OpenEdge Development: Mobile Applications - Product ...

progress.data.JSDO class
progress.data.JSDO class
The progress.data.JSDO is a JavaScript class that provides access to ABL
application services as OpenEdge Mobile resources. A single progress.data.JSDO
object (JSDO) provides access to one Mobile resource in an OpenEdge Mobile service.
A Mobile resource maps to an ABL singleton procedure or class running on an
OpenEdge AppServer. The JSDO provides application-oriented, JavaScript methods
to invoke the internal procedures, user-defined functions, or methods (ABL routines) of
the corresponding singleton procedure or class. A Mobile resource maps specified ABL
routines as one of several supported Mobile operation types, each of which
corresponds to a particular method of the JSDO.
You identify how a JSDO maps JavaScript methods to operations of a given Mobile
resource by adding annotations to the singleton procedure or class source code. These
annotations define a Mobile interface for accessing the procedure or class as a Mobile
resource. You can define a Mobile interface using features of Progress Developer
Studio for OpenEdge (Developer Studio) in two ways: 1) when creating an ABL
Business entity class, which supports common business operations on data models,
and 2) for any existing ABL singleton class or procedure, whether or not the singleton
accesses a separate Business entity object.
You can also use Developer Studio to define a Mobile resource as part of a Mobile
service, and to generate the Mobile service together with the client-side artifacts
required to create a corresponding JSDO for the resource. These client-side artifacts
include a JSDO catalog file that identifies how a JSDO that you create can access the
corresponding Mobile resource using methods of the JSDO.
At run time, the JSDO maintains local storage for managing temp-table data that is
exchanged between the AppServer and JavaScript client, and it provides methods to
read and write the data in JSDO local storage as individual JavaScript record objects.
To support this data exchange, a Mobile resource can be organized into basic
operation types that include built-in create, read, update, and delete (CRUD)
operations, and non-built-in invoke operations. The built-in Mobile operations can
operate on a single temp-table or on a single ProDataSet containing one or more
temp-tables. Each built-in operation type maps to a corresponding built-in method of
the JSDO. The records of each temp-table are presented as an array of record objects,
which the built-in methods use to exchange the data with the AppServer. The built-in
methods, through their corresponding operation types, support the common business
operations that can be generated directly from an ABL Business entity. Other methods
of the JSDO provide access to individual record objects of JSDO local storage. Based
on the results of its methods, the JSDO also maintains a working record for each
temp-table in its local storage that you can access directly using table and field
references (see the notes). Thus, using the methods of a JSDO and its table
references, you can interact with a corresponding Mobile resource in a consistent
manner from one resource (and its corresponding JSDO) to another.
A JSDO also supports non-built-in invoke operations that allow specific ABL routines
to be exposed in a Mobile resource and executed as corresponding JavaScript
methods. You can do this in Developer Studio by annotating ABL routines specifically
as invoke operations. You can then call each ABL routine annotated as an invoke
operation using a unique invocation method on the JSDO. Note that data exchanged
between the AppServer and client using invoke operations is not automatically stored
in JSDO local storage. It is initially accessible only through parameters and return
values of the invocation methods provided by the JSDO. You can subsequently use
JSDO methods for accessing JSDO local storage to exchange data between the
invocation methods and local storage, which is maintained and synchronized with the
AppServer using the JSDO built-in methods.
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