Phidget Dictionary - Revision history

Burley: /* General Overview */

2012-09-11T16:37:41Z

General Overview

← Older revision		Revision as of 16:37, 11 September 2012
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	The 'Internal' Dictionary is really just the internal workings of the Phidget Webservice itself. This shares the key-value pair database with the user Dictionary. In fact, when using a dictionary object, if you catch all key events you will see ones that are produced by Phidgets! You should never modify these keys - i.e. ones that start with /PSK/ or /PCK/ - unless you want to explicitly modify Phidget-specific data. This is highly discouraged, as it’s very easy to break things; however, listening to these keys is fine if so desired.		The 'Internal' Dictionary is really just the internal workings of the Phidget Webservice itself. This shares the key-value pair database with the user Dictionary. In fact, when using a dictionary object, if you catch all key events you will see ones that are produced by Phidgets! You should never modify these keys - i.e. ones that start with /PSK/ or /PCK/ - unless you want to explicitly modify Phidget-specific data. This is highly discouraged, as it’s very easy to break things; however, listening to these keys is fine if so desired.

	The 'User' Dictionary what you can build with a Phidget Dictionary object in your code. It is whatever collection of key-value pairs you might need for your network-distributed program, even if for just one computer.		The 'User' Dictionary is what you can build with a Phidget Dictionary object in your code. It is whatever collection of key-value pairs you might need for your network-distributed program, even if for just one computer.

	At this point, you may be wondering: Why go to all the trouble of using the Dictionary? Why not just save state within your client program? Well, the Phidget Dictionary offers two advantages:		At this point, you may be wondering: Why go to all the trouble of using the Dictionary? Why not just save state within your client program? Well, the Phidget Dictionary offers two advantages:

Cora at 22:12, 27 June 2012

2012-06-27T22:12:32Z

← Older revision		Revision as of 22:12, 27 June 2012
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			[[Category:Overview]]
	==General Overview==		==General Overview==

Cora at 18:30, 20 June 2012

2012-06-20T18:30:37Z

← Older revision		Revision as of 18:30, 20 June 2012
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	==General Overview==		==General Overview==

	The Phidget Dictionary is a service provided by the [[Phidget WebService]]. It allows you to store program data centrally - in the form of key-value pairs - on the same server as your Phidgets.		The Phidget Dictionary is a central key-pair database for networked programs. It is a service provided by the [[Phidget WebService]]. It allows you to store program data centrally - in the form of key-value pairs - on the same server as your Phidgets.

	A Dictionary is like any other Phidget software object: You create and open it (though you don't have to wait for attachment or attach it in any way). You can subscribe to data change events, and get updates on these events from multiple devices. And when you're done, you simply close and delete it. Just like any other Phidget software object over the network, you run the functional code on your client, and the server simply runs the Phidget WebService, which includes the Phidget Dictionary.		A Dictionary is like any other Phidget software object: You create and open it (though you don't have to wait for attachment or attach it in any way). You can subscribe to data change events, and get updates on these events from multiple devices. And when you're done, you simply close and delete it. Just like any other Phidget software object over the network, you run the functional code on your client, and the server simply runs the Phidget WebService, which includes the Phidget Dictionary.

Cora at 17:28, 20 June 2012

2012-06-20T17:28:06Z

← Older revision		Revision as of 17:28, 20 June 2012
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	The 'Internal' Dictionary is really just the internal workings of the Phidget Webservice itself. This shares the key-value pair database with the user Dictionary. In fact, when using a dictionary object, if you catch all key events you will see ones that are produced by Phidgets! You should never modify these keys - i.e. ones that start with /PSK/ or /PCK/ - unless you want to explicitly modify Phidget-specific data. This is highly discouraged, as it’s very easy to break things; however, listening to these keys is fine if so desired.		The 'Internal' Dictionary is really just the internal workings of the Phidget Webservice itself. This shares the key-value pair database with the user Dictionary. In fact, when using a dictionary object, if you catch all key events you will see ones that are produced by Phidgets! You should never modify these keys - i.e. ones that start with /PSK/ or /PCK/ - unless you want to explicitly modify Phidget-specific data. This is highly discouraged, as it’s very easy to break things; however, listening to these keys is fine if so desired.

	The 'User' Dictionary ~~is the typical functionality of the~~ Phidget Dictionary object ~~that you can create and use~~ in your code. ~~Although both the Phidget Dictionary and the Webservice use the same data repository (because they are, as described in the previous paragraph, actually the same thing),~~ you ~~usually won't be concerned with Phidget data and will instead be creating and storing your own data to run~~ your program ~~with state~~.		The 'User' Dictionary what you can build with a Phidget Dictionary object in your code. It is whatever collection of key-value pairs you might need for your network-distributed program, even if for just one computer.

	~~With the two-computer example above~~, you may be wondering: Why go to all the trouble of using the Dictionary? Why not just save state within your client program?		At this point, you may be wondering: Why go to all the trouble of using the Dictionary? Why not just save state within your client program? Well, the Phidget Dictionary offers two advantages:
			* It takes care of all database management for you - all you have to do is write pairs and listen for pair changes via events
			* You don't have to write any code, it is already included in the WebService!
			Although both the Phidget Dictionary and the Webservice use the same data repository (because they are, as described in the previous paragraph, actually the same thing), you usually won't be concerned with Phidget data and will instead be creating and storing your own data to run your program with state.

