Someone having a heart attack does not necessarily need a defibrillator, it is normally needed when someone suffers a cardiac arrest. If they are breathing and conscious they would not require a defibrillator.

The usual process, if someone is suspected of having a cardiac event, is to phone 999, and the call centre can advise you were the nearest defibrillator is located and supply the unlock code if it is required. Calling 999 also ensures medical assistance is on the way

Once switched on the defibrillator will talk you through the whole process and if needed guide you through CPR. There is no need to be concerned about wrongly shocking a patient as the defibrillator analyses the situation and will not allow a shock to be administered if it is not required. Depending on the type of defibrillator you may be ask to press a button to administer the shock (which tends to be the most common and preferred option) or it will happen automatically.

Getting a machine.

The defib store has been used by people in Orkney. They are used to sending the machines with the Lithium batteries to Orkeny.

Defibs recently purchased (April 2023) are the iPAD SP1 semi-automatic units by CU medical Systems and the cabinet was the defibstore 4000

The prices quoted on defib store are – iPad SP1 £1134 (including VAT) , and 4000 cabinet £598.80. Replacement pads cost £66 and battery £246 All prices include VAT, Defibstore are offering free shipping at the moment.

One advantage of the iPAD SP1 is that you can switch between infant (under 8 years old) and adult modes.

The defib should be registered with “The Circuit” which allows the emergency services to know its location and availability and they can allow public access when required. This does require a responsible person to log on to the web site at regular intervals to confirm the defib is in good order and available.

Maintenance

A weekly health check of the defibrillator (usually indicated by a green light).

A monthly check to make sure the key-press combination lock is in working order, and a light spray of WD40 to the combination lock and hinges.

Replace the pads every 2 years (£65).

Replace the battery – about 4-5 years (£100 – £200).

The external cabinet should have a main s supply so a small thermostatically controlled heater can maintain good storage conditions for the defibrillator.

If you can specify an environment variable you can trace the C file operations.

This did not give much useful information, as it did not give the name of the file being processed, and I could not trace the file which was causing fopen problems, so overall a good idea – but a poor implementation.

How to set it up

See File I/O trace, Locating the file I/O trace and the environment variable _EDC_IO_TRACE

For example

export _EDC_IO_TRACE="(*,2,1M)"

Where filter is

Filter Indicates which files to trace.

• //DD:filter Trace will include the DD names matching the specified filter string.
• //filter Trace will include the MVS™ data sets matching the specified filter string. Member names of partitioned data sets cannot be matched without the use of a wildcard. filter Trace will include the Unix files matching the specified filter string.
• //DD:* Trace will include all DD names.
• //* Trace will include all MVS data sets. This is the default setting.
• /* Trace will include all Unix files.
• * Trace will include all MVS data sets and Unix files.

Detail – use 2.

Buffer size such as 1M or 50K .

The output goes to a file such as /tmp, but you can change this with

export _CEE_DMPTARG=”.”

This worked for me … but initially I could not read the output file. (It may because it came from Python which has been compiled with ASCII option.

The command ls -ltrT showed the file was tagged in ASCII, so I used

chtag -r EDC*

to reset it, and I could edit the file.

Sample output

Trace details for ((POSIX)):
        Trace detail level:  2 
        Trace buffer size:   1024K                                                                  
        fdopen(10,r)                                                                 
        fldata: 
            __recfmF:1........ 0            __dsorgVSAM:1..... 0 
            __recfmV:1........ 0            __dsorgHFS:1...... 1 
            __recfmU:1........ 1            __openmode:2...... 1 
...

Which is not very helpful as it does not tell you the file that has been opened!

When I traced a Python program, I only got information on 5 files – instead of the hundreds I was expecting.

Various abends and problems

I’ll list them here for search engines to find.

CEE3250C The system or user abend U4000 R=00007017 was issued.

U4000

• Explanation: The assembler user exit could have forced an abend for an unhandled condition. These are user-specified abend codes.
• System action:Task terminated.
• Programmer response:
• Check the Language Environment message file for message output. This will tell you what the original abend was.

There were no other messages. BPXBATCH ended with return code 2304 which means a kill -9 was issued.

If I remove the _EDC_IO_TRACE it works.

I also got a file BST-1.20220809.110241.83951661 etc which is tagged as ASCII – but is not.

This file had the trace for they Python file which was being run – including the name of the file.

I was trying to recreate the commands for the MQ certificates and keyring, so I could create a new set for a second queue manager.

