What is N-Tier architecture

Question

I ve seen quite a few developer job postings recently that include a sentence that reads more or less like this   Must have experience with N-Tier architecture   or  Must be able to develop N-Tier apps    This leads me to ask  what is N-Tier architecture  How does one gain experience with it

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It s a buzzword that refers to things like the normal Web architecture with e g   Javascript - ASP Net - Middleware - Database layer  Each of these things is a  tier

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N-tier data applications are data applications that are separated into multiple tiers  Also called  distributed applications  and  multitier applications   n-tier applications separate processing into discrete tiers that are distributed between the client and the server  When you develop applications that access data  you should have a clear separation between the various tiers that make up the application   And so on in http   msdn microsoft com en-us library bb384398 aspx

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If I understand the question  then it seems to me that the questioner is really asking  OK  so 3-tier is well understood  but it seems that there s a mix of hype  confusion  and uncertainty around what 4-tier  or to generalize  N-tier architectures mean   So   what s a definition of N-tier that is widely understood and agreed upon    It s actually a fairly deep question  and to explain why  I need to go a little deeper   Bear with me   The classic 3-tier architecture  database   business logic  and presentation  is a good way to clarify how to honor the principle of separation of concerns   Which is to say  if I want to change how  the business  wants to service customers  I should not have to look through the entire system to figure out how to do this  and in particular  decisions business issues shouldn t be scattered willy-nilly through the code     Now  this model served well for decades  and it is the classic  client-server  model   Fast forward to cloud offerings  where web browsers are the user interface for a broad and physically distributed set of users  and one typically ends up having to add content distribution services  which aren t a part of the classic 3-tier architecture  and which need to be managed in their own right    The concept generalizes when it comes to services  micro-services  how data and computation are distributed and so on   Whether or not something is a  tier  largely comes down to whether or not the tier provides an interface and deployment model to services that are behind  or beneath  the tier   So a content distribution network would be a tier  but an authentication service would not be    Now  go and read other descriptions of examples of N-tier architectures with this concept in mind  and you will begin to understand the issue   Other perspectives include vendor-based approaches  e g  NGINX   content-aware load balancers  data isolation and security services  e g  IBM Datapower   all of which may or may not add value to a given architecture  deployment  and use cases

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from https   docs microsoft com en-us azure architecture guide architecture-styles n-tier  An N-tier architecture divides an application tires into logical tiresand physical tiers mainly and their are divide to sub parts    Layers are a way to separate responsibilities and manage dependencies  Each layer has a specific responsibility  A higher layer can use services in a lower layer  but not the other way around   Tiers are physically separated  running on separate machines  A tier can call to another tier directly  or use asynchronous messaging  message queue   Although each layer might be hosted in its own tier  that s not required  Several layers might be hosted on the same tier  Physically separating the tiers improves scalability and resiliency  but also adds latency from the additional network communication   A traditional three-tier application has a presentation tier  a middle tier  and a database tier  The middle tier is optional  More complex applications can have more than three tiers  The diagram above shows an application with two middle tiers  encapsulating different areas of functionality   An N-tier application can have a closed layer architecture or an open layer architecture   In a closed layer architecture  a layer can only call the next layer immediately down  In an open layer architecture  a layer can call any of the layers below it    A closed layer architecture limits the dependencies between layers  However  it might create unnecessary network traffic  if one layer simply passes requests along to the next layer

User · Answer

It s a buzzword that refers to things like the normal Web architecture with e g   Javascript - ASP Net - Middleware - Database layer  Each of these things is a  tier

User · Answer

It s my understanding that N-Tier separates business logic  client access and data from each other using separate physical machines   The theory is that one of them can be updated independently of the others

User · Answer

An N-tier application is an application which has more than three components involved  What are those components    Cache Message queues for asynchronous behaviour Load balancers Search servers for searching through massive amounts of data Components involved in processing massive amounts of data Components running heterogeneous tech commonly known as web services etc    All the social applications like Instagram  Facebook  large scale industry services like Uber  Airbnb  online massive multiplayer games like Pokemon Go  applications with fancy features are n-tier applications

User · Answer

It s based on how you separate the presentation layer from the core business logic and data access  Wikipedia    3-tier means Presentation layer   Component layer   Data access layer    N-tier is when additional layers are added beyond these  usually for additional modularity  configurability  or interoperability with other systems

