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Architectural Styles
Team 1: Interpreter; event driven Team 2: Peer-to-peer; plug-in Team 3: Service-oriented; publish-subscribe Team 4: Rule-based; mobile code
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Architectural Style: Interpreter
Team Onesies: Jaime Pena, Carlos Montijo
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◦ What is it?
◦ What problem does it solve?
◦ How does it solve the problem?
◦ Who are the actors or main elements?
◦ How do they relate to each other?
◦ What are the strengths and drawbacks?
◦ Example applications?
Interpreter
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Takes a program written in one language and interprets it to another language to execute a series of commands
Also known as Virtual Machine Style
Interpreter: What is it?
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Facilitates coding in high level language, which can be interpreted into lower level language
Interpreter can be used in different machines
Suitable for applications in which most appropriate language or machine for executing solution is not directly available
Interpreter: What problem does it solve?
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Interpreter translates programming language for the user without requiring user to know the language
Interpreter allows for portability
Code interpreted in one machine will execute the same in another
Interpreter: How does it solve the problem?
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Interpreter Engine◦ receives input and generates output
Interpreter State◦ state of interpreter engine
Program State◦ progress of code interpreted
Data Store Field◦ source code
Interpreter: Who are the actors?
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Input to the interpreted program component is sent to the program state, where it is read by the program running on the interpreter
Program output is placed in the program state, where it can result in output from the interpreted program component's interface
Interpreter: How do they relate to each other?
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Advantages Portability and
flexibility of application or languages across various platforms
Supports dynamic change
“Sandbox” safety
Disadvantages Slow Hard to design and
test Cannot generate
all possible programs to be executed
Advantages vs. Disadvantages
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Java, Java Virtual Machine (JVM) Python-based applications Lisp Perl
Example Applications
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Architectural Style: Event-Driven
Team Onesies:Alexandra Rebollosa, Achim Schweighofer, Heber Ramirez
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A framework that orchestrates behavior around the production, detection and consumption of events as well as the responses they evoke
Request/Response pattern
Consists of “event creators” and “event consumers” Event: Any identifiable occurrence that has significance for
system hardware/software Creator: Source of the event, only knows the event has occurred Consumer: Entity that needs to know the event has occurred,
they might be involved in processing the event or they might simply be affected by the event
Event-Driven : What is it?
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Real-time analysis of data and response of system
Takes care of discrepancies in the system by following step-by-step rules◦ E.g., when buying online using Amazon, a login is
required in order to complete an order. If the customer is not a registered user, a new user must be created
Event-Driven : What problem does it solve?
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It enables a large number of creators and consumers to exchange status and response information in near real-time.
Most effective when existing business rules, triggers, and related stored procedures are surfaced and made available to the middleware’s event processor.
In the short run, this means additional work for the database administrator.In the long run, it simplifies data management by making changes easier.
Event-Driven : How does it solve the problem?
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Event Generator◦ Detects an event
Event Channel◦ Entry point to function, TCP/IP-Connection, File …
Event Processing Engine◦ Selection of appropriate reaction
Downstream Event-Driven Activity◦ Reaction to event
Event-Driven: Who are the actors?
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Event generator senses facts and converts the collected data into a standardized form
The collected data is transferred over event channels to event engine (asynchronously)
Event processing identifies the event, selects and executes the appropriate reaction Downstream event-driven activity
Event-Driven: How do they relate to each other?
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Advantages Strong support for
reuse. Adding and
replacing components with minimum effect on other components in the system.
Disadvantages Loss of control, for
example, in which order will components be evoked?
Correctness hard to ensure since it depends on order of invocation.
