Reader Class CL_LDQ_READER
The class CL_LDQ_READER serves to initialize the table of queues for the LDQ reading use case. The class implements the interface IF_LDQ_READER.
The CONFIRM_QUEUE_UNITS method in this class is the only LDQ method that executes an implicit commit. All other methods of this class and the other LDQ classes require an Explicit Commit to persist their work in the database.
UML Representation:
Attribute Overview:
Attribute |
Visibility/Level |
Description |
---|---|---|
M_APPLICATION_NAME |
Protected Instance |
LDQ application name |
Method overview:
Method |
Visibility/Level |
Description |
---|---|---|
SET_QUEUE_NAME |
Public Instance |
The method creates an LDQ unit reader object. The method requires an LDQ queue name and returns an interface reference. The method throws an exception when the queue is in use by another reader. |
SET_QUEUE_NAME_BY_OFFSET |
Public Instance |
Creates an LDQ unit reader object for a given queue with a given offset for the queue's Read Counter. If the offset is greater than the current Read Counter (= attempt to skip reading some units), an exception is thrown. If the offset is smaller than the current Top Counter (= attempt to read units already confirmed), an exception is thrown. |
CONFIRM_QUEUE_UNITS |
Public Instance |
Marks for deletion the units already read up to a given sequence number. If the offset counter is greater than the current Read Counter (= attempt to confirm a unit that was never read), an exception is thrown. If the offset counter is smaller than the current Top Counter (= attempt to confirm units already confirmed), an exception is thrown. Note: This method executes an Implicit Commit. |
Unit Reader Class CL_LDQ_UNIT_READER
The class CL_LDQ_UNIT_READER provides a handle to a specific LDQ queue for the purpose of reading one or more LDQ units. The class implements the interface IF_LDQ_UNIT_READER.
UML Representation:
Attribute Overview:
No public or protected attributes.
Method overview:
Method |
Visibility/Level |
Description |
---|---|---|
GET_NEXT_STATES |
Public Instance |
Reads the next units'states. The method requires the number of units to read and returns a table of unit states. |
GET_NEXT_CONTENTS |
Public Instance |
Reads the next units'contents. The method requires the number of units to read and returns a table of unit contents. |
GET_TOTAL_NUMBER_OF_UNITS |
Public Instance |
Gets the total number of entries in the queue. |
CONFIRM |
Public Instance |
Marks for deletion the units already read. |
CHECK_READ_SEQUENCE |
Private Static |
Verify the order in which units have been read. |
ON_ROLLBACK |
Public Static |
Roll Back Called LDQ Units. |
AFTER_COMMIT |
Public Static |
Delete the internal tables. |
ON_COMMIT |
Public Static |
Delete the read LDQ units in the database. All methods of LDQ classes persist their work in the database by an Explicit Commit, with the exception of the CONFIRM_QUEUE_UNITS method in the IF_LDQ_READER interface, which executes an Implicit Commit. |
CLASS_CONSTRUCTOR |
Public Static |
Class constructor. |
CONSTRUCTOR |
Public Instance |
Constructor. |
Unit State Reader Class CL_LDQ_UNIT_STATE_READER
The class CL_LDQ_UNIT_STATE_READER reads the state data of one or more LDQ units, that is the unit size, unit format and unit id. The class implements the interface IF_LDQ_UNIT_STATE_READER.
UML Representation:
Attribute Overview:
No public or protected attributes.
Method overview:
Method |
Visibility/Level |
Description |
---|---|---|
GET_FORMAT |
Public Instance |
The method returns the format of the LDQ unit data. |
GET_UNIT_ID |
Public Instance |
The method returns the Unit-ID of the LDQ unit. |
GET_SEQUENCE_NUMBER |
Public Instance |
The method returns the sequence number of an LDQ unit. |
GET_SUCCESSOR_COUNT |
Public Instance |
The method returns the number of following units in the queue. |
GET_SIZE |
Public Instance |
The method returns the size of the LDQ unit data. |
GET_DESCRIPTION |
Public Instance |
The method returns the appended description of an LDQ unit. |
CONSTRUCTOR |
Public Instance |
Constructor. The constructor requires the state of the LDQ unit. |
CHECK_COMMIT_ROLLBACK |
Private Instance |
The method checks, whether the LDQ unit is valid. |
Unit Content Reader Class CL_LDQ_UNIT_CONTENT_READER
The class CL_LDQ_UNIT_CONTENT_READER reads the payload of one or more LDQ units in a specified LDQ queue.
UML Representation:
Attribute Overview:
No public or protected attributes.
Method overview:
Method |
Visibility/Level |
Description |
---|---|---|
GET_CDATA |
Public Instance |
The method reads character-like data. The method returns a character string. |
GET_XDATA |
Public Instance |
The method reads binary data. The method returns a byte string. |
GET_FORMAT |
Public Instance |
The method returns the format of the LDQ unit data. |
GET_UNIT_ID |
Public Instance |
The method returns the Unit-ID of the LDQ unit. |
GET_SEQUENCE_NUMBER |
Public Instance |
The method returns the sequence number of an LDQ unit. |
GET_SUCCESSOR_COUNT |
Public Instance |
The method returns the number of following units in the queue. |
GET_DESCRIPTION |
Public Instance |
The method returns the appended description of an LDQ unit. |
GET_SIZE |
Public Instance |
The method returns the size of the LDQ unit data. |
CONSTRUCTOR |
Public Instance |
Constructor, requiring a reference to an LDQ unit reader object, the unit state and the unit data. |