Creating an api in Cache

Roberto

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Oct 30, 2013, 2:35:46 PM10/30/13

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Can people in this group provide best practices for creating an api (REST) in Cache/CSP?

Thanks for your responses.

-Roberto

Tom Fitzgibbon

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Oct 30, 2013, 2:53:04 PM10/30/13

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Roberto -

Below might help, I just got something going with a jQuery mobile autocomplete. Disclaimer: I'm not an expert in REST/Cache yet, so it's not necessarily a best practice example.

The CSP page below calls the class, which reads the Cache Global, repackages data in JSON and returns in the AJAX call.

Tom Fitzgibbon | Multidata | 212-967-6700 x537

Class Supplying JSON data from Cache Global ------------------------------

Class HD2.TKFREST1 Extends %CSP.Page

{

ClassMethod OnPage() As %Status [ ServerOnly = 1 ]

{

s RDcallback = %request.Data("callback",1)

s RDq=%request.Data("q",1)

;Make JSON from global

s ResJSON=..MakeJSON(RDq),x=RDcallback_ResJSON

s ^TKF=x

w x

Q $$$OK

}

ClassMethod MakeJSON(RDq) As %String [ ServerOnly = 1 ]

{

;select appropriate globals from ^TKFC and package in JSONP

s ResJSON="([",city="",URDq=$zconvert(RDq,"U")

f s city=$o(^TKFC(city)) q:'$l(city) i city[URDq s ResJSON=ResJSON_""""_^TKFC(city)_""""_","

s ResJSON=$e(ResJSON,1,$l(ResJSON)-1)

s ResJSON=ResJSON_"]);"

Q ResJSON

}

ClassMethod OnPreHTTP() As %Boolean [ ServerOnly = 1 ]

{

Do %response.SetHeader("Content-Type","text/json")

Q 1

}

CSP Page Providing Autocomplete that consumes JSON data from Class Above ----------------------------

<!DOCTYPE html>

<html>

<head>

<title>TKF - Listview Autocomplete - jQuery Mobile Demos</title>

$( document ).on( "pageinit", "#myPage", function() {

$( "#autocomplete" ).on( "listviewbeforefilter", function ( e, data ) {

var $ul = $( this ),

$input = $( data.input ),

value = $input.val(),

html = "";

$ul.html( "" );

if ( value && value.length > 2 ) {

$ul.html( "<li><div class='ui-loader'><span class='ui-icon ui-icon-loading'></span></div></li>" );

$ul.listview( "refresh" );

$.ajax({

//url: "http://gd.geobytes.com/AutoCompleteCity",

url: "http://172.77.100.100/hd/HD2.TKFREST1.cls",

dataType: "jsonp",

crossDomain: true,

data: {

q: $input.val()

}

})

.then( function ( response ) {

$.each( response, function ( i, val ) {

html += '<li class="city" id="city_' + val.id + '"">' + val + "</li>";

});

$ul.html( html );

$ul.listview( "refresh" );

$ul.trigger( "updatelayout");

$('.city').click(function(){

var val=$(this).html();

alert(val); //do something

$('.city').panel('close');

});

}

});

</script>

<style>

.ui-listview-filter-inset {

margin-top: 0;

}

</style>

</head>

<body>

<h1>Listview Autocomplete</h1>

</div>

<h2>Remote autocomplete with listview filter</h2>

<h3>Cities worldwide</h3>

<p>After you enter <strong>at least three characters</strong> the autocomplete function will show all possible matches.</p>

</div>

</div>

</div>

curl http://time.jsontest.com

</div>

</div>

</div>

</body>

</html>

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Roberto

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Oct 30, 2013, 3:19:16 PM10/30/13

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Hello Tom,

Thanks for the example. I can use this in the future!

What about things like security?

I know for something like Google maps I need an api key. Have you (or anyone here) implemented something like that?

It should be pretty easy to do, but I've never done it in Cache.

Also what about licensing? Any issue with that?

Thanks,

-Roberto

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Tom Fitzgibbon

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Oct 30, 2013, 3:27:55 PM10/30/13

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Roberto - Don't have answers for security and licensing yet. Let's keep talking about these and other issues.

I'm also trying to figure out if Cache 2014 has some Zen.JSON stuff to read Cache tables and return usable JSON, but as Bill M. points out different jQuery components want data back in different JSON formats. We keep running into Tower of Babel problem with formats, languages, libraries, etc.

- Tom

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Roberto

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Oct 30, 2013, 3:31:52 PM10/30/13

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Yes, we are very interested in this.

We realize that a creating an api library like this is a lot simpler than creating web services. But we need to address a lot of questions first.

I saw your posting about the different json format, but was not quite sure about the issue.

Can you post the 2 different sample jsons? Maybe I can help you with that.

-Roberto

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DAiMor

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Oct 30, 2013, 4:47:28 PM10/30/13

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Now, you can create your REST API in versions from 2014.1.

This version introduces support for handling REST requests, routing them to a given namespace, and processing them.
This support is at the level of the CSP Gateway.
This feature is predicated on providing a Web application that routes all requests to a given handler class that, based on a
URL mapping facility, then dispatches the calls to the correct class and method implementation. With this feature, Caché
can now handle any REST interface; for data transport, Caché supports XML or JSON.

среда, 30 октября 2013 г., 22:35:46 UTC+4 пользователь Roberto написал:

Roberto

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Oct 30, 2013, 4:51:34 PM10/30/13

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That's good to know!

Is 2014.1 release candidate out yet?

I thought they were still working on 2013.2?

-Roberto

Dmitry Maslennikov

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Oct 30, 2013, 4:55:31 PM10/30/13

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They changed version 2013.2 to 2014.1 and this version in fieldtest yet.

31.10.2013 0:51 пользователь "Roberto" <rcah...@gmail.com> написал:

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rtweed

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Oct 31, 2013, 7:57:08 AM10/31/13

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Rather than use CSP, you can use EWD.js (previously known as EWD Lite)

See http://gradvs1.mgateway.com/download/EWDjs.pdf

Specifically see the chapter titled "Web Service Interface"

Rob

Roberto

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Oct 31, 2013, 8:44:58 AM10/31/13

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Hi Rob,

I've checked out EWD before (read docs/pdf, went to the website). It looks like with EWD you need node.js running with Cache. This is another layer that we are not familiar with.

Maybe during the holiday break (Thanksgiving, U.S.) I will take a deeper look at EWD and see how we can implement it.

Thank you.

-Roberto

rtweed

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Oct 31, 2013, 10:37:38 AM10/31/13

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That's correct - you need Node.js, but on the other hand you dispense with CSP and Apache/IIS. Plus the web services you expose are automatically secured via the same mechanism used by Amazon Web Services.

Anyone who's serious about browser-based applications these days needs to understand JavaScript, and that's what Node.js is: JavaScript on the server. In fact, IMO, everyone should be finding out about Node.js.

I recommend you try it out with Mike Clayton's Linux installer - if you're an Amazon EC2 user, you can have a fully-working environment (based on GlobalsDB) up and running in about 10 minutes. See the Appendix in the EWD.js documentation. Everything that applies to GlobalsDB applies to Cache, except that with Cache you have the added advantage of being able to invoke Cache code from within Node.js

Rob

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Tony

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Nov 3, 2013, 11:02:44 AM11/3/13

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Hi Roberto

Another approach to creating a web API into Caché is to use the CSP session key to encrypt the various server methods a client can call, see example below. The list build values are event class, method and number of parameters. The downside to this approach is you have to define all the web methods that could be called, but is does mean you hide the implementation from the user (i.e. URL path).

// Create a new global object for storing data and functions

var cspPage = {

appTimeout: #(%session.AppTimeout)#,

serverHandle: '#($Select(%session.UseSessionCookie '= 2: %session.CSPSessionCookie, 1: ""))#',

serverMethod: {

save: '#(..Encrypt($ListBuild("User.Models.Person", "Save", 0)))#'

}

};

</script>

You then have a single entry point back into Caché (e.g. 'User.Controllers.HomeController.cls') that decrypts the web event (e.g. 'serverMethod.save') which then calls the appropriate class method (e.g. 'Save' in 'User.Models.Person'), see example below.

save: function () {

var qString = '?WEVENT=' + cspPage.serverMethod.save;

if (cspPage.serverHandle != '') { qString += '&CSPCHD=' + cspPage.serverHandle; }

//qString += '&WARG_1=' + someArg;

$.ajax({

url: "User.Controllers.HomeController.cls" + qString,

type: "post",

data: ko.toJSON(this),

contentType: "application/json",

success: function (result) {

cspPage.fn.resetTimeout(); // reset page timeout

console.log('result.message=', result.message);

$('#myModal div.modal-body p').html('<p>' + result.message + '</p>');

$('#myModal').modal({

show: true

});

}

});

}

On the server-side it is assumed JSON data is being exchanged, see example below.

Class User.Controllers.HomeController Extends %CSP.Page

{

Parameter CONTENTTYPE = "application/json";

ClassMethod OnPage() As %Status

{

// chunk the output

Set stream = %session.Data("json")

Do stream.Rewind()

While 'stream.AtEnd {

Set length = 1024

Write stream.Read(.length)

}

// end of method

Quit $$$OK

}

ClassMethod OnPreHTTP() As %Boolean

{

Set ok = 1

Try {

// get requested event

Set evtData = $Get(%request.Data("WEVENT", 1))

If evtData = "" ZTrap

Set evtData = ..Decrypt(evtData)

Set evtClss = $ListGet(evtData, 1)

Set evtMthd = $ListGet(evtData, 2)

Set evtArgs = $ListGet(evtData, 3)

// define json data from client

Set jsonData = %request.Content

Set sc = jsonData.Rewind()

// get the required parameters and invoke appropriate class method

For i = 1:1:evtArgs Set evtArgs(i) = $Get(%request.Data("WARG_"_i, 1))

If 'evtArgs Set jsonBack = $ClassMethod(evtClss, evtMthd, jsonData)

If evtArgs = 1 Set jsonBack = $ClassMethod(evtClss, evtMthd, jsonData, evtArgs(1))

If evtArgs = 2 Set jsonBack = $ClassMethod(evtClss, evtMthd, jsonData, evtArgs(1), evtArgs(2))

If evtArgs = 3 Set jsonBack = $ClassMethod(evtClss, evtMthd, jsonData, evtArgs(1), evtArgs(2), evtArgs(3))

// add json stream oref to session data

Set %session.Data("json") = jsonBack

} Catch exception {

Set ok = 0

Do BACK^%ETN

Set %response.Status = "500 Internal Server Error"

}

// end of method

Quit ok

}

I have used the above code whilst experimenting with the 'Model-View-View Model (MVVM)' design pattern based on the 'KnockoutJS (http://knockoutjs.com/)' framework. I know the above mechanism is not really RESTful, but some may find it meets their needs.

Tony

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