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Re: When you ask a webservice in JSON, what do you probably get back ?
Henry,
My i side stuff is written in Java. In fact all of the web
application code I have runs in Java Servlets running under Tomcat. I
do that because I have customers that run on i and some who,
inexplicably, run on Windows servers ;-)
Basically you need to be familiar with Ajax techniques to start with
because it is Ajax that will call the server (i) side programs that
will generate the content. If you are familiar with Ajax, returning
JSON formatted content is trivial. If you are not familiar with Ajax,
then spend some time understanding how it works and write a couple of
simple routines that make the round trip to the server for data. I am
sure there are several CGIDEV examples that use Ajax so that you could
write some RPG code on the i to generate and deliver the data.
What JSON brings to the table is that the data is already formatted so
that Javascript will see it as an object. If you are using a
framework like jQuery or Dojo or Prototype, working with *objects*
becomes important and helpful. So JSON complements the so called "Web
2.0" techniques by delivering ready to use data objects.
There is a simple and easy to use and understand JSON example I found
here: [1]http://www.xul.fr/ajax-javascript-json.html#Example The data
in this case is is in a file in the same folder as the HTML (you can
run this demo without any server side code). But then you *could*
have your CGIDEV (or whatever i side web application) return the
contents using an ajax call, rather than loading it locally. Really
that would be the only difference. The JSON formatted data is the
key, not *where* the data comes from. But, in the example, you can
see how easily the data can be used once it has been returned as a
JSON object. The menu generating code is pretty trivial.
I *could* write a servlet to return the JSON data that this example
gets from the local folder but that would be overkill and probably
wouldn't help you if you are looking to write the server side code in
RPG.
I hope this helps a bit.
Pete
Kwong, Henry wrote:
Hi Pete
Can you share with me a sample iseries program to read the JSON
response. Our application is very simple, just passing few input
parameters, and return with the response code and output parameters.
Please help
Henry Kwong | Lead System Analyst
Mattel Global IT - Managed Services
Mattel, Inc. | 333 Continental Blvd. | El Segundo, CA 90245
* 310-252-3205 | * [2]Henry.Kwong@xxxxxxxxxx
-----Original Message-----
From: [3]ftpapi-bounces@xxxxxxxxxxxxxxxxxxxxxx
[[4]mailto:ftpapi-bounces@xxxxxxxxxxxxxxxxxxxxxx] On Behalf Of Pete Helgren
Sent: Wednesday, October 14, 2009 3:58 PM
To: HTTPAPI and FTPAPI Projects
Subject: Re: When you ask a webservice in JSON, what do you probably get
back ?
Since JSON is *javascript* object notation why would you want to do
anything with it on the i? Just pass it to the browser as a string and
then let javascript handle it like it is supposed to (maybe "eval" it
but that is all you'd need).
I build JSON data all the time (using Java rather than CGIDEV) and I do
that specifically because it works so well with javascript, otherwise it
is rather pointless to create a JSON stream. If you plan to parse it
on the i, why not *send* it to the i in something more "readable"?
Or is it that some web services only return JSON (haven't run into that)
and you need to manually parse that out?
Pete
[5]hr@xxxxxxxxxxxx wrote:
JSON ;-)
and there is no way to read JSON on an iSeries,
so I'm working on a new method that is able to
convert a recieved JSON object to a XML document
in the CGIDEV2 Responce Object ....
Input:
json = '{'
+ 'data:['
+ '[select:"Y",display:"Y - Yes"]'
+ ' ,[select:"N",display:"N - No"]'
+ ' ] }';
Output:
<tree1 type="object">
<data type="array">
<tree3 type="array">
<select>Y</select>
<display>Y - Yes</display>
</tree3>
<tree3 type="array">
<select>N</select>
<display>N - No</display>
</tree3>
</data>
</tree1>
It's a little bit tricky because JSON comes back
in many formats and not always up to the standards
descibed.
But it can be done in rather few statements, and
here is a first shot that in the end will be packed
into PXAPICGI in a single method like
convertJSONtoXML(addr:length);
buffaddr = bufAddr();
buffsize = bufSize();
// do whatever you like
First shot code:
/free
clearSrvPgm();
setContent('*none');
json = '{'
+ 'data:['
+ '[select:"Y",display:"Y - Yes"]'
+ ' ,[select:"N",display:"N - No"]'
+ ' ] }';
// packed in method
nodeDepth = 1;
nodeLength = 256;
for i = 1 to NodeLength;
cPrev = c;
c = %subst(json:i:1);
if nodeOpen = *off;
select;
when c = *blank;
when c = '"';
when c = '{';
nodeAttr = 'tree'+%char(nodeDepth);
nodeArray(nodeDepth) = nodeAttr;
xmlNode(nodeAttr:'type="object"');
nodeAttr = '';
nodeDepth += 1;
when c = '}';
nodeDepth -= 1;
xmlEndNode();
when c = '[';
nodeAttr = 'tree'+%char(nodeDepth);
nodeArray(nodeDepth) = nodeAttr;
xmlNode(nodeAttr:'type="array"');
nodeAttr = '';
nodeDepth += 1;
when c = ']';
nodeDepth -= 1;
xmlEndNode();
when c = ':';
nodeOpen = *on;
when c = ',';
other;
nodeAttr += c;
endsl;
else;
select;
when nodeOpenC = *on;
select;
when c = '"' and cPrev = '\';
nodeData += c;
when c = '\' and cPrev = '\';
nodeData += c;
when c = '"'
or c = ' ' and nodeOpenB = *on
or c = ',' and nodeOpenB = *on;
xmlNode(nodeAttr:'':nodeData);
nodeAttr = '';
nodeData = '';
nodeOpen = *off;
nodeOpenC = *off;
nodeOpenB = *off;
other;
nodeData += c;
endsl;
when c = *blank;
when c = '"';
nodeOpenC = *on;
// number, true, false, null
when c >= '0' and c <= '9'
or c = '-'
or c = '.'
or c = 't'
or c = 'f'
or c = 'n';
nodeData += c;
nodeOpenC = *on;
nodeOpenB = *on;
when c = '{';
nodeArray(nodeDepth) = nodeAttr;
xmlNode(nodeAttr:'type="object"');
nodeAttr = '';
nodeDepth += 1;
nodeOpen = *off;
when c = '}';
nodeDepth -= 1;
xmlEndNode();
when c = '[';
nodeArray(nodeDepth) = nodeAttr;
xmlNode(nodeAttr:'type="array"');
nodeAttr = '';
nodeDepth += 1;
nodeOpen = *off;
when c = ']';
nodeDepth -= 1;
xmlEndNode();
when c = ':';
when c = ',';
other;
endsl;
endif;
endfor;
// back on the outside again
buffaddr = bufAddr();
buffsize = bufSize();
dsply result;
echoToStmf('/json.xml':1252);
*inlr = *on;
return;
/end-free
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References
1. http://www.xul.fr/ajax-javascript-json.html#Example
2. mailto:Henry.Kwong@xxxxxxxxxx
3. mailto:ftpapi-bounces@xxxxxxxxxxxxxxxxxxxxxx
4. mailto:ftpapi-bounces@xxxxxxxxxxxxxxxxxxxxxx
5. mailto:hr@xxxxxxxxxxxx
6. http://www.scottklement.com/mailman/listinfo/ftpapi
7. http://www.scottklement.com/mailman/listinfo/ftpapi
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