Change DDM File (CHGDDMF)

Parameters

Keyword	Description	Choices	Notes
FILE	DDM file	Qualified object name	Required, Key, Positional 1
	Qualifier 1: DDM file	Name
	Qualifier 2: Library	Name, LIBL, CURLIB
RMTFILE	Remote file	Single values: SAME Other values: Element list*	Optional, Positional 2
	Element 1: File	Single values: NONSTD Other values: Qualified object name*
	Qualifier 1: File	Name
	Qualifier 2: Library	Name, LIBL, CURLIB
	Element 2: Nonstandard file 'name'	Character value
RMTLOCNAME	Remote location	Single values: RDB Other values: Element list*	Optional, Positional 3
	Element 1: Name or address	Character value, SAME, DEVD
	Element 2: Type	SAME, SNA, *IP
LVLCHK	Record format level check	SAME, RMTFILE, *NO	Optional
RDB	Relational database	Name, *SAME	Optional
TEXT	Text 'description'	Character value, SAME, BLANK	Optional
DEV	Device	Element list	Optional
DEV	Element 1: APPC device description	Name, SAME, LOC	Optional
LCLLOCNAME	Local location	Communications name, SAME, LOC, *NETATR	Optional
MODE	Mode	Communications name, SAME, NETATR	Optional
RMTNETID	Remote network identifier	Communications name, SAME, LOC, NETATR, NONE	Optional
PORT	Port number	1-65535, SAME, DRDA	Optional
ACCMTH	Access method	Single values: SAME, RMTFILE, COMBINED Other values: Element list*	Optional
	Element 1: Remote file attribute	KEYED, ARRIVAL
	Element 2: Local access method	BOTH, RANDOM, *SEQUENTIAL
SHARE	Share open data path	SAME, NO, *YES	Optional
PTCCNV	Protected conversation	SAME, NO, *YES	Optional

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Remote file (RMTFILE)

Specifies the name of the remote file as it is coded on the target system. The remote file does not need to exist when the Distributed Data Management (DDM) file is changed.

Note: This file name must be specified in code page 500.

Single values

*SAME: The name of the remote file does not change.

Element 1: File

Single values

*NONSTD: The remote file name is not at standard iSeries file name. Specify the complete file name in apostrophes for the second element of this parameter.

Qualifier 1: File

name: Specify the name of the remote file as it is known on the remote system. If the remote system is an iSeries system, specify the file name. The file name can be up to 10 characters in length. If the remote system is a System/36, the file name is the same as its System/36 file label. The file name can be up to eight characters in length. If the remote system is a System/38, a simple (unqualified) file name can be specified. The file name can be up to 10 characters in length. Labels for all other remote systems (including qualified file names for System/38) must use *NONSTD followed by the remote file name in apostrophes.

Qualifier 2: Library

*LIBL: All libraries in the library list for the current thread are searched until the first match is found.
*CURLIB: The current library for the job is used to locate the file. If no library is specified as the current library for the job, QGPL is used.
name: Specifies the library where the file is located.

Note: The library name is used only if the target system is an iSeries system.

Element 2: Nonstandard file 'name'

character-value

For target systems that allow naming conventions other than those used by the iSeries system and System/36, and when specifying a qualified System/38 file name and when specifying a member name of a remote iSeries or System/38 file, specify up to 255 characters for the name of the remote file to be accessed. The name must be coded in the form required by the target system. The name must always be enclosed in apostrophes, and may contain lowercase letters, blanks, periods, or any other special characters.

Names for the iSeries system, System/38, and System/36 must be in uppercase, and no blanks are allowed.

If the target system is an iSeries system or a System/38, a file name, library name, and member name can all be specified. If a member name is specified, the full file name must be enclosed in apostrophes and must follow the value *NONSTD, and the member name must be enclosed in parentheses and immediately follow (with no space) either the library name (System/38) or the file name (iSeries).

Remote location (RMTLOCNAME)

Specifies the remote (target) system location name or address used with the distributed data management (DDM) file. Multiple DDM files can use the same remote location for the target system.

Single values

*RDB: The remote location information from the relational database entry specified for the Relational database (RDB) parameter is used to determine the remote system.

Element 1: Name or address

*SAME

The remote location name specified in the file description does not change.

*DEVD

The remote location name defined in the device description specified for the Device (DEV) parameter is used.