User · Answer

Wikipedia      In software engineering  multi-tier   architecture  often referred to as   n-tier architecture  is a   client-server architecture in which    the presentation  the application   processing and the data management are   logically separate processes  For   example  an application that uses   middleware to service data requests   between a user and a database employs   multi-tier architecture  The most   widespread use of  multi-tier   architecture  refers to three-tier   architecture    It s debatable what counts as  tiers   but in my opinion it needs to at least cross the process boundary  Or else it s called layers  But  it does not need to be in physically different machines  Although I don t recommend it  you can host logical tier and database on the same box     Edit  One implication is that presentation tier and the logic tier  sometimes called Business Logic Layer  needs to cross machine boundaries  across the wire  sometimes over unreliable  slow  and or insecure network  This is very different from simple Desktop application where the data lives on the same machine as files or Web Application where you can hit the database directly   For n-tier programming  you need to package up the data in some sort of transportable form called  dataset  and fly them over the wire   NET s DataSet class or Web Services protocol like SOAP are few of such attempts to fly objects over the wire

User · Answer

It s a buzzword that refers to things like the normal Web architecture with e g   Javascript - ASP Net - Middleware - Database layer  Each of these things is a  tier

User · Answer

It s my understanding that N-Tier separates business logic  client access and data from each other using separate physical machines   The theory is that one of them can be updated independently of the others

User · Answer

When we talk of Tiers  we generally talk of Physical Processes  having different memory space    Thus  in case  Layers of an application are deployed in different processes  those different processes will be different tiers       E g  In a 3-tier application  business tier talks to Mainframes  separate process  and talks to Reporting Service  separate process   then that application would be 5 tier    Hence  the generic name is n-tier

User · Answer

It s a buzzword that refers to things like the normal Web architecture with e g   Javascript - ASP Net - Middleware - Database layer  Each of these things is a  tier

User · Answer

When we talk of Tiers  we generally talk of Physical Processes  having different memory space    Thus  in case  Layers of an application are deployed in different processes  those different processes will be different tiers       E g  In a 3-tier application  business tier talks to Mainframes  separate process  and talks to Reporting Service  separate process   then that application would be 5 tier    Hence  the generic name is n-tier

User · Answer

N-tier data applications are data applications that are separated into   multiple tiers  Also called  distributed applications  and  multitier   applications   n-tier applications separate processing into discrete   tiers that are distributed between the client and the server  When you   develop applications that access data  you should have a clear   separation between the various tiers that make up the application       A typical n-tier application includes a presentation tier  a middle   tier  and a data tier  The easiest way to separate the various tiers   in an n-tier application is to create discrete projects for each tier   that you want to include in your application  For example  the   presentation tier might be a Windows Forms application  whereas the   data access logic might be a class library located in the middle tier    Additionally  the presentation layer might communicate with the data   access logic in the middle tier through a service such as a service    Separating application components into separate tiers increases the   maintainability and scalability of the application  It does this by   enabling easier adoption of new technologies that can be applied to a   single tier without the requirement to redesign the whole solution  In   addition  n-tier applications typically store sensitive information in   the middle-tier  which maintains isolation from the presentation tier    Taken from Microsoft website

User · Answer

An N-tier application is an application which has more than three components involved  What are those components    Cache Message queues for asynchronous behaviour Load balancers Search servers for searching through massive amounts of data Components involved in processing massive amounts of data Components running heterogeneous tech commonly known as web services etc    All the social applications like Instagram  Facebook  large scale industry services like Uber  Airbnb  online massive multiplayer games like Pokemon Go  applications with fancy features are n-tier applications

User · Answer

It s my understanding that N-Tier separates business logic  client access and data from each other using separate physical machines   The theory is that one of them can be updated independently of the others

User · Answer

It s based on how you separate the presentation layer from the core business logic and data access  Wikipedia    3-tier means Presentation layer   Component layer   Data access layer    N-tier is when additional layers are added beyond these  usually for additional modularity  configurability  or interoperability with other systems

User · Answer

If I understand the question  then it seems to me that the questioner is really asking  OK  so 3-tier is well understood  but it seems that there s a mix of hype  confusion  and uncertainty around what 4-tier  or to generalize  N-tier architectures mean   So   what s a definition of N-tier that is widely understood and agreed upon    It s actually a fairly deep question  and to explain why  I need to go a little deeper   Bear with me   The classic 3-tier architecture  database   business logic  and presentation  is a good way to clarify how to honor the principle of separation of concerns   Which is to say  if I want to change how  the business  wants to service customers  I should not have to look through the entire system to figure out how to do this  and in particular  decisions business issues shouldn t be scattered willy-nilly through the code     Now  this model served well for decades  and it is the classic  client-server  model   Fast forward to cloud offerings  where web browsers are the user interface for a broad and physically distributed set of users  and one typically ends up having to add content distribution services  which aren t a part of the classic 3-tier architecture  and which need to be managed in their own right    The concept generalizes when it comes to services  micro-services  how data and computation are distributed and so on   Whether or not something is a  tier  largely comes down to whether or not the tier provides an interface and deployment model to services that are behind  or beneath  the tier   So a content distribution network would be a tier  but an authentication service would not be    Now  go and read other descriptions of examples of N-tier architectures with this concept in mind  and you will begin to understand the issue   Other perspectives include vendor-based approaches  e g  NGINX   content-aware load balancers  data isolation and security services  e g  IBM Datapower   all of which may or may not add value to a given architecture  deployment  and use cases