Advantages vs. Disadvantages
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Java Swing API JavaScript WinForms API
Example Applications
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1. http://books.google.com/books?id=WHMksQOj6ScC&pg=PA76&lpg=PA76&dq=interpreter+software+architecture&source=bl&ots=Wz3582xfgT&sig=E18v3bzd0LMGcKGHQynBW5Y5dh0&hl=en&sa=X&ei=waMoT4CBCuiU2AWOy83iAg&ved=0CHcQ6AEwCA#v=onepage&q=interpreter%20software%20architecture&f=false
2. http://etd.lsu.edu/docs/available/etd-07082004-152330/unrestricted/Banerjee_thesis.pdf
3. http://www.thomasalspaugh.org/pub/fnd/architecture.html#Interpreter
4. http://cs.queensu.ca/~ahmed/home/teaching/CISC322/F09/slides/CISC322_03_ArchitectureStyles.pdf
5. https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CFUQFjAD&url=http%3A%2F%2Fwww.courses.utep.edu%2FPortals%2F870%2Ff11-s12%2520handouts%2FSlides%2FL04b-%2520More%2520Software%2520Architectures.pptx&ei=EEYuUqnhGaacygHwvoHwBQ&usg=AFQjCNGxOvLMOaUHiBd6duOo46mlx5BbBw&sig2=bnzA9WbAGiwme8hbIiGemA&bvm=bv.51773540,d.aWc&cad=rja
6. http://se.inf.ethz.ch/courses/2011a_spring/soft_arch/lectures/14_softarch_styles.pdf
7. http://kristiannissen.wordpress.com/2009/10/15/javascript-event-driven-architecture/
8. http://en.wikipedia.org/wiki/Event-driven_architecture
9. http://www.omg.org/soa/Uploaded%20Docs/EDA/bda2-2-06cc.pdf
10. http://searchsoa.techtarget.com/definition/event-driven-architecture
11. http://msdn.microsoft.com/en-us/architecture/aa699424.aspx
Sources
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Architectural Styles: Peer-to-Peer & Plug-
InTeam 2
Monica GalindoAndrea Dominguez
Berenice OlivasSteven Werner
Carlos LuevanosDaniel Guzman
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Peer-to-Peer Type of decentralized and distributed
network architecture in which individual nodes in the network (called "peers") act as both suppliers and consumers of resources.
(http://en.wikipedia.org/wiki/Peer-to-peer)
The P2P style allows the client and server to swap their roles in order to distribute and synchronize files and information across multiple clients. It extends the client/server style through multiple responses to requests, shared data, resource discovery, and resilience to removal of peers.
(http://msdn.microsoft.com/en-us/library/ee658117.aspx)
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Topology
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What Problem does it solve? They solve the client-server problem where
client nodes request access to resources provided by central servers.
No need for centralized coordination from servers
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How does it solve the problem? By allowing peers to make their resources
available to other network participants Resources such as processing power, disk
storage or network bandwidth
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Main elements Peers: independent components, having their own
state and control thread. Connectors: Network protocols, often custom. Data Elements: Network messages Topology: Network (may have redundant connections
between peers); can vary arbitrarily and dynamically Supports: decentralized computing with flow of
control and resources distributed among peers. Highly robust in the face of failure of any given node.
• Caution: Scalable in terms of access to resources and computing power. But caution on the protocol.
(csse.usc.edu/classes/cs578_2013/Styles.ppt)
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How do they relate to each other? They relate to each other by sharing all
their components i.e processors
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Advantages
It is easy to install and so is the configuration of computers on this network.
All the resources and contents are shared by all the peers, unlike server-client architecture where server shares all the contents and resources.
P2P is more reliable as central dependency is eliminated. Failure of one peer doesn’t affect the functioning of other peers. In case of Client –Server network, if server goes down whole network gets affected.
There is no need for full-time System Administrator. Every user is the administrator of his machine. User can control their shared resources.
The over-all cost of building and maintaining this type of network is comparatively very less.
http://www.ianswer4u.com/2011/05/peer-to-peer-network-p2p-advantages-and.html#axzz2ePzeqMIW
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Disadvantages In this network, the whole system is decentralized thus it is
difficult to administer. That is one person cannot determine the whole accessibility setting of whole network.
Security in this system is very less. Viruses, spywares, trojans, and malwares can easily be transmitted over this P2P architecture.
Data recovery or backup is very difficult. Each computer should have its own back-up system.
Lot of movies, music and other copyrighted files are transferred using this type of file transfer. P2P is the technology used in torrents.
http://www.ianswer4u.com/2011/05/peer-to-peer-network-p2p-advantages-and.html#axzz2ePzeqMIW
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Challenges Distribution of copyrighted files. Security issues. Bandwidth consumption.
http://www.slideshare.net/srijish/p2p-principle-architecture-and-challenges-presentation
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Examples Fault Tolerance: Decentralized logical
networks which could support any type of data.
