Article
· Nov 1, 2016 9m read
Reflection in Caché

The topic of reflection hasn't been raised in Caché forums or blogs too often. Perhaps, it happened because the notion of reflection is not explicitly defined in Caché. However, it exists in Caché and can be a very useful development tool.

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This text is a continuation of my article where I explained the structure a Caché database. In this article, I described the types of blocks, connections between them and their relation to globals. The article was purely theoretical. I made a project that helps visualize the block tree - and this article will explain how it works in great detail.

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Article
· Jul 14, 2016 1m read
Caché Haiku

Alex Koblov posted today a #CachéHaiku:

Full command names

Make your code more readable

Than compact versions

My haiku:

Caché Globals

Shows you keys to the value

If you $order it

Your variant? ;)

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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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Article
· Oct 7, 2016 4m read
Forwarding Requests in a REST Service

One useful feature of our REST framework is the ability for a dispatch class to identify request prefixes and forward them to another dispatch class. This approach of modularizing your URL map will improve code readability, enable you to easily maintain separate versions of an interface, and provide a means to protect API calls that only certain users will be allowed to access.

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A group of students at the Chalmers University of Technology (Gothenburg, Sweden) tried different approaches to automatically rating the quality of emergency calls, including iKnow.

Excerpt: "The most impressive results produced by iKnow is its ability to correctly classify 100% of the calls using the Average algorithm. This is quite surprising since iKnow only compares low-level concepts, how words relates to each other."

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Article
· Dec 12, 2016 3m read
Generate and Validate Captcha Code

Suppose you have developed your own web app with InterSystems technologies stack and now want to perform a captcha validation on the client side in order to determine whether or not the user is human and make it safer. There are some modern frameworks to address the captcha issue, however most part of them needs internet access to generate codes and sometimes are complex to implement. Take this as basic example considering that image recognition has gotten too good. That's why you nowadays you tend to see more pattern recognition captchas than mere reading ones. (I.e.

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This post is meant to provide a quick possible explanation for a very perplexing problem.

Scenario: You’ve just created your own administrative user in your 2014.1 (or later) instance of Caché. You gave it every possible security role (including %All), so it should in theory be able to do anything within the instance.

You’ve written a very advanced routine with a break command in it for debugging:

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Article
· Jul 18, 2016 15m read
Remote proxy objects via dynamic dispatch

This article created as side effect of preparations to the longer set of articles about simple, but still handy MapReduce implementation in Caché. I was looking for relatively easy way to pass arguments to (potentially) multiple targets via remote calling facilities. And after several attempts I have realized that we do have very powerful mechanism in the Caché ObjectScript which might be of particular help here – dynamic dispatch for methods and properties.

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After reading Stephen Wilson's article "Windows 7 performs shutdown too fast for Cache to close and so it gets forced down" I've recalled another solution that was based on Local Group Policy, which allows to control extra actions that should occur on computer startup or shutdown. How to add a computer shutdown script is well documented in MS Technet article.

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Article
· Feb 17, 2016 3m read
Listing files in folder

Question:

How do I get a list of files residing in a certain folder/directory, according to some wildcard/filter.

For example all '*.txt' files in 'C:\Temp'.

Answer:

In CACHE –

You can use the %Library.File's FileSet class query.

Here's some sample code using it (also attached):

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Article
· 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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At Global Summit back in April, in his keynote speech, John Paladino mentioned that improvements to our documentation search were being made. You might have wondered, since things seemed to go quiet, whether anything was really happening. Well, we had an internal demo of some of the upcoming features recently, and the new capabilities look really cool – searching documentation has been frustrating for InterSystems staff too! So, I thought it might be good to pass on a few details to give a taste of what is coming. Of course, InterSystems will be putting together much better information

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** Revised Feb-12, 2018

While this article is about InterSystems IRIS, it also applies to Caché, Ensemble, and HealthShare distributions.

Introduction

Memory is managed in pages. The default page size is 4KB on Linux systems. Red Hat Enterprise Linux 6, SUSE Linux Enterprise Server 11, and Oracle Linux 6 introduced a method to provide an increased page size in 2MB or 1GB sizes depending on system configuration know as HugePages.

