Article
· Mar 19, 2019 9m read
A Tutorial On WebSockets

Intro

Most server-client communication on the web is based on a request and response structure. The client sends a request to the server and the server responds to this request. The WebSocket protocol provides a two-way channel of communication between a server and client, allowing servers to send messages to clients without first receiving a request. For more information on the WebSocket protocol and its implementation in InterSystems IRIS, see the links below.

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For some years I missed being able to offer, to everybody interested in ObjectScript, a tutorial more or less complete, to start with ObjectScript. Something that could help more and make things easier to those new developers that come to our technology... something intermediate, halfway between the common "Hello World!", that doesn't really get you further, and the "Advanced Training", that is unaffordable because of lack of time,etc.

If there were something truly helpful not only as an introduction to the ecosystem, but as a starting point, as a boost, to really start to walk into ObjectScript and move forward by yourself... wouldn't that be awesome?

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Article
· May 20, 2016 12m read
Collations in Caché

Order is a necessity for everyone, but not everyone understands it in the same way
(Fausto Cercignani)

Disclaimer: This article uses Russian language and Cyrillic alphabet as examples, but is relevant for anyone who uses Caché in a non-English locale.
Please note that this article refers mostly to NLS collations, which are different than SQL collations. SQL collations (such as SQLUPPER, SQLSTRING, EXACT which means no collation, TRUNCATE, etc.) are actual functions that are explicitly applied to some values, and whose results are sometimes explicitly stored in the global subscripts. When stored in subscripts, these values would naturally follow the NLS collation in effect (“SQL and NLS Collations”).

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Article
· Jul 8, 2020 7m read
Tips for debugging with %Status

Introduction

If you're solving complex problems in ObjectScript, you probably have a lot of code that works with %Status values. If you have interacted with persistent classes from an object perspective (%Save, %OpenId, etc.), you have almost certainly seen them. A %Status provides a wrapper around a localizable error message in InterSystems' platforms. An OK status ($$$OK) is just equal to 1, whereas a bad status ($$$ERROR(errorcode,arguments...)) is represented as a 0 followed by a space followed by a $ListBuild list with structured information about the error. $System.Status (see class reference) provides several handy APIs for working with %Status values; the class reference is helpful and I won't bother duplicating it here. There have been a few other useful articles/questions on the topic as well (see links at the end). My focus in this article will be on a few debugging tricks techniques rather than coding best practices (again, if you're looking for those, see links at the end).

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In this article you will have access to the curated base of articles from the InterSystems Developer Community of the most relevant topics to learning InterSystems IRIS. Find top published articles ranked by Machine Learning, Embedded Python, JSON, API and REST Applications, Manage and Configure InterSystems Environments, Docker and Cloud, VSCode, SQL, Analytics/BI, Globals, Security, DevOps, Interoperability, Native API. Learn and Enjoy!

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Article
· Dec 23, 2015 1m read
Caché ObjectScript Quick Reference

In the Caché Foundations course, students are learning about Caché Development and ObjectScript syntax at the same time. To help students complete the exercises, we provide an ObjectScript Quick Reference (aka "the Cheat Sheet").

It is not a reference for all of ObjectScript! It is a list of the ObjectScript commands and functions that students use during the course, along with common syntax for objects, collections, etc. It also contains some useful macros.

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Hi Developers, I'm currently doing a demo about building a front end UI doing data analytics and setup a performance test with large data objects, therefore using "Populate Utility" could help me auto generate some sample data that I can play with.

Within this post I would like to share my experience of using Populate Utility, including using POPSPEC Parameter.

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Terminal scripts can be used to run pre-designed commands on the terminal, like a batch file. You can write anything that can be executed on terminal, like for loop, if else and so on, inside Terminal scripts. In this article, I will show you how to call Terminal scripts, how to use parameters in Terminal scripts and how to avoid session disconnected when running Terminal scripts. If you have any information about how to use Terminal scripts or you have any feedback, please feel free to leave a comment.

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Article
· Sep 13, 2018 1m read
Find a table given its name

The following code snippet includes a class method "test" that runs code to find a class based on the class's name. "test" takes one argument, which is the name of the table:


Class objectscript.findTable Extends %RegisteredObject
{
    classmethod test(name as %String="mytable")  
    {
            #Dim result as %ResultSet
            #Dim tName as %String
            #Dim contain as %Integer
     
            Set contain=0
            Set result = ##class(%ResultSet).%New("%Dictionary.ClassDefinition:Summary")
            Do result.Execute()

            While(result.Next()) 
            {
                Set tName=$get(result.Data("Name"))
                &sql(select position (:name in :tName) into :contain)
                Write:contain'=0 tName, " ... ", name, " (", contain,")", !
            }
            Return $$$OK
     }
}

Here's a link to the code on GitHub

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Article
· Jul 25, 2019 1m read
Disabling an Ensemble Production

I'm not saying that this is in anyway "best practices," but I'm in a peculiar situation where I need to restrict users from starting a "retired" Ensemble Production in a namespace that's been renamed. It's still an "Ensemble-activated" namespace; we need to keep it available for Ensemble Message Viewer access ... fortunately, only for a little while.

