Caché

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In recent discussion on CachéQuality I was (friendly) blamed for old syntax promotion and deliberate obfuscation of the code. Therefore I decided to clarify my point and shed some light on one of possible source of side effects that may unexpectedly occur with RETURN command with an argument.

Last comment 15 March 2019
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InterSystems Data Platform includes utilities and tools for system monitoring and alerting, however System Administrators new to solutions built on the InterSystems Data Platform (a.k.a Caché) need to know where to start and what to configure.

This guide shows the path to a minimum monitoring and alerting solution using references from online documentation and developer community posts to show you how to enable and configure the following;

  1. Caché Monitor: Scans the console log and sends emails alerts.

  2. System Monitor: Monitors system status and resources, generating notifications (alerts and warnings) based on fixed parameters and also tracks overall system health.

  3. Health Monitor: Samples key system and user-defined metrics and compares them to user-configurable parameters and established normal values, generating notifications when samples exceed applicable or learned thresholds.

  4. History Monitor: Maintains a historical database of performance and system usage metrics.

  5. pButtons: Operating system and Caché metrics collection scheduled daily.

Remember this guide is a minimum configuration, the included tools are flexible and extensible so more functionality is available when needed. This guide skips through the documentation to get you up and going. You will need to dive deeper into the documentation to get the most out of the monitoring tools, in the meantime, think of this as a set of cheat sheets to get up and running.

Last comment 11 March 2019
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I know it's late, but I really love the advent of code theme each year to find some project ideas to go out and code something and push myself.

I had the intentions of completing the AOC 2018 before the new year, but I've got 2 young kids (1yo and 4yo), so most nights I just want to sleep.

I've been looking at this on my half hourly commute each day before and after work.

So whilst doing this, I found not many people had posted what they had done and in previous years.

Last comment 4 March 2019
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In this series of articles, I'd like to present and discuss several possible approaches toward software development with InterSystems technologies and GitLab. I will cover such topics as:

  • Git 101
  • Git flow (development process)
  • GitLab installation
  • GitLab Workflow
  • Continuous Delivery
  • GitLab installation and configuration
  • GitLab CI/CD

In the previous article, we covered Git basics, why a high-level understanding of Git concepts is important for modern software development, and how Git can be used to develop software. Still, our focus was on the implementation part of software development, but this part presents:

  • GitLab Workflow - a complete software life cycle process - from idea to user feedback
  • Continuous Delivery - software engineering approach in which teams produce software in short cycles, ensuring that the software can be reliably released at any time. It aims at building, testing, and releasing software faster and more frequently.

Last comment 1 March 2019
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Hi guys,

 

Couple days ago, a customer approached me with the wish to enhance their existing legacy application, that uses SOAP (Web)Services so it shares the same authorization with their new application API based on REST. As their new application uses OAuth2, the challenge was clear; how to pass access token with SOAP request to the server.

After spending some time on Google, it turned out, that one of possible ways of doing so was adding an extra header element to the SOAP envelope and then making sure the WebService implementation does what is needed to validate the access token.

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WebSockets as a communication technology wins increasing importance.
In the SAMPLES namespace, you find a nice example for running a WebSocket Server.
There is also a useful example for a Browser Client. But it is still in the browser. 

My point is:
How to consume the output of a WebSocket Server in your application?

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WebSockets as a communication technology wins increasing importance.
In the SAMPLES namespace, you find a nice example for running a WebSocket Server.
There is also a useful example for a Browser Client. JavaScript does most of the work. 

My point is:
How to consume the output of a WebSocket Server in your application?

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Intro

 

Please note, this article is considered deprecated, check out the new revision over here: https://community.intersystems.com/post/tutorial-websockets

The goal of this post is to discuss working with Websockets in a Caché environment. We are going to have a quick discussion of what websockets are and then talk through an example chat application implemented on top of Websockets.

Last comment 28 January 2019
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GraphQL is a standard for declaring data structures and methods of data access that serves as a middleware layer between the client and the server. If you’ve never heard about GraphQL, here is a couple of useful online resources: here, here and here.

In this article, I will tell you how you can use GraphQL in your projects based on InterSystems technologies.

Last comment 22 January 2019
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Headache-free stored objects: a simple example of working with InterSystems Caché objects in ObjectScript and Python

Neuschwanstein Castle

Tabular data storages based on what is formally known as the relational data model will be celebrating their 50th anniversary in June 2020. Here is an official document – that very famous article.  Many thanks for it to Doctor Edgar Frank Codd. By the way, the relational data model is on the list of the most important global innovations of the past 100 years published by Forbes.