User · Answer

It s my understanding that N-Tier separates business logic  client access and data from each other using separate physical machines   The theory is that one of them can be updated independently of the others

User · Answer

When constructing the usual MCV  a 3-tier architecture  one can decide to implement the MCV with double-deck interfaces  such that one can in fact replace a particular tier without having to modify even one line of code    We often see the benefits of this  for instance in scenarios where you want to be able to use more than one database  in which case you have a double-interface between the control and data-layers     When you put it on the View-layer  presentation   then you can  hold on    replace the USER interface with another machine  thereby automate REAL input       - and you can thereby run tedious usability tests thousands of times without any user having to tap and re-tap and re-re-tap the same things over and over again   Some describe such 3-tier architecture with 1 or 2 double-interfaces as 4-tier or 5-tier architecture  implicitly implying the double-interfaces   Other cases include  but are not limited to  the fact that you - in case of semi-or-fully replicated database-systems would practically be able to consider one of the databases as the  master   and thereby you would have a tier comprising of the master and another comprising of the slave database    Mobile example  Therefore  multi-tier - or N-tier - indeed has a few interpretations  whereas I would surely stick to the 3-tier   extra tiers comprising of thin interface-disks wedged in between to enable said tier-swaps  and in terms of testing  particularly used on mobile devices   you can now run user tests on the real software  by simulating a users tapping in ways which the control logic cannot distinguish from a real user tapping  This is almost paramount in simulating real user tests  in that you can record all inputs from the users OTA  and then re-use the same input when doing regression tests

User · Answer

from https   docs microsoft com en-us azure architecture guide architecture-styles n-tier  An N-tier architecture divides an application tires into logical tiresand physical tiers mainly and their are divide to sub parts    Layers are a way to separate responsibilities and manage dependencies  Each layer has a specific responsibility  A higher layer can use services in a lower layer  but not the other way around   Tiers are physically separated  running on separate machines  A tier can call to another tier directly  or use asynchronous messaging  message queue   Although each layer might be hosted in its own tier  that s not required  Several layers might be hosted on the same tier  Physically separating the tiers improves scalability and resiliency  but also adds latency from the additional network communication   A traditional three-tier application has a presentation tier  a middle tier  and a database tier  The middle tier is optional  More complex applications can have more than three tiers  The diagram above shows an application with two middle tiers  encapsulating different areas of functionality   An N-tier application can have a closed layer architecture or an open layer architecture   In a closed layer architecture  a layer can only call the next layer immediately down  In an open layer architecture  a layer can call any of the layers below it    A closed layer architecture limits the dependencies between layers  However  it might create unnecessary network traffic  if one layer simply passes requests along to the next layer

User · Answer

It s based on how you separate the presentation layer from the core business logic and data access  Wikipedia    3-tier means Presentation layer   Component layer   Data access layer    N-tier is when additional layers are added beyond these  usually for additional modularity  configurability  or interoperability with other systems

User · Answer

Martin Fowler demonstrating clearly   Layering is one of the most common techniques that software designers use to break apart a complicated software system  You see it in machine architectures  where layers descend from a programming language with operating system calls into device drivers and CPU instruction sets  and into logic gates inside chips  Networking has FTP layered on top of TCP  which is on top of IP  which is on top of ethernet   When thinking of a system in terms of layers  you imagine the principal subsystems in the software arranged in some form of layer cake  where each layer rests on a lower layer  In this scheme the higher layer uses various services defined by the lower layer  but the lower layer is unaware of the higher layer  Furthermore  each layer usually hides its lower layers from the layers above  so layer 4 uses the services of layer 3  which uses the services of layer 2  but layer 4 is unaware of layer 2   Not all layering architectures are opaque like this  but most are   or rather most are mostly opaque    Breaking down a system into layers has a number of important benefits       You can understand a single layer as a coherent whole without knowing much about the other layers  You can understand how to build an FTP service on top of TCP without knowing the details of how ethernet works       You can substitute layers with alternative implementations of the same basic services  An FTP service can run without change over ethernet  PPP  or whatever a cable company uses       You minimize dependencies between layers  If the cable company changes its physical transmission system  providing they make IP work  we don   t have to alter our FTP service       Layers make good places for standardization  TCP and IP are standards because they define how their layers should operate       Once you have a layer built  you can use it for many higher-level services  Thus  TCP IP is used by FTP  telnet  SSH  and HTTP  Otherwise  all of these higher-level protocols would have to write their own lower-level protocols  From the Library of Kyle Geoffrey Passarelli  Layering is an important technique  but there are downsides       Layers encapsulate some  but not all  things well  As a result you sometimes get cascading changes  The classic example of this in a layered enterprise application is adding a field that needs to display on the UI  must be in the database  and thus must be added to every layer in between       Extra layers can harm performance  At every layer things typically need to be transformed from one representation to another  However  the encapsulation of an underlying function often gives you efficiency gains that more than compensate  A layer that controls transactions can be optimized and will then make everything faster  But the hardest part of a layered architecture is deciding what layers to have and what the responsibility of each layer should be

