudson, North River, New York 1990</ref>''' Eliyahu M. Goldratt, 1990, What is this thing called Theory of Constraints and how should it be implemented?''' This book walks through the crucial stages of a continuous program: the five steps of focusing; the process of change; how to prove effect-cause-effect; and how to invent simple solutions to complex problems. Goldratt is the one who originally introduced TOC and his way of introducing it is a little bit different ~~then~~ others~~. The book is fun to read but at the same, you are not sure that you are reading a book about theory~~. The book is used in this article to get a better understanding of the Five Forces and TOC in whole.		*<ref name="TOCBOK"> Goldratt, Eliyahu M. "What is this thing called THEORY OF CONSTRAINTS and how should it be implemented?", '''', Croton-on-Hudson, North River, New York 1990</ref>''' Eliyahu M. Goldratt, 1990, What is this thing called Theory of Constraints and how should it be implemented?''' This book walks through the crucial stages of a continuous program: the five steps of focusing; the process of change; how to prove effect-cause-effect; and how to invent simple solutions to complex problems. Goldratt is the one who originally introduced TOC and his way of introducing it is a little bit different than the others. The book is used in this article to get a better understanding of the Five Forces and TOC in whole.

	*<ref name="TOCSE"> Tendon, Steve. [http://chronologist.com/blog/2012-07-27/theory-of-constraints-and-software-engineering/ "Theory of Constraints and Software Engineering"], ''The TameFlow Chronologist'', Published July 27th 2012. Retrieved on 13 September 2016. </ref> ''' Steve Tendon, 2012, Theory of Constraints and Software Engineering.''' This article is looking at TOC and how it can be applied to Software Engineering Management. The article examines how Throughput Accounting can be used to take important management decisions. The article compares Cost Accounting versus Throughput Accounting with Software Engineering in mind along with explaining Throughput Accounting for Software Engineering. The article is used to get a better understanding how Throughput Accounting is used in Software Engineering.		*<ref name="TOCSE"> Tendon, Steve. [http://chronologist.com/blog/2012-07-27/theory-of-constraints-and-software-engineering/ "Theory of Constraints and Software Engineering"], ''The TameFlow Chronologist'', Published July 27th 2012. Retrieved on 13 September 2016. </ref> ''' Steve Tendon, 2012, Theory of Constraints and Software Engineering.''' This article is looking at TOC and how it can be applied to Software Engineering Management. The article examines how Throughput Accounting can be used to take important management decisions. The article compares Cost Accounting versus Throughput Accounting with Software Engineering in mind along with explaining Throughput Accounting for Software Engineering. The article is used to get a better understanding on how Throughput Accounting is used in Software Engineering.

	== References ==		== References ==
	<references />		<references />

IdunnTara: /* 5. If in the previous steps a constraint has been brokes, go back to step one, but do not allow inertia to cause a system constrain */

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5. If in the previous steps a constraint has been brokes, go back to step one, but do not allow inertia to cause a system constrain

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	Elevating a software developer from a constraint can be done in various ways. According to David J. Anderson the most obvious way used in the software industry is unpaid overtime, therefore the constraint in stretched. Managers could also hire more developers, introduce shift working or even use a better developer <ref name="Anderson"></ref>.		Elevating a software developer from a constraint can be done in various ways. According to David J. Anderson the most obvious way used in the software industry is unpaid overtime, therefore the constraint in stretched. Managers could also hire more developers, introduce shift working or even use a better developer <ref name="Anderson"></ref>.

	==== 5. If in the previous steps a constraint has been ~~brokes~~, go back to step one, but do not allow inertia to cause a system constrain ====		==== 5. If in the previous steps a constraint has been broken, go back to step one, but do not allow inertia to cause a system constrain ====

	=== Throughput Accounting (TA) ===		=== Throughput Accounting (TA) ===

IdunnTara: /* 4. Elevate the system´s constraints */

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4. Elevate the system´s constraints

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	==== 4. Elevate the system´s constraints ====		==== 4. Elevate the system´s constraints ====
	In step 4 the objective is to elevate the constraint and might require more substantive changes. Investment of time and/or money is something that might ~~need~~ to elevate the constraint. <ref name="Lean"></ref>.		In step 4 the objective is to elevate the constraint and might thus require more substantive changes. Investment of time and/or money is something that might be needed to elevate the constraint. <ref name="Lean"></ref>.

	Elevating a software developer from a constraint can be done in various ways. According to David J. Anderson the most obvious way used in the software industry is unpaid overtime, therefore the constraint in stretched. Managers could also hire more developers or introduce shift working or even use a better developer <ref name="Anderson"></ref>.		Elevating a software developer from a constraint can be done in various ways. According to David J. Anderson the most obvious way used in the software industry is unpaid overtime, therefore the constraint in stretched. Managers could also hire more developers, introduce shift working or even use a better developer <ref name="Anderson"></ref>.

	==== 5. If in the previous steps a constraint has been brokes, go back to step one, but do not allow inertia to cause a system constrain ====		==== 5. If in the previous steps a constraint has been brokes, go back to step one, but do not allow inertia to cause a system constrain ====

IdunnTara: /* 3. Subordinate everything else to the above decision */

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3. Subordinate everything else to the above decision

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	==== 3. Subordinate everything else to the above decision ====		==== 3. Subordinate everything else to the above decision ====

	The primary objective in step three is to support the needs of the constraint ~~and~~ the focus in on non-constraint equipment <ref name="Lean"></ref>.		The primary objective in step three is to support the needs of the constraint as the focus is on non-constraint equipment <ref name="Lean"></ref>.

	Some useful techniques for this step include:		Some useful techniques for this step include:
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	\|}		\|}

	If constraints ~~should be fully exploited~~ in Software Engineering the developers should not be loaded with any more than they can reasonably handle. So the rest of the system of software production must be subordinated to this notion.		To fully exploit constraints in Software Engineering the developers working should not be loaded with any more than they can reasonably handle. Thus the rest of the system of the software production must be subordinated to this notion.

	==== 4. Elevate the system´s constraints ====		==== 4. Elevate the system´s constraints ====

IdunnTara: /* 2. Decide how to exploit the system´s constraints */

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2. Decide how to exploit the system´s constraints

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	==== 2. Decide how to exploit the system´s constraints ====		==== 2. Decide how to exploit the system´s constraints ====
	When the constraints have been identified and prioritized ~~and~~ a decision about how ~~they are going~~ to be ~~managed has been decided, the~~ vast majority of the system´s resources that are not constraints have to be managed also. <ref name="TOCBOK"></ref> The objective ~~with~~ this step is to make the most of what you have and maximize throughput of the constraint using currently available resources. The step focuses on quick wins and rapid relief; leaving more complex and substantive changes for later. <ref name="Lean"></ref>		When the constraints have been identified and prioritized, a decision about how to manage them has to be made. The vast majority of the system´s resources that are not constraints have to be managed also. <ref name="TOCBOK"></ref> The objective off this step is to make the most of what you have and maximize throughput of the constraint using currently available resources. The step focuses on quick wins and rapid relief; leaving more complex and substantive changes for later. <ref name="Lean"></ref>

	In the following table items that could improve constraint are described in general:		In the following table items that could improve constraint are described in general:
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	*Requirements she is given are of good quality <ref name="Lean"></ref>		*Requirements she is given are of good quality <ref name="Lean"></ref>

	If the actions taken in this step solve the constraint, next step is step five, otherwise continue to step three.		If the actions taken in this step solve the constraint the next step is to go on to step five, otherwise continue to step three.

	==== 3. Subordinate everything else to the above decision ====		==== 3. Subordinate everything else to the above decision ====

IdunnTara: /* 1. Identify the system´s constraints */

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1. Identify the system´s constraints

