WebFund 2014W Lecture 13
The video from the lecture given on February 28, 2014 is available:
MongoDB
Data "types":
- Databases: sets of collections
- collections: sets of documents
- documents: sets of properties and values
Database operations:
- create/add a database
- drop/delete a database
- add a collection to a database
- remove a collection from a database
- select a collection to use
Collection operations:
- retrieve all documents
- retrieve specific documents matching a set of conditions
- add/insert a document
- remove/delete a document
- replace a set of document
Document operations:
- stored as a JS object with _id unique identifier
- set/change value of a property
- retrieve value of a property
- => key/value store or associative array
Transactions: (not in MongoDB)
- start a transaction
- specify queries to match documents/records
- specify changes to those documents/records
- commit changes if none of the specified data has been changed by others
- if others have changed documents/records, abort transactions and undo all changes
- Airline example: reserve seat and record payment
- If you want transactions, use SQL (e.g., PostgreSQL, Oracle, MySQL (sort of)), at the price of some performance
Ethics
client-side JS
Key difference between client-side and server-side JS: THE DOM
- DOM = document object model
- tree representation of an HTML document
- with lots of access methods
- purpose: read and change HTML page under control of JS
jQuery
- standardized methods for accessing DOM (and other stuff)
- pattern: specify nodes => change nodes
- specify nodes via tag, id, & class (same identifiers used by CSS)