At first glance it looked like writing it in rexx would involve a lot of parsing, so I started using the RACF callable service to extract information certificate and keyring information from RACF using a C/assembler interface.

This was a slow journey with many pitfalls, and I ended up using a REXX program.

I’ve put the code up on git hub for both the RACF and the C interface, to help other people who may be considering going into the RACF callable services swamp.

Using the C interface

You use the R_datalib or IRRSDL00 callable service.

The key bits of code  are

#pragma linkage(IRRSDL00 ,OS) 
- - - - - - - - - - - - - - - - - 
char * workarea = (char *) malloc(1024) ;
- - - - - - - - - - - - - - - - - 
struct {  
   char length; 
   char value[8]; 
} RACF_userid; 
memcpy(RACF_userid.value,"START1 ",8); 
RACF_userid.length = 6; 
- - - - - - - - - - - - - - - - - 
int parmlist_version = 0; 
- - - - - - - - - - - - - - - - - 
char DataGetFirst = 0x01 ; /*Data getFirst */ 
int attributes = 0; 
rc= IRRSDL00( workarea, // WORKAREA 
   &ALET1 , // ALET 
   &SAF_RC, // SAF RC 
   &ALET2, // ALET 
   &RACF_RC,// RACF RC 
   &ALET3 , // ALET 
   &RACF_RS,// RACF Reason 
   &DataGetFirst ,// function code 
   &attributes, // option 
   &RACF_userid, // RACF userid 
   &ring_name, // certificate fw ... cert 
   &parmlist_version, // Aplication userid 
   &parmlist ); 

That code was not particularly difficult – it got more difficult using the parmlist.

#pragma pack(1) 
struct { 
  char * results_handle ; //in  offset 0 
  int certificate_usage ; //out offset 4 
  int isDefault ; // out 8 
  int certificate_length; //in/out c 
  char * certificate ; // in 10 
  int private_key_length; //in/out 14 
  char * private_key ; //in 18 
  int private_key_type ; //out 1c 
  int private_bitsize ; //out 20 
  int label_length ; //in/out 24 
  char * label ; //in 28 
  char cert_useridl; // in 2c 
  char cert_userid[8]; // in 2d 
  char temp[3] ; //     offset 35
  int subjects_dn_length ; //in 38 
  char * subjects_dn_ptr ; //in 3c  
  int record_length ; //in/out 40
  char * record_ptr ; //inp 44 
  int cert_status ; //in/out 48 
} parmlist; 
 #pragma pack(4)
- - -
 char certificate[2000]; 
parmlist.certificate_length = 2000 ; 
parmlist.certificate =( char *) &certificate;  

Notes:

1. The temp[3] is not in the documentation and I got various errors without it – such as internal error.   This was because the pointers following it were at the wrong offset.
2. parmlist.cert_useridl must be set to 8, and the value must be padded on the right with blanks.  This is different to the RACF_userid field in IRRSDL00 which is the true length of the userid. 

Compile it

//S1 JCLLIB ORDER=CBC.SCCNPRC 
//DOCLG EXEC PROC=EDCCBG,INFILE='ADCD.C.SOURCE(C)', 
// CPARM='OPTF(DD:COPTS)' 
//* CPARM='LIST,SSCOMM,SOURCE,LANGLVL(EXTENDED)' 
//COMPILE.COPTS DD * 
LIST,SSCOMM,SOURCE,LANGLVL(EXTENDED) 
aggregate(offsethex) xref 
TEST 
/*
//COMPILE.SYSIN DD * 
... 
//BIND.SYSLMOD DD DISP=SHR,DSN=ADCD.PDSE.LOADLIB(CERT) 
//BIND.CSS DD DISP=SHR,DSN=SYS1.CSSLIB 
//BIND.SYSIN DD * 
INCLUDE CSS(IRRSDL00) 
/* 

The output

The subject ( what I was after) had a format like in hex and ASCII is

00000000 : 3038310B 30090603 55040613 02474231 081.0...U....GB1 
00000010 : 0C300A06 0355040A 0C035353 53310B30 .0...U....SSS1.0 
00000020 : 09060355 040B0C02 4341310E 300C0603 ...U....CA1.0... 
00000030 : 5504030C 05535343 4138              U....SSCA8 

If I list the certificate it reports Subject’s Name: CN=SSCA8.OU=CA.O=SSS.C=GB, you can see the elements in the hex dump.

The data is DER encoding of ANS.1 format. Buried within this,  is a field with value “GB” which is a type 2.5.4.6 which is country.   Information is stored in certificate in ASCII and in DER format, so I was not surprised to see the data in this format.