	The ~~answer becomes obvious~~ when you have more than one client computer. This is one of the powerful aspects of the Phidget Webservice; that is, more than one computer can control Phidgets by making your system networked. In this case, having a centralized store of data that all clients can 'subscribe' to in order to act when it changes is a very powerful tool:		The benefits above become even more useful when you have more than one client computer. This is one of the powerful aspects of the Phidget Webservice; that is, more than one computer can control Phidgets by making your system networked. In this case, having a centralized store of data that '''all''' clients can 'subscribe' to in order to act when it changes is a very powerful tool:

	[[Image:App guide dictionary webservice multi.png\|500px\|link=\|alt=]]		[[Image:App guide dictionary webservice multi.png\|500px\|link=\|alt=]]
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	To use the Dictionary, you would create a Dictionary object within your code, just like you would any other Phidget software object. We describe - in a general manner - how to create software objects on the [[General Phidget Programming]] page, and even more information can be found specific to your language on the [[Software Overview#Language Support\|page for your language]]. To "listen" to changes of the value associated with a key, the Dictionary has a {{Code\|KeyValueChanged()}} (or similar) event function. The dictionary makes use of extended regular expressions for key matching to execute code for specific keys.		To use the Dictionary, you would create a Dictionary object within your code, just like you would any other Phidget software object. We describe - in a general manner - how to create software objects on the [[General Phidget Programming]] page, and even more information can be found specific to your language on the [[Software Overview#Language Support\|page for your language]]. To "listen" to changes of the value associated with a key, the Dictionary has a {{Code\|KeyValueChanged()}} (or similar) event function. The dictionary makes use of extended regular expressions for key matching to execute code for specific keys.

			Note that you don't even need a Phidget to use the Dictionary! You can use our libraries and the WebService without any Phidgets. Usually, there's not much to broadcast on the WebService without a Phidget, but the Dictionary is the exception. With it, you'll have access to centralized key-value pair database management, pre-written, that can work across many computers on a local network.

Cora: Created page with "==General Overview== The Phidget Dictionary is a service provided by the Phidget WebService. It allows you to store program data centrally - in the form of key-value pai..."

2012-06-20T17:17:48Z

Created page with "==General Overview== The Phidget Dictionary is a service provided by the Phidget WebService. It allows you to store program data centrally - in the form of key-value pai..."

New page

==General Overview==

The Phidget Dictionary is a service provided by the [[Phidget WebService]]. It allows you to store program data centrally - in the form of key-value pairs - on the same server as your Phidgets.

A Dictionary is like any other Phidget software object: You create and open it (though you don't have to wait for attachment or attach it in any way). You can subscribe to data change events, and get updates on these events from multiple devices. And when you're done, you simply close and delete it. Just like any other Phidget software object over the network, you run the functional code on your client, and the server simply runs the Phidget WebService, which includes the Phidget Dictionary.

This works because the WebService ''already'' maintains a centralized dictionary of key-value pairs - this is what runs the WebService itself. We expose this data storage to you, the user, so that it can be customized and can be accessed and changed from any number of clients.

Since the Dictionary is a popular feature on our Phidget Single Board Computer (SBC), we will use that as an example. You may have already seen this image of how the WebService works using the Phidget SBC from the [[Phidget WebService]] page:

[[Image:webservice_general_sbctopc.png|500px|link=|alt=]]

Now that we know about the Phidget Dictionary, if we were to expand the WebService out into its components, it would look like this:

[[Image:App guide dictionary webservice flow.png|500px|link=|alt=]]

The 'Internal' Dictionary is really just the internal workings of the Phidget Webservice itself. This shares the key-value pair database with the user Dictionary. In fact, when using a dictionary object, if you catch all key events you will see ones that are produced by Phidgets! You should never modify these keys - i.e. ones that start with /PSK/ or /PCK/ - unless you want to explicitly modify Phidget-specific data. This is highly discouraged, as it’s very easy to break things; however, listening to these keys is fine if so desired.

The 'User' Dictionary is the typical functionality of the Phidget Dictionary object that you can create and use in your code. Although both the Phidget Dictionary and the Webservice use the same data repository (because they are, as described in the previous paragraph, actually the same thing), you usually won't be concerned with Phidget data and will instead be creating and storing your own data to run your program with state.

With the two-computer example above, you may be wondering: Why go to all the trouble of using the Dictionary? Why not just save state within your client program?

The answer becomes obvious when you have more than one client computer. This is one of the powerful aspects of the Phidget Webservice; that is, more than one computer can control Phidgets by making your system networked. In this case, having a centralized store of data that all clients can 'subscribe' to in order to act when it changes is a very powerful tool:

[[Image:App guide dictionary webservice multi.png|500px|link=|alt=]]

The intended use for the dictionary is as a central repository for communication and persistent storage of data between several client applications. For example, it can be used as a higher level interface exposed by one application that controls the Phidgets for others to access, rather then every client talking directly to the Phidgets themselves.

==Using The Dictionary==

To use the Dictionary, you would create a Dictionary object within your code, just like you would any other Phidget software object. We describe - in a general manner - how to create software objects on the [[General Phidget Programming]] page, and even more information can be found specific to your language on the [[Software Overview#Language Support|page for your language]]. To "listen" to changes of the value associated with a key, the Dictionary has a {{Code|KeyValueChanged()}} (or similar) event function. The dictionary makes use of extended regular expressions for key matching to execute code for specific keys.