Phidget Dictionary - Revision history

Burley at 17:53, 6 March 2019

2019-03-06T17:53:09Z

← Older revision		Revision as of 17:53, 6 March 2019
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	It is an error to {{Code\|Add()}} a key that already exists in the dictionary. {{Code\|Set()}} should be used to update existing keys, creating the key if it does not already exist.		It is an error to {{Code\|Add()}} a key that already exists in the dictionary. {{Code\|Set()}} should be used to update existing keys, creating the key if it does not already exist.

	There is no way to directly list all of the keys in a dictionary. The {{Code\|Scan()}} method allows code to access the existing keys, but only returns the number of keys that can be held in a limited sized buffer. This interface was chosen as the dictionary could contain more keys than could reasonably returned in a single network request.		There is no way to directly list all of the keys in a dictionary. The {{Code\|Scan()}} method allows code to access the existing keys, but only returns the number of keys that can be held in a limited sized buffer. This interface was chosen as the dictionary could contain more keys than could reasonably be returned in a single network request.

Burley at 17:50, 6 March 2019

2019-03-06T17:50:38Z

← Older revision		Revision as of 17:50, 6 March 2019
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	[[Image:Dictionary-networkserver.jpg\|600px\|link=\|alt=]]		[[Image:Dictionary-networkserver.jpg\|600px\|link=\|alt=]]

	Dictionary is Phidget channel class that exports a key-value pair database. Dictionaries are created and made accessible by the [[Phidget Network Server]]. A Dictionary channel is created and opened like any other Phidget channel. Matching is done using either the serial number or the label assigned to the dictionary.		The Dictionary is a Phidget channel class that exports a key-value pair database. Dictionaries are created and made accessible by the [[Phidget Network Server]]. A Dictionary channel is created and opened like any other Phidget channel. Matching is done using either the serial number or the label assigned to the dictionary.

	The backing pseudo-device that exports the Dictionary device channel is maintained by the [[Phidget Network Server]], and is created when the server starts. When the server exits, the pseudo-device is deleted, and any changes made to a dictionary are lost.		The backing pseudo-device that exports the Dictionary device channel is maintained by the [[Phidget Network Server]], and is created when the server starts. When the server exits, the pseudo-device is deleted, and any changes made to a dictionary are lost.

Mparadis at 18:53, 20 July 2017

2017-07-20T18:53:08Z

← Older revision		Revision as of 18:53, 20 July 2017
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	[[Category:Overview]]		[[Category:Overview]]
	==General Overview==		==General Overview==

			[[Image:Dictionary-networkserver.jpg\|600px\|link=\|alt=]]

	Dictionary is Phidget channel class that exports a key-value pair database. Dictionaries are created and made accessible by the [[Phidget Network Server]]. A Dictionary channel is created and opened like any other Phidget channel. Matching is done using either the serial number or the label assigned to the dictionary.		Dictionary is Phidget channel class that exports a key-value pair database. Dictionaries are created and made accessible by the [[Phidget Network Server]]. A Dictionary channel is created and opened like any other Phidget channel. Matching is done using either the serial number or the label assigned to the dictionary.

Chad: /* General Overview */

2017-07-13T15:16:16Z

General Overview

← Older revision		Revision as of 15:16, 13 July 2017
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	==General Overview==		==General Overview==

	Dictionary is Phidget channel class that exports a key-value pair database. Dictionaries are ~~create~~ and made accessible by the [[Phidget Network Server]]. A Dictionary channel is created and opened like any other Phidget channel. Matching is done using either the serial number or the label assigned to the dictionary.		Dictionary is Phidget channel class that exports a key-value pair database. Dictionaries are created and made accessible by the [[Phidget Network Server]]. A Dictionary channel is created and opened like any other Phidget channel. Matching is done using either the serial number or the label assigned to the dictionary.

	The backing pseudo-device that exports the Dictionary device channel is maintained by the [[Phidget Network Server]], and is created when the server starts. When the server exits, the pseudo-device is deleted, and any changes made to a dictionary are lost.		The backing pseudo-device that exports the Dictionary device channel is maintained by the [[Phidget Network Server]], and is created when the server starts. When the server exits, the pseudo-device is deleted, and any changes made to a dictionary are lost.

Chad: /* Notes */

2017-07-12T20:48:11Z

Notes

← Older revision		Revision as of 20:48, 12 July 2017
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	==Notes==		==Notes==

			A common mistake is to assume an event will be delivered to the channel that triggered the event. This is not the case. For example, when a channel adds a key, that channel's add event handler is not called.