The easiest way of decoding this is to use gskit (IBM global security kit).   Gskit provides c routines for encryption/decryption and management of certificates.

Using GSKIT

Change the compile JCL

//S1 JCLLIB ORDER=CBC.SCCNPRC 
//DOCLG EXEC PROC=EDCCBG,INFILE='ADCD.C.SOURCE(C)', 
// CPARM='OPTF(DD:COPTS)', 
// GREGSIZ='0M' 
//COMPILE.COPTS DD * 
LIST,SSCOMM,SOURCE,LANGLVL(EXTENDED) 
TEST 
LSEARCH(/usr/lpp/gskssl/include/) 
SEARCH(//'CEE.SCEEH.+',/usr/lpp/gskssl/include/) 
DEFINE(MVS),LONGNAME,RENT,DLL,EXPMAC 
aggregate(offsethex) xref 
//COMPILE.SYSIN DD * 

 #pragma runopts(POSIX(ON)) 
..

//BIND.SYSLMOD DD DISP=SHR,DSN=ADCD.PDSE.LOADLIB(CERT) 
//BIND.IMP DD DISP=SHR,DSN=SYS1.SIEASID 
//BIND.CSS DD DISP=SHR,DSN=SYS1.CSSLIB 
//BIND.SYSIN DD * 
INCLUDE CSS(IRRSDL00) 
include imp(GSKSSL) 
include imp(GSKCMS31) 
/* 

How to decode the returned data

Gskit uses a gsk_buffer structure to handle strings.  It is easy to use as it has

• length – the length of the string
• data – a pointer to the string

If gskit returns a gsk_buffer to your program, you should use gsk_free_buffer(…) to release the buffer when you have finished with it.

gsk_buffer name; 
x509_name out; 
name.length = parmlist.subjects_dn_length; 
name.data = parmlist.subjects_dn_ptr; 
gskrc = gsk_decode_name(& name, &out); 
if ( gskrc != 0) 
   printf("gsk_decode_name %s\n",gsk_strerror(gskrc)); 

All this routine does it to convert the ANS.1 encoded string, into a structure of elements.  You can then use the following to print it

gskrc = gsk_name_to_dn(&out,&pName); 
if ( gskrc != 0) 
   printf("gsk_name_to_dn %s\n",gsk_strerror(gskrc)); 
else printf("Name:%s\n",pName); 

This produced

Name:CN=SSCA8,OU=CA,O=SSS,C=GB 

As an exercise I wrote some code to format some of the x509 value –

for ( int i = 0; i < out.u.dn.count;i++) 
{ 
  for (int j = 0;j < out.u.dn.rdns[i].count; j++ ) 
  {  
    printf("Type %s ",px509_attribute_type( 
        out.u.dn.rdns[i].attributes[j].attributeType )); 
        char * p2 = out.u.dn.rdns[i]. attributes[j]. name.data; 
        int l = out.u.dn.rdns[i]. attributes[j]. name.length; 
         printf("%*.*s\n",l,l, fromascii(p2,l)); 
   } 
} 

It took an hour or so to work out how to access the elements:  out.u.dn.rdns[i].attributes[j].attributeType .  I had to write a routine px509_attribute_type which took the attribute type and return a string such as “CN” etc.  I already had a function fromascii which took and ASCII string and converted it to EBCDIC.  Using gsk_name_to_dn was much easier.

I struggled for a while trying to get GitHub hub to display some html. It can be done, but not as slickly as other GitHub functions.

I had a page at https://github.com/colinpaicemq/zpymqi/blob/main/docs/test.html, but whenever I displayed it, the raw html was displayed. My challenge was to display the html as rendered html.

Display your repository in a web browser, and select the “settings” icon. On the settings page, click on “pages” in the left hand window. When it displays “GitHub Pages”, go down to source and select on the “None” pull down.

Select “main” to make pages available, or none to make them unavailable.

Click “save”.

It will then display

Your site is ready to be published at https://colinpaicemq.github.io/zpymqi/

After a several minute delay I could display my page at

https://colinpaicemq.github.io/zpymqi/docs/test.html

There is always a few minute delay before displaying the pages.

Compare this site with my source site

• https://github.com/colinpaicemq/zpymqi/blob/main/docs/test.html
• https://colinpaicemq.github.io/zpymqi/docs/test.html

I’ve been on holiday, visiting friends and family, and one of my friends gave me three impossible puzzles. I thought I would pass them on.

