Re: a little for the node.js / javascript freaks on a sunday afternoon -- WEB400

In the past I've had issues where the TCPIP connection wouldn't let go. I
resolved it by going into NETSTAT *CNN and ending the entry for that
particular port. That's not exactly the scenario being talked about in
some of these scenarios but I thought I'd share my experience (both Node.js
and Ruby)

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

On Tue, Feb 28, 2017 at 7:56 AM, Henrik Rützou <hr@xxxxxxxxxxxx> wrote:

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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To post a message email: WEB400@xxxxxxxxxxxx
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