			It is an error to {{Code\|Add()}} a key that already exists in the dictionary. {{Code\|Set()}} should be used to update existing keys, creating the key if it does not already exist.

			There is no way to directly list all of the keys in a dictionary. The {{Code\|Scan()}} method allows code to access the existing keys, but only returns the number of keys that can be held in a limited sized buffer. This interface was chosen as the dictionary could contain more keys than could reasonably returned in a single network request.

Chad: /* Using The Dictionary */

2017-07-12T20:34:50Z

Using The Dictionary

← Older revision		Revision as of 20:34, 12 July 2017
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	</syntaxhighlight>		</syntaxhighlight>
	</div>		</div>

			==Notes==

Chad: /* Using The Dictionary */

2017-07-12T20:34:05Z

Using The Dictionary

← Older revision		Revision as of 20:34, 12 July 2017
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	==Using The Dictionary==		==Using The Dictionary==

	To access a dictionary, create a channel, set the serial number or the label and open the channel.		To access a dictionary, create a channel, set the serial number or the label, and open the channel.
	To "listen" for changes to the Dictionary, {{Code\|onAdd()}}, {{Code\|onRemove()}}, and {{Code\|onUpdate()}} event handlers can be set. Refer to the {{Phidget22API}} to see the methods supported by Dictionary.		To "listen" for changes to the Dictionary, {{Code\|onAdd()}}, {{Code\|onRemove()}}, and {{Code\|onUpdate()}} event handlers can be set. Refer to the {{Phidget22API}} to see the methods supported by Dictionary.

Chad: /* Creating a Dictionary */

2017-07-12T20:33:06Z

Creating a Dictionary

← Older revision		Revision as of 20:33, 12 July 2017
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	==Creating a Dictionary==		==Creating a Dictionary==
	Dictionaries are managed by the [[Phidget Network Server]]. To create a dictionary, go to the [[Phidget Control Panel]] and click on the '''Network Server''' tab. There are options to create and manage dictionaries. The server must be enabled for clients to access dictionaries.		Dictionaries are managed by the [[Phidget Network Server]]. To create a dictionary, go to the [[Phidget Control Panel]] and click on the '''Network Server''' tab. There are options to create and manage dictionaries. The server must be enabled for clients to access dictionaries.

			On Linux, refer to the README for information on how to enable the dictionary feature in the [[Phidget Network Server]], and for the syntax of dictionary configuration files.

	==Using The Dictionary==		==Using The Dictionary==

Chad: /* General Overview */

2017-07-12T20:28:49Z

General Overview

← Older revision		Revision as of 20:28, 12 July 2017
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	Dictionary is Phidget channel class that exports a key-value pair database. Dictionaries are create and made accessible by the [[Phidget Network Server]]. A Dictionary channel is created and opened like any other Phidget channel. Matching is done using either the serial number or the label assigned to the dictionary.		Dictionary is Phidget channel class that exports a key-value pair database. Dictionaries are create and made accessible by the [[Phidget Network Server]]. A Dictionary channel is created and opened like any other Phidget channel. Matching is done using either the serial number or the label assigned to the dictionary.

	The backing pseudo-device that exports the Dictionary device channel is maintained by the [[Phidget Network Server]], and is created when the server starts. When the server exits, the pseudo-device is deleted, and any changes to ~~dictionaries~~ are lost.		The backing pseudo-device that exports the Dictionary device channel is maintained by the [[Phidget Network Server]], and is created when the server starts. When the server exits, the pseudo-device is deleted, and any changes made to a dictionary are lost.

	The basic functionality of a Dictionary is to maintain configuration information in a central location. Multiple clients can attach to the same dictionary, and set handlers for ''add'', ''update'' and ''delete'' events, making the dictionary useful for monitoring and communicating state.		The basic functionality of a Dictionary is to maintain configuration information in a central location. Multiple clients can attach to the same dictionary, and set handlers for ''add'', ''update'' and ''delete'' events, making the dictionary useful for monitoring and communicating state.

