- Author:
- David Nickerson <nickerso@users.sourceforge.net>
- Date:
- 2009-07-16 02:00:03+12:00
- Desc:
- the starting point for the HH tutorial example
- Permanent Source URI:
- https://models.fieldml.org/workspace/a1/rawfile/f6a8f90307388eb4b040ee3566b84d88b59247f7/dojo-presentation/js/dojo/dojox/off/_common.js
dojo.provide("dojox.off._common");
dojo.require("dojo.gears");
dojo.require("dojox.storage");
dojo.require("dojox.sql");
dojo.require("dojox.off.sync");
// Author: Brad Neuberg, bkn3@columbia.edu, http://codinginparadise.org
// summary:
// dojox.off is the main object for offline applications.
dojo.mixin(dojox.off, {
// isOnline: boolean
// true if we are online, false if not
isOnline: false,
// NET_CHECK: int
// For advanced usage; most developers can ignore this.
// Time in seconds on how often we should check the status of the
// network with an automatic background timer. The current default
// is 5 seconds.
NET_CHECK: 5,
// STORAGE_NAMESPACE: String
// For advanced usage; most developers can ignore this.
// The namespace we use to save core data into Dojo Storage.
STORAGE_NAMESPACE: "_dot",
// enabled: boolean
// For advanced usage; most developers can ignore this.
// Whether offline ability is enabled or not. Defaults to true.
enabled: true,
// availabilityURL: String
// For advanced usage; most developers can ignore this.
// The URL to check for site availability. We do a GET request on
// this URL to check for site availability. By default we check for a
// simple text file in src/off/network_check.txt that has one value
// it, the value '1'.
availabilityURL: dojo.moduleUrl("dojox", "off/network_check.txt"),
// goingOnline: boolean
// For advanced usage; most developers can ignore this.
// True if we are attempting to go online, false otherwise
goingOnline: false,
// coreOpFailed: boolean
// For advanced usage; most developers can ignore this.
// A flag set by the Dojo Offline framework that indicates that the
// user denied some operation that required the offline cache or an
// operation failed in some critical way that was unrecoverable. For
// example, if the offline cache is Google Gears and we try to get a
// Gears database, a popup window appears asking the user whether they
// will approve or deny this request. If the user denies the request,
// and we are doing some operation that is core to Dojo Offline, then
// we set this flag to 'true'. This flag causes a 'fail fast'
// condition, turning off offline ability.
coreOpFailed: false,
// doNetChecking: boolean
// For advanced usage; most developers can ignore this.
// Whether to have a timing interval in the background doing automatic
// network checks at regular intervals; the length of time between
// checks is controlled by dojox.off.NET_CHECK. Defaults to true.
doNetChecking: true,
// hasOfflineCache: boolean
// For advanced usage; most developers can ignore this.
// Determines if an offline cache is available or installed; an
// offline cache is a facility that can truely cache offline
// resources, such as JavaScript, HTML, etc. in such a way that they
// won't be removed from the cache inappropriately like a browser
// cache would. If this is false then an offline cache will be
// installed. Only Google Gears is currently supported as an offline
// cache. Future possible offline caches include Firefox 3.
hasOfflineCache: null,
// browserRestart: boolean
// For advanced usage; most developers can ignore this.
// If true, the browser must be restarted to register the existence of
// a new host added offline (from a call to addHostOffline); if false,
// then nothing is needed.
browserRestart: false,
_STORAGE_APP_NAME: window.location.href.replace(/[^0-9A-Za-z_]/g, "_"),
_initializeCalled: false,
_storageLoaded: false,
_pageLoaded: false,
onLoad: function(){
// summary:
// Called when Dojo Offline can be used.
// description:
// Do a dojo.connect to this to know when you can
// start using Dojo Offline:
// dojo.connect(dojox.off, "onLoad", myFunc);
},
onNetwork: function(type){
// summary:
// Called when our on- or offline- status changes.
// description:
// If we move online, then this method is called with the
// value "online". If we move offline, then this method is
// called with the value "offline". You can connect to this
// method to do add your own behavior:
//
// dojo.connect(dojox.off, "onNetwork", someFunc)
//
// Note that if you are using the default Dojo Offline UI
// widget that most of the on- and off-line notification
// and syncing is automatically handled and provided to the
// user.
// type: String
// Either "online" or "offline".