Note: If *LOC is specified for the DEV parameter, a remote location name must be specified for this parameter.

character-value

Specify the name or address of the remote location that is associated with the target system. The remote location, which is used in accessing the target system, does not need to exist when the DDM file is created but must exist when the DDM file is opened. The remote location can take several forms:

SNA remote location name (LU name). Specify a maximum of 8 characters for the remote location name. If this form is used, the address type of this parameter must be *SNA (the default).
SNA remote network identifier and remote location name separated by a period. Specify a maximum of 8 characters for the remote location name, and a maximum of 8 characters for the remote network identifier. If this form of the parameter is used, the address type of this parameter must be *SNA (the default), and any value specified for the RMTNETID parameter must agree. If the RMTNETID parameter is not specified, the RMTNETID value will be set to agree with the RMTLOCNAME parameter.
IP address in dotted decimal form. Specify an internet protocol address in the form nnn.nnn.nnn.nnn where each nnn is a number in the range 0 through 255. If this form is used, the address type of this parameter must be specified as *IP.
IP host domain name. Specify an internet host domain name of up to 254 characters in length. If this form is used, the address type of this parameter must be specified as *IP.

If *IP is specified for the address type, the DDM server at the remote location must support the use of TCP/IP, and the DEV, LCLLOCNAME, RMTNETID, and MODE parameters will be ignored.

If *IP is not specified, the DDM server must support SNA connectivity, and the PORT parameter will be ignored.

Element 2: Type

*SAME: The address type does not change.
*SNA: The remote location has a Systems Network Architecture (SNA) address type.
*IP: The remote location has an Internet Protocol (IP) address type.

Record format level check (LVLCHK)

Specifies whether the level identifiers in the program are checked with the level identifiers of the record formats in the remote file when the distributed data management (DDM) file is opened. If they do not match, an error message is sent to the program requesting the open, and neither the DDM file nor the associated remote file is opened. This parameter value can be overridden by an Override Database File (OVRDBF) command before the remote file is opened.

*SAME: The level identifiers value does not change.
*RMTFILE: The level identifiers of the record formats of the remote file are checked at the time the DDM file is opened.
Note: For systems other than iSeries systems, the program must be compiled (or recompiled) by using the DDM file. During the compile operation, the DDM file is used to establish communications with the target system, get the remote file's attributes from the target system, and create the level identifier values so they can be included in the compiled program for later level checking.

*NO: The level identifiers are not checked when the file is opened.

Device (DEV)

Specifies the name of the advanced program-to-program communications (APPC) device description on the source system that is used with this DDM file.

This parameter will be ignored if *IP is specified for the Remote location (RMTLOCNAME) parameter.

More information on device names is in the APPC Programming book, SC41-5443.

*SAME: The device name specified in the file description does not change.
*LOC: The device associated with the remote location is used. If several devices are associated with the remote location, the system determines which device is used.
Note: If *DEVD is specified for the RMTLOCNAME parameter for the remote location, a device name must be specified for this parameter.
name: Specify the name of a communications device that is associated with the remote location. If the device name is not valid for the remote location, an escape message is sent when the DDM file is opened.

Remote network identifier (RMTNETID)

Specifies the remote network identifier (remote network ID) in which the remote location resides, and which is used to communicate with the target system.

If this parameter is specified, the value specified for the Remote location (RMTLOCNAME) parameter must be consistent with the RMTNETID parameter. If the RMTLOCNAME parameter specified a network ID, this parameter must agree (otherwise, an error message will be issued). If the RMTLOCNAME parameter does not specify any network ID, there is no possibility of conflict with this parameter.

This parameter will be ignored if *IP is specified for the RMTLOCNAME parameter.

More information on remote network IDs is in the APPC Programming book, SC41-5443.

*SAME: The remote network ID specified in the file description does not change.
*LOC: The remote network ID associated with the remote location is used.

*NETATR: The remote network identifier specified in the network attributes is used.

*NONE: No remote network ID is used.
communications-name: Specify the remote network ID to be associated with the remote location. The remote network ID is specified only if the user wants to indicate a specific remote network ID for the remote location. If the remote network ID is not valid for the remote location, an escape message is sent when the distributed data management (DDM) file is opened.

Access method (ACCMTH)

Specifies the distributed data management (DDM) access method used to open the remote file and access its records when the target system is not an iSeries system. Specifying a value other than *RMTFILE for this parameter may improve performance when requests to remote files are processed on the target system. This parameter is ignored when the target system is an iSeries system or a System/38. The remote system file is accessed as if it is a local file.

