Technology Questions

The address resolution protocol(ARP) is used to associate the 32 bit IP address with the 48 bit physical address, used by a host or a router to find the physical address of another host on its network by sending a ARP query packet that includes the IP address of the receiver.

The reverse address resolution protocol (RARP) allows a host to discover its Internet address when it knows only its physical address.

The interface org.apache.struts.upload.FormFile is used for the struts file upload application. This interface represents a file that has been uploaded by a client. It is the only interface or class in upload package which is typically referenced directly by a Struts application.

This is not specific to Struts in case of DHTML but the two things that are needed in DHTML page is: first, the form needs to specify an enctype of multipart/form-data and second an <input> form control of type file.

Following are the steps to load file in DHTML:

- Creating a bean

- Writing the ActionClass.

- Mapping the bean in struts-config.xml

- Defining actionmapping

- Developing the DHTML page.

Multiple inheritance is not supported directly but it is achieved through the concept of Interface

Asc() - Returns ANSI Character Code 

Chr() - Returns Character from ANSI Code 

InStr() - Find a string within another 

InStrRev() - Find a string within another (Reverse) 

LCase() - Convert a string to lowercase 

Left() - Crops a string from left 

Len() - Determine the length of a string 

LTrim() - Remove leading spaces from a string 

Mid() - Crops a string 

Replace() - Replace a substring within a string 

Right() - Crops a string from right 

RTrim() - Remove trailing spaces from a string 

Space() - Creates a string with the specified number of spaces 

StrComp() - Compare two strings 

String() - Creates a repeated character string 

StrReverse() - Reverse the characters of a string 

Trim() - Remove both leading and trailing spaces from a string 

UCase() - Convert a string to uppercase 

A package is a collection of related PL/SQL objects. The package contains a body and a specification. The package specification has the declaration which is public and can be used in the PL/SQL sub programs inside the package.

The package body holds the implementation of all the PL/SQL objects declared in the specification.

Example of a PL/SQL Package.

CREATE OR REPLACE PACKAGE emp_data AS 

PROCEDURE add_employee (

      ename VARCHAR2,

      job VARCHAR2,

      mgr NUMBER,

      sal NUMBER,

      deptno NUMBER);

END emp_actions;

CREATE OR REPLACE PACKAGE BODY emp_data AS 

PROCEDURE add_employee (

       ename VARCHAR2,

       job VARCHAR2,

       mgr NUMBER,

       sal NUMBER,

       deptno NUMBER) IS

BEGIN

         INSERT INTO emp VALUES (empno_seq.NEXTVAL, ename, job, mgr, SYSDATE, comm, deptno);

END add_employee;

END emp_data;

Advantages of  PL/SQL packages :

Packages are easier for application designing, encapsulating data, additional functionality and better performance. An application has various modules which can be placed in packages and handled easier.

Buffer class could be a global class and may be accessed in application without importing buffer module. A Buffercould be a quite an array of integers and corresponds to a raw memory allocation outside the V8 heap. A Buffer can not be resized.

Dealing with primitives as objects is easier at times. Most of the objects collection store objects and not primitive types. Many utility methods are provided by wrapper classes. To get these advantages we need to use wrapper classes. As they are objects, they can be stored in any of the collection and pass this collection as parameters to the methods.

Features of the Java wrapper Classes:

- Wrapper classes convert numeric strings into numeric values.

- The way to store primitive data in an object.

- The valueOf() method is available in all wrapper classes except Character

- All wrapper classes have typeValue() method. This method returns the value of the object as its primitive type.

By using two types of function modules to be called in SAP Script:

1)HELP_OBJECT_SHOW_FOR_FIELD
2)HELP_OBJECT_SHOW