On the other hand, oddly enough, Codd viewed relational databases and SQL as a distorted implementation of his theory.  For general guidance, he created 12 rules that any relational database management system must comply with (there are actually 13 rules). Honestly speaking, there is zero DBMS's on the market that observes at least Rule 0. Therefore, no one can call their DBMS 100% relational :) If you know any exceptions, please let me know.

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This is a quick note on what happens when, on your CSP page, you call a cache script which returns a %Boolean and store that value in a javascript variable.

When you call a script with language="cache" and returntype="%Boolean" from a javascript script, the return value is interpreted as a string, not as a boolean.

Here's an example:

A cache script that returns (in theory) a "false" value:

Last comment 16 January 2019
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This code snippet sends an XML request to a server and saves the response to a file. The class method "test" runs the code:


Class objectscript.postXML
{
    classmethod test() {
        Set HTTPRequest = ##class(%Net.HttpRequest).%New()
        Set HTTPRequest.ContentType = "text/xml"
        Set HTTPRequest.NoDefaultContentCharset = 1
        Set HTTPRequest.Location = "ITOMCZ"
        Set HTTPRequest.Server = "wph.foactive.com"
        Do HTTPRequest.RemoveHeader("User-Agent")  
        Do HTTPRequest.RemoveHeader("Accept-Encoding") 
        Do HTTPRequest.RemoveHeader("Connection")
        Do HTTPRequest.SetHeader("Expect","100-continue")
     
        Set RequestXML = ##class(%Library.File).%New("c:\test.xml")
        Do RequestXML.Open("RS")
        Do HTTPRequest.EntityBody.CopyFrom(RequestXML)
        Do RequestXML.%Close()
     
        Do HTTPRequest.Post(HTTPRequest.Location)
     
        Do $System.OBJ.Dump(HTTPRequest)
        Do $System.OBJ.Dump(HTTPRequest.HttpResponse)
     
        Write HTTPRequest.HttpResponse.Data.Size
        Write HTTPRequest.ContentLength
     
        Set ResponseStream = ##class(%Stream.FileBinary).%New()
        // Second part is typically the file extension, i.e.: application/pdf -> pdf
        Set FileType = $Piece(HTTPRequest.HttpResponse.GetHeader("CONTENT-TYPE"),"/",2)
        Set ResponseStream.Filename = "C:\test."_FileType
     
        Write ResponseStream.CopyFrom(HTTPRequest.HttpResponse.Data)
     
        Write ResponseStream.%Save()
        Do ResponseStream.%Close()
    }
}

Here's a link to the code on GitHub

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This is a posting about a particular feature of Caché which I find useful but is probably not well known or used. I am referring to the feature of Language Extensions.

This feature allows you to extend the commands, special variables and functions available in Caché Object Script with commands, special variables and functions of your own. This functionality also applies to other languages the Caché supports at the server, including Caché Basic and Multivalue Basic.  


Why would I need or want to add new commands ?

Last comment 11 January 2019
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This post is intended to guide you through the new JSON capabilities that we introduced in Caché 2016.1. JSON has emerged to a serialization format used in many places. The web started it, but nowadays it is utilized everywhere. We've got plenty to cover, so let's get started.

Last comment 11 January 2019
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Astronomers’ tools

5 years ago, on December 19, 2013, the ESA launched an orbital telescope called Gaia. Learn more about the Gaia mission on the official website of the European Space Agency or in the article by Vitaly Egorov (Billion pixels for a billion stars).

However, few people know what technology the agency chose for storing and processing the data collected by Gaia. Two years before the launch, in 2011, the developers were considering a number of candidates (see “Astrostatistics and Data Mining” by Luis Manuel Sarro, Laurent Eyer, William O’Mullane, Joris De Ridder, pp. 111-112):

Comparing the technologies side-by-side produced the following results (source):

TechnologyTime
DB213min55s
PostgreSQL 814min50s
PostgreSQL 96min50s
Hadoop3min37s
Cassandra3min37s
Caché2min25s

The first four will probably sound familiar even to schoolchildren. But what is Caché XEP?

Last comment 9 January 2019
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There's a new and exciting enhancement to QEWD that has just been released - it's an additional layer of abstraction known as QEWD-Up.  QEWD-Up hides away all the mechanics of QEWD itself, allowing you to focus on just your REST APIs and the code that implements them.

Additionally, and importantly, QEWD-Up simplifies the maintenance of your REST APIs, allowing you (and others) to quickly and easily understand their life-cycle and implementation.

Last comment 2 January 2019
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As we all know, Caché is a great database that accomplishes lots of tasks within itself. However, what do you do when you need to access an external database? One way is to use the Caché SQL Gateway via JDBC. In this article, my goal is to answer the following questions to help you familiarize yourself with the technology and debug some common problems.

Last comment 28 December 2018
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