Container Images

In this second post on containers fundamentals, we take a look at what container images are.

What is a container image?

A container image is merely a binary representation of a container.

A running container or simply a container is the runtime state of the related container image.

Please see the first post that explains what a container is.

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Istvan Hahn · May 16, 2016 11m read
Accelerate Ensemble

Introducing non-persistent messages. eXpert-to-eXpert


InterSystems Ensemble as a tool does a lot for the Developer. One of the nice features is the Message trace utility. It shows a message flow diagram. The diagram shows the progress of the message processing real time. You can get many-many useful information from the production. In any case, someone needs to find a bug in a production implementation, without the Message trace utility it could turn into a real nightmare. 

On the other hand, keeping message “traceability” is not for free. A heavy loaded production can very quickly run out of resources just because of the house keeping functions of Ensemble. House keeping functions such as maintaining message header, log entries, message queue generates a significant load on the Caché database used by Ensemble.

This article is about to show how to force Ensemble work more for the everyday life, instead of being prepared for “any-time-debugging”.

This is an eXpert-to-eXpert article. Therefore, I assume the deep understanding of Ensemble.

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Eduard Lebedyuk · Mar 4, 2016 7m read
Weather station on Arduino

It was InterSystems hackathon time and our team, consisting of Artem Viznyuk and me had Arduino board (one) and various parts of it (in overabundance). And so like that our course of action was set - like all other Arduino beginners, we decided to build a weather station. But with data persistent storage in Caché and visualization in DeepSee!

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We finished our last lesson with our Widgets Direct page iterating over a list of widgets, displaying an ID and a Name value.  While we have been able to achieve this with only a small amount of coding, the page itself is not the most visually appealing place to be.  The AngularJS framework is providing a powerful Model-View-Controller framework for our structure and logic, but it does not implement anything that will provide a nice UI experience.

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



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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How are we doing THIS year versus the same period LAST year? 
This is a common need in Business Intelligence. In fact, many design specifications for reports make use of a comparison between a selected period (year, quarter, etc) up to a certain date (for example November 15th, 2016) and a summary of the same information for the previous year (i.e. up to November 15th, 2015). 
This post shows how to implement this in DeepSee.

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Carter Tiernan · 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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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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Jorma Sinnamo · Nov 8, 2016 4m read
Returning Disk Space to File Systems

This is the first article in a series discussing how to regain disk space from Caché databases at the operating system level. This introductory article discusses Caché database growth and gives an overview of various methods you can use to return unused disk space that is allocated to database files back to the file system. But before we talk about returning space to the file system, let’s first review how does it get allocated in the first place.

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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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Istvan Hahn · Oct 6, 2016 4m read
RESTful Exception Handling

A beginner’s guide to Exception Handling in RESTful web services. The article gives an example how the various error conditions during processing a service request can be handled.

We expect our client – server communication working in a flawless operational condition, running error free software. But we are prepared to handle exceptions. Are we? So far in the examples of the previous sessions were not. We did not care about exceptions. The result? In any error incident it took ages to figure out what the problem is and more importantly how to fix it.

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This article was written as an attempt to share the experience of installing the InterSystems Caché DBMS for production environment.
We all know that the development configuration of a DBMS is very different from real-life conditions.
As a rule, development is carried out in “hothouse conditions” with a bare minimum of security measures, but when we publish our project online, we must ensure its reliable and uninterrupted operation in a very aggressive environment.

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John Hotalen · Oct 4, 2016 1m read
How to Parse a URL in Caché

How to parse a URL in Caché:

Let's pretend you are working on a project where you may be retrieving a URL for some purpose and you have the need to be easily able to parse apart that URL to get the various components that make up the URL.

Here's how to do that:

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Integrating Cache with .net may be difficult, as we need to know both technologies and tools involved. Let’s follow the simplest possible example and see the pitfalls lurking on our way.


1. Creating .Net Assembly


.Net assembly is unit that contains compiled code and other resources.

Let’s create the simplest .Net assembly that will contain the code we want to execute.


We will use assembly of type Class Library, as we will use classes and their methods contained within. This type of assembly has .dll extension.

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