The impossible puzzle

X and Y are two different whole numbers greater than 1. Their sum is not greater than 100, and Y is greater than X. S and P are two mathematicians (and consequently perfect logicians); S knows the sum X + Y and P knows the product X × Y. Both S and P know all the information in this paragraph.

The following conversation occurs (both participants are telling the truth):

• S says “P does not know X and Y.”
• P says “Now I know X and Y.”
• S says “Now I also know X and Y.”

What are X and Y?

The Seemingly Impossible “Guess The Number Logic Puzzle“

I got this from Mind your decisions by Presh Talwalkar.

Alice and Bob are on a game show. Each is secretly told a whole, positive number. They are told the two numbers are consecutive, but neither knows the other person’s number. For example, if Alice is told 20, she does not know if Bob was told 19 or 21. And if Bob is told 21, he does not know if Alice was told 20 or 22. The point of the game is to guess the other person’s number. The game works as follows.

• Alice and Bob cannot communicate with each other, and they are not allowed to plan their strategy either.
• The two are in a room where a clock rings every minute.
• After the clock rings, either player can call out a guess of the other player’s number, or they can stay silent.
• The game continues until Alice or Bob makes a guess. After the first guess is made, the game ends.
• Alice and Bob win $1 million each if the guess is correct, and they lose and get nothing if the guess is incorrect.

How should Alice and Bob play this game to have the best chance of winning? Each knows the other person is perfect at logical reasoning.

Pirates, and being thrown overboard

Some pirates caught a yacht on the high seas. The 8 people on the yacht were all logicians.

The pirate king said “Tomorrow I will put a red dot or a black dot on your forehead. You cannot see the dot, but every one else can. I will place you in a circle, so you can see every one else, and I will ask each of you in turn, if you have a red dot or a black dot. If you get it right – you live, if you get it wrong you walk the plank, and feed the sharks. Now go to the cell and plan your strategy, arr Jim lad”.

What strategy should they use to save most people.

I was having problems accessing the IBM documentation from my Firefox browser. Nothing was displayed. The Firefox error log reported problems with some of the HTML. I started getting problems with other sites, such as being unable to logon to gmail. I was getting annoyed with all of these little problems, so I decided to find out why.

I eventually fixed the problems by refreshing Firefox. Type about:support on the input line, and click the box saying “Refresh Firefox”. After a few moments it came back and worked.

I can access all sites, including the IBM documentation.

I only regret clearing my cache beforehand!

I’ve spent an hour struggling with a web site trying to download some files and was amazed at the poor usability of the web site. I tried an alternate supplier, and this was just as bad.

It feels like I am in a world which is upside down, and what is obvious to me, is clearly not obvious to other people who design build these web sites.

I was talking to someone who lives in an “architect designed house” which looks very smart, but is not very practical. There is an open plan kitchen, flowing into the seating area, and upstairs to the open plan master bedroom. When smelly food is being cooked, you smell it in the lounge and in the master bedroom ; just imagine waking up the the smell of last night’s curry. The master bedroom has very little privacy. The master bedroom has a bath in it, with views over the town and hills. Your bedroom will be full of damp air! An “architect designed” does not mean practical and useful. Perhaps the same architect also builds web sites.

The design brainstorm

I can visualise the conference room where Dilbert’s Pointy Haired Boss is telling the team about the goals of the new web site for ordering CDs

• “A good measure of a web site, is how much time people spend on it. I hear people spend all day on Facebook and that is popular”
• “Real estate is valuable – so use as much as you can”
• Use the latest Java Script tools to make it look really modern; Can we display lines where nothing is displayed until you move your mouse over it? That would be really cool.

Marketing terms

“These are the “upside down” terms we will use in our Marketing material – please ensure you follow them”

• “Improved” : worse;slower
• “Intuitive”: When you’ve used the interface for a few weeks, you know how your way around, and know the pitfalls.
• “Elegant”: we use the design for a mobile phone on a web page, so the users have a narrow column of data, and do not use the available space in the web browser.
• “Modern”: more (or less) rounded corners; different fonts (which make it harder to read – do not use the fonts which dyslexics find easier to read).
• “Uncluttered”: provide less information on the screen; remove visual clues.
• “Dynamic”: we use a lot of interactive scripts which look cool; such as windows that disappear when you move your mouse over them.
• “Smart icons”: for example FEEDback is about FEEDing which is about food – so use a knife and fork for the icon – clever idea isn’t it?.

