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The API Corner: Just What Release Am I On?

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Find out by using the Retrieve Product Information (QSZRTVPR) API.

 

A question that seems to come up on a regular basis is "How can a program tell what release level of the operating system it's running on?" To answer this question, we'll look at a category of system APIs that many of you may not have reviewed in the pastthe Software Product APIs, which are introduced here.

We will not be looking at all of the available APIs today, but by using these APIs you can create your own products, support your company's products with PTFs, license your products…basically have the i support your products in the same manner it supports IBM-provided software products.

The specific API we'll be looking at today is the Retrieve Product Information (QSZRTVPR) API. While this API can return quite a bit of information about a software product, our interest today is in simply determining the release level of the operating system. The API defines six parameters:

Required Parameter Group:

1

Receiver variable

Output

Char(*)

2

Length of receiver variable

Input

Binary(4)

3

Format name

Input

Char(8)

4

Product information

Input

Char(*)

5

Error code

I/O

Char(*)


  Optional Parameter:

6

Product information format name

Input

Char(8)

If you're familiar with retrieve-type APIs, you should see no surprises in this parameter list. If you aren't familiar with retrieve-type APIs, you may want to review the earlier articles "System API Basics," "Understanding API Data Types," and the series of articles starting with "Retrieving Information, Part I."

The QSZRTVPR API currently supports nine formats when returning information. Format PRDR0100, which is what we will be using, returns basic information, such as the product ID, the release level of the product, the option of the product being returned, the minimum release of the operating system the product can be saved to, etc. The other formats can be used to access more specific information such as:

PRDR0200A list of the libraries and exit programs associated with the product

PRDR0300A list of the folders associated with the product

PRDR0400A list of the packaged objects associated with the product

PRDR0900A list of the software agreement documents associated with the product

Below are listed the first few fields (there are many more) that are returned with format PRDR0100 along with their QSYSINC definitions. Note that the field Release level at decimal offset 19 is our specific field of interest.

Offset

Type

Field

Dec

Hex

0

0

BINARY(4)

Bytes returned

4

4

BINARY(4)

Bytes available

8

8

BINARY(4)

Reserved

12

C

CHAR(7)

Product ID

19

13

CHAR(6)

Release level

25

19

CHAR(4)

Product option

DQSZR0100         DS                                        

D*                                            Qsz PRDR0100  

D QSZBRTN                 1     4B 0                        

D*                                             Bytes Returned

D QSZBAVL                 5     8B 0                        

D*                                            Bytes Available

D QSZRSV1                 9     12B 0                        

D*                                             Reserved 1    

D QSZPI01               13     19                          

D*                                            Product Id    

D QSZRL03               20     25                          

D*                                             Release Level

D QSZPO01               26     29                          

D*                                            Product Option

The Product information parameter of the QSZRTVPR API is used to identify the product we're interested in. The default format for this parameter is format PRDI0100 which, along with its QSYSINC definition, is shown below:

Offset

Type

Field

Dec

Hex

0

0

CHAR(7)

Product ID

7

7

CHAR(6)

Release level

13

D

CHAR(4)

Product option

17

11

CHAR(10)

Load ID

DQSZPIR           DS                                            

D*                                            Qsz Product Info Rec

D QSZPI00                 1     7                              

D*                                             Product Id        

D QSZRL02                 8     13                              

D*                                           Release Level    

D QSZPO00               14     17                              

D*                                             Product Option    

D QSZLI01               18     27                              

D*                                            Load Id          

Product ID (QSZPI00) identifies the product of interest and supports the special value *OPSYS to return information related to the operating system.

Release level (QSZRL02) identifies the release of the product we're interested in and supports (among other special values) the special value *CUR, indicating that the release level of the currently installed operating system should be used.

Product option (QSZPO00) identifies the option of interest with the value '0000' indicating the base option.

Load ID (QSZLI01) identifies the load of interest with the special value '*CODE' indicating the code load for the product.

Using these special values, the following program displays the current release of the operating system.

h dftactgrp(*no)                                                

                                                                

d RtvPrdInfo     pr                 extpgm('QSZRTVPR')        

d RcvVar                       1a   options(*varsize)          

d LenRcvVar                   10i 0 const                      

d Format                       8a   const                      

d PrdI                       4096a   const options(*varsize)    

d ErrCde                             likeds(QUSEC)              

d PrdIFmt                       8a   const options(*nopass)    

                                                                

/copy qsysinc/qrpglesrc,qszrtvpr                                

/copy qsysinc/qrpglesrc,qusec                                    

                                                                

/free                                                          

                                                                

QUSBPrv = 0;                                                    

 

QSZPI00 = '*OPSYS';                                      

QSZRL02 = '*CUR';                                        

QSZPO00 = '0000';                                        

QSZLI01 = '*CODE';                                        

                                                          

RtvPrdInfo(QSZR0100 :%size(QSZR0100) :'PRDR0100'        

             :QSZPIR :QUSEC);                              

dsply QSZRL03;                                            

                                                          

*inlr = *on;        

return;            

                      

/end-free            

As you can see, accessing the current release of the operating system is very straightforward. The program:

  • Prototypes the QSZRTVPR API
  • Includes the QSYSINC-provided definitions for the API (QSZRTVPR) and the standard API error code structure (QUSEC)
  • Sets the API error code bytes provided field to send exceptions in the case of an API error
  • Sets the Product information parameter to identify the product to be retrieved as being the current (*CUR) operating system (*OPSYS) base option ('0000') code load (*CODE)
  • Calls the API
  • Dsplys the returned release level (QSZRL03)

Assuming the previous RPG source is stored in member RTVOSINF (Retrieve Operating System Information) of source file QRPGLESRC, you can create and run the program using the following commands:

CRTBNDRPG RTVOSINF

CALL RTVOSINF

It's as simple as that to determine the current release level of the system a given program is running on. I find this ability to quickly ascertain such information to be quite handy when I have developed some code that runs across a range of release levels and the system provides more efficient ways to perform a given function (perhaps a new or enhanced API) on later release levels.

As usual, if you have any API questions, send them to me at This email address is being protected from spambots. You need JavaScript enabled to view it.. I'll see what I can do about answering your burning questions in future columns.

Bruce Vining

Bruce Vining is president and co-founder of Bruce Vining Services, LLC, a firm providing contract programming and consulting services to the System i community. He began his career in 1979 as an IBM Systems Engineer in St. Louis, Missouri, and then transferred to Rochester, Minnesota, in 1985, where he continues to reside. From 1992 until leaving IBM in 2007, Bruce was a member of the System Design Control Group responsible for OS/400 and i5/OS areas such as System APIs, Globalization, and Software Serviceability. He is also the designer of Control Language for Files (CLF).A frequent speaker and writer, Bruce can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it.. 


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