Conference Central API

The API supports user authentication, user profiles, conference information, and various manners in which to query the conference data.

The front end was written as a skeleton and I implemented the backend API endpoints used to support the webapp.

6/29/2015 code written by: Roman Levitas, Wesley Chun of Google, & Udacity team

Directions given: https://docs.google.com/document/d/1H9anIDV4QCPttiQEwpGe6MnMBx92XCOlz0B4ciD7lOs/pub

Deployed version of Conference Central can be accessed here: https://scalable-apps-example.appspot.com

                 CONFERENCE CENTRAL

************************Summary******************************* This zip contains all necessary files & foldersto run the fully functional Conference Central web application using the Google App Engine to host & scale with incoming users. Besides the front end functionality of the web app, multiple endpoints have been implemented to expand the functionality of the application. User authentication via Google+ is also implemented for users to personalize their experience by registering for conferences, etc.

The files and folders are: 1) conference.py 2) models.py 3) settings.py 4) utils.py 5) main.py 6) app.yaml 7) cron.yaml 8) index.yaml 9) ./templates 10) ./static

************************General Usage************************* An installation of Python 2.7 is required to run the web application.

To run the Conference Central Web App project:

  1. Download Google App Engine (GAE) for your OS with the Python SDK.

  2. Run GAE Launcher and go to 'File'->'Add Existing Application'. Choose the directory where you have unzipped all the above mentioned files & folders.

  3. Select the 'scalable-apps-example' project and hit 'Run'. Click 'Logs' and see which port to use to locally run the web app. Something like the following should appear: "Starting admin server at: http://localhost:8002"

  4. Open a webbrowser and navigate to http://localhost:xxxx where xxxx is your designated port from the logs.

****************************files & folders****************************

1) conference.py

This is the main file of the application which contains all of the API endpoints used for the backend of the Conference Central UI as well as some more endpoints which can be accessed via: localhost:xxxx/_ah/api/explorer where xxxx is the port to your local admin server.

These endpoints extend the functionality of Conference Central to include sessions and are assigned in tasks 1 & 3 (more on task 2 below). Sessions can have speakers, start time, duration, type of session (workshop, lecture etc.), highlights, etc. (the etc. is specified in the models.py file) The endpoints associated with Sessions are listed below:


Task 1: Basic Session functionality within a conference as well as 2 queries

createSession(SessionForm, websafeConferenceKey) -- open only to the organizer of the conference, Session created as child of conference

getConferenceSessions(websafeConferenceKey) -- Given a conference, return all sessions Uses helper method _copySessionToForm(Session) to copy ndb Session object to protoRPC form for transmission

getConferenceSessionsByType(websafeConferenceKey, typeOfSession) -- Given a conference, return all sessions of a specified type (eg lecture, keynote, workshop)

getSessionsBySpeaker(speaker) -- Given a speaker, return all sessions given by this particular speaker,

across all conferences

Task 3: 2 Additional Session queries & Query problem

sessionMaxDuration(maximumDuration) -- Given a maximum duration in minutes for a session, return all Sessions across all conferences that satisfy this time restraint

sessionsbyTime(startTime) -- Given a specific start time in the form of HH:mm using 24 hour format, return all Sessions across all conferences which start at that time

"Solve the following query related problem

Let’s say that you don't like workshops and you don't like sessions after 7 pm. How would you handle a query for all non-workshop sessions before 7 pm? What is the problem for implementing this query? What ways to solve it did you think of?"

The != (not-equal) operations are implemented by combining inequality filters using the OR operation.

!= value is implemented as

(property < value) OR (property > value)

and then the session after 7pm would be another inequality filter on a different property than topics, specifically time.

Directly from the GAE docs: "Note: As mentioned earlier, the Datastore rejects queries using inequality filtering on more than one property."

So the problem with implementing this query is using inequality filtering on two different properties.

A way around this dilemma would be to use equality filters (==) and combine it with OR() to search for other topics in a conference. If we want to avoid workshops, we can set equality to all remaining topics (ie. topic == lecture) and combine all available topics using OR ie.

OR(topic == lecture, topic == seminar, etc)

Task 2: adding/retrieving Sessions to/from Wishlist

Users should be able to mark some sessions that they are interested in and retrieve their own current wishlist. The following endpoints are associated with the Wishlist functionality:

addSessionToWishlist(SessionKey) -- adds the session to the user's list of sessions they are interested in attending. Wishlist is open to all conferences.

getSessionsInWishlist() -- query for all the sessions in a conference that the user is interested in


Task 4: When a new session is added to a conference, the speaker is checked in createSession(SessionForm, websafeConferenceKey). If there is more than one session by this speaker, he/she is added to the SpeakerDictionary in ndb as a key (speaker name) value pair (number of times speaker is appearing) and also added as a new Memcache entry that features the speaker.

getFeaturedSpeaker() -- Reads and returns featured speaker from memcache entry

2) models.py

The models file contains all of the classes for storing and communicating data. Specifically, they are sub-classes of the ndb.Model class for storing into NDB datastore and messages.Message class for communicating data in the form of ProtoRPC messages to and from endpoints.

New classes include: Session (sub-class of ndb.Model and child of specific Conference), SessionForm & SessionForms (protoRPC messages) and SpeakerDict(sub-class of ndb.Model which is used to store a dictionary in NDB using the PickleProperty).

Session class consists of the following fields: sessionName = ndb.StringProperty(required=True) highlights = ndb.StringProperty() speaker = ndb.StringProperty() duration = ndb.IntegerProperty() typeOfSession = ndb.StringProperty(repeated=True) Date = ndb.DateProperty() startTime = ndb.TimeProperty()

Speaker is implemented using a string for simplicity's sake.

SessionForm mirrors the Session class with all the same properties but also includes the confwebsafeKey for the parent conference to be passed in.

SessionForms is a repeated set of SessionForm.

Class SpeakerDict(ndb.Model) has the following two fields identifier= ndb.IntegerProperty(default = 1234) speaker_num = ndb.PickleProperty(default={}) which is basically a dictionary that is stored in ndb using the pickleproperty and a hardcoded identifier for easy extraction/query.

The remainder of the file was given.

3) settings.py

File contains web client id generated by GAE to authorize the web application

4) utils.py

File contains only one function: getUserId which does what it states.

5) main.py

This file is responsible for Tasks such as: sending out an email alert for a new created conference, setting announcement handler, and checking featured speaker handler.

6) app.yaml

Contains application id as well as url handlers.

7) cron.yaml

Sets cron job settings for announcements.

8) index.yaml

Contains indexes necessary for complex/composite queries.

9) ./templates

Folder contains all the HTML templates necessary for rendering all available urls in web application.

10) ./static

Folder contains css file for styling HTML templates.

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