Attributes
Each channel has common attributes called predefined attributes, which are created when a channel is committed to the network. Predefined attributes extend across all subjects for a channel.
Attributes are essential to filtering content, whether you are returning simple text messages or developing rich content:
- Attribute filters enable you to create detailed content without building a finely-tuned subject hierarchy.
- Attribute filters facilitate rapid publication of content to narrowly-defined audiences.
Predefined attributes
Predefined attributes may be accessed by the application developer by name or position; predefined attributes are also defined by data type.
Here are a few predefined attributes for the Hobby channel:
- experience level
- craft
- material
- message
The predefined attribute referenced in the first tutorial is Message. The attributes of Channel 40, which we reference in the second tutorial, include Message, Age, Gender, and UserName.
Discretionary attributes
Application designs which require special filtering for a particular subject within a channel must include their own discretionary attributes.
Discretionary attributes allow you to deliver content tailored to the needs of the subscriber. If you would like to create attributes unique to a subject or subcategory, you would create discretionary attributes rather than create a new subject for the channel.
Discretionary attributes facilitate the development of unique content and relationships among publishers and subscribers:
- Discretionary attributes enable you to authorize subscriber-defined content.
- Carefully drawn discretionary attributes can enhance performance as you more narrowly target subscribers.
In the second tutorial, we will create one discretionary attribute, Interest.
Channel configuration
Each application operates in an environment defined by a channel description. The NetInjector administrator defines the channels' subjects and attributes according to the application's needs, which themselves reflect specific business objectives.
Channel description — Basic Case
The channel description for the first tutorial's application defines a channel with two subjects, Sample and Sample.Intro1. The channel description also defines an attribute for the channel, Message, of type PC_CHARARRAY.
Channel description — Common Cases
The second tutorial's channel description defines a channel with two subjects, Sample and Sample.Chat. The channel description also defines several attributes for the channel — Message, Age, Gender, and UserName — which are of three different data types.
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