At first HugePages required to be assigned at boot time, and if not managed or calculated appropriately could result in wasted resources. As a result various Linux distributions introduced Transparent HugePages with the 2.6.38 kernel as enabled by default. This was meant as a means to automate creating, managing, and using HugePages. Prior kernel versions may have this feature as well however may not be marked as [always] and potentially set to [madvise].

Transparent Huge Pages (THP) is a Linux memory management system that reduces the overhead of Translation Lookaside Buffer (TLB) lookups on machines with large amounts of memory by using larger memory pages. However in current Linux releases THP can only map individual process heap and stack space.

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I am pleased to announce the field test of Caché and Ensemble 2016.3 - with many new improvements.

The product team at InterSystems looks forward to your participation in the field test and feedback over the coming months.

Some of the more signification changes in 2016.3 are new RESTful APIs for iKnow and broader APIs for programmatic control of multiple servers (enterprise manager). As always, there are a host of scalability and performance improvements, including improvements to the core database and SQL. And hundreds of smaller improvements and corrections.

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Hi!

Want to share with you code snippet of try catch block I usually use in methods which should return %Status.


{ 
 try {
  	$$$TOE(sc,StatusMethod())
 }
 catch e {
 	set sc=e.AsStatus()
 	do e.Log()
 }

Quit sc 
}

Here $$$TOE is a short form of $$$TROWONERROR macro.

Inside macro StatusMethod is any method you call which will return %Status value. This value will be placed into sc variable.

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Article
· Jun 21, 2016 1m read
Simple Cache systemd Unit

Hello

I have noticed that Cache (2016.1 at the time of writing) doesn't come with a systemd startup script for RHEL7.

Here is a small example script I have built.

[Unit]
Description=Intersystems Cache

[Service]
Type=forking
ExecStart=/bin/bash -c '/usr/cachesys/cstart 2>&1 | logger -t cache_start'
ExecStop=/bin/bash -c '/usr/cachesys/cstop quietly 2>&1 | logger -t cache_stop'
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target

The file should be placed as /usr/lib/systemd/system/cache.service

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I was recently asked whether we have a function to convert LDAP date time stamps into $HOROLOG format or other formats and the answer is not at the moment, but there is a simple method to do the conversion.

Let us look at the facts and figures involved...

1) Active Directory's (AD) date 0 (zero) is 1601-01-01 00:00:00.000 or January 1st, 1601 at midnight (00:00:00)

2) AD timestamps are calculated as the number of 100 nanosecond intervals from date 0

3) 864000000000 is the number of 100 nanosecond intervals per day

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Here you have an easy way to write and execute COS code from your unix scripts. This way one does not need to write routines or even open Studio or Atelier. It can be an option for simple and small actions for instance things like installation tasks or compiling.

See sample bash script (compile.sh) to compile classes:

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Caché Localization Manager

CLM is a tool for localization/internationalization/adding multi-language support to a project based on InterSystems Caché.

Imagine that you have a ready project where all the content is in Russian, and you need to add an English localization to it. You wrap all your strings into resources, translate them into English and call the necessary resource for Russian or English when necessary. Nothing tricky, if you think about it. But what if there are lots of strings and there are mistakes in Russian (or English)? What if you need to localize in more than one language – say, ten? This is exactly the kind of project where you should use CLM. It will help you localize the entire content of your project into the necessary language and retain the possibility to correct entries.

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Article
· Mar 10, 2016 2m read
New Book, Caché and MUMPS – Part II

New Book, Caché and MUMPS – Part II

By Paul Mike Kadow

Edited by Deborah Graham and John J. Mitchell

Go to http://cosmumps.org for a download of just the examples of the book and the table of contents.

From the Forward

InterSystems, from a humble beginning, has grown into a worldwide company with its flagship product, Caché, leading the way.

First, this book chronicles and explores some of the many areas InterSystems has grown into and has influenced over the years.

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