APM normally focuses on the activity of the application but gathering information about system usage gives you important background information that helps understand and manage the performance of your application so I am including the IRIS History Monitor in this series.

In this article I will briefly describe how you start the IRIS or Caché History Monitor to build a record of the system level activity to go with the application activity and performance information you gather. I will also give examples of SQL to access the information.

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In the first article I started discussing RESTForms - REST API for your persistent classes. We talked about basic features, now, I'd like to discuss advanced features - mainly queries capabilites:

  • Basic queries
  • Query arguments
  • Custom queries

Queries

Queries allow getting slices of data, based on arbitrary criteria. There are two query types in RESTForms:

  • Basic queries work for all RESTForms classes once defined and they differ only by the field list
  • Custom queries work only for the classes in which they are specified and available, but the developer has full access to query text
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Greetings! This article describes yet another simple way of creating installers for the solutions based on InterSystems Caché. The topic covers applications, which can be installed or completely removed from Caché with one action only. If you are still documenting installation instructions that have more than one step to do to install your application — it’s high time you automated this process.

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Hello.

The idea of this post is to introduce Frontier: An abstraction layer that allows Rapid REST development.

REQUIREMENTS:

Why?

Have you ever found yourself dealing with repetitive tasks like mounting objects, serializing them and eventually handling multiple errors for multiple cases? Frontier can boost your development by making you focus on what really matters: your application.

Frontier is made to stop you from WRITE'ing by instead forcing your methods to return values.
It's designed to make you code clean, and you'll see the why pretty soon.

This is the Part 1, where you'll learn he basics about how to work with Frontier. That means at the end of this part you should be capable of

creating GET requests without difficulties. Since this also serves as a way to introduce the framework, I'll be calling this part: Core concepts.

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If I have defined a class query in one of my classes and I want to use that query from a method of another class, what are the pros and cons of using the %SQL.Statement interface versus the %Library.ResultSet interface?

I believe %SQL.Statement is the newer interface.

So if the old way is:

USER>s rs=##class(%Library.ResultSet).%New("%Library.File:FileSet")
 
USER>s sc=rs.Execute("c:\s\","*.txt")
 
USER>w sc
1
USER>while rs.%Next() {w !,rs.Data("Name")}

...

then the new way is:

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This is the first article of a series diving into visualization tools and analysis of time series data. Obviously we are most interested in looking at performance related data we can gather from the Caché family of products. However, as we'll see down the road, we are absolutely not limited to that. For now we are exploring python and the libraries/tools available within that ecosystem.

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Article
· Dec 22, 2016 2m read
The Polymetric Dashboard

> Customizable System Monitoring. ## Introduction The Polymetric Dashboard is a stand-alone module that provides enhanced monitoring tools for a Caché environment. Equipped with over one hundred sensors that monitor key system metrics, a robust REST API, and a modular AngularJS user interface, the Polymetric Dashboard is fully functional out of the box. However, the Polymetric Dashboard is designed to be customizable; any system metric can be monitored by creating a new sensor, and the visualization of collected data can be tailored to specific requirements and purposes.

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Article
· Dec 7, 2017 3m read
Asynchronous REST

In this article I'd like to discuss asynchronous REST and approaches to implementing it.

Why do we need asynchronous REST? Simply put - answering the request takes too much time. While most requests usually can be satisfied immediately, some can't. The reasons are varied:

  • You need to perform time-consuming calculations
  • Performing action actually takes time (for example container creation)
  • etc.

The solution to these problems is asynchronous REST. Asynchronous REST works by separating request and real response. Here's an example, let's consider the following simple async REST broker:

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Article
· May 26, 2016 1m read
Windows, Caché and virus scanners

I have seen a customer problem recently where the use of a virus scanner running over Caché databases was causing intermittent application slow downs and bad user response times.

This is a surprisingly common problem, so this short post is just a reminder to exclude key Caché components from your virus scanning.

Generally virus scanning must exclude the CACHE.DAT database files and Caché binaries. If an anti-virus is scanning CACHE.DATs and InterSystems files then system performance will be significantly impacted.

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Article
· Mar 4, 2016 1m read
Getting my head around a class model

There's plenty of goodness in the %-packages InterSystems supplies, and it seems that every new version of Caché brings something new. The browser-based class documentation (a.k.a. Documatic) generally provides a good level of information, but on the basis that "a picture is worth a thousand words" I sometimes want a diagram.

For example, when trying to navigate the %Dictionary package for a project that needed to find out about class definitions, here's one of the UML class diagrams I created.

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Article
· Jun 12, 2017 1m read
Setting the Windows service account

I recently helped a site investigate a problem that appeared after they upgraded their Windows instance of Caché from 2015.1 to 2017.1. A terminal session launched from the server's desktop cube was unable to run OS-level commands using the $ZF(-1) function. For instance, using the no-op command "REM" as follows:

write $zf(-1,"rem")

was returning -1, indicating that the Windows command could not be issued.

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Whether you are accessing DeepSee for the first time ever or you are configuring DeepSee on a new instance, there are two common issues that are encountered after clicking on the “DeepSee” option in the System Management Portal.

Issue #1: Architect/Analyzer is grayed out!

Issue #2: DeepSee must be enabled before use.

Issue #1: Architect/Analyzer is grayed out!

There are two common causes for this problem.

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Article
· Apr 12, 2017 5m read
Bug killing development tips

Does anyone NOT use a debugger? I can't remember the last time I did. It's not because I don't dislike them, I just don't need to use them. The main reason for this is because I have a certain development methodology that either produces less bugs, catches them at a unit test level, or makes tracking them down much easier.

Here are my tips...

1. Write your own COS cheat-sheet.

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Importance and Collection of Exact Version Information ($zv / $zversion)
The explanation of:
- why collecting $zv is important (The WHY),
- what the components of $zv mean (The WHAT),
- and how to collect $zv (The HOW).
(The Ultimate $zv Guide to the ISC Galaxy in large, friendly letters)
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or "Didn't you say you would cover Persistent Objects in Part 5, Chris?"

Yes, that was the plan. This is a pretty important topic, so it get's its own Article

Up until now, we've display widget JSON that has been created by a basic loop. Clearly this isn't of much value. Now we have our stack connected together, and we can see that the data is flowing to the Welcome page, it's time to complete the stack and start feeding our service from "real" data.

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If a picture is worth a thousand words, what's a video worth? Certainly more than typing a post.

Please check out my "Coding talks" on InterSystems Developers YouTube:

1. Analysing InterSystems IRIS System Performance with Yape. Part 1: Installing Yape

https://www.youtube.com/embed/3KClL5zT6MY
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Running Yape in a container.

2. Yape Container SQLite iostat InterSystems

https://www.youtube.com/embed/cuMLSO9NQCM
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Extracting and plotting pButtons data including timeframes and iostat.

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Article
· Mar 3, 2016 2m read
Class Projections and Projection Classes

The purpose of this post is to raise the profile of a powerful mechanism that has long been available to us, and to open a discussion about ways in which it can be used or abused.

You can read more detail about the mechanism here. To summarize, your class definition can use the Projection keyword to reference one or more projection classes. A projection class can implement methods that get invoked at key points in the lifecycle of your class.

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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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Article
· Jul 4, 2016 8m read
Introduction to the iKnow REST APIs

After a five-part series on sample iKnow applications (parts 1, 2, 3, 4, 5), let's turn to a new feature coming up in 2017.1: the iKnow REST APIs, allowing you to develop rich web and mobile applications. Where iKnow's core COS APIs already had 1:1 projections in SQL and SOAP, we're now making them available through a RESTful service as well, in which we're trying to offer more functionality and richer results with fewer buttons and less method calls. This article will take you through the API in detail, explaining the basic principles we used when defining them and exploring the most important ones to get started.

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