HP 3000 Manuals HP 3000 Manuals
Unloading and Loading Applications - Overview The next few pages provide an overview of the HP ALLBASE/4GL application unloading and loading utilities. Before you attempt to use these utilities, read through these pages to gain an understanding of the procedures. The application unload and load utilities allow you to unload applications from the HP ALLBASE/4GL S-files or to load an application into the S-files. The application unload utility unloads an application definition from the S-files into a single MPE/iX file. This file is identified as NAME in the group and account identified by the variable HP4APPNPATH, and NAME is the name of the application. The application unloading facility does not delete the original application or change it in any way. If you want to delete an application from the system, use the administrator deletions screen.
NOTE You cannot create files in any account other than your login account. If the HP4APPNPATH variable is not set, or refers to a group and account that is not writable, HP ALLBASE/4GL displays an error message and the application unloading process aborts.
The application load utility reverses this process and loads an application into the S-files from a previously unloaded application file. These functions in combination allow you to unload an application and load it into a different set of S-files, or even transport it to a different MPE/iX system. Unloading Versions HP ALLBASE/4GL allows you to unload up to 10 versions with an application. Note however, that you cannot unload a version without the base application. Under some conditions, unloading run-only copies of more than one version with an application may result in data file corruption when the application and version are loaded onto the target system. If you unload two or more versions with an application, HP ALLBASE/4GL displays a warning message asking if you want to proceed with the unload. Refer to "Version Data Files" , for more information about the conditions that may result in version data file corruption. Application Definition Records HP ALLBASE/4GL allows you to unload an application with or without the application definition records. These records hold the details that have been entered on the application definition screen. Normally, you would include the application definition records with the application if you are unloading an application for first release to another HP ALLBASE/4GL system. This means that the application definition records are written into the S-files on the destination system when the application is loaded. If you are unloading an application for first release to an HP ALLBASE/4GL run-time environment, you must include the application definition records with the application. The run-time environment does not allow the administrator to create new application definitions. In general, you would not include the application definition records if you are unloading an application for subsequent release to a run-time environment. In this case, the existing application definition, which contains the user names and password definition for the application, should not be overwritten. Run-Only Applications You can unload a run-only copy of an application for a run-time environment without unloading the source code for generated components. If you unload a run-only copy of an application, the generated components of the application cannot be modified after the application has been loaded to a different HP ALLBASE/4GL system. In this format, the following components of the application cannot be modified: * Calculated items. * Decision tables. * Functions. * Messages. * Processes. * Record layouts. * Reports. * Screens. * SQL logic blocks. Most other components in an application can be secured against modification with a development security code. Refer to Chapter 4 for more information about application security. You can also unload the source code with the application. In this case, a developer can modify any components in the application that are not secured with a development security code. KSAM Data Files The application unloading and loading utilities do not unload or load any KSAM data files used by the application. To load an application to an HP ALLBASE/4GL system, you may also need to install a set of data files on the target system. Application developers can create KSAM data files directly using the data file creation facilities in the developer application. Alternatively, you can copy a set of data files onto the system from tape, disk or cartridge. These files can be empty or can contain data. To load an application to an HP ALLBASE/4GL run-time environment, you must also load the data files for the application from tape. Without the developer application, HP ALLBASE/4GL cannot create KSAM data files directly, so you need to load at least an empty set of data files to the data file group and account (indicated by the HP4DATAPATH variable). The HP ALLBASE/4GL run-time environment then maintains these data files. KSAM Data File Reformatting Under some circumstances, KSAM application data files used by HP ALLBASE/4GL applications must be reformatted during the application loading procedure. If you are loading an application to update an existing application, the data files must be reformatted under the following circumstances: * Dictionary field specifications have changed. * The number of fields or the sequence of fields on any file record layouts has changed. * The number, names, or positions of any key fields on record layout have changed. In the HP ALLBASE/4GL developer environment, application developers can use the data file reformat screen in the dictionary menu to reformat KSAM data files. The source code for the application must be present to allow this screen to be used to reformat data files. In the HP ALLBASE/4GL run-time environment, or in a developer environment where source code for the application is not present, the data file reformat screen cannot be used to reformat data files. HP ALLBASE/4GL provides an automatic data file reformatting system to reformat data files in these circumstances.
NOTE The HP ALLBASE/4GL automatic data file reformat system can only reformat data files in the MPE/iX group and account identified by the variable HP4DATAPATH. Data files in other MPE/iX groups and accounts are not reformatted during application loading.
The automatic data file reformat system uses a file that contains information about the structure of the application data files. HP ALLBASE/4GL creates this file-structure file during the unloading process for run-only applications. This file has the same name as the application, and is created in the group and account identified by the variable HP4FSPATH. The HP4FSPATH variable must exist, and must identify a writable group before you execute the unloading process for a run-only application. The unload utility extracts the definition of the application data files from the S-files and writes this information into the file-structure file. The data file reformat system also uses the structure files for KSAM data files. The structure file is identified as NAMES.!HP4DATAPATH where NAME is the name of the file. The actions taken by the data file reformat system depend on the presence or absence of these files. In general, there should be one file-structure file for each application, and one structure file for each KSAM data file. If the file-structure file exists, and the structure files for the data files exist, HP ALLBASE/4GL reformats the data files for the application automatically during the application loading process. If the structure file for any application data file is not present, that data file is not reformatted. Removing or renaming the structure file for a data file is one way of preventing a file from being reformatted. If the file-structure file is not present during the loading procedure, HP ALLBASE/4GL does not reformat any data files.
NOTE To reformat a data file under the MPE/iX operating system, you must be the owner of the file.
Version Data Files. If a version uses data files that have a format that is different from the format of the data files for the base application, HP ALLBASE/4GL only reformats the version data files. The base application data files are not reformatted. During the unloading process for run-only applications, HP ALLBASE/4GL extracts the definitions of data files from the S-files and writes the information into the file-structure file. If you are unloading a version with a base application and the version file format is different from the base application file format, HP ALLBASE/4GL only writes the version file definitions to the file-structure file. Under these conditions, the base application file definitions are not written to the file-structure file.
CAUTION Don't attempt to unload more than one version of an application if the versions use different data file structures. If you do unload multiple versions that all have different file structures, the file-structure definitions of subsequent versions are added to the file-structure file. When you load the application and versions to the target system, the version data files may be corrupted.
If you need to reformat data files for a number of versions of an application and the versions all use different data file formats, you must unload and subsequently reload the versions individually. (Note that you must unload the base application with each version. You cannot unload a version without unloading the base application.) If you need to reformat the data files for a base application, you must load a copy of the application by itself without any versions. To do this, the application must first be unloaded without any versions. HP ALLBASE/SQL Applications The application unloading and loading process involves some additional functions for unloading and loading applications that use HP ALLBASE/SQL databases. Database Module Files. The complete definition of an application that uses an HP SQL database consists of the application definition file for the application, plus the database module containing the stored sections for the application. HP ALLBASE/4GL normally creates an MPE/iX file containing the database module for an application when the application is generated, or all SQL blocks in an application are generated. The database module file for an application or version has the same name as the application or version, and is created in the group and account identified by the HP4DBMPATH variable. Note that HP ALLBASE/4GL creates one database module file for an application, and one module file for each version of an application. To load an application into an HP ALLBASE/4GL system, the application definition file for the application, the database module file for the application (and the database module files for each version of the application) must be present on the destination MPE/iX system. The HP ALLBASE/4GL application unloading utility allows you to generate an application before you unload it. This ensures that the database module files for the application are up-to-date. Database Module Installation. During the application loading process, HP ALLBASE/4GL installs the database modules contained in the database module files into the database environment for the application. The database environment for the application should exist before you start the application loading process. If the database environment does not exist, HP ALLBASE/4GL will display an error message during the application loading procedure. Under these conditions, HP ALLBASE/4GL displays a message allowing you to enter the name of a database environment. Database Table Creation. During loading, HP ALLBASE/4GL automatically creates HP ALLBASE/SQL tables required by HP ALLBASE/4GL applications. If the tables required by the application don't exist, HP ALLBASE/4GL creates them. If the tables already exist, they are not changed in any way. HP ALLBASE/SQL Table Reformatting. HP ALLBASE/4GL does not provide facilities for reformatting HP ALLBASE/SQL tables. If you need to reformat an HP ALLBASE/SQL table to reflect changes to field types or the structure of record layouts, you can use the HP ISQL UNLOAD and LOAD facilities. These facilities allow you to write the contents of an HP ALLBASE/SQL table to a file and then reload the file into a new restructured HP ALLBASE/SQL table. Refer to the HP ISQL manuals for more information about using the UNLOAD and LOAD utilities. HP TurboIMAGE/iX Applications No extra procedures are necessary to unload applications that access one or more HP TurboIMAGE/iX databases. HP TurboIMAGE/iX Data Set Reformatting. HP ALLBASE/4GL does not have facilities for reformatting HP TurboIMAGE/iX data sets. If you need to reformat an HP TurboIMAGE/iX data set to reflect changes to field types or the structure of record layouts, you can use HP TurboIMAGE DBchange/XL, if it exists on your system. This tool allows you to alter the security and structure of an HP TurboIMAGE/iX database with ease. Disk Space Requirements The unloaded application file, the file-structure file, and the database module files (if required) for large applications may require a megabyte or more of disk space. Make sure that you have sufficient disk space available on the MPE/iX system before you start the application unloading procedure. When you are loading an application, the target system must have sufficient disk space to accommodate the unloaded application files. If the loading process involves reformatting KSAM data files, you must have additional free disk space to accommodate the temporary files that HP ALLBASE/4GL creates during the reformat. You must have enough free disk space to hold a copy of the largest single data file that will be reformatted.