User · Answer

Wikipedia      In software engineering  multi-tier   architecture  often referred to as   n-tier architecture  is a   client-server architecture in which    the presentation  the application   processing and the data management are   logically separate processes  For   example  an application that uses   middleware to service data requests   between a user and a database employs   multi-tier architecture  The most   widespread use of  multi-tier   architecture  refers to three-tier   architecture    It s debatable what counts as  tiers   but in my opinion it needs to at least cross the process boundary  Or else it s called layers  But  it does not need to be in physically different machines  Although I don t recommend it  you can host logical tier and database on the same box     Edit  One implication is that presentation tier and the logic tier  sometimes called Business Logic Layer  needs to cross machine boundaries  across the wire  sometimes over unreliable  slow  and or insecure network  This is very different from simple Desktop application where the data lives on the same machine as files or Web Application where you can hit the database directly   For n-tier programming  you need to package up the data in some sort of transportable form called  dataset  and fly them over the wire   NET s DataSet class or Web Services protocol like SOAP are few of such attempts to fly objects over the wire

User · Answer

Wikipedia      In software engineering  multi-tier   architecture  often referred to as   n-tier architecture  is a   client-server architecture in which    the presentation  the application   processing and the data management are   logically separate processes  For   example  an application that uses   middleware to service data requests   between a user and a database employs   multi-tier architecture  The most   widespread use of  multi-tier   architecture  refers to three-tier   architecture    It s debatable what counts as  tiers   but in my opinion it needs to at least cross the process boundary  Or else it s called layers  But  it does not need to be in physically different machines  Although I don t recommend it  you can host logical tier and database on the same box     Edit  One implication is that presentation tier and the logic tier  sometimes called Business Logic Layer  needs to cross machine boundaries  across the wire  sometimes over unreliable  slow  and or insecure network  This is very different from simple Desktop application where the data lives on the same machine as files or Web Application where you can hit the database directly   For n-tier programming  you need to package up the data in some sort of transportable form called  dataset  and fly them over the wire   NET s DataSet class or Web Services protocol like SOAP are few of such attempts to fly objects over the wire

User · Answer

When constructing the usual MCV  a 3-tier architecture  one can decide to implement the MCV with double-deck interfaces  such that one can in fact replace a particular tier without having to modify even one line of code    We often see the benefits of this  for instance in scenarios where you want to be able to use more than one database  in which case you have a double-interface between the control and data-layers     When you put it on the View-layer  presentation   then you can  hold on    replace the USER interface with another machine  thereby automate REAL input       - and you can thereby run tedious usability tests thousands of times without any user having to tap and re-tap and re-re-tap the same things over and over again   Some describe such 3-tier architecture with 1 or 2 double-interfaces as 4-tier or 5-tier architecture  implicitly implying the double-interfaces   Other cases include  but are not limited to  the fact that you - in case of semi-or-fully replicated database-systems would practically be able to consider one of the databases as the  master   and thereby you would have a tier comprising of the master and another comprising of the slave database    Mobile example  Therefore  multi-tier - or N-tier - indeed has a few interpretations  whereas I would surely stick to the 3-tier   extra tiers comprising of thin interface-disks wedged in between to enable said tier-swaps  and in terms of testing  particularly used on mobile devices   you can now run user tests on the real software  by simulating a users tapping in ways which the control logic cannot distinguish from a real user tapping  This is almost paramount in simulating real user tests  in that you can record all inputs from the users OTA  and then re-use the same input when doing regression tests