BitTorrent: P2P file sharing protocols. It accounts for a significant amount of traffic on the Internet.
Peercasting: Like broadcasting. Method of streaming content to consumers.
http://p2peducation.pbworks.com/w/page/8897427/FrontPage
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Plug-in Architecture
[1]
Structural version:Futuristic Vertical City Holds Plug-In Hexagonal Housing Units
Software version:We currently use all the time…
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Software Architecture: Plug-in
A plug in is a software component that adds a specific feature to an existing software application
Works as a puzzle piece, adding to the big picture, not changing it
[2]
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Reasons to Have Plug-in Support to enable third-party developers to create
abilities which extend an application to support easily adding new features to reduce the size of an application to separate source code from an application
because of incompatible software licenses.
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What problem does it solve? Many, even unknown ones…
◦ Adding functionality for specific purpose Examples: OneTab for Chrome Browser
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More Example Applications
Firefox
[3]
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More Example Applications
Word
[4]
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How does it solve the problem?
Provides framework for developers to add features
Does not require source code to do it
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Example Plug-In Framework
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Who are the actors (i.e., main elements)?
Separate valid plug-in modules◦ Implemented independently◦ Usually one function/focus◦ Contribute functionality to many applications that
fit the architecture Host Application
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How do they relate to each other?
Each plug-in has a well defined interface Host application must define a plug-in
architecture Plug-in fits like a piece to a puzzle
(application) Abstract base class (principle class) included
as part of plug-in bundle◦ Support code and resources
Host application checks if it conforms to requirements◦ If yes, then an instance is generated
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Pros and Cons
Strengths
Expandability◦ Include new features
Parallel Development◦ Multiple features can be
developed simultaneously
Clear Development◦ Well defined interface
Simplicity◦ Plugin typically only does
one thing
Weaknesses
Extensibility◦ Poor interface design
restricting extension Maintainability
◦ Managing backward compatibility
Complexity◦ Plugin interactions cause
bugs Testing
◦ Cumbersome without mock plugin runner
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Resources: Peer-to-Peer http://
www.slideshare.net/srijish/p2p-principle-architecture-and-challenges-presentation
http://www.ianswer4u.com/2011/05/peer-to-peer-network-p2p-advantages-and.html#axzz2ePzeqMIW
http://msdn.microsoft.com/en-us/library/ee658117.aspx
csse.usc.edu/classes/cs578_2013/Styles.ppt http://www.dmst.aueb.gr/dds/pubs/jrnl/2004-
ACMCS-p2p/html/AS04.html http://p2peducation.pbworks.com/w/page/88
97427/FrontPage (http://en.wikipedia.org/wiki/Peer-to-peer)
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Resources: Plug-in Images:
◦ [1] http://inhabitat.com/plug-your-hexagonal-house-into-this-vertical-city/◦ [2] https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/LoadingCode/Concepts/Plugins.html◦ [3] https://addons.mozilla.org/en-US/firefox/◦ [4] http://msdn.microsoft.com/en-us/library/office/◦ aa189710(v=office.10).aspx
References◦ http://stackoverflow.com/questions/2818415/what-are-the-advantages-and-disadv
antages-of-plug-in-based-architecture
◦ https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/LoadingCode/Concepts/Plugins.html
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Software Architecture
Publish-Subscriber StyleService-Oriented Style
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Publish-Subscriber
What? Why?
Message pattern where senders of the messages (publishers) do not program the messages to be sent directly to a specific receiver (subscribers).
the message will be seen by a subscriber once they have subscribed to the publisher
publishers don’t have to know who the subscribers are
subscribers will only have information of subscribers that they are interested with
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Publish-Subscriber How: This architecture uses filtering in order to ensure that
only certain information is delivered to specific users Actors:
◦ Publisher◦ Event Channel◦ Subscriber
Actor Relations:◦ Subscribers choose which publisher they wish to receive
information for◦ Publishers publish an even to a “channel” ◦ The channel receives information of subscribers as well as
publishers allowing the subscriber to receive pertinent information from the chosen publisher
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Publish-Subscriber
Strength Drawbacks
scalability, through clever protocols the publisher/subscriber pattern allows for higher message loads from a small number of data center
This favors scalability through parallel operations, and tree or network based routing
by not being dependent on each other they can work independently despite the state of the others.
