Re: a little for the node.js / javascript freaks on a sunday afternoon

I am using child_process in my own code....so point taken - if you are
using a package that forks a child process and that does not expose the
options, you are shafted until they fix it fully.

-----Original Message-----
From: WEB400 [mailto:web400-bounces@xxxxxxxxxxxx] On Behalf Of Aaron
Bartell
Sent: 28 February 2017 15:34
To: Web Enabling the IBM i (AS/400 and iSeries) <web400@xxxxxxxxxxxx>
Subject: Re: [WEB400] a little for the node.js / javascript freaks on a
sunday afternoon

*>The PTF partialy fixes it as long as you use silent:true when forking the
child-process.*

Is this a manual fork you're doing or is it being done by another npm?

Aaron Bartell
IBM i hosting, starting at $157/month. litmis.com/spaces


On Tue, Feb 28, 2017 at 9:28 AM, Kevin Turner <kevin.turner@xxxxxxxxxxxxxx

wrote:

Yes I get it to all close down OK in a normal environment. It is when

the

parent process ends unexpectedly that things go awry. The PTF partialy
fixes it as long as you use silent:true when forking the child-process.

-----Original Message-----
From: WEB400 [mailto:web400-bounces@xxxxxxxxxxxx] On Behalf Of Henrik
Rützou
Sent: 28 February 2017 13:56
To: Web Enabling the IBM i (AS/400 and iSeries) <web400@xxxxxxxxxxxx>
Subject: Re: [WEB400] a little for the node.js / javascript freaks on
a sunday afternoon

Hi Kevin,

well problems calls for innovation ;-)

A little LIBHTTP programs that files a *LR to the node server through
a GET should fix the problem.

process.exit(0)

close down the node.js program



On Mon, Feb 27, 2017 at 1:32 PM, Kevin Turner
<kevin.turner@xxxxxxxxxxxxxx

wrote:

" Annoying error, when a nodes program is ended wirh an EDBJOB
*IMMED sometime the QP0XSPWT hangs until next IP. Ehat is worse is
that it blocks the IP port."

I have been working on this (or a similar) issue with IBM. Node
child processes can become orphaned when the parent process ends

unexpectedly.

They would go to EOJ status and stick there. If you end them the go
to

END

status and hang. ENDJOBABN will usually kill them off. The PMR was
74327,999,866 and eventually solicited a partial fix with PTF SI63892
combine with starting child processes with silent:true. In reality

the

problem runs far deeper and we now have PMR 20128,999,866 for the
investigation.


[https://www.netcracker.com/assets/img/netcracker-social-final.png]
ƕ -----Original Message-----
From: WEB400 [mailto:web400-bounces@xxxxxxxxxxxx] On Behalf Of
Henrik Rützou
Sent: 26 February 2017 15:33
To: Web Enabling the AS400 / iSeries <web400@xxxxxxxxxxxx>
Subject: [WEB400] a little for the node.js / javascript freaks on a
sunday afternoon

*First a little elaboration about the use of the EVAL instruction,
JSON and objects in javascript.*


Originally javascript was a script language that was executed
statement by statement of the script code.


Today javascript is JIT compiled into binaries to be executed by
the javascript VM. This is why you get javascript syntax error’s
already at load time but also why javascript is a very fast language.


The problem and why EVAL should be avoided is the EVAL is an
instruction that may create executable code within the script itself.
So whenever the
V8 engine meets an EVAL instruction that is executed it will
decompile the running code and maube recompile the code after the
EVAL instruction or it will fall back and execute the javascript in
bytecode creating huge overheads in processing time.


If you have the time see this presentation by Lars Bak on how V8
handles
code: https://youtu.be/r5OWCtuKiAk


In regards to JSON (that is what it say’s it is - an intermediate
string based notation of an javascript object or array) - functions
are allowed in a javascript object, not in JSON:


___ myObj = {}

___ myObj.MYSCRIPT = function(message) { alert(message) }

___ myObj.MYSCRIPT(“Hello World”)


But if you stringify MyObj to JSON it will drop MYSCRIPT since
typeof ‘function’ isn’t supported in JSON because any imported JSON
would then trigger a recompile.