},
initialize: function(){ /* void */
// summary:
// Called when a Dojo Offline-enabled application is finished
// configuring Dojo Offline, and is ready for Dojo Offline to
// initialize itself.
// description:
// When an application has finished filling out the variables Dojo
// Offline needs to work, such as dojox.off.ui.appName, it must
// this method to tell Dojo Offline to initialize itself.
// Note:
// This method is needed for a rare edge case. In some conditions,
// especially if we are dealing with a compressed Dojo build, the
// entire Dojo Offline subsystem might initialize itself and be
// running even before the JavaScript for an application has had a
// chance to run and configure Dojo Offline, causing Dojo Offline
// to have incorrect initialization parameters for a given app,
// such as no value for dojox.off.ui.appName. This method is
// provided to prevent this scenario, to slightly 'slow down' Dojo
// Offline so it can be configured before running off and doing
// its thing.
//console.debug("dojox.off.initialize");
this._initializeCalled = true;
if(this._storageLoaded && this._pageLoaded){
this._onLoad();
}
},
goOffline: function(){ /* void */
// summary:
// For advanced usage; most developers can ignore this.
// Manually goes offline, away from the network.
if((dojox.off.sync.isSyncing)||(this.goingOnline)){ return; }
this.goingOnline = false;
this.isOnline = false;
},
goOnline: function(callback){ /* void */
// summary:
// For advanced usage; most developers can ignore this.
// Attempts to go online.
// description:
// Attempts to go online, making sure this web application's web
// site is available. 'callback' is called asychronously with the
// result of whether we were able to go online or not.
// callback: Function
// An optional callback function that will receive one argument:
// whether the site is available or not and is boolean. If this
// function is not present we call dojo.xoff.onOnline instead if
// we are able to go online.
//console.debug("goOnline");
if(dojox.off.sync.isSyncing || dojox.off.goingOnline){
return;
}
this.goingOnline = true;
this.isOnline = false;
// see if can reach our web application's web site
this._isSiteAvailable(callback);
},
onFrameworkEvent: function(type /* String */, saveData /* Object? */){
// summary:
// For advanced usage; most developers can ignore this.
// A standard event handler that can be attached to to find out
// about low-level framework events. Most developers will not need to
// attach to this method; it is meant for low-level information
// that can be useful for updating offline user-interfaces in
// exceptional circumstances. The default Dojo Offline UI
// widget takes care of most of these situations.
// type: String
// The type of the event:
//
// * "offlineCacheInstalled"
// An event that is fired when a user
// has installed an offline cache after the page has been loaded.
// If a user didn't have an offline cache when the page loaded, a
// UI of some kind might have prompted them to download one. This
// method is called if they have downloaded and installed an
// offline cache so a UI can reinitialize itself to begin using
// this offline cache.
// * "coreOperationFailed"
// Fired when a core operation during interaction with the
// offline cache is denied by the user. Some offline caches, such
// as Google Gears, prompts the user to approve or deny caching
// files, using the database, and more. If the user denies a
// request that is core to Dojo Offline's operation, we set
// dojox.off.coreOpFailed to true and call this method for
// listeners that would like to respond some how to Dojo Offline
// 'failing fast'.
// * "save"
// Called whenever the framework saves data into persistent
// storage. This could be useful for providing save feedback
// or providing appropriate error feedback if saving fails
// due to a user not allowing the save to occur
// saveData: Object?
// If the type was 'save', then a saveData object is provided with
// further save information. This object has the following properties:
//
// * status - dojox.storage.SUCCESS, dojox.storage.PENDING, dojox.storage.FAILED
// Whether the save succeeded, whether it is pending based on a UI
// dialog asking the user for permission, or whether it failed.
//
// * isCoreSave - boolean
// If true, then this save was for a core piece of data necessary
// for the functioning of Dojo Offline. If false, then it is a
// piece of normal data being saved for offline access. Dojo
// Offline will 'fail fast' if some core piece of data could not
// be saved, automatically setting dojox.off.coreOpFailed to
// 'true' and dojox.off.enabled to 'false'.
//
// * key - String
// The key that we are attempting to persist
//
// * value - Object
// The object we are trying to persist
//
// * namespace - String
// The Dojo Storage namespace we are saving this key/value pair
// into, such as "default", "Documents", "Contacts", etc.