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	==== 1. Identify the system´s constraints ====		==== 1. Identify the system´s constraints ====
	The first thing to do in order to use Theory of Constraints to improve a system is to identify the constraints and prioritize them according to their impact on the goal. As said before, constraints can take many forms and the most known constraints are bottlenecks~~, the physical constraint~~ and therefore it can be a good idea to start identifying them. It is generally assumed that there is only one global system constraint at any given time. Once a constraint has been identified, a decision must be made on how to minimize its constraining ability on the system. The constraint must be fully utilized and according to David J. Anderson; every unit of production lost in the constraint is a unit lost in the whole system <ref name="Anderson"></ref>.		The first thing to do in order to use Theory of Constraints to improve a system is to identify the constraints and prioritize them according to their impact on the goal. As said before, constraints can take many forms and the most known constraints are bottlenecks and therefore it can be a good idea to start identifying them. It is generally assumed that there is only one global system constraint at any given time. Once a constraint has been identified, a decision must be made on how to minimize its constraining ability on the system. The constraint must be fully utilized and according to David J. Anderson; every unit of production lost in the constraint is a unit lost in the whole system <ref name="Anderson"></ref>.

	==== 2. Decide how to exploit the system´s constraints ====		==== 2. Decide how to exploit the system´s constraints ====

IdunnTara at 14:45, 25 September 2016

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IdunnTara at 10:53, 25 September 2016

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	<span class="plainlinks">[https://en.wikipedia.org/wiki/Theory_of_constraints Theory of Constraints]</span> (TOC) is a methodology invented by [https://en.wikipedia.org/wiki/Eliyahu_M._Goldratt Dr. Eliyahu M. Goldratt] a scientist, physicist, author, educator and consultant<ref name="TOCMAN">McMullen, Jr., Thomas B. "Introduction to the Theory of Constraints (TOC) Management System", ''APICS'' Pub.1998</ref>. With the methodology the most important limiting factor, that hinders a goal to be achieved, is identified ~~and then~~ that factor (i.e. constraint) is improved until it is no longer the limiting factor. Since Goldratt introduced the Theory of Constraints in his bestselling 1984 novel, ''[https://en.wikipedia.org/wiki/The_Goal_(novel) "The Goal"]'', the methodology has continued to evolve and develop into many different fields including [https://en.wikipedia.org/wiki/Software_engineering Software Engineering]. <ref name="Lean"></ref>		<span class="plainlinks">[https://en.wikipedia.org/wiki/Theory_of_constraints Theory of Constraints]</span> (TOC) is a methodology invented by [https://en.wikipedia.org/wiki/Eliyahu_M._Goldratt Dr. Eliyahu M. Goldratt] a scientist, physicist, author, educator and consultant<ref name="TOCMAN">McMullen, Jr., Thomas B. "Introduction to the Theory of Constraints (TOC) Management System", ''APICS'' Pub.1998</ref>. With the methodology the most important limiting factor, that hinders a goal to be achieved, is identified. Then that factor (i.e. constraint) is improved until it is no longer the limiting factor. Since Goldratt introduced the Theory of Constraints in his bestselling 1984 novel, ''[https://en.wikipedia.org/wiki/The_Goal_(novel) "The Goal"]'', the methodology has continued to evolve and develop into many different fields including [https://en.wikipedia.org/wiki/Software_engineering Software Engineering]. <ref name="Lean"></ref>

	The goals of Software Engineering is the creation of software systems that meet the needs of customers and are efficient, maintainable and reliable in addition the systems should meet project schedules and budgets along with being produced in an economical way.<ref name="SoftwareBOK"></ref> Applying analogous set of approaches to the development of software, one can expect the production of software that meets the goals of Software Engineering. <ref name="SoftwareBOK"></ref>		The goals of Software Engineering is the creation of software systems that meet the needs of customers and are efficient, maintainable and reliable in addition the systems should meet project schedules and budgets along with being produced in an economical way.<ref name="SoftwareBOK"></ref> Applying analogous set of approaches to the development of software, one can expect the production of software that meets the goals of Software Engineering. <ref name="SoftwareBOK"></ref>

