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Dmitry Maslennikov · Dec 20, 2017

(& and !) can be used almost everywhere, but not recommended because both operands will be calculated. And sometimes it can cause some unexpected behaviour. Look at my example

USER>set a=1 if a!$i(a) zw a
a=2

even when the first expression already truth second one also calculated and increased the value

USER>set a=1 if a||$i(a) zw a
a=1

In this case, the first expression already truthy, and in OR condition it's enough to make full logical expression truthy as well, and not need to calculate the second expression.

Dmitry Maslennikov · Dec 15, 2017

right from the documentation

You can combine multiple Boolean logical expressions by using logical operators. Like all Caché expressions, they are evaluated in strict left-to-right order. There are two types of logical operators: regular logical operators (& and !) and short-circuit logical operators (&& and ||).

When regular logical operators are used to combine logical expressions, Caché evaluates all of the specified expressions, even when the Boolean result is known before all of the expressions have been evaluated. This assures that all expressions are valid.

When short-circuit logical operators are used to combine logical expressions, Caché evaluates only as many expressions as are needed to determine the Boolean result. For example, if there are multiple AND tests, the first expression that returns 0 determines the overall Boolean result. Any logical expressions to the right of this expression are not evaluated. This allows you to avoid unnecessary time-consuming expression evaluations.

Some commands allow you to specify a comma-separated list as an argument value. In this case, Caché handles each listed argument like an independent command statement. Therefore, IF x=7,y=4,z=2 is parsed as IF x=7 THEN IF y=4 THEN IF z=2, which is functionally identical to the short-circuit logical operators statement IF (x=7)&&(y=4)&&(z=2).

Dmitry Maslennikov · Dec 15, 2017

You wrong because you missed something important in the documentation. The third parameter is not about string, it is about the list of chars, and the last one the same. So, it will remove everything at the beginning if any of defined characters it will be. And order does not matter.

Write $ZSTRIP("ZZZZTESTSLOCKTEST","<","ETSZ")

return the same

If you have to remove fixed string, you can use $piece or $replace

Write $p("ZZZZTESTSLOCKTEST","ZZZZTEST",2,*)
SLOCKTEST
Dmitry Maslennikov · Dec 15, 2017

Each Application Server uses own Global Buffer plus Server Buffer, to fetch data, but the speed of the connection between those servers also matter.

If you don't care where to run so rare queries, you can do it on Database Server. ECP connection only gives a way to get access to the data in databases. And does not help to call any code on Database Server directly. And since %Net.RemoteConnection already deprecated, you can use other ways to call the main server or any other, and SOAP can be one of the ways, but I would prefer JSON Rest API, which in result will transfer fewer data.

Dmitry Maslennikov · Dec 14, 2017

To set any response header, you should overwrite OnPreHTTP method in your CSP Page class.

 Class User.Page Extends %CSP.Page
{

ClassMethod OnPage() As %Status
{
  &html<<html>
<head>
</head>
<body>>
  ; To do...
  &html<</body>
</html>>
  Quit $$$OK
}

/// Event handler for <b>PreHTTP</b> event: this is invoked before
/// the HTTP headers for a CSP page have been sent. All changes to the
/// <class>%CSP.Response</class> class, such as adding cookies, HTTP headers,
/// setting the content type etc. must be made from within the OnPreHTTP() method.
/// Also changes to the state of the CSP application such as changing
/// %session.EndSession or %session.AppTimeout must be made within the OnPreHTTP() method.
/// It is prefered that changes to %session.Preserve are also made in the OnPreHTTP() method
/// as this is more efficient, although it is supported in any section of the page.
/// Return <b>0</b> to prevent <method>OnPage</method> from being called.
ClassMethod OnPreHTTP() As %Boolean [ ServerOnly = 1 ]
{
  Do %response.SetHeader("X-MyHeader", "some info")
  quit 1
}

}

​

Dmitry Maslennikov · Dec 13, 2017

In HTTP/2 added some features which are impossible or maybe possible in Cache

  • Server Push - allows pushing some resource from server to client, at any time, in parallel 
  • Data compression for HTTP Headers. How it will be now when I will need to read headers in a request.

And other features which also important but mostly on TCP Stack, and maybe really not Cache part.

Dmitry Maslennikov · Dec 7, 2017

In the first implementation, I tried to actually build the tree. But missed something, and got some duplications in the lowest branches. Then using the same tree trying to solve second part, I found more than one unbalanced branches and a long time had not noticed how it could be until I noticed duplications. Then I removed this way, and first part becomes much simpler if just search node which does not have parents. In the second part, you actually already have a tree when you know when it started from the first part.

Dmitry Maslennikov · Dec 7, 2017

Looks like just some simple implementation for Long Pulling requests.

But how about getting not just a progress but how to get some data before task finished. 

And also, I see beg security Issue, when I can get information from any other process. You use TaskId directly from the request like you trust everybody. And also easy to get SUBSCRIPT error.

BTW: do you suppose to acept someone's answer? Looks like it is mostly just discissing topic.

Dmitry Maslennikov · Dec 6, 2017

For current process

USER>f fmt="enuw","rusw","current","" do ##class(%SYS.NLS.Format).%New(fmt) w !,fmt,?10,$zd($h,11),?15,$zd($h,12)
 
enuw      Wed  Wednesday
rusw      Сре  Среда
current   St   středa
          Wed  Wednesday

Or for all new processes, without restart

%SYS>write $zd($h,12)
Wednesday
%SYS>Set ^SYS("NLS","Config","LocaleFormat")=1
 
%SYS>write $zd($h,12)
Wednesday
%SYS>Do Locale^NLSLOAD("rusw")
 
%SYS>write $zd($h,12)
Среда