User · Answer

N-tier data applications are data applications that are separated into   multiple tiers  Also called  distributed applications  and  multitier   applications   n-tier applications separate processing into discrete   tiers that are distributed between the client and the server  When you   develop applications that access data  you should have a clear   separation between the various tiers that make up the application       A typical n-tier application includes a presentation tier  a middle   tier  and a data tier  The easiest way to separate the various tiers   in an n-tier application is to create discrete projects for each tier   that you want to include in your application  For example  the   presentation tier might be a Windows Forms application  whereas the   data access logic might be a class library located in the middle tier    Additionally  the presentation layer might communicate with the data   access logic in the middle tier through a service such as a service    Separating application components into separate tiers increases the   maintainability and scalability of the application  It does this by   enabling easier adoption of new technologies that can be applied to a   single tier without the requirement to redesign the whole solution  In   addition  n-tier applications typically store sensitive information in   the middle-tier  which maintains isolation from the presentation tier    Taken from Microsoft website

User · Answer

It s based on how you separate the presentation layer from the core business logic and data access  Wikipedia    3-tier means Presentation layer   Component layer   Data access layer    N-tier is when additional layers are added beyond these  usually for additional modularity  configurability  or interoperability with other systems

User · Answer

N-tier data applications are data applications that are separated into multiple tiers  Also called  distributed applications  and  multitier applications   n-tier applications separate processing into discrete tiers that are distributed between the client and the server  When you develop applications that access data  you should have a clear separation between the various tiers that make up the application   And so on in http   msdn microsoft com en-us library bb384398 aspx

User · Answer

Wikipedia      In software engineering  multi-tier   architecture  often referred to as   n-tier architecture  is a   client-server architecture in which    the presentation  the application   processing and the data management are   logically separate processes  For   example  an application that uses   middleware to service data requests   between a user and a database employs   multi-tier architecture  The most   widespread use of  multi-tier   architecture  refers to three-tier   architecture    It s debatable what counts as  tiers   but in my opinion it needs to at least cross the process boundary  Or else it s called layers  But  it does not need to be in physically different machines  Although I don t recommend it  you can host logical tier and database on the same box     Edit  One implication is that presentation tier and the logic tier  sometimes called Business Logic Layer  needs to cross machine boundaries  across the wire  sometimes over unreliable  slow  and or insecure network  This is very different from simple Desktop application where the data lives on the same machine as files or Web Application where you can hit the database directly   For n-tier programming  you need to package up the data in some sort of transportable form called  dataset  and fly them over the wire   NET s DataSet class or Web Services protocol like SOAP are few of such attempts to fly objects over the wire

User · Answer

Martin Fowler demonstrating clearly   Layering is one of the most common techniques that software designers use to break apart a complicated software system  You see it in machine architectures  where layers descend from a programming language with operating system calls into device drivers and CPU instruction sets  and into logic gates inside chips  Networking has FTP layered on top of TCP  which is on top of IP  which is on top of ethernet   When thinking of a system in terms of layers  you imagine the principal subsystems in the software arranged in some form of layer cake  where each layer rests on a lower layer  In this scheme the higher layer uses various services defined by the lower layer  but the lower layer is unaware of the higher layer  Furthermore  each layer usually hides its lower layers from the layers above  so layer 4 uses the services of layer 3  which uses the services of layer 2  but layer 4 is unaware of layer 2   Not all layering architectures are opaque like this  but most are   or rather most are mostly opaque    Breaking down a system into layers has a number of important benefits       You can understand a single layer as a coherent whole without knowing much about the other layers  You can understand how to build an FTP service on top of TCP without knowing the details of how ethernet works       You can substitute layers with alternative implementations of the same basic services  An FTP service can run without change over ethernet  PPP  or whatever a cable company uses       You minimize dependencies between layers  If the cable company changes its physical transmission system  providing they make IP work  we don   t have to alter our FTP service       Layers make good places for standardization  TCP and IP are standards because they define how their layers should operate       Once you have a layer built  you can use it for many higher-level services  Thus  TCP IP is used by FTP  telnet  SSH  and HTTP  Otherwise  all of these higher-level protocols would have to write their own lower-level protocols  From the Library of Kyle Geoffrey Passarelli  Layering is an important technique  but there are downsides       Layers encapsulate some  but not all  things well  As a result you sometimes get cascading changes  The classic example of this in a layered enterprise application is adding a field that needs to display on the UI  must be in the database  and thus must be added to every layer in between       Extra layers can harm performance  At every layer things typically need to be transformed from one representation to another  However  the encapsulation of an underlying function often gives you efficiency gains that more than compensate  A layer that controls transactions can be optimized and will then make everything faster  But the hardest part of a layered architecture is deciding what layers to have and what the responsibility of each layer should be

[architecture] What is N-Tier architecture?

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