Autumn 2014

TIES456 Introduction to SOA and Cloud Computing, 5 ECTS

TIES532 - Service oriented architectures and cloud computing for developers, 5 ECTS

Today

• Last week’s work
• Where are we now?
• What is still to come?
• Next weeks exercise

General feedback - Last week’s task

• The heaviest task in the course
• A lot of parts
  • Web service client (WSDL/SOAP - wsimport)
  • Rest client (Geocoding API)
  • (Rate limiting)
  • Cache
  • Web service server (JAX-WS)
  • Rest server (JAX-RS)
  • Web interface (website with map)

General feedback - Submission

• Only few groups are completely ready
  • The assignments are not checked yet (only roughly)
  • => Combined with next week’s assignment

Last week’s task - To be completed by Friday

• Some improvements are needed (does not apply to all groups!)
  • Refactor the code you created last week so that methods and packages have a normal name.

    • Noooo… :

        package main.java;
      
        public class TestServer(){
            void startServer();
            Double getGDPByCountryCode(double latitude, double longitude);
        }

  • Remove unused files generated by IDEs
  • Split your client and server code
    • Separate projects/packages
      • Projects makes dependencies more visible
  • Next weeks exercise will continue from the results of this week.
• By Friday

General feedback - Creation of Proper types

• Using a String for CountryCode and 2 Doubles for location works.

    String getCountryCode(double latitude, double longitude);
    Double getGDPByCountryCode(String countryCode);

• More readability and safety : Make a CountryCode and Location class which checks the bounds.

    CountryCode getCountryCode(Location location);
    GDP getGDPByCountryCode(CountryCode countryCode);

  • Should be used early in the call chain (early error detection)

  • Overhead is minimal.

General feedback - Same origin policy of browsers

• When visiting a site on http://localhost:8088 , it cannot make a request to http://localhost:8089
  • Seems to be browser independent.
• Example
• Too much information from Browser Security Handbook, part 2
• Basic info on wikipedia

General feedback - REST Anti-Patterns

1. Tunneling everything through GET

    http://example.com/some-api?method=deleteCustomer&id=1234

2. Tunneling everything through POST
3. Ignoring caching
4. Ignoring response codes
5. Misusing cookies
6. Forgetting hypermedia
   • Your representation should contain links to connect to other aspects of the service
   • When making a getCountryList service, it could include links to get the GDP of these countries.
7. Ignoring MIME types

8. Breaking self-descriptiveness

source

Where are we now? - SOA maturity model.

Picture credit:Open source SOA (Jeff Davis)

Where are we now? - 1. Low level Services and Components

• RESTfull
• HTTP
• SOAP
• Servlets
• Web servers

Where are we now? - 2. Governance

• Keeping track of what you are doing - management - discipline
• WSDL
• Writing documentation for RESTful service
• Put these to repositories
• Related to Enterprise Architecture (not organized this academic year : TJTSE25)

Where are we now? - 3. Composite services - Business Rules Engine

• LocalGDP is a composite service
• Business Rules Engines are software packages for creating complicated composite services, for instance BPEL

Where are we now? - 4. Event & Messaging Infrastructure

• Not really handled in this course, included things like
  • Message queues
  • Publish-subscriber models
  • Event handling
  • Message brokers
  • Monitoring
  • Routing
  • Load balancing
• Used implicitly when using PaaS solutions like GAE and Heroku
• In TIES454 Agent Technologies for Developers there is some overlap.

Where are we now? - 5. Business Process Management & Enterprise Decision Management

• BPM is supposed to “eliminate the need for application development” *
• Corporate level flow
• Works for business workflows, but not for individual applications *
  • Hard to design, develop, test, debug, maintain, and understand
    • See Tutka
• EDM is collecting and managing business rules.

What is still to come? - Cloud computing

• SaaS
  • Software as a Service
  • We did this already - didn’t we?
  • How do you get paid for service use?
• PaaS
  • Platform as a Service
  • An organization provides a place where you can run your code
  • Next weeks task
• IaaS
  • Infrastructure as a Service
  • You get a bare server
  • AWS

What is still to come? - Cloud computing related topics

• System administration
• NoSQL databases
• In memory caching
• Process virtualization?
• Map reduce?

Next weeks exercise - PaaS - deployment on GAE

Week 40

This week

• Before Thursday
  • Read prerequisite material
• Before Friday (23:59)
  • Make corrections to last week’s exercise
• On Thursday and Monday
  • Make the assignment in groups
• Before Monday (23:59)
  • Submit assignment using git (tip of master branch)