// Optional.
if(type == "save"){
if(saveData.isCoreSave && (saveData.status == dojox.storage.FAILED)){
dojox.off.coreOpFailed = true;
dojox.off.enabled = false;
// FIXME: Stop the background network thread
dojox.off.onFrameworkEvent("coreOperationFailed");
}
}else if(type == "coreOperationFailed"){
dojox.off.coreOpFailed = true;
dojox.off.enabled = false;
// FIXME: Stop the background network thread
}
},
_checkOfflineCacheAvailable: function(callback){
// is a true, offline cache running on this machine?
this.hasOfflineCache = dojo.gears.available;
callback();
},
_onLoad: function(){
//console.debug("dojox.off._onLoad");
// both local storage and the page are finished loading
// cache the Dojo JavaScript -- just use the default dojo.js
// name for the most common scenario
// FIXME: TEST: Make sure syncing doesn't break if dojo.js
// can't be found, or report an error to developer
dojox.off.files.cache(dojo.moduleUrl("dojo", "dojo.js"));
// pull in the files needed by Dojo
this._cacheDojoResources();
// FIXME: need to pull in the firebug lite files here!
// workaround or else we will get an error on page load
// from Dojo that it can't find 'console.debug' for optimized builds
// dojox.off.files.cache(dojo.config.baseRelativePath + "src/debug.js");
// make sure that resources needed by all of our underlying
// Dojo Storage storage providers will be available
// offline
dojox.off.files.cache(dojox.storage.manager.getResourceList());
// slurp the page if the end-developer wants that
dojox.off.files._slurp();
// see if we have an offline cache; when done, move
// on to the rest of our startup tasks
this._checkOfflineCacheAvailable(dojo.hitch(this, "_onOfflineCacheChecked"));
},
_onOfflineCacheChecked: function(){
// this method is part of our _onLoad series of startup tasks
// if we have an offline cache, see if we have been added to the
// list of available offline web apps yet
if(this.hasOfflineCache && this.enabled){
// load framework data; when we are finished, continue
// initializing ourselves
this._load(dojo.hitch(this, "_finishStartingUp"));
}else if(this.hasOfflineCache && !this.enabled){
// we have an offline cache, but it is disabled for some reason
// perhaps due to the user denying a core operation
this._finishStartingUp();
}else{
this._keepCheckingUntilInstalled();
}
},
_keepCheckingUntilInstalled: function(){
// this method is part of our _onLoad series of startup tasks
// kick off a background interval that keeps
// checking to see if an offline cache has been
// installed since this page loaded
// FIXME: Gears: See if we are installed somehow after the
// page has been loaded
// now continue starting up
this._finishStartingUp();
},
_finishStartingUp: function(){
//console.debug("dojox.off._finishStartingUp");
// this method is part of our _onLoad series of startup tasks
if(!this.hasOfflineCache){
this.onLoad();
}else if(this.enabled){
// kick off a thread to check network status on
// a regular basis
this._startNetworkThread();
// try to go online
this.goOnline(dojo.hitch(this, function(){
//console.debug("Finished trying to go online");
// indicate we are ready to be used
dojox.off.onLoad();
}));
}else{ // we are disabled or a core operation failed
if(this.coreOpFailed){
this.onFrameworkEvent("coreOperationFailed");
}else{
this.onLoad();
}
}
},
_onPageLoad: function(){
//console.debug("dojox.off._onPageLoad");
this._pageLoaded = true;
if(this._storageLoaded && this._initializeCalled){
this._onLoad();
}
},
_onStorageLoad: function(){
//console.debug("dojox.off._onStorageLoad");
this._storageLoaded = true;
// were we able to initialize storage? if
// not, then this is a core operation, and
// let's indicate we will need to fail fast
if(!dojox.storage.manager.isAvailable()
&& dojox.storage.manager.isInitialized()){
this.coreOpFailed = true;
this.enabled = false;
}
if(this._pageLoaded && this._initializeCalled){
this._onLoad();
}
},
_isSiteAvailable: function(callback){
// summary:
// Determines if our web application's website is available.
