Untangling - fall2017 - week 8
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This document provides an agenda for a class on databases and asynchronous JavaScript. It includes presentations of Project 2, a review of asynchronous concepts like callbacks, promises, and async/await. It also covers differences between SQL and NoSQL databases, examples of using SQL and MongoDB, and an introduction to using a Postgres database on Bluemix. Homework involves SQL queries on a Stack Overflow database and students are notified to begin working on Project 3, which will involve a database backend and chatbot.
Untangling - fall2017 - week 8
- 1. UNTANGLING THE WEB FALL 2017 WEEK 8 – PROJECT 2, DEEPER INTO DATABASES, ASYNCHRONOUS JAVASCRIPT, NOTES ABOUT NODE
- 2. AGENDA • Project 2 presentations • Asynchronous javascript • Promises • Async/await • Databases – SQL vs. NoSQL • Looking more at NodeJS • Routes and views • How to render to the client • A more detailed look at Cloudant programming • Getting ready for project 3
- 3. PROJECT 2 PRESENTATIONS • Keep it under 5 minutes • Show off all the functionality in your front end • Talk about the business model, including value proposition (pains and gains) • Make sure you have emailed me • A link to github • A link to the running website • SEO, business model canvas, value proposition canvas links
- 4. REVIEW OF FUNCTIONS • A block of named code able to be called from other places • Variables in js are untyped, so they can hold function references • Parameters to a function can also be functions • Anonymous function – a function that is not given a name but is rather just passed to another function
- 5. A FEW UTILITY FUNCTIONS WE’LL RUN INTO TODAY • setTimeout(function, delay in ms) – delay and then call a function • Math.random – generate a random number • Math.ceil – round up
- 6. ASYNCHRONOUS JAVASCRIPT • What’s a callback? You’ve used them before! In the maps example • What’s a promise? • What’s a promise chain? • Anyone come across async/await?
- 7. CALLBACK EXAMPLE • https://jsfiddle.net/3cew460a/ • https://www.youtube.com/watch?v=QqiNn3GfTMc
- 8. PROMISE EXAMPLE • https://jsfiddle.net/s3m4xv1o/ • https://www.youtube.com/watch?v=VmMDG6h-bVQ
- 9. PROMISE CHAINING EXAMPLE • https://jsfiddle.net/8Lf4zof3/ • https://www.youtube.com/watch?v=a1cTkiNuEwM
- 10. ASYNC/AWAIT • It is an ES7 feature, so will have to use babel as a transpiler if we want to use it • https://www.youtube.com/watch?v=COKdtOgopWQ
- 11. DATABASES • SQL versus noSQL • Flavours of SQL and noSQL • Why use a database at all? • Advanced database topics • Schema design • Replication • Transactions
- 12. SQL VERSUS NOSQL • SQL – Structured Query Language • Relational database • Use when you need multiple tables and when you need to construct queries that span those tables • More functional than flat databases, but also slower and more complex • Can exist in either client or server flavours NoSQL databases – anything that isn’t relational! MongoDB is a popular server-based flavor Redis is a local memory-mapped flavor Cloudant, couchDB, etc. there are many, many types All are good for rapid, flat table access Avoid the complexities of relational databases while still preserving the benefits
- 13. LOCAL SQL EXAMPLE – CARS DATABASE • https://jsfiddle.net/m5rh3a83/1/ • (for more details see here: https://www.tutorialspoint.com/html5/html5_web_sql.htm)
- 14. MORE REALISTIC SQL EXAMPLE • http://sqlfiddle.com/#!9/1d643/23 • (video help here: https://www.youtube.com/watch?v=DDVOMRvyAS4)
- 15. SQLZOO • http://sqlzoo.net/ • Go do some exercises! • (https://www.sqlteaching.com is an alternative if you want some more exercises)
- 16. MULTIPLE TABLES • You will usually have more than one table • If you have only one table, it is time to consider a NoSQL database • Look on SQLZoo for the JOINS sections and make sense of that • http://sqlzoo.net/wiki/The_JOIN_operation • If you want more complex examples on a real database you can play here: • http://data.stackexchange.com/stackoverflow/queries • More about joins • https://blog.codinghorror.com/a-visual-explanation-of-sql-joins/
- 17. POSTGRESSQL ON BLUEMIX • Here’s a decent started project: https://github.com/IBM-Bluemix/compose-postgresql-helloworld- nodejs
- 18. FOR PROJECT 3 • You’ll have to decide whether to use a flat database, like the cloudant example we walked through last week, or a relational database like postgresSQL • How do you make that decision? • Complexity of your data • Performance requirements • Development difficulty
- 19. NODEJS • We’ll look through: • Package.json (review) • App.js (the webserver) • Routes and views
- 20. CONCEPTS (ALSO TO BE COVERED IN MORE DETAIL NEXT WEEK) • JSON and how to parse it • http get, put, post, delete, etc. (reminder about CRUD pattern) • Nodejs • Require statement • App.js
- 21. HOMEWORK 8 (DUE START OF CLASS NOV 1ST) • Submit a github link with a file containing the query and results for each question • Using the stackoverflow database here: http://data.stackexchange.com/stackoverflow/queries • List the oldest 10 Victoria, BC users and order them by age. • List the top 10 highest reputation users in Victoria that have answered questions with the tag javascript. • List the top 5 Victoria developers by accepted answer percentage • List the top 10 Victoria developers by accepted answer percentage on questions with the tag javascript
- 22. PROJECT 3 • If anyone needs to change groups get it figured out this week • You’ll need to implement a database backend for your project and a chatbot • Database should have new item, search, and delete (optionally edit) from the ui • You’ll need to host your project on bluemix • You’ll need to show a working demo of project 2 hooked up to these backend services