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#Caché

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InterSystems Caché is a multi-model DBMS and application server. See more details here.

Documentation.

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
· 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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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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The goal of this writing was to illustrate how to restore backup before the patch would be applied. The alert notes that:

The risk can be avoided by applying journals from the beginning of the journal file that was switched to at the start of the backup, rather than accepting the default of starting from the journal marker position.

Having non-patched Caché 2015.1.4, I ran sample database backup and restore just to get where I should answer "No". Collecting journal info from the backup log:

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Article
· Feb 2, 2016 1m read
Cache' databases as UNIX sparse files

Some third party backup products may by default restore CACHE.DAT files as UNIX sparse files when there are trailing zeroes in the backup file.

The support for sparse files vary from UNIX distribution and file system types. Sparse files attempt to use file system space more efficiently when blocks allocated to the file are mostly empty similar to thin-provisioned storage. The file system transparently converts metadata representing empty blocks into "real" blocks filled with zero bytes at runtime. The application is suppose to be unaware of this conversion.

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There have been a few use cases recently within InterSystems where we've needed to connect to Caché-based web services from PHP. The first of these was actually the Developer Community itself, which uses web services as part of Single Sign-On with other InterSystems sites/applications. The following example demonstrates how to connect to a Caché-based web service (particularly, the web service in the SAMPLES namespace) from PHP, using password authentication.

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Mirror Outage Procedures

Caché mirroring is a reliable, inexpensive and easy to implement high availability and disaster recovery solution for Caché and Ensemble-based applications. This article provides an overview of recommended procedures for dealing with a variety of planned and unplanned mirror outage scenarios.

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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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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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The Art of Mapping Globals to Classes (4 of 3)

The forth in the trilogy, anyone a Hitchhikers Guide to the Galaxy fan?

If you are looking to breathe new life into an old MUMPS application follow these steps to map your globals to classes and expose all that beautiful data to Objects and SQL.

If the above does not sound familiar to you please start at the beginning with the following:

The Art of Mapping Globals to Classes (1 of 3)

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Article
· Feb 19, 2016 2m read
Simple $system.Event examples

The attached file contains two $system.Event examples that processes work asynchronously using persistent queues:

Events_Simple

This is a very basic example that creates some worker processes and then enqueue messages to them using $system.Event.

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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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  1. Don’t use Python built into Mac. Because of System Integrity Protection (SIP) you will not be able to access the libraries that the InterSystems Python binding requires. The Python build into the MAC has baked in what libraries it can use.
  2. Install another Python. Don’t put this other ahead of Mac Python on path since this could break things. Apple regards its Python as part of the its OS, and may use that Python in its system operations.
  3. This Python will not be installed into the protected area.
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In this article I'll describe how to set up web services and/or REST services using EWD 3.

Since EWD 3 is designed to be modular, you can construct the environment that exactly meets your needs, but for much of the time you'll probably find that the pre-built EWD 3 ewd-xpress super-module does most of what you need because it hooks together all the core EWD 3 and other building-blocks you'll need:

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Interesting anecdote I want to share. Not 100% Caché related, but I hope it would be useful.

When CSP Gateway is configured on IIS, opening CSP Gateway Configuration page is prohibited by default -- as IIS blocks URLs with '/bin' in it.

In our documentation we advise to add <remove segment="bin" /> to applicationHost.config file.
That is correct.

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Article
· Nov 17, 2016 11m read
ECP and Process Management API

The technology of load balancing between several servers with relatively low capacity has been a standard feature of Caché for quite a while. It is based on the distributed cache technology called ECP (Enterprise Cache Protocol). ECP provides a host of possibilities for horizontal scaling of an application, and yet keeping the project budget fairly low. Another apparent advantage of ECP network is the possibility to conceal its architecture in the depths of Caché configuration so that applications developed for the traditional (vertical) architecture can be fairly easily migrated to a horizontal ECP environment. The ease of this process is so mesmerizing, that you start wishing it was always this way. For instance, everybody is used to having a possibility to control Caché processes: the $Job system variable and associated classes/functions work magic in skilful hands. Stop, but now processes can end up being on different Caché servers…

This article is about how to gain as much transparency in controlling processes in ECP environment as in traditional (non ECP) one.

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