Single values

*SAME: The access method does not change.
*RMTFILE: The source system selects the access method that is compatible with the attributes of the remote file identified by the Remote file (RMTFILE) parameter and the access methods supported by the target system for that file. For target systems other than iSeries systems, if this value is used and the source system cannot select an access method when the file is opened, a message is sent to the program user.
*COMBINED: The DDM combined access method is used for the remote file. This access method combines the file processing capabilities of the combined by key (*KEYED *BOTH) and the combined by record number (*ARRIVAL *BOTH) access methods, as shown in the following table. The record can be selected with a key value or a record number. From that position, the position can be set relatively or randomly by key value or by record number. If duplicate keys are present in the file, they are processed in the order defined by each target system's implementation of the DDM architecture.

Element 1: Remote file attribute

*KEYED: Remote file is a keyed file.
*ARRIVAL: Remote file is a non-keyed file.

Element 2: Local access method

*BOTH: Remote file allows both sequential and random record access.
*RANDOM: Remote file allows random record access.
*SEQUENTIAL: Remote file allows sequential record access.

Determining the Access Method

The two elements of this parameter indicate the access method to be used to access the remote file. The following table shows the combinations of values for the ACCMTH parameter. The remote file attributes (in the far left column) refer to the type of file on the target system. The local access method (in the last three columns) refers to the way in which the source iSeries program intends to access the records in the remote file.

**Figure: Access Method Combinations of Values**
Remote Local Access Method File Attributes SEQUENTIAL RANDOM BOTH ---------- ------------ ------------ ------------ ARRIVAL Relative by Random by Combined by record number record number record number *KEYED Relative by Random by Combined by key key key

Figure: Access Method Combinations of Values

Remote                   Local Access Method
File
Attributes     *SEQUENTIAL     *RANDOM         *BOTH
----------     ------------    ------------    ------------
*ARRIVAL       Relative by     Random by       Combined by
               record number   record number   record number
*KEYED         Relative by     Random by       Combined by
               key             key             key

Relative by record number access method (*ARRIVAL *SEQUENTIAL):: This method allows access to records relative to the current position in record number sequence. The record number is not specified to identify the record.
Random by record number access method (*ARRIVAL *RANDOM):: This method allows access to records by specifying a record number in a random sequence determined by the requester.
Combined by record number access method (*ARRIVAL *BOTH):: This method combines the capabilities of the relative by record number and random by record number access methods.
Relative by key access method (*KEYED *SEQUENTIAL):: This method allows records in a keyed file accessed in key value sequence. Records can be accessed by moving forward or backwards in key sequence from the current record. The key value is not specified to identify the record.
Random by key access method (*KEYED *RANDOM):: This method allows records in a keyed file accessed in a random sequence. Records are selected by their key value and not their position in the file.
Combined by key access method (*KEYED *BOTH):: This method combines the capabilities of the relative by key and random by key access methods.

Protected conversation (PTCCNV)

Specifies whether the DDM conversation that is started for the DDM file is a protected conversation or not. A protected conversation is a conversation that uses two-phase commit protocols to ensure, even if a failure occurs, updates made on the remote system are synchronized with updates to other remote or local resources. A protected conversation is required to use two-phase commitment control with DDM. More information on using two-phase commitment control with DDM is in the Distributed Data Management information in the iSeries Information Center at http://www.ibm.com/eserver/iseries/infocenter. PTCCNV(*NO) must be specified if *IP is specified for the Remote location (RMTLOCNAME) parameter.

*SAME: The value does not change.
*NO: The DDM conversation started, using this DDM file, is not a protected conversation.
*YES: The DDM conversation started, using this DDM file, is a protected conversation. Two-phase commitment control can be used with this DDM file.

Examples

The following examples describe the changing of a DDM file.

Example 1: Changing the Communications Mode System

CHGDDMF   FILE(SOURCE/SALES)  MODE(MODEX)

This command changes the communications mode for the DDM file named SALES stored in the SOURCE library on the source system. The mode is changed to MODEX.

Example 2: Changing a DDM File to Access a File through TCP/IP

CHGDDMF   FILE(OTHER/SALES)  RMTLOCNAME(ROCHESTER.XYZ.COM *IP)
          PORT(*DRDA)

This command changes the remote location name for the DDM file named SALES stored in the OTHER library on the source system. The remote location is changed to the TCP/IP host having the domain name of ROCHESTER.XYZ.COM. The host listens on the standard DRDA port of 446.

Example 3: Changing a DDM File to Access a File through TCP/IP using Dotted Decimal IP Address and a Numeric Port Number

CHGDDMF   FILE(OTHER/SALES)  RMTLOCNAME('9.5.36.17' *IP)
          PORT(5021)

This command changes the remote location name for the DDM file named SALES stored in the OTHER library on the source system. The remote location is changed to the TCP/IP host with the IP address of 9.5.36.17. The host listens on port 5021.