OpenEdge Development: Mobile Applications - Product ...

Chapter 3: Creating Mobile Services
Coding ABL routines to implement a Mobile resource
When you create a Mobile resource in Developer Studio (see the “Creating Mobile
resources” section on page 77), you can either create a new class to implement the
resource using the New Business Entity wizard or you can use the Define Service
Interface wizard to create the resource from an existing ABL class or external
procedure coded to run as a singleton. Using these wizards, you can define ABL
routines that provide the interface to one or more Mobile resources, each of which
supports one or more Mobile operations.
The two basic options that you must define for any class or procedure that implements
a Mobile resource include the data model and the Mobile operations that the class or
procedure supports. As described previously (see Chapter 1, “OpenEdge Mobile
Overview”), a Mobile resource can support a single data model that is managed by its
built-in Mobile operations, create, read, update, and delete (CRUD). This data model
can be the ABL definition for a single temp-table or a single ProDataSet that contains
one or more temp-tables, including any data-relations defined for them. In the
Developer Studio wizards, you select the data model from any temp-tables and
ProDataSets that are defined in the class or procedure file, or in an external file that
you specify. Once completed, the wizard, if directed, inserts the selected data definition
in the main block of the class or procedure.
Creating an ABL class with the New Business Entity wizard
When you create a Business entity class to define the Mobile resource (using the New
Business Entity wizard), it defines either a single Mobile read operation or a full set of
Mobile CRUD operations for the selected data model. If the selected data model is a
ProDataSet with multiple temp-tables, it also defines a separate invoke operation for
each temp-table that is intended to read the table and return its data to a Mobile App
as a JavaScript object.
Each Mobile CRUD operation is defined by a single VOID ABL method whose name
consists of a concatenation of the operation name with the name of the resource data
model instance, has an empty code block, and has a parameter list that is tailored to
reference the selected data model. The exact parameter list for each method is
prescribed by the Mobile operation that it implements. For example, if the data for the
resource is a ProDataSet named dsCustomer and the read operation is being defined,
the method name is created as ReaddsCustomer. You must then add the code for each
Mobile CRUD operation to implement each operation according to OpenEdge Mobile
functional requirements. For more information, see the “Coding the ABL for Mobile
operations” section on page 71.
In addition, when the wizard is directed to generate a Mobile interface, both the first
ABL statement in the file and each METHOD statement in the class are preceded by a
set of annotations that start with the '@' character and specify how the class and each
method is to be accessed and executed as a Mobile resource and operation.
Caution: Do not modify the annotations in the ABL source file for a Mobile resource.
Doing so can make the resource inaccessible from a Mobile App or otherwise
fail to function.
70 OpenEdge ® Development: Mobile Applications