A Jelly Bean for the person who can use the greatest number of these terms.

The outcome

• Allow search for some topics, such as Pop group – but not the name of the CD.
• Use lots of space on the web page. For example we could easily display 40 items on a page – let’s display just 10 and make them ask for the next page by a “more”button. Though having just one line per screen would be silly – wouldn’t it?
• List information like “Beatles hits by year” – but not the name of the CD. You have to select on each line to see what the CD is.
• When they click to see what is in each CD, do not display all of the contents, just display 3 entries “inline” and give them another “more button”
• When you click on a line you can select “Buy”. When they use the browser back button – do not go back to where they came from, go to the start of the web site, and so more clicks on our site. They stay logged on – it would be stupid to make them logon every time wouldn’t it?
• Make the site inconsistent. Sometimes you can click on a line for more information, sometime you have to click on the button at the end of the line – that only appears when you hover over it.
• Have buttons on the page which have no description or hover text, until you have clicked on it. For example ‘contact us’.
• Use really big fonts to use more space.
• Can we sell a course on how to use our interface? If people who have never used our web site before can quickly order things this counts as a failure because they didn’t spend much time on the web site.
• Make it slow – so people spend more time on the site – but provide some good animation (such as a greyhound racing) to make people think it is doing something useful.

Back in the real world.

I remember having a talk about 20 years ago by  a UI expert.  I cannot remember all of it, but the points I remember were….

• Make it easy for the end user
  1. Minimise the actions the user has to take (clicks, scrolls etc). Put the “up arrow” adjacent to the “down arrow”- not at different ends of the screen. If they have to keep clicking a button – put the buttons close to the same place on each page.
  2. Make actions obvious
  3. If the web site is slow, and you have to keep doing “next” this will frustrate the user.  Is it better to have one page to load slowly with all of the information – or have smaller pages which take seconds to load?
  4. Test it in a typical environment.  I remember trying to use the IBM documentation web site from a customer using a dial up in Indonesia,  going to the UK, to go to the US.  IBM support said the response time was “ok” because they were in the same building as the server!  For me it was taking me minutes per page.
  5. Creating a dyslexia friendly workplace is a very useful site.
• Make the best use of available space
  1. Use the appropriate font.  For one page – do you need a big font?  No.    For a 50 “page” you need bigger fonts to make the sections visible.
  2. Try to provide the most information on the screen as possible – without going too far.   For a list of items consider colouring every 3rd or 5th line to help the user keep their eye on the line.
  3. Make all information visible – do not hide it.  Do not make users move the mouse over something to display it.
  4. If you have icons, make sure the icons are “standard”.
  5. Consider how much you display before having a “more” button.  If you expect people to “find” data, then have more lines, and make it scrollable.  Too much data ( > 1000 lines) can make it slow to load.   I think 100 -200 lines is acceptable.
  6. Provide information the end user wants.  If all the items in a list are for “ABC Wonderful software product for new users”. 
     • This would be clearer
       • ABC Wonderful software product for new users English edition
       1. version 1
       2. version 2
       3. version 3
     • than
       1. ABC Wonderful software product for new users V1English edition
       2. ABC Wonderful software product for new users V2 English edition
       3. ABC Wonderful software product for new users v3 English edition.

• Make it clear what each part is, for example a link (it is underlined).   it should be obvious from looking at it – the end user should not have to move the mouse to display it.  ( I know modern “standards” seem to say do not underline a link – let the end user guess). Consider  people with screen readers and how they read and navigate it.
• Less is more.   I know of this from my acting.  A character who is still, with small moves, is often more powerful than big gestures.  People expect a web site with response time of around 1-2 seconds.  The BBC new web site https://www.bbc.co.uk/news/uk displays for me in under 2 seconds ( usually 1 second) with full graphics.  Some sites I use frequently take over 5 seconds, sometimes 10 seconds.  Do we really need clever animation etc.?
• The word “Intuitive” is often abused.
  1. If you use windows 10 as your primary work station then move to windows 11; the GUI is the same as before.   You find it “intuitive”.   I come from Linux, and having to use Windows, a lot is not intuitive.   Similarly someone going from Windows to Linux will not find it entirely intuitive.   You have to allow for people who are not familiar with the web site as well as people who use frequently use the web site (eg the web site developer and testers).
  2. Icons are often not obvious.   Giving them useful information via a hover is a good start.
• When testing usability of web pages, use people who have never used your site before. The worst people for testing the new user experience, are those who use it every day and who work round the problems.