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Aleksandar Kovacevic · Mar 27, 2019 go to post

Hello Dmitry, First of all, very nice article! Do you know, or where can I find, how exactly are the data written within each of these blocks? I would like to see kind of a byte-to-byte representation. Further, when it is being said about data being stored as a B* tree, is it meant in a sense of tree of above mentioned blocks or is there also a tree-like structure within each of the blocks? For example, if I search for ^C(9996,46, yellow), I would jump to block #1346 and from there on I will iterate through each element of the block until I get to ^C(9996,46,yellow). Is this correct?

Aleksandar Kovacevic · Apr 3, 2019 go to post

Hey Eduard,

The code I sent you, which communicates with OPC UA Server is example for binary protocol (opc.tcp://Server). However, as a new version of old OPC, focus was to make old OPC more available to new trends. Therefore, by standard, each OPC UA server should be able to communicate also as a web service (http://Server). However, I could not find much of the OPC UA servers that offer Web Service capability. Maybe some commercial implementations.

OPC UA is organized similarly to Service Oriented Architecture (SOA) Standard, with a secure channel.

OPC UA Java Library that I use in my PoC implementation has whole stack implemented. It connects to the OPC UA Server, downloads certificates required for communication, and creates the secure channel to communicate with the server. There are two main messages: Browse Request und Read Service Request. The data on OPC UA server are organized in form of a tree, where every node has different types; metadata, attribute, variable, etc. Read Service Request is very sensitive about node types.

I used https://github.com/OPCFoundation/UA-Java-Legacy repository as a basis to build Java Business Host, but this repo is not maintained, so if there are some newer versions of the standard, this repository might not be up to date anymore.

Aleksandar Kovacevic · Apr 4, 2019 go to post

What I saw from the implementations so far, binary TCP communication is somehow preferred way because it is more optimised (no bulky soap messages sent over), but in theory, standard says it should be possible.

Aleksandar Kovacevic · Apr 10, 2019 go to post

Hello Jose,

Taking into account only the amount of complexity of OPC UA standard, I could imagine it might need a bit more time to have it implemented natively. I am not much experienced in COS to be able to estimate that, but I would say quicker solution is still JBH+external library. I will work further on this (hopefully temporal) JBH solution.

Aleksandar Kovacevic · Jun 17, 2019 go to post

Hey Murillo,

As for the 1st thing, Match() method only returns true if the whole string is matching regular expression. In your case, it is not so, as there are multiple > in between.

Groups are in the regular expression defined with ( ), and are not meant for iterations in the way you expect. For example below, I am trying to extract every <ABC> DEF </ABC>

Set tRegEx = "<([^>]*)>([^<]*?)</([^>]*)>"
Set htmlSnippet = "<h1>Hello1</h1><h1>Hello2</h1>"
Set regex=##class(%Regex.Matcher).%New(tRegEx,htmlSnippet)

while regex.Locate() {  
	WRITE "BANG MATCH" 
	for i=1:1:regex.GroupCount { 
		WRITE i_" - "_regex.Group(i) 
		} 
	}
Aleksandar Kovacevic · Mar 13, 2020 go to post

Extremely uneducated question:

If we have a global with its nice tree structure (like for example that Persons tree built in Globals Introduction by InterSystems Learning Services) without specific schema (e.g. class definition), would graphql be able to be used to make specific condition/wild-card based queries?

Aleksandar Kovacevic · Apr 26, 2020 go to post

So this means, that when you create a Person class, while it is in memory, you can define in which global should it be stored, regardless of the namespace?
This way you can dynamically choose where you want to save it. That sounds cool!

Aleksandar Kovacevic · Dec 1, 2021 go to post

I agree with you Guillaume, Objectscript is very powerful language and more you know it, more you get to realize just how powerful it is. But this comes with a years and years of experience. This experience is harder and harder to find nowadays in the market. That is why when talking about programming languages, the world has moved on from creating proprietary languages in favor of standardized ones, exactly for that reason. If you know the language already, it will take you much less time to get up to speed.

Having Embedded Python there as a equal to Objectscript allows IRIS Data Platform to get much better attention from the developer community world-wide, exactly the one it finally deserves.
 

Aleksandar Kovacevic · Dec 25, 2021 go to post

Thanks very much for this message. Do you know what can I do if I get error: "ERROR #345: Cannot dismount manager's database" when trying to dismount IRISLIB. Is there a way to dismount it programmatically, without using Management Portal?
Edit: ah, I just need to do %Save, and it is done without needing to dismount and mount again.