Autumn 2015

TIES456 Introduction to SOA and Cloud Computing, 5 ECTS

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

Today

• Feedback on this week’s exercise
• Reflective questions
• Next weeks exercise

General feedback - Received submissions

• Check from the table
  • Details will be put in your repository after the lecture
• Use references when answering to questions. Especially when taking quotes.

General feedback - Repository structure

• Keep a project structure
  • Repository reflects working setting
  • Do not dump source files in root directory.
  • Do not put compressed files in the repo
• Include group number in project and package names (just easier for me correcting things)

General feedback - Repository clean-up

• Clean up stuff which is not used.
  • Unused imports, methods, classes
• Check out a clean copy of your repository and see whether you get it working

Coding style - Use of null

• Do ‘never’ return null from any method.
  • Returning ‘null’ Considered Dishonest
  • Mainly true for Java because it has (checked) exceptions! But also for many other languages.
  • An empty list and null are very different things.
• The same counts for using
  • -1
  • ""
  • any valid value for the type to indicate failure.
  • In some cases it is reasonable (programming language dependent).

Coding style - Use of static and Singleton

• Singleton is a widely used design pattern, but
  • horrible for testing
    • No way you can mock it out
  • largely overused
    • performance??
    • Often have data races or synchronization problems
• The same applies to public static methods

Copying slides from last week - Streams or String

    .asString()
    .toString
    EntityUtils.toString(...)
    int k;
    String st = "";
    while ((k = stream.read()) != -1) {
        st += (char) k;
    }

• All create in memory stored strings.
  • Fine for small deployment
    • A disaster for large scale deployments (if the string is very large)
• Use streams instead

Questions for discussion

• Most REST services do not use WSDL and SOAP. What could be reasons for this?
• SOAP and WSDL use XML, would it be better if they would use something more modern like JSON?
• How did you handle errors and how should it be done? Imagine that your application is running on a production server.

Questions for discussion 1

• Most REST services do not use WSDL and SOAP. What could be reasons for this?

Questions for discussion 2

• SOAP and WSDL use XML, would it be better if they would use something more modern like JSON?

Questions for discussion 3

• How did you handle errors and how should it be done? Imagine that your application is running on a production server.

Tasks for week 39

• This weeks task …

This week

• Before Thursday
  • Read prerequisite material
• On Thursday and Monday
  • Make the assignment in groups
• Before Monday (23:59)
  • Submit assignment using git (tip of master branch)