html5 programming
TRANSCRIPT
HTML5 ProgrammingNam Ho
KMS Technology
HTML5 won’t be ready until 2022!
Do I need to wait for the specifications are complete?
Real-world browser support is what matters!
A mobile example
http://m.microsoft.com/windowsphone/en-us/demo/index.html
Why programming?
This presentation doesn’t cover
• Semantics & Markups• HTML5 Forms• Web Workers• WebGL• CSS3• SVG• …
This presentation covers
• Video• Canvas• WebSocket• Data Storage • Offline• FileSystem• Geolocation
Multimedia
These specifications defines the video/audio elements with all the available methods, attributes and events. Through the new APIs you can access, control and manipulate timeline data and network states of the files. With the coming additions to the APIs you will be able to read and write raw data to audio files (Audio Data API) or manipulate captions in videos (Timed Track API).
Video
• Native video• Video tag
– <video src=“light.ogv” controls autoplay />
• Formats– .mp4 = H.264 + AAC– .ogg/.ogv = Theora + Vorbis– .webm = VP8 + Vorbis
• Legacy browser fallback
Audio
• Native audio• Audio tag
– <audio src=“hello.ogg” controls />
• Formats– .ogg/.oga– .mp3– .wav– .aac (Advanced Audio Coding)
• Legacy browser fallback
MIME types
Format Attribute type MIME type
.ogg video/ogg application/ogg
.mp4 video/mp4 video/mpeg
.webm video/webm video/webm
.mp3 audio/mp3 audio/mpeg
.wav audio/wav audio/wav
.aac audio/aac audio/aac
.mp4 audio/mp4 audio/mp4
Canvas
The canvas element provides scripts with a resolution-dependent bitmap canvas, which can be used for rendering graphs, game graphics, or other visual images on the fly.
Canvas
• Native drawing surface• Canvas tag
– <canvas id=“square” width=“10” height=“10” />
• JavaScript API for 2D drawing
WebSocket
To enable Web applications to maintain bidirectional communications with server-side processes, this specification introduces the WebSocket interface.
WebSocket
• WebSocket object• New protocol
– ws://html5rocks.websocket.org/echo
• Establishing an open connection– Client and server can send data at any time– Realtime web application
WebSocket example
Web Storage
This specification introduces two related mechanisms, similar to HTTP session cookies, for storing structured data on the client side.
Web storage
• Avoiding HTTP overhead of cookies• Key-value pairs• Local storage• Session storage• Quota– Needing user confirmation if exceeding storage
capability
Indexed Database
This specification defines APIs for a database of records holding simple values and hierarchical objects. Each record consists of a key and some value. Moreover, the database maintains indexes over records it stores. An application developer directly uses an API to locate records either by their key or by using an index. A query language can be layered on this API. An indexed database can be implemented using a persistent B-tree data structure.
Indexed database
• Object based data store• Asynchronous API• Execute commands and open cursor inside
transactions
Opening indexed database
Creating an Object Store
Storing data into Object Store
Querying data by cursor
Offline
In order to enable users to continue interacting with Web applications and documents even when their network connection is unavailable — for instance, because they are traveling outside of their ISP's coverage area — authors can provide a manifest which lists the files that are needed for the Web application to work offline and which causes the user's browser to keep a copy of the files for use offline.
Application cache
• Cache resources locally– HTML, CSS, JavaScript, images, etc.
• Use a manifest file to specify resources in order to cache• Download caching resources in a transaction• window.applicationCache• Add manifest attribute to html tag
– manifest=“example.appcache”• MIME type
– text/cache-manifest appcache• Clear cache: chrome://appcache-internals/
Manifest fileCACHE MANIFEST#v1.0.0
CACHEindex.htmlstyle.cssScripts/main.jsimages/logo.png
FALLBACKtime.js fallback_time.js
Updating to new version
FileSystem
This specification defines an API to navigate file system hierarchies, and defines a means by which a browser may expose sandboxed sections of a user's local file system to web applications.
File system
• Sandboxed environment• Allow create/edit/delete files and directories
Geolocation
The Geolocation API defines a high-level interface to location information associated only with the device hosting the implementation, such as latitude and longitude. The API itself is agnostic of the underlying location information sources. Common sources of location information include Global Positioning System (GPS) and location inferred from network signals such as IP address, RFID, WiFi and Bluetooth MAC addresses, and GSM/CDMA cell IDs, as well as user input. No guarantee is given that the API returns the device's actual location.
Geolocation• Allow users to share their location for location-aware services
– Application >> Browser >> 3rd services such as Skyhook or Google
• Privacy– Users are asked to share their location
• navigator.geolocation– getCurrentPosition– watchPosition
• Location metadata– latitude/longtitude/altitude– accuracy/altitudeAccuracy– heading/speed
Resources
• HTML5 rocks– http://www.html5rocks.com/en/
• Modernizr– http://www.modernizr.com/
• Mobile HTML5– http://mobilehtml5.org/
• Source code– http://bit.ly/tZ6eBn
Thank you for joining!