xml performance

[Greg Eriksen]

My boss has asked me to post this question.

We have a database being developed in-house for tracking chronic conditions like asthma and diabetes, and the programmers would prefer to use xml format for any inbound data.

My boss has responded with the following:

Quote:

The HIPAA standards committee specifically chose to not endorse XML as one of its integration standards because performance was determined to be approx a factor of 4 beyond the overhead of other formats.

I’m not sure what the source of this informations was, but can anyone here point to evidence, or relay their direct experience, that either supports or refutes this contention?

Topic

[Scott Lee]

I can’t speak to the source of the quote but here’s my $.02…

XML is a very ‘wordy’ format.  Since it is self documenting a lot more information is sent with each message than just the raw data.  For example, with HL7 the patient name is sent as…

|lname^fname^mname|

in XML that would be

fname

lname

mname

The HL7 example is 19 bytes.  The XML example is 84 bytes.

It will depend alot on the amount of data you need to process.  If the volume is such that mulitplying the raw data times 4 would overload the interface then XML may not be the way to go.

Scott

[Anonymous]

Not sure if there are that many out there that receive the “Business Integration Journal” (http://www.bijonline.com) but there is an interesting article by one of the columnists.  Here are some quotes from an article titled “XML Effeciency” in the May 2005 issue.

I think that he’s chiding the XML industry for arguing about things rather than making changes that would be helpful.  But in doing this he reveals some interesting things about XML.

“A case in point is the painfully slow progress on XML effeciency.  As anyone who has used it in real applications knows, XML is verbose.  XML chews up network bandwidth as if it were IT’s free lunch.  That characteristic makes it of doubtful value for any application in which large amounts of data are exchanged or high transaction rates are necessary.”

Read the entire article:  http://www.bijonline.com/Article.asp?ArticleId=1161

Please don’t take this out of context, XML is useful for many things.  This doesn’t mean that XML is bad or evil somehow.  It just means that it has it’s place.  And just like with any interface, if you’ve got the hardware for it, great.

I invite anyone who wants to discuss XML to do so.  As you know HL7 is trying to release an XML version and Cloverleaf will support it.  Anyone getting any projects to do XML?

[Greg Eriksen]

Thanks to both of you for your responses.

Scott, your explanation and example helped me to understand that the four-fold increase in message sizes will only become a performance issue depending on the volume of transactions.

In fairness to one of the programmers, I’ll mention that he responded by saying:

Quote:

His XML example is “element” based and that’s not the only way you can represent data.  There is also “attribute” based XML, something like: FirstName=”fname” LastName=”lname” MiddleName=”mname”, which cuts the number of characters by 3rd.

[Debra Downs]

In answer to your question, Greg, we will have an XML project next fall.

[Terry Kellum]

My XML understanding is a bit limited, but as with all subjects, it gets clearer with every user’s group that I attend.   😉

My understanding of XML attributes is that they should be used for metadata elements, or “data about data” rather than as a transport for the data itself.

Goutham, Would you consider it “valid” to carry the data as an attribute as described here, or is this an attempt to “cook” the data just to reduce the transaction size?

[David Harrison]

I have got to get to grips with sending HL7 XML messages.

If anyone out there has a sample XML schema for any type of HL7 message, I would be grateful if you would share it with me so I have something to play around with.

Thanks,

Dave

[Rob Parnell]

I just came back from a conference put on by CIHI and HL7 Canada and they were displaying HL7 version 3.  It looks like HL7 is moving in the XML direction.  I definately agree that the XML files are alot bigger and are going to chew up bandwith.  I know that some of the province level applications are using V3 and more are looking at implementing it.  

Is Quovadx going to build some default translation that can convert V3 to V2 or vice versa?

Thanks,

Rob Parnell

Grand River Hospital

[Rick Brown]

Rob,

I asked Rey Currie about this and I have posted his response below.  It looks like it is in the plans for down the road.

Here is his response…

We do have plans to make it easier for customers migrating from HL7 v2 to v3. But since v2 and v3 are so fundamentally different

[Author]

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