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A data port is a mechanism that either provides data into a UDM, or consumes data from a UDM, or both. For example, the database port is a data port that both provides data (i.e., can be read) and consumes it (i.e., can be written). In contrast, the integer sequence port is a data port that produces data but does not consume it. You can create nodes that exchange data with different kinds of data ports, even within the same UDM.
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Data types. Each data port is capable of providing (or consuming) any of a range of different types of data. For example, the range of types supported by the database data port corresponds directly to the tables in the database, while the date decoder supports just one type of data. Each such "data type" is usually a collection of named attributes, e.g., for a database, it is the names of the table's columns. When you choose a data port and data type for a node, the zDE automatically creates children for the node corresponding to each attribute of that data type.
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List (vector) nodes. Some data ports are capable of producing multiple values for their nodes. For
instance, we can create a list node for the database port, setting it up to retrieve all the records in its Customer table. Other data ports (e.g., the Expression and the Date Decoder) can only produce a single value (or a single aggregate value) at a time.
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Bind variables. Data ports sometimes need bind variables that control their behavior. A data port's bind variable can be thought of as a "parameter" -- it is used to pass values from the UDM to the data port. For example, the date decoder must be told the identity of the node UDM node whose date value it must decode, so the date decoder uses a bind variable whose value will be that node. This association of bind variables to values is done at the time you create a new node that uses that data port.
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Here is a brief summary of
some of the the data ports currently available within the zeroCode Design Environment. (You can, of course, write your own.)
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Database |
The source from which you can retrieve, delete, insert or update data.
It is associated with the database used by the site and
the data types correspond to the tables in the database. |
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Template
expander |
This
data port can retrieve a specified UDM's data,
substitute the data into a specified template string,
and return the resulting string |
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Mail
data port |
This
dataport helps in
sending and receiving e-mail via a UDM. If you use this
data port, you must specify the mail sender and receiver
hosts in your config.txt file. |
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Integer Sequence |
This
dataport can be used for constructing a range of integer
values, e.g., for use as the days of a week. It
generates a sequence for the number fields. |
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Date decoder |
It facilitates retrieval of the server date and decomposes it into year, month, date, day of the month, day of the week, day of the year, hour, minute, second, millisecond. |
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Expression |
It includes the
data types integer, date & time and string. It helps in retrieving a record using an expression. However, if the dataport type is expression it is not possible to create a vector node. |
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