Article
· Mar 2, 2017 1m read
Trusting the code you import

As more people join Developer Community, and with increasing efforts to promote code sharing, I'd like to draw fresh attention to this post I wrote a year ago. It spotlights a feature within the class compiler which is both useful and dangerous. When importing code (e.g. from an XML export of classes received from someone), it's worth considering the risks.

Even if that post doesn't seem relevant to you at the moment you may wish to note it for the future. A handy way of doing this is to click the star icon at the end of it.

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Hi!

Consider I have a class Package.Data with Property UniqueStringValue as %String.

I introduced the Index for this property:

 Index ValueIndex on UniqueStringValue [Unique];

It works well. But if I try to check if there is an object with the certain value in code like this:

if ##class(Package.Data).ValueIndexExists(value)  

this expression fails, if value="value", even if there is an instance with instance.UniqueStingValue="Value"

How can I set the index to prevent saving case sensitive values in this class?

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Article
· Feb 24, 2017 1m read
Collision for SHA-1 hash algorithm

The recent announcement of a collision for the SHA-1 hash algorithm has caused some consternation:

https://shattered.io/

Here is some background to help put this in perspective.

Cryptographic hash functions can have a variety of properties. The property at issue here is:

"Collision resistance - it is computationally infeasible to find any two distinct inputs x, x' which hash to the same output, i.e., such that h(x) = h(x')."

(Menezes, van Oorchot, and Vanstone, "Handbook of Applied Cryptography", section 9.2.2)

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Hi everyone, I have and Zen Mojo application, it's all working but I have some doubts about what is recommended to use: There is some reports of employees, for example, and actually I'm using some plugins : "Excelent export" to generate Excel reports and "jspdf" to generate PDF reports in client side.

I have an REST service, that receives the request, process and returns JSON, after client side receive the response it's processed.

- This can be slow/bad in applications with large data?

- It's better/recommended to use ZenReports even with ZenMojo applications?

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While I can see the benefits that $ZSTORAGE could have if used properly, I have not seen it used in the environments I have worked in. I was wondering if there are any developers that promote its usage.

If used properly, I would imagine it could be highly effective in maximizing free memory since some processes will never go over X amount, while others may very well need much more.

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Question
· Feb 21, 2017
Parse %ObjectIdentity

Hi!

I'm trying to implement %OnAfterDelete ClassMethod for persistent class. As a parameter it gets oid As %ObjectIdentity for the deleted object.

ClassMethod %OnAfterDelete(oid As %ObjectIdentity) As %Status

My question is: how to get ID value from %ObjectIdentity ?

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Hi,

I am trying the following command in order to freeze the instance before backup is done:

csession CACHE -U%SYS "##Class(Backup.General).ExternalFreeze()"

The command requires user name and password to be supplied when prompted. Is there any way that this command can be run where it doesn't query the credentials? I am wondering if it can use OS level permissions (root or effective user who owns Cache processes etc) .

My test is on a CentOS 6 machine if that helps.

Thanks,

Raghu

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Hopefully this is a simple questions to respond to. Can you do Delegated Authentication for SOAP web service calls. I ask as I am not seeing this work as expected. I have this authentication turned on and enabled in for he CSP Web Application yet I keep getting a "Security Token could not be Authenticated. And a global I was setting to capture some of the available data is not being loaded.

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I use the HS_IHE_ATNA_Repository.Aggregation table a lot. Someone just referred me to the HS_IHE_ATNA_Repository.Document table, which has an AggregationId column.

I assume that column references the ID column in the .Aggregation table. If so, does this mean that if the same document was requested 1,000 times that there will be 1,000 entries for it in the .Document table? This seems inefficient to me. Why not have one record in the document table and have a DocumentId column in the Aggregation table?

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Article
· Feb 14, 2017 1m read
Portal tip: The inconspicuous Menu button

Amongst the large fonts and chunky icons of Portal's pages, the Menu button in the top left corner is easily overlooked:

When clicked, it often produces the following menu:

When I remember it's there, I find the "View Console Log" option particularly handy.

I wrote "often" above because I've also noticed that the Menu contents change when I'm on a page within the Ensemble section of Portal:

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