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
• Short presentations
• Making groups
• Next week’s exercise

General feedback - Received submissions

• Check for your name

General feedback - Repositories

• Most repositories are clean
• Some contain all kind of project files
  • Sometimes this is good
• Do not store passwords in repositories
  • Everything which has once been put on git, will stay there.

General feedback - Submission

• You can use a structure in the repo from which one can continue the work
  • maven project
  • eclipse/netbeans/… project
• Remove all unused code! You can always go back in the history!

  • Commit more often

  • Unused imports, methods, classes

  • 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.
• Please make/edit the README file.

General notes - 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)
• 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.
    • "result":"Success" vs "result":"Fail"

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’ programming languages.

          Reader in = new InputStreamReader(url.openConnection().getInputStream());
          String inputLine = in.readLine();
          in.close();
          int s1 = inputLine.indexOf("get_session_token");
          int s2 = s1 + 36;
          int s3 = inputLine.indexOf("secret_key");
          int s4 = s3 - 3;
          String sessionToken = inputLine.substring(s2,s4);
          System.out.println("Session token: " + sessionToken);

General note - Use of URI Builders

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

General note - Exceptions

• Code examples

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

• Did anyone implement URL encoding correctly, without adding the parameters one by one?

• 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

Example code

• A short example http://yousource.it.jyu.fi/~miselico/miselicos-week37-2

• A long example http://yousource.it.jyu.fi/ties456-2015/week37-testable

Making groups

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)