Chad: /* Using The Dictionary */

2017-07-12T20:26:30Z

Using The Dictionary

← Older revision		Revision as of 20:26, 12 July 2017
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	The basic functionality of a Dictionary is to maintain configuration information in a central location. Multiple clients can attach to the same dictionary, and set handlers for ''add'', ''update'' and ''delete'' events, making the dictionary useful for monitoring and communicating state.		The basic functionality of a Dictionary is to maintain configuration information in a central location. Multiple clients can attach to the same dictionary, and set handlers for ''add'', ''update'' and ''delete'' events, making the dictionary useful for monitoring and communicating state.

			==Creating a Dictionary==
			Dictionaries are managed by the [[Phidget Network Server]]. To create a dictionary, go to the [[Phidget Control Panel]] and click on the '''Network Server''' tab. There are options to create and manage dictionaries. The server must be enabled for clients to access dictionaries.

	==Using The Dictionary==		==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~~. To "listen" to ~~changes of~~ the ~~value associated with a key~~, ~~the Dictionary has a~~ {{Code\|onAdd()}}, {{Code\|onRemove()}}, and {{Code\|onUpdate()}} event ~~functions (exact name dependant on programming language used)~~. ~~You can write code in these event handlers~~ to ~~react differently depending on which pair is being changed.~~		To access a dictionary, create a channel, set the serial number or the label and open the channel.
			To "listen" for changes to the Dictionary, {{Code\|onAdd()}}, {{Code\|onRemove()}}, and {{Code\|onUpdate()}} event handlers can be set. Refer to the {{Phidget22API}} to see the methods supported by Dictionary.
	~~Go into~~ the ~~[[Phidget Control Panel]] and click on~~ the ~~'''Network Server'' tab and ensure the server is started~~.

	Here's an example of how you might use the dictionary in a C program:		Here's an example of how you might use the dictionary in a C program:



	<div class="source">		<div class="source">
	<syntaxhighlight lang=c>		<syntaxhighlight lang=c>

	~~// Declare the dictionary handle~~
	PhidgetDictionaryHandle dict;		PhidgetDictionaryHandle dict;
			char val[32];

	~~// Create the new dictionary object using the handle~~
	PhidgetDictionary_create(&dict);		PhidgetDictionary_create(&dict);
	~~PhidgetDictionary_addDictionary(5000,"myDictionary"); //set a serial number and label for the dictionary~~

	// Open connection to the dictionary using the serial number		// Open connection to the dictionary using the serial number
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	Phidget_open(dict);		Phidget_open(dict);

	// ~~Add~~ a key~~-value pair to the dictionary~~		PhidgetDictionary_add(dict, "my_key", "my_value"); // add a key that does not already exist
	~~char *key1 =~~ "~~001~~";		PhidgetDictionary_get(dict, "my_key", val, sizeof (val)); // get the value back
	~~char *val1 =~~ "~~first~~";		printf("Value: %s\n",newValue);
	~~PhidgetDictionary_add(dict,key1~~,~~val1~~);

	~~// Access and print a value from the dictionary based on a given key~~		PhidgetDictionary_remove(dict, "my_key"); // remove the key
	~~char newValue[20];~~
	~~PhidgetDictionary_get~~(dict, ~~key1, &newValue,20~~); // ~~'20' refers to~~ the ~~length of the buffer used to store the result~~
	~~printf("Value: %s",newValue);~~

	~~// Remove a pair from the dictionary based on a given key~~
	~~PhidgetDictionary_remove(dict, key1);~~

	~~// Close and clean up the dictionary object~~
	Phidget_close(dict);		Phidget_close(dict);
	PhidgetDictionary_delete(&dict);		PhidgetDictionary_delete(&dict);
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	</syntaxhighlight>		</syntaxhighlight>
	</div>		</div>


	Have a look at the {{Phidget22API}} documentation to learn how to use these methods in the language of your choice. Select your preferred language from the first drop-down box, and select '''Dictionary API''' from the second box.

	~~When you create a dictionary in your code, the [[Phidget Control Panel]] will also be able to see it if you have remote Phidgets enabled in the options. Here's what it will look like:~~

	~~[[File:dictionary-panel.jpg\|link=\|420px\|left]]~~
	~~[[File:dictionary-example.jpg\|420px\|link=]]~~
	~~<br clear="all">~~

	On the left, you can see that dictionaries appear just like attached and remote Phidget devices do. On the right, you can see the contents of the dictionary after double-clicking on it. You can add and remove tags from here as well.

	Interestingly, you don't even need a Phidget to use the Dictionary! You can use our libraries and the [[Phidget Network Server]] without any Phidgets. Usually, there's not much to broadcast on the Network Server 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.