The pattern must be carefully coded to allow certain features like guaranteed delivery of messages
There may be an assumption of an audience when one may not be present
Loose Coupling is also a disadvantage because it is hard to guarantee outcomes since the publisher has little information from subscribers
Examples: RSS Feeds, YouTube
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Service-Oriented
What? Why?
Computing based on request and reply.
Provides application functionality as service.
Allow easy cooperation of a large number of computers that are connected over a network.
Modules driven implementation. It gives the ability to develop new functions rapidly.
Improved information flow. Organizational flexibility. Lower software
development and management costs. (re-use).
Security attacks. Data confidentiality and
integrity. Maintenance and
upgrade. Reliability.
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Service-Oriented How: This architecture takes advantage of previously defined services
in order to promote re-usability as well as quick delivery of services
Actors: ◦ Service provider, ◦ Service directory (registry),◦ Service consumer
Actor Relations:◦ The service provider publishes and secures the service
in a service directory.◦ The service consumer locates and accesses the
service in the service directory. ◦ The service consumer manages the service provided
by the service provider.
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Service-Oriented
Strengths Drawbacks
◦ Service can be re-used.◦ Messaging: control,
monitoring, transformation, security.
◦ Complex event processing (ability to adapt)
◦ service discovery◦ Virtualization (improved
reliability)◦ Model-driven implementation.◦ Easy maintenance. ◦ Loose Coupling
◦ Overhead◦ Complexity◦ Configuration
management ◦ Governance◦ Hard to implement when
starts at zero.
Examples: TurboTax, Wells Fargo, Cricket wireless, Facebook, Dropbox
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Resources (P.S.) Birman, K. and Joseph, T. "Exploiting virtual
synchrony in distributed systems" in Proceedings of the eleventh ACM Symposium on Operating systems principles (SOSP '87), 1987
Hasan, Souleiman, Sean O'Riain, and Edward Curry. 2012. "Approximate Semantic Matching of Heterogeneous Events.“
http://msdn.microsoft.com/en-us/magazine/hh201955.aspx
http://en.wikipedia.org/wiki/Publish%E2%80%93subscribe_pattern
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Resources (S.O.) http://searchsoa.techtarget.com/definition/
service-oriented-architecture http://www.javaworld.com/javaworld/jw-06-
2005/jw-0613-soa.html http://www.opengroup.org/soa/source-
book/soa/soa_features.html www.exforsys.com
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Rule-Based System
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What is it? Software that can duplicate human
knowledge and reason from it. A collection of knowledge, which can be a
set of rules. Database of facts Based on Condition-Action Rules
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What Problem Does it Solve and How? Shortage of experts.
◦ Duplicating expert reasoning quickly.
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Who are the actors? And How do they Relate to each other?
Rule EngineInference
EngineProcess
Rule BasePermanent
Data
Working Memory
Temporary Data
User Interface
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Strengths and Drawbacks Strengths
◦ Knowledge of experts can be duplicated.◦ Can be adapted to many different fields.◦ Easy for humans to understand
Drawbacks◦ Can only be used were knowledge can be
describe as an If-Then statement.◦ The larger the number of statements the slower
the system will perform.◦ Is it possible to capture all knowledge?
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Example Applications AI Voice Server Health Care Financial Service.
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Mobile Based Architecture
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Mobile Code: Strengths and Weaknesses Code is portable since it can run anywhere No installation load on server is reduced, since the code is
run on client machine interoperability user unaware that mobile code is executing
on their machine
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Applications java applets activeX controls macros in MS office scripts
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Sources
"Mobile Code." Mobile Code. 11 Sept. 2013 <http://courses.ischool.berkeley.edu/i206/f97/GroupC/sld003.htm>.
"Mobile Code Security." Mobile Code Security. 11 Sept. 2013 <http://seit.unsw.adfa.edu.au/staff/sites/lpb/papers/mcode96.html>.
Ireson-Paine, Jocelyn. "What is a rule-based system?" What is a rule-based system? 14 Feb. 1996. 11 Sept. 2013 <http://www.j-paine.org/students/lectures/lect3/node5.html>.
