#Caché

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)

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.

Order is a necessity for everyone, but not everyone understands it in the same way
(Fausto Cercignani)

Disclaimer: This article uses Russian language and Cyrillic alphabet as examples, but is relevant for anyone who uses Caché in a non-English locale.
Please note that this article refers mostly to NLS collations, which are different than SQL collations. SQL collations (such as SQLUPPER, SQLSTRING, EXACT which means no collation, TRUNCATE, etc.) are actual functions that are explicitly applied to some values, and whose results are sometimes explicitly stored in the global subscripts. When stored in subscripts, these values would naturally follow the NLS collation in effect (“SQL and NLS Collations”).

Now, let’s say you can’t access the terminal or simply you just rather execute it from a web interface. In this article, I will show you how to execute terminal commands from a simple web page.

For example, in the image below you see how we execute $zv on a webpage:

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.

One of the great availability and scaling features of Caché is Enterprise Cache Protocol (ECP). With consideration during application development distributed processing using ECP allows a scale out architecture for Caché applications. Application processing can scale to very high rates from a single application server to the processing power of up to 255 application servers with no application changes.

In this posting I want to raise the profile of a feature that arrived in 2009.1 but is perhaps not very well known.

It is sometimes useful to make certain packages, globals or routines available to all of your namespaces. Of course you can add the necessary mappings whenever you create a new namespace, but here's a simpler way.

End users sure love Excel tables. So, how can you deliver the second to the first? Read this post to find out.

This sample class will add parameter DSINTERVAL to each class containing the parameter DSTIME

To execute it from a Terminal :

When my COS code is executing in a Caché process it might want to interact with the host operating system. For the purpose of this post I'm focusing on a Windows host, but much of it applies to other host OS platforms as well.

A common example of host OS interaction is when my process wants to read from or write to a file. What credentials will apply when Windows is checking whether or not to allow me access to the file?

To answer that we need to consider another question. How did our process start?

NewBie's Corner Session 29 Documentation on the Caché/MUMPS Global Structure

Welcome to NewBie's Corner, a weekly or biweekly post covering basic Caché Material.

This post contains several links to very good documentation of the Caché Globals Structure.

Like I said, "Perhaps the most difficult concept in Caché/MUMPS is its Global Structure."

universalNoSQL.pdf - http://mgateway.com/docs/universalNoSQL.pdf

February 25, 2016 – Alert: Incorrect SQL Results
InterSystems has corrected a defect that can cause incorrect results for certain SQL INSERT, UPDATE, and DELETE statements.

This defect is present only in Caché and Ensemble 2015.2 and HealthShare distributions based on them. The problem affects all platforms.

Incorrect results occur only when two or more of these statements are nested within each other.

The example below demonstrates one possible way for this problem to happen:

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 ?

Recently I have been posting some updates to our JSON capabilities and I am very glad that so many of you provided feedback. Today I would like to focus on another facet: Producing JSON with a SQL query.