Diagram 1: Centralised Database

Diagram 1: Centralised Database

We are at the stage where we are looking at the potential solution for a ticketing system set up by the PTC consortium. One of the technical concepts that we are trying to get our heads around is a distributed database and what that might look like as a viable solution. To get to this point, we first looked at the following concepts:

The links are all to the collaborative wikispace that we: myself, Andrew Churches (Kristin School NZ) and Julie set up to share with ITGS students (and teachers) who will sit the exam in May or November this year.

Distributed Database

Diagram 2

To help understand a potential solution based on distributing the data, we are about to tackle these questions:

Generic Technical Questions
  1. Define centralised database.
  2. Define distributed database. What are the advantages/disadvantages.
  3. Define DDBMS.
  4. Examine the diagrams and look at the research and notes posted in the wikispace. Does each model (centralised, decentralised and distributed) require the same hardware, DBMS and operating system?
  5. What are the networking requirements for users to access the data for each model? 1. centralised, 2. decentralised, 3. distributed?
  6. What is a VPN? Which models would require a VPN and for what purposes?
  7. Review the ACID: Atomicity, Consistency, Isolation, Durabilty.
  8. Discuss the advantages of having a centralised db system over DDBMS (Your response should review some of the aspects of the ACID model).
  9. Discuss the advantages of having a DDBMS over a centralised db (Your response should review some of the aspects of the ACID model).
Questions relating to the case study

Use of technical terminology and explicit links to the case study are required here.

  1. Assume you are worked for CT at Site 1 (the first small theatre). How many locations can the same data be stored and accessed from in for each of the three configurations?
  2. What happens if two customers want to book the same seats at the same time at (site 1) CT for each of the three configurations?
  3. What are the advantages for (site 1) CT for staying as they are – ie their own database system? (diagram 3)
  4. What are the advantages for (site 2) MTG for staying as they are? (See diagram 3)
  5. Would a centralised system (site) be better for CT? (see diagram 1, the database is stored in one place at site, and not at site 1, CT)
  6. Would a centralised system be better for MTG? (likewise, see diagram 1)

    Diagram 3: Decentralised Database

    Diagram 3: Decentralised Database

  7. Would a distributed db system be better for (site 1) CT and (site 2) MTG? See diagram 2, the data for CT is stored on a server at CT (site 1) however users can also access data for other theatre companies in the PTC, for example site 2 and others.
  8. Overall, in your opinion and based on the case study and the points discussed above, what system should PTC adopt?


We aim to post some responses in our wiki here. We welcome any contributions so please post here or contact us in the wiki.


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…Or are you looking for a way to collaborate with colleagues?

Over the last week, I’ve been using crocodoc.com with my IB examining colleagues in order to discuss samples of students work. I can certainly see many benefits for us in the High School.

Crocodoc is a very easy way to annotate and mark student’s work that is in PDF, word document for or even images. You create an account and upload files which you can then share with students and colleagues. Anyone you share with can add comments, highlight areas and make annotations.

And a note about the upcoming mock exams…

Now that we are coming to the examination season, our Grade 12 IB ITGS Diploma students are required to ‘hand-write’ their papers which means that there is one hard copy of the student’s work. That’s fine as you can physically mark and comment on the paper and give feedback to the individual student. However, why not consider scanning, uploading and annotating electronically one or two high-scoring papers to Crocodoc to share with your students to provide and discuss the marking and allow all students the benefit of the feedback as well as providing good model answers? An added benefit is that you have an online record of the annotated work that you may want to share with other students or colleagues for moderation purposes in the future.

To get started and try out Crocodocs, go here.

Example of editing student work

Crocodocs is FREE and currently available here in China….so get started and see how you go!

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