An ugly work around is to stringfy the function in the javascript
object before you convert it into JSON:


___ myObj.MYSCRIPT = myObj.MYSCRIPT.toString();

___ myJSON = JSON.stringify(myObj);


And in the receiving end


___ myNewObj = JSON.parse(myJSON);

___ myNewObj.MYSCRIPT = eval('(' + myNewObj.MYSCRIPT + ')')


That of course will trigger a decompile and/or shift to bytecode L


It is important to remember that JSON never has been intended to be
a data interchange format but originally is made for cloning objects
since direct copy of objects in javascript is done by reference.



___ myObj = {}

___ myObj.NAME = “Henrik”

___ myNewObj = myObj

___ myNewObj.NAME = “Scott”


Will also change the content of myObj since myNewObj just is a name
that points back to myObj. (this is exactly what happens in my clean
up code in the result of db2/db2a )


To create a shallow copy as a clone of myObj you need to convert it
to a string and then create a new object without references to the old.


___ myJSON = JSON.stringify(myObj)

___ myNewObj = JSON.parse(myJSON)


To create a deep copy as a clone of myObj (a copy that includes the
original object properties but have no reference to the old object)
requires a lot more coding but can be done.





*IBM’s db2/db2a DB2 connector*


Many think that IBM’s DB2 connecter in node.js returns JSON in the
sqlResult, It doesn’t – it returns a javascript object an I order to
find out what is inside the object (actually in any javascript
object) there are two native ways without using tools:


___ myJSON = JSON.stringify(sqlResult)


That doesn’t include object elements typeof ‘function’ or object
properties


or


console.log(sqlResult)


that (at least in crome and node.js ) returns the entire object
including object properties to the console

and not … console.log(“my sqlresult: “ + sqlResult) that just like
an
alert() returns “my sqlresult: [object] [object]” in the console


To summarize on db2a

- Returns a javascript object, not JSON

- Terrible slow (not only an IBM i problem)

- All fields are returned as typeof string regardless of the

type

of fields you specifies

- All fields are returned with writespaces / all string in
javascript are variable length


Work around code:



stmt.fetchAllSync(function callback(result) {


// clean up IBM's db2a mess

var rowObj = {}

for (i= 0; i < result.length; i++) {

___ rowObj = result[i]

___ for (var key in rowObj) {

______ if (rowObj.hasOwnProperty(key)) {

_________ if (typeof rowObj[key] == 'string') {

____________ if (isNaN(rowObj[key]) == false && rowObj[key].trim()
!=
'') {

_______________ rowObj[key] = parseFloat(rowObj[key])

____________ } else {

_______________ rowObj[key] = rowObj[key].trimRight()

____________ }

_________ }

______ }

___ }

}

…




*IBM and CCSID*


This is probably an error since file written by FS starts i CCSID
819 but if the are rewritten a couple of time they shift to CCSID
1208




*IBM and QP0ZSPWT jobs Hangs and locks the IP port*



Annoying error, when a nodes program is ended wirh an EDBJOB *IMMED
sometime the QP0XSPWT hangs until next IP. Ehat is worse is that it
blocks the IP port.




*IBM S812 - one core or 4 cores*


When IBM annouced this new entry level POWER8 they have excluded 3
cores if it is ordered with IBM i while they are included if ordered
with Aix - one core is a node.js killer and one is better of on a
$500 PC with 4 cores, is that the direction IBM wants us to go?






*powerEXT zdb – a NoSql database for node.js*


As a consequence of the SQLs slowliness I have decided to build a
little NoSql DBMS that are platform agnostic. My tests show a RLA
access time in node.js on 0.006ms for keyed index search,
0.012/0.014ms for corresponden object retreival that is acceptable
compared with native RPGLE RLA on 0.048ms.


This is of course not for big tables but for referential tables that
can be bound to a SQL result by late bindings making the SQL simpler
and

faster.

Btw. IMHO SQL is also over-engineered and has become a "write a
whole program in one (very long) statement". At the same time SQL
has become DB propietary wich makes it unportable. Don't expect a
SQL statement written for DB2i to run on either DB2 LUW or SQL Server

or vice versa.

Besides that I build program generators where some generates EXTJS
UI code on the fly while other generates server side code such as
REST/CRUD services where I have decided maybe best resides in their
systems native environment and with native I mean not only native
IBM I SQLRGLE but also native .NET C# since my target are both IBM I
and MS SQL Server customers, but that’s another story (*).


Program generators (whatever program language that is the output)
requires a lot of specific metadata, templates and in many cases
access

to SYSCOLUMN.

If the program generation is intended for ‘on the fly’ UI generation
at also requires user rules and all these data can’t be put into a
SQL View where a single row request in a table may take 50ms in
node.js and where a big UI may require 5,000 lookup’s it will take
25 seconds in SQL while it only takes approx 75ms in zdb.