It's a bit of a hack ...

Open the Production class in Studio and add the following classmethod:

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Sometimes, we need to copy part of the properties of an object into a different one.
The simplest thing would be to do the following:

Set obj1.FirstName = obj2.FirstName

Set obj1.SecondName = obj2.SecondName

What happens if the object contains a large number of properties? or we just want to extract an important group of data, and complement the information in another object?

Having the following classes:

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Some time ago I got a WRC case transferred where a customer asks for the availability of a raw DEFLATE compression/decompression function built-in Caché.

When we talk about DEFLATE we need to talk about Zlib as well, since Zlib is the de-facto standard free compression/decompression library developed in the mid-90s.

Zlib works on particular DEFLATE compression/decompression algorithm and the idea of encapsulation within a wrapper (gzip, zlib, etc.).
https://en.wikipedia.org/wiki/Zlib

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Article
· Aug 2, 2020 1m read
Application Errors Analytics

Hi Developers!

As you know the application errors live in ^ERRORS global. They appear there if you call:

d e.Log() 

in a Catch section of Try-Catch.

With @Robert Cemper's approach, you can now use SQL to examine it.

Inspired by Robert's module I introduced a simple IRIS Analytics module which shows these errors in a dashboard:

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EDIT: This article has been updated with up-to-date information about the Port project, which now includes a tutorial for basic usage.

The Port project is something that I've introduced more than two years ago but I hadn't enough room to elaborate a tutorial on how to use it till now.


First, the motivation:

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Article
· Mar 4, 2022 4m read
How to become a time lord - Time travel

Time travel is like visiting Paris. You can't just read the guide, you have to throw yourself into it. Eat the food, use the wrong verbs, get double the charges, and end up kissing complete strangers.

The Doctor

We are now going to travel through time, that is, we are going to see future and past dates and how to calculate them in different formats. The TARDIS doesn't wait, take the controls and hold on tight.

Travel in TARDIS

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Introduction

Visual Studio Code (VS Code) is a free source code editor made by Microsoft for Windows, Linux, and macOS. It provides built-in support for JavaScript, TypeScript, and Node.js. You can add extensions to provide support for numerous other languages including ObjectScript.

The InterSystems extensions enable you to use VS Code to connect to an InterSystems IRIS server and develop code in ObjectScript. The Visual Studio Code Documentation is an excellent resource on VS Code, so it is a good idea to be familiar with it.

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Hi developers!

Just want to share an old but always relevant best practice on namespaces changing @Dmitry Maslennikov shared with me (again).

Consider method:

classmethod DoSomethingInSYS() as %Status

{

set sc=$$$OK

set ns=$namespace

zn "%SYS"

// try-catch in case there will be an error

try {

// do something, e.g. config change

}

catch {}

 zn ns    ; returning back to the namespace we came in the routine

return sc

}

And with new $namespace the method could be rewritten as:

classmethod DoSomethingInSYS() as %Status

{

set sc=$$$OK

new $namespace

set $namespace="%SYS"

// do something

return sc

}

So! The difference is that we don't need to change the namespace manually as it will be back automatically once we return the method.

and we don't need try-catch (at least for this purpose) too.

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Article
· May 7, 2020 4m read
Unit Testing with ZPM

Hi Developers!

I want to share with you the approach you can use working with Unit Testing which I personally find very convenient and robust.

Will not talk much here about Unit Testing, we have documentation, enough good articles on the topic not only on the Internet but here on Developers Community too, e.g. this one.

How can you manage the Unit Testing of your ZPM module?

This is pretty handy with ZPM. It has a special command "test" which runs all the tests you mentioned in the module. You can execute it as shown below:

zpm:USER>module-name test

And this command runs all the tests you mentioned in module.xml.

Let's see how it works.

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*** archived ***

The question has come up several times and I saw mixed answers and no quick example

My personal preference is using CPIPE device as you get back exactly the output you will get at the command line interface of your OS .
The tricky thing is to stop reading in time.
The example just displays what you normally see in your console.
it becomes useful if you look for things that you can't get from any $system.whatever()

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Article
· Mar 28, 2019 2m read
ObjectScript error handling snippets

ObjectScript has at least three ways of handling errors (status codes, exceptions, SQLCODE, etc.). Most of the system code uses statuses but exceptions are easier to handle for a number of reasons. Working with legacy code you spend some time translating between the different techniques. I use these snippets a lot for reference. Hopefully they're useful to others as well.

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