lightlink/README.md

Client package for lightlink.io allowing progressive loading (display the first page of data that is transmitted already while the rest AJAX request is still in loading)

# npm
NPM client package for LightLink.io

## Exports default function
```
lightlink( [ string ] url, [ Object, optional ] params,   [ Object, optional ] options )
```

Calls lightlink.io service allowing progressive loading (intermediate callbacks on partial data loaded)
### Parameters:
- `url` - The URL to call
- `params` - an object containing request parameters
- `options` - callbacks and progressive loading options 

##### Valid `options` are :
* `partial` callback on partial response. Parameters: (data, isPartial /*=true * /, xmlhttp)
* `success` callback on successful response. Parameters: (data, isPartial /*=false * /, xmlhttp)
* `successOrPartial` callback on successful or partial response. Parameters: