1. Enterprise Systems & Frameworks
CS25010 - Web Programming
Connor Goddard
5th November 2015
Aberystwyth University
1
2. INTRODUCTION
In today’s session, we will aim to cover the following:
• Multi-tier Architectural Patterns
• Enterprise Systems
• Web Frameworks
2
3. INTRODUCTION
If you’re on Twitter, jump on your phones!
During the presentation, look out for tweets from @cgddrd with
the hashtag #cs25010.
These tweets will contain links to other material you may find
useful.
Feel free to tweet back with any questions.
3
4. A LITTLE BIT ABOUT ME
I’m a fifth-(and final!)-year MEng Software Engineering student.
Previous web modules include: CS15020, CS25010, CS25210, SE31520 &
SEM5640 (so pretty much them all…)
I spent my IY working at Renishaw plc, developing advanced web and
mobile applications (Android, iOS & hybrid)
I’ve played around with most web-related technologies including:
• PHP, ASP.NET, Node.js, Ruby-on-Rails, Python & OO-Javascript
4
5. WEB APPLICATIONS
• What do we mean by a “web application”?
• What makes a web application different to other
applications?
• Where does “the cloud” fit into it all?
5
6. WEB APPLICATIONS
To a typical consumer, web applications can appear… mystical.
Most do not appreciate all that has to go on “under the hood”.
What problems could this present on development projects?
6
[1]
[1] http://imgflip.com
7. ENTERPRISE SYSTEMS
When designing non-trivial web applications, we typically will
want to decompose the system into smaller parts.
• Separate presentation from business logic and data sources.
• Possibly delegate across multiple servers.
These are known as “multi-tier/n-tier” or “enterprise” systems.
As a consequence, interconnectivity between separate systems
and their servers becomes essential.
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12. MULTI-TIER ARCHITECTURES
There is a clear distinction between tiers and layers.
What is the difference between the two terms?
‣ Layer: Logical organisation/separation of code (e.g. separating code
associated with presentation from that of business logic)
‣ Tier: Physical deployment of layers (e.g. across multiple servers)
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13. MULTI-TIER ARCHITECTURES
Why would we want to use multi-tier systems?
• What would be the advantages?
• What would be the disadvantages?
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14. MULTI-TIER ARCHITECTURES
Why would we want to use multi-tier systems?
Advantages:
• Separation of concerns
• Improved scalability
• Help to avoid single point of failure
• Improved problem solving/bug tracking (isolation of issues to specific part of system)
• Easier mapping of system entities to developer workload
Disadvantages:
• Could prove to be ‘overkill’ for very small projects
• Likely increase in code size and complexity
• Steeper learning curve - greater potential for bugs to be introduced
• Use of M-TA introduces greater risk for poor design choices - these can become expensive to fix later
• Easier mapping of system entities to developer workload - “Too many cooks spoil the broth.”
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19. WEB FRAMEWORKS
Frameworks aim to assist in the development of web
applications by alleviating some of the overhead associated
with common tasks:
• Database access, ORM, templates, authorisation, web services,
scaffolding, testing, caching, session management etc.
Web frameworks are not the same as CMS software (e.g.
Wordpress or Drupal)
• Frameworks provide general solutions to developing web applications.
• CMS software builds on top of underlying frameworks.
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20. SCAFFOLDING
Scaffolding refers to a process whereby the ‘skeleton’ of an
application is automatically generated by the web framework.
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Typically the reference to a database
is given, from which the code
relating to standard CRUD operations
is enacted without input from the
developer.
Scaffolded systems provide a good
starting point from which the main
application can be built upon.
[1] https://scaffoldinginsouthwest.wordpress.com/
[1]
21. SCAFFOLDING - RoR
One of the first ‘mainstream’ frameworks to support scaffolding
was Ruby-on-Rails.
Generating a new web application in RoR takes 3 lines of code:
21
1 # Step 1: Generate new web application.
2 rails new mywebapp && cd mywebapp
3
4 # Step 2: Create new model entity and scaffold
5 CRUD operations (controller and views).
6 rails generate scaffold User surname firstname
7 age:integer is_student:boolean
8
9 # Step 3: Migrate the new model into SQLite
10 database (pre-created)
11 rake db:migrate
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13 # Step 4: Start the server (navigate to http://<url>/users)
14 rails server
22. SCAFFOLDING - ASP.NET
ASP.NET is another framework that provides automatic creation
of web controllers and views from a pre-existing data model.
This is particularly useful within MVC projects where we are also
utilising object-relational mapping.
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23. OBJECT-RELATIONAL MAPPING
Object-relational mapping (ORM) provides a mechanism for
representing and querying relational entities using an object-
based paradigm.
In other words: ORM allows us to map data stored in a
relational/tabular format into an OO format for use in
applications.
ORM helps to address an issue known as ‘Object-Relational
Impedance Mismatch’.
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24. OBJECT-RELATIONAL MAPPING
Relational - Object mapping:
With ORM, it doesn’t matter what persistent storage mechanism we are
using (e.g. MySQL, NoSQL, XML data files etc.)
The framework handles this all for us.
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Relational Model ORM
Table Class
Row Instance
Field Property
25. FRAMEWORKS, ORM & MVC
Many frameworks adopt an MVC pattern, supported by
mechanisms including scaffolding and ORM.
25
Generated via
ORM
Class for each model
responsible for:
• Handling incoming requests
• Retrieving model data
• Re-directing user to
appropriate view templates
Template files used
to render dynamic
data to end user (e.g.
HTML, XML, JSON)
[1] https://en.wikipedia.org/wiki/Model–view–controller
[1]
26. MVC - MODEL
26
ASP.NET (C#) PHP
1 namespace HelloMVC.Models
2 {
3 public class BlogPost
4 {
5
6 public virtual int Id
7 {
8 get; set;
9
10 }
11
12 public virtual string Title
13 {
14 get; set;
15
16 }
17
18 }
19 }
1 <?php
2
3 class BlogPost {
4
5 public $id;
6 public $title;
7
8 public function __construct($id, $title) {
9 $this->id = $id;
10 $this->title = $title
11 }
12
13 function save();
14 function setTitle();
15 ...
16
17 } ?>
27. 1 namespace HelloMVC.Controllers
2 {
3 public class BlogPostController : Controller
4 {
5 private HelloMVCContext db = new HelloMVCContext();
6
7 public ActionResult Index()
8 {
9 return View(db.BlogPosts.ToList());
10 }
11
12 public ActionResult Create()
13 {
14 return View();
15 }
16
17 [HttpPost]
18 [ValidateAntiForgeryToken]
19 public ActionResult Create([Bind(Include = "Id,Title")] BlogPost blogPost)
20 {
21 if (ModelState.IsValid)
22 {
23 db.BlogPosts.Add(blogPost);
24 db.SaveChanges();
25 return RedirectToAction("Index");
26 }
27
28 return View(blogPost);
29 }
30 }
31 }
MVC - CONTROLLER
27
ASP.NET (C#) PHP
1 <?php
2
3 class BlogController {
4
5 function indexAction();
6 function createAction();
7
8 ...
9
10 } ?>
GET Request
POST Request
29. APPLICATION SERVERS
Of course, once we have developed our web application, we need to be able to
host and run it.
Application Server: Software designed to handle communication between a
front-end website, and a business back-end system.
Features include:
• Performance optimisation (caching, profiling etc.)
• Database management (population, transactions etc.)
• Load Balancing
• Logging/Debugging
• Security
• Data integrity support
• Deployment
• Recovery management (application isolation)
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30. APPLICATION SERVERS
Application servers provide services and features appealing for
enterprise systems.
Remember: Enterprise systems imply large volumes of data,
high potential for scalability and co-ordination of business
processes across multi-tier architecture.
30[1] http://maaw.info/ArticleSummaries/ArtSumDavenport98.htm
[1]
32. IDEAS FOR ASSIGNMENT
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While use of frameworks and multi-tier architectures is not an
explicit requirement for the assignment, you could always
investigate their use for your own learning…
… plus perhaps for some extra marks (cough cough)
Ideas to consider include:
• Database management functions
• Templates/server-side includes
• ORM
33. 33
Many thanks for your time.
Questions?
@cgddrd
clg11@aber.ac.uk
http://cgddrd.me