// description:
// This method will asychronously determine if our web
// application's web site is available, which is a good proxy for
// network availability. The URL dojox.off.availabilityURL is
// used, which defaults to this site's domain name (ex:
// foobar.com). We check for dojox.off.AVAILABILITY_TIMEOUT (in
// seconds) and abort after that
// callback: Function
// An optional callback function that will receive one argument:
// whether the site is available or not and is boolean. If this
// function is not present we call dojox.off.onNetwork instead if we
// are able to go online.
dojo.xhrGet({
url: this._getAvailabilityURL(),
handleAs: "text",
timeout: this.NET_CHECK * 1000,
error: dojo.hitch(this, function(err){
//console.debug("dojox.off._isSiteAvailable.error: " + err);
this.goingOnline = false;
this.isOnline = false;
if(callback){ callback(false); }
}),
load: dojo.hitch(this, function(data){
//console.debug("dojox.off._isSiteAvailable.load, data="+data);
this.goingOnline = false;
this.isOnline = true;
if(callback){ callback(true);
}else{ this.onNetwork("online"); }
})
});
},
_startNetworkThread: function(){
//console.debug("startNetworkThread");
// kick off a thread that does periodic
// checks on the status of the network
if(!this.doNetChecking){
return;
}
window.setInterval(dojo.hitch(this, function(){
var d = dojo.xhrGet({
url: this._getAvailabilityURL(),
handleAs: "text",
timeout: this.NET_CHECK * 1000,
error: dojo.hitch(this,
function(err){
if(this.isOnline){
this.isOnline = false;
// FIXME: xhrGet() is not
// correctly calling abort
// on the XHR object when
// it times out; fix inside
// there instead of externally
// here
try{
if(typeof d.ioArgs.xhr.abort == "function"){
d.ioArgs.xhr.abort();
}
}catch(e){}
// if things fell in the middle of syncing,
// stop syncing
dojox.off.sync.isSyncing = false;
this.onNetwork("offline");
}
}
),
load: dojo.hitch(this,
function(data){
if(!this.isOnline){
this.isOnline = true;
this.onNetwork("online");
}
}
)
});
}), this.NET_CHECK * 1000);
},
_getAvailabilityURL: function(){
var url = this.availabilityURL.toString();
// bust the browser's cache to make sure we are really talking to
// the server
if(url.indexOf("?") == -1){
url += "?";
}else{
url += "&";
}
url += "browserbust=" + new Date().getTime();
return url;
},
_onOfflineCacheInstalled: function(){
this.onFrameworkEvent("offlineCacheInstalled");
},
_cacheDojoResources: function(){
// if we are a non-optimized build, then the core Dojo bootstrap
// system was loaded as separate JavaScript files;
// add these to our offline cache list. these are
// loaded before the dojo.require() system exists
// FIXME: create a better mechanism in the Dojo core to
// expose whether you are dealing with an optimized build;
// right now we just scan the SCRIPT tags attached to this
// page and see if there is one for _base/_loader/bootstrap.js
var isOptimizedBuild = true;
dojo.forEach(dojo.query("script"), function(i){
var src = i.getAttribute("src");
if(!src){ return; }
if(src.indexOf("_base/_loader/bootstrap.js") != -1){
isOptimizedBuild = false;
}
});
if(!isOptimizedBuild){
dojox.off.files.cache(dojo.moduleUrl("dojo", "_base.js").uri);
dojox.off.files.cache(dojo.moduleUrl("dojo", "_base/_loader/loader.js").uri);
dojox.off.files.cache(dojo.moduleUrl("dojo", "_base/_loader/bootstrap.js").uri);
// FIXME: pull in the host environment file in a more generic way
// for other host environments
dojox.off.files.cache(dojo.moduleUrl("dojo", "_base/_loader/hostenv_browser.js").uri);
}
// add anything that was brought in with a
// dojo.require() that resulted in a JavaScript
// URL being fetched
// FIXME: modify dojo/_base/_loader/loader.js to
// expose a public API to get this information
for(var i = 0; i < dojo._loadedUrls.length; i++){
dojox.off.files.cache(dojo._loadedUrls[i]);
}
// FIXME: add the standard Dojo CSS file
},
_save: function(){
// summary:
// Causes the Dojo Offline framework to save its configuration
// data into local storage.
},
_load: function(callback){
// summary:
// Causes the Dojo Offline framework to load its configuration
// data from local storage
dojox.off.sync._load(callback);
}
});
// wait until the storage system is finished loading
dojox.storage.manager.addOnLoad(dojo.hitch(dojox.off, "_onStorageLoad"));
// wait until the page is finished loading
dojo.addOnLoad(dojox.off, "_onPageLoad");
