Migrating Existing Applications

This document covers the following topics:

Impact of Unicode on Existing Applications

On Windows, UNIX and OpenVMS platforms, Natural has internally been Unicode-enabled which means that many structures containing strings have Unicode format now. For example, the Natural source area has now Unicode format. For this reason, data which is only available in code page format is internally converted to Unicode format. This applies, for example, to the Natural sources and to the Natural library names and object names. However, a conversion from code page to Unicode and vice versa can only be performed successfully if the correct code page is used for conversion. Even if an application is not changed but only re-cataloged, the code page information is important because for cataloging an object is loaded into the Natural source area. If all objects are coded in the system code page, no changes are necessary. If the objects are not coded in the system code page, see Migrating Existing Objects on Windows, UNIX and OpenVMS Platforms for further information.

On Windows, the Natural output window has been Unicode-enabled which means that all fields have Unicode format now. In case of A format fields where the code page string length differs from the Unicode string length, the behavior of the Natural output window has changed slightly. This is especially relevant for double-byte code pages where the code page string length is normally twice as long as the Unicode string length. For A format input fields, it is now possible to enter "Unicode-string-length" characters in the field. When leaving the field and the default code page is a double-byte code page, all characters which do not fit into the target A format field are removed.

The internal Unicode structure will most probably need more memory. If you have defined a low value for the profile parameter USIZE, it may be necessary to increase this value.

Migrating Existing Objects

Natural has been extended so that the code page information can be defined on several levels:

  • The Natural profile parameter CP defines the default Natural code page.

  • For several objects (Natural sources, Natural batch input/output files, work files of type ASCII, ASCII compressed, Unformatted and CSV) an object-specific code page can be defined.

If neither an object-specific code page nor a default code page is defined, Natural will use the operating system's code page.

Since it is not possible to identify the correct code page automatically, it is important that you define the required code page information yourself. The following scenarios are possible:

Status Effort Action
All data is available in the operating system's code page. No effort No action.
All data is stored with one code page, but this code page differs from the operating system's code page. Easy The Natural profile parameter CP has to be set to the correct code page.
The data is available in different code pages. Depends on the number of sources and code pages The correct code page has to be defined for every Natural object:
  • Sources
    If only few objects are affected, change the code page via the Properties dialog box. If several objects (for example, an entire library) are affected, use the FTOUCH utility for changing the code page.

  • Batch Files
    Set the Natural profile parameters CPOBJIN, CPSYNIN and CPPRINT to the correct code page.

  • Work Files
    Set correct code page for the work files in the Configuration Utility.

Different code pages are mixed in one object (for example, in a source) High The object has to be rewritten in UTF-8 format.

Adding Unicode Support to Existing Applications

It is easy to extend existing applications with new source code based on the U format. The following rules have to be regarded for the U format (as compared with the A format):

  • A REDEFINE of U to a format other than U should be avoided because this may result in split characters.

  • U format is endian-dependent. This has to be considered when moving between the formats B and U.

  • Align U in DEFINE DATA for performance reasons (better performance on UNIX and OpenVMS).

  • Keep in mind that characters may be lost when moving U to A.

If you want to change existing fields from A format to U format, the following rules have to be regarded:

  • Code which assumes a specific encoding of strings has to be changed (for example, comparison with a B field).

  • All REDEFINE statements of the field have to be checked for their validity.

  • A REDEFINE to N is not possible (that is: you will not get the expected result).

  • The database field has to be migrated to Unicode (provided that this is supported by your database).

  • You may have to change the length of the field: if the A field contains DBCS characters, half the length is required for the U field.

Migrating Natural Remote Procedure Calls (RPC)

The profile parameter CP has been renamed to CPRPC. In earlier Natural versions, CP was used to specify the name of the code page used by the Entire Conversion Service (ECS) and applied only to the Natural RPC (Remote Procedure Call) when the transport protocol ACI (that is, EntireX Broker) was used.

A new CP parameter is available which defines the default code page for Natural data. When you are working with Natural RPC and have previously used the CP parameter dynamically, you have to change this parameter to CPRPC.

When you use parameter files from a previous version, you need not change anything; the Configuration Utility automatically migrates CP to CPRPC.