The database will work in any number of HTTP Daemons one may launch;
its physical data is placed in an IFS file per. table in JSON format
while it runs in javascript objects internally in node.js.


The IFS file may be overridden (renewed) by either node.js or native
programs that may regenerate the table from content in DB files that
however may cause data loss. The synchronization with a DB table may
be done from node.js by calling a REST/CRUD service where the zdb
acts

client.

A DB table can of course also be created by loading the table from
the IFS file.


There zdb are based on a configuration file – all is still subject
to
change:


var zdbConf = [

___ {

______ tableName : "AAA",

______ tablezdb : "./zdb/aaa.table",

______ tableScope : "$global",

______ tableReadOnly : false,

______ tableCloneObj : true,

______ tableAutoLoad : true,

______ tableSync : true,

______ tableSyncRest :
"http://127.0.0.1:8080/pextwebcgi/AAArest.pgm";,

______ tableSyncType : "POST",

______ tableKey : ["MYID"],

______ tableMandatory : ["MYID","ABC"]

___ }

]



Creating of internal Database


___ scope = new zdb(‘scope’);



Load of tables:


(zdb represent the scope name)

___ zdb.loadAuto(scope) // load all tables in the scope with
tableAutoLoad attribute = true

___ zdb.open(tableName,scope) // Manual load or forced reload



Methods:

___ obj = zdb.readByKey(tableName,key)

___ obj = zdb.readByRrn(obj)

___ ... (obj or objClone are decided by the tables 'tableCloneObj'
property and is only recommended if tableReadOnly is true

___ rc = zdb.join(tableName,toObj,key,joinElementName)

___ ... joinElementName will join the zdb object in a single element
otherwise elements are addedin the receiving object root and will
overwrite elements with the same name.



__ … metods where tableReadOnly property = false

___ rc = zdb.write(objClone)

___ rc = zdb.update(objClone)

___ rc = zdb.delete(objClone)

___ rc = zdb.save(tableName) // force save


It all sounds relative simple, but it is not if you look at the
structure any node.js has to go through before it is called:


___ HTTP Server Apache

_______ PROXY/FASTCGI

__________ LOAD BALANCER

_____________ HTTP DAEMON

________________ YOURFUNCTION


The PROXY/FASTCGI and LOAD BALANCER works very similar to the
QZSRCGI programs where the server lauches a number of job so if one
is busy another is chosen. Besides that you are first with the
node.js environment when you enter the HTTP DAEMON who's role are to
redirect requests to YOURFUNCTION and other functions.


YOURFUNTION may load data, but the function only exists between it
is required by the HTTP DAEMON to it ends by sending data to the
requester, afterwards it is destroyd and requested data hereby also
are lost. Often used tables must be controlled and passed by the
HTTP

DAEMON.

Yes, there are other ways to construct node.js on, one HTTP port per
App is one (results often in 100,000 statements monoliths) or
requirering all functions when the HTTP DAEMON is initialized but
that requires that all funtions is able to act as a module and so on.
EXPRESS may also have another solution but as far I have read it
doesn't met the requirements I seek.


The bottom line is that zdb can be loaded by my HTTP DAEMON and
shared by any function through the object that also holds other
global

variables.

And please remember what powerEXT for node.js is about, if you want
to run chat forums or control your neighbor's drone chose otherwise,
this is about OLTP Business Applications.






*(*) The story*


When EXT JS went from version 4 to version 5 they removed their open
source version and made their licenses come in packages of 5
developers. At that time they had approx. 500,000 users of their
forum where most ran on the Open Source license.


They were overloaded with questions and free support and even those
who ran on a single license generated the same amount (if not even
more) that their “customers with a budget for both license and

education” did.

The big question for me is where do I find “customers with a budget”
not for powerEXT Core for node.js or IBM I that is MIT licensed -
but what follows – the EXT JS UI generator. You can be dam sure
these customers doesn’t run their OLTP business critical
applications on mongoDB or MySQL, most will run on MS SQL Server,
DB2 and in some degree

Oracle.

Besides that I live in a country where 80% of “customers with a budget”
runs MS Business Solutions on MS SQL Server ;-)




--
Regards,
Henrik Rützou

http://powerEXT.com <http://powerext.com/>
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--
Regards,
Henrik Rützou

http://powerEXT.com <http://powerext.com/>
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