IdunnTara: /* Limitations */

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Limitations

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	== Limitations ==		== Limitations ==
	When applying the Theory of Constraints, one has to be aware of its limitations before implementing it.		When applying the Theory of Constraints, one has to be aware of its limitations before implementing it.
	First of all, the identification is really important. The theory might work on a constraint that is caused by another constraining factor or it might focus on an irrelevant constraint. That could lead to waste of resources and time to limit some problem that is not critical to the success of the company. Another limitation of the theory is lack of consideration of variable factors. If the constraint is a demand for product, that varies independently from any action taken through the theory, resources invested in increasing the ~~demandd~~ could have been more beneficial in expanding the production capacity. Theory of Constraints limits itself to short-term effects which is a limitation that can be overcome by examine the long-term effects of the work. If the short-term effect remains valid over a longer time-frame, the strategy indicated by the theory may be valid. If not, then other constraints have to be identified that result in long term benefits.<ref name="Limit"> Bert Markgraf. [http://yourbusiness.azcentral.com/limitations-theory-constraints-16352.html "Limitations of the Theory of Constraints"], ''studioD'', Date unknown. Retrieved on 25. September 2016. </ref>		First of all, the identification of the constraint is really important. The theory might work on a constraint that is caused by another constraining factor or it might focus on an irrelevant constraint. That could lead to waste of resources and time to limit some problem that is not critical to the success of the company. Another limitation of the theory is lack of consideration of variable factors. If the constraint is a demand for product, that varies independently from any action taken through the theory, resources invested in increasing the demand could have been more beneficial in expanding the production capacity. Theory of Constraints limits itself to short-term effects which is a limitation that can be overcome by examine the long-term effects of the work. If the short-term effect remains valid over a longer time-frame, the strategy indicated by the theory may be valid. If not, then other constraints have to be identified that result in long term benefits.<ref name="Limit"> Bert Markgraf. [http://yourbusiness.azcentral.com/limitations-theory-constraints-16352.html "Limitations of the Theory of Constraints"], ''studioD'', Date unknown. Retrieved on 25. September 2016. </ref>

	== Annoted Bibliography ==		== Annoted Bibliography ==

← Older revision		Revision as of 14:45, 25 September 2016
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	<span class="plainlinks">[https://en.wikipedia.org/wiki/Theory_of_constraints Theory of Constraints]</span> (TOC) is a methodology invented by [https://en.wikipedia.org/wiki/Eliyahu_M._Goldratt Dr. Eliyahu M. Goldratt] a scientist, physicist, author, educator and consultant<ref name="TOCMAN">McMullen, Jr., Thomas B. "Introduction to the Theory of Constraints (TOC) Management System", ''APICS'' Pub.1998</ref>. With the methodology the most important limiting factor, that hinders a goal to be achieved, is identified. Then that factor (i.e. constraint) is improved until it is no longer the limiting factor. Since Goldratt introduced the Theory of Constraints in his bestselling 1984 novel, ''[https://en.wikipedia.org/wiki/The_Goal_(novel) "The Goal"]'', the methodology has continued to evolve and develop into many different fields including [https://en.wikipedia.org/wiki/Software_engineering Software Engineering]. <ref name="Lean"></ref>		<span class="plainlinks">[https://en.wikipedia.org/wiki/Theory_of_constraints Theory of Constraints]</span> (TOC) is a methodology invented by [https://en.wikipedia.org/wiki/Eliyahu_M._Goldratt Dr. Eliyahu M. Goldratt] a scientist, physicist, author, educator and consultant<ref name="TOCMAN">McMullen, Jr., Thomas B. "Introduction to the Theory of Constraints (TOC) Management System", ''APICS'' Pub.1998</ref>. With the methodology the most important limiting factor, that hinders a goal to be achieved, is identified. Then that factor (i.e. constraint) is improved until it is no longer the limiting factor. Since Goldratt introduced the Theory of Constraints in his bestselling 1984 novel, ''[https://en.wikipedia.org/wiki/The_Goal_(novel) "The Goal"]'', the methodology has continued to evolve and develop into many different fields including [https://en.wikipedia.org/wiki/Software_engineering Software Engineering]. <ref name="Lean"></ref>

	The goals of Software Engineering is the creation of software systems that meet the needs of customers ~~and are~~ efficient, maintainable and reliable in addition ~~the systems should meet~~ project schedules and budgets ~~along with being~~ produced in an economical way.<ref name="SoftwareBOK"></ref> Applying analogous set of approaches to the development of software, one can expect the production of software that meets the goals of Software Engineering. <ref name="SoftwareBOK"></ref>		The goals of Software Engineering is the creation of software systems that meet the needs of customers. The systems should be efficient, maintainable and reliable in addition to meeting project schedules and budgets and be produced in an economical way.<ref name="SoftwareBOK"></ref> Applying analogous set of approaches to the development of software, one can expect the production to be a software that meets the goals of Software Engineering. <ref name="SoftwareBOK"></ref>

	Theory of Constraints (TOC) in relevance to Software Engineering is two folded. First of all, it is used to improve the flow of new products to the market and second determining the real value of a proposed project or a feature to the final user. The assumption is that if the real value to the user is known, then it is possible to develop the right marketing and sales approach to materialize the value to the user and the software organization. <ref name="Anderson"></ref>		Theory of Constraints (TOC) in relevance to Software Engineering is two folded. First of all, it is used to improve the flow of new products to the market and second determining the real value of a proposed project or a feature to the final user. The assumption is that if the real value to the user is known, then it is possible to develop the right marketing and sales approach to materialize the value to the user and the software organization. <ref name="Anderson"></ref>

	This article will introduce how Theory of Constraints can be used in Software Engineering to achieve set goals (projects for example) ~~along with~~ guidance to apply the methodology.		This article will introduce how the Theory of Constraints can be used in Software Engineering to achieve a set of previously identified goals (projects for example). The article will also give guidance on how to apply and use the methodology in practice.


	== Theory of Constraints ==		== Theory of Constraints ==
	Before improving a system or any part of it, one must define system’s global goal and the measurements that will ~~enable him~~ to ~~judge~~ the ~~effect~~ of any subsystem ~~and any~~ local decision on the goal. When measurements have been defined, the constraint that limits the system to reach its goal can be found. <ref name="TOCBOK"></ref>		Before improving a system or any part of it, one must define the system’s global goal and the measurements that will be used to evaluate the effects of any subsystem or local decision on the goal. When measurements have been defined, the constraint that limits the system to reach its goal can be found. <ref name="TOCBOK"></ref>

	Theory of Constraints (TOC) is a methodology that is used to identify the most important constraints in a system and then improving the constraint until it is no longer the limiting one. According to TOC every complex system consists of multiple linked activities and one of these activities is a constraint upon the whole system.		Theory of Constraints (TOC) is a methodology that is used to identify the most important constraints in a system and then improving the constraint until it is no longer the limiting one. According to TOC every complex system consists of multiple linked activities and one of these activities can be a constraint upon the whole system.
	=== Constraints ===		=== Constraints ===
	Constraints are like said before, anything that prevents the organization from making progress towards its goal. Constraints can take many forms ~~other than~~ equipment ~~and there~~ are differing opinions how to categorize them, one approach is shown in the table below:		Constraints are like said before, anything that prevents the organization from making progress towards its goal. Constraints can take many forms and are not necessarily only equipment. There are differing opinions on how to categorize different constraints, them, one approach is shown in the table below:

	{\| class="wikitable" style="width: 600px;"		{\| class="wikitable" style="width: 600px;"
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	Theory of Constraints provides powerful set of tools to achieve the ultimate goal of ~~companies~~: '''Make profit '''.		Theory of Constraints provides powerful set of tools to achieve the ultimate goal of a company: '''Make a profit '''.

	Two of ~~these~~ tools will be introduced in the following chapter and later on explained in relation to Software Engineering ~~and~~ how to use them.		Two of those tools will be introduced in the following chapter and later on explained in relation to Software Engineering along with explanation on how to use them.
	=== The Five Focusing Steps ===		=== The Five Focusing Steps ===
	TOC provides the Five Focusing Steps to identify and eliminate the constraints, the steps are described in the table below:		TOC provides the Five Focusing Steps to identify and eliminate the constraints, the steps are described in the table below:
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	=== [https://en.wikipedia.org/wiki/Throughput_accounting The Throughput Accounting] ===		=== [https://en.wikipedia.org/wiki/Throughput_accounting The Throughput Accounting] ===
	Throughput Accounting is TOC´s approach to accounting, a decision tool designed to ensure decisions that might have financial impact take a holistic perspective and do not optimize on metric or area of the business at the expense of the whole. Throughput ~~accounting~~ takes a decision regarding the constraint and values it according to financial terms ~~because it~~ acknowledges that the constraint determines capacity, hence profit potential of the company.<ref name="Finance"> Tarantino, Anthony & Cernauskas, Deborah "Risk Management in Finance: Six Sigma and Other Next-Generation Techniques", ''John Wiley & Sons, Inc'', 2009, chapter 21</ref> Cost accounting is known to perform gross margin analysis at the product level while Throughput Accounting determines profitability at the system level and looks at the production process ~~to be~~ a single system that must be optimized. Irrespective of the number of units created, Throughput Accounting assumes most production costs are required to maintain a system of production ~~along with assuming~~ most production costs do not vary directly with incremental production of a single product.		Throughput Accounting is TOC´s approach to accounting, a decision tool designed to ensure decisions that might have a financial impact take a holistic perspective and do not optimize one metric or area of the business at the expense of the whole system. Throughput Accounting takes a decision regarding the constraint and values it according to its financial terms. It acknowledges that the constraint determines capacity, hence profit potential of the company.<ref name="Finance"> Tarantino, Anthony & Cernauskas, Deborah "Risk Management in Finance: Six Sigma and Other Next-Generation Techniques", ''John Wiley & Sons, Inc'', 2009, chapter 21</ref> Cost accounting is known to perform gross margin analysis at the product level while Throughput Accounting determines profitability at the system level and looks at the production process as a single system that must be optimized. Irrespective of the number of units created, Throughput Accounting assumes that most production costs are required to maintain a system of production. The approach also assumes that most production costs do not vary directly with incremental production of a single product.

	== Theory of Constraints in Software Engineering ==		== Theory of Constraints in Software Engineering ==

	Theory of Constraints was first introduced in relation to manufacturing ~~where~~ the goal is to identify bottlenecks in the production line ~~but since then the method has been applied in engineering, project management, sales, accounting and other business processes~~. ~~In manufacturing, the~~ constraint can be found where there are queues of ''[https://en.wikipedia.org/wiki/Work_in_process Work In Progress] '' (WIP) in front of specific equipment and therefore causes extra inventories. In Software Engineering, the whole idea is to identify and manage what causes the inventory, but what is inventory in Software Engineering?		Theory of Constraints was first introduced in relation to manufacturing. In manufacturing the goal is to identify bottlenecks in the production line. The constraint can be found where there are queues of ''[https://en.wikipedia.org/wiki/Work_in_process Work In Progress] '' (WIP) in front of specific equipment and therefore causes extra inventories.

			Since the method was first applied, has it been applied in project management, engineering, sales, accounting and other business processes. In Software Engineering, the whole idea is to identify and manage what causes the inventory, but what is inventory in Software Engineering?

	The list of client-value functionality that Software Developers have to solve is an inventory in Software Engineering. <ref name="TOCSE"></ref>		The list of client-value functionality that Software Developers have to solve is an inventory in Software Engineering. <ref name="TOCSE"></ref>
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	== Applying Theory of Constraints in Software Engineering ==		== Applying Theory of Constraints in Software Engineering ==
	According to David J. Anderson, producing and holding too much inventory is ~~much worse~~ in software because of the perishable nature of the inventory where requirements can go stale because of changes in the market or the fickle nature of the customer. Requirements have time ~~value i.e. they have time to market~~ value. With time, the throughput from the transformation of the requirement into working code decreases, specially when requirements are replaced by change requests for new requirements with a current market value. Requirements that become stale are pure waste <ref name="Anderson"></ref>.		According to David J. Anderson, producing and holding too much inventory is really bad in software because of the perishable nature of the inventory where requirements can go stale because of changes in the market or the fickle nature of the customer. Requirements have time value. With time, the throughput from the transformation of the requirement into working code decreases, specially when requirements are replaced by change requests for new requirements with a current market value. Requirements that become stale are pure waste <ref name="Anderson"></ref>.

	In this chapter the applying of the theory will be explained through Five Focusing Steps and Throughput Accounting in relevance to Software Engineering		In this chapter the applying of the theory will be explained through Five Focusing Steps and Throughput Accounting in relevance to Software Engineering