SDML Data Tags Overview

Data tags provide access to the production data of the application within the synchronization components of the mobile application.

This includes access to property values, global definition values, query constants, and client and server information system information. Each of these items just listed are referred to as the data tag’s data source.

In addition to the tag’s data source, all data tags also have a certain data type. The data source and the data type of a tag combine to give the data tag its overall behavior. This behavior includes how the value is expanded during data tag expansion, as well as the parameters that the tag will support. By and large, the data tags created for properties are the tags that have the most complex behavior.

Data tags that provide access to data other than from properties or globals are strings. Those data tags that are based on a property definition are one of several data types, based on the property data type.

Data Tag Data Types

Within the SDML, all data tags have a data type. This data type affects how the data tag is processed during tag expansion. Do not confuse the data tag’s type with the data type for that same value in the back end system. When the Agentry Server has completed tag expansion the resulting values within the script are plain text. At this point, the methodology for denoting the value’s data type will depend on the type of back end system in use.

As an example, for a database system connection, data tags with a data type of date and time will be expanded with the date and time conversion function for that database as a part of the text, as in:
If this data tag is a date and time and used in a script for an Oracle database, it would expand to:
to_date(‘01/12/2004 14:23:45’, ‘mm/dd/yyyy hh24:mi:ss’)

As you can see, the date and time value has been wrapped in the to_date function call for Oracle, which converts string values into dates and times.

The data types for data tags are as follows. Note that all data types other than string are applicable only to tags for global and property values:
  • String
  • Integral Number
  • Decimal Number
  • Boolean
  • Date
  • Time
  • Date and Time
  • Signature

The Scope of Data Tags

The data tags within the SDML may or may not be valid in one area verses another. The scope of a data tag will vary from one to the next. Certain tags are only valid in steps used by a fetch. Others are only available in steps used by transactions. Still others are available globally. It is important to note that for scripts within step definitions, the scope for a data tag is determined by the type of step definition and also the step usage definition referencing the step to be processed at run time. For example, the data tags that are in scope for a step used by an object read step will be different from the tags that are in scope for a step used by a transaction’s server update step. The terms used to describe a data tag’s scope are:
  • Global: A data tag with Global scope is valid in all scripts processed by the Agentry Server. NOTE: Do not confuse the term Global used here to denote a tag’s scope with the definition type global. Values for a global definition do have a global scope. However, there are other data tags that also are globally available to the application’s synchronization components.
  • Definition-Type: A data tag with the Definition-Type scope is one that is in scope only for a certain type of definition, such as a Transaction or Object. The Type portion of this scope specifies the definition type for which the data tag is applicable.
  • Definition: A data tag with the Definition scope is one that is only in scope for instances of a specific definition. For example, the data tags in scope for an Object named Customer will be different than those for an Object named Order. Data tags that have a Definition scope are those that provide access to the properties of an object.