CL 5.8 – JSON format

[Rob Lindsey]

Anyone ever tried to deal with JSON formatted data messages either with TCL or Xlates.  I know with TCL there is a way to do it with a proc if you have TCL 8.5 but not with 8.4.  

Yes I know that I can upgrade and get TCL 8.5 but that is a few months off at the earliest and of course they want this data from JSON to HL7 2.3.1 sooner rather than later.  I am sure that I can figure out how to do it but I thought I would reach out to the community and see if anyone has done it in the past.

TIA

Rob

Topic

[Rob Abbott]

There are style sheets available that will convert JSONXML.  You could then deal with the data as XML inside Cloverleaf.

Rob Abbott
Cloverleaf Emeritus

[Levy Lazarre]

Another alternative is to use the json package that is part of Tcllib. It includes a parser for JSON. Very easy to use.

However, the JSON text is converted to a Tcl dictionary. Therefore, if you are on Tcl 8.4, you will also have to download and install the “dict” package for 8.4, besides Tcllib.

package require json

Then use the command “::json::json2dict” to parse your JSON text into a Tcl dict.

Example from the command line:

Code:

% package require json
1.1.2
% set jsontxt {[
   {
       “id”: 2,
       “name”: “An ice sculpture”,
       “price”: 12.50,
       “tags”: [”cold”, “ice”],
       “dimensions”: {
           “length”: 7.0,
           “width”: 12.0,
           “height”: 9.5
       },
       “warehouseLocation”: {
           “latitude”: -78.75,
           “longitude”: 20.4
       }
   },
   {
       “id”: 3,
       “name”: “A blue mouse”,
       “price”: 25.50,
       “dimensions”: {
           “length”: 3.1,
           “width”: 1.0,
           “height”: 1.0
       },
       “warehouseLocation”: {
           “latitude”: 54.4,
           “longitude”: -32.7
       }
   }
]

}

% ::json::json2dict $jsontxt

{id 2 name {An ice sculpture} price 12.50 tags {cold ice} dimensions {length 7.0 width 12.0 height 9.5} warehouseLocation {latitude -78.75 longitude 20.4}} {id 3 name {A blue mouse} price 25.50 dimensions {length 3.1 width 1.0 height 1.0} warehouseLocation {latitude 54.4 longitude -32.7}}

Once your JSON is parsed into a dictionary, you use the regular dict commands to retrieve the desired data elements.

I hope this helps.

[Jim Kosloskey]

My reading on this topic – and I admit I just started to pay attention to it – indicates both the json package and using stylesheets have drawbacks primarilly due to the apparent ‘on the fly’ nature of JSON.

This appears to be expressed in the literature as ambiguity.

My take away is there is no real standard and no real ‘defintion’ of the message  other than what one finds actually in the message.

So perhaps the handling of the messages could break easily.

Looks fast to setup and perhaps a pain to maintain and administer.

Again some fairly uneducated thoughts on my part.

email: jim.kosloskey@jim-kosloskey.com 30+ years Cloverleaf, 60 years IT – old fart.

[Levy Lazarre]

This may have been true in the past, but the JSON format has been rigorously defined since 2013 by the ECMA-404 international standard. There are literally dozens of libraries in Java, JavaScript, Ruby, Perl, Groovy, and many other languages that allow to parse and serialize JSON.

http://www.json.org

Similarly to XML, one can define schemas for documents

http://www.json-schema.org

In fact, the format is so well established that the new HL7 standard (FHIR) offers two data interchange formats (XML and JSON), with JSON being favored because it’s a lot more efficient and less verbose than XML.

[Jim Kosloskey]

Good information.

This will help focus my research – thanks Levy.

email: jim.kosloskey@jim-kosloskey.com 30+ years Cloverleaf, 60 years IT – old fart.

[Rob Lindsey]

Thanks all.

I will let you know which route will be taken.

Rob

[Keith McLeod]

Was there ever a resolve in using JSON with a REST webservice in cloverleaf?  I am being required to receive JSON and map to xml on the client side.

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