Autumn 2014

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
• Short presentations
• Making groups
• Next weeks exercise

General feedback - Received submissions

• Check for your name

General feedback - Repositories

• Most repositories are fairly clean
• Some contain all kind of project files
  • Sometimes this is good
• Do not store passwords in repositories

General feedback - Submission

• You can use a structure in the repo which is easy for you
• Clean up stuff which is not used.

  • Unused imports, methods, classes

    • Everything which has once been put on git, will stay there.

  • after removing stuff locally, it is not removed from git yet!

    git rm file.txt

  • demonstrate?

General feedback - Documentation

• No full documentation needed, this is an exercise.

  • But it does not harm!
  • Especially when you do something smart.

• Very good in some groups.

• Please make a README file.

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.
• The same counts for using
  • -1
  • “”
  • any valid value for the type to indicate failure.
  • In some cases it is reasonable.

General feedback - Streams or String

    .asString()
    .toString
    EntityUtils.toString(...)
    

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

General note - Streams and Readers

• Reader/Writer
  • Used for characters (a .txt file, JSON, XML, …)
• InputStream/OutputStream
  • User for bytes - binary data (e.g. an image, sound, …)
• InputStreamReader and OutputStreamWriter bridge between the byte and chatacter world
  • You can and should specify a character encoding for the conversion
    • otherwise some default will be used (= bad things will happen to ö, ä, 错, …).
  • Why is there no ReaderInputStream and WriterOutputStream ?

General feedback - ErrorChecking

• Only implemented well by very few groups
  • If the HTTP reponse code 200 = OK
    • The HTTP communication succeeded!
  • Check in the response message whether the call also succeeded.

General feedback - Manual XML/JSON conversion

• Used by some, but error prone (even more for XML as for JSON).
• Might be more efficient in some rare cases
  • There are several options for parsing available in all languages.

General note - Use of URI Builders

• Seem awkward sometimes - why do they throw these annoying exceptions?

General note - Exceptions

• Code examples

Making groups

Moving Thurday’s lecture

• start of ITKST42 Tietoturvallisuustekniikka, 5 op, Data analysis, data mining and anomaly detection I
• Thursday 18.09 11:15 - 14 (Ylistö)
• 14:15?

Questions for discussion

• Is the API provided by mediafire REST_API according to the principles which are listed in the IBM article RESTful API?
  • Use HTTP methods explicitly
  • Be stateless
  • Expose directory structure-like URIs
  • Transfer XML, JSON, or both

Questions for discussion

• Is it safe to send parameters in the query string of the URL?

    https://www.mediafire.com/api/user/get_session_token.php?email=mumail%40gmail.com&password=lookatme&application_id=37456&signature=deadbeef&response_format=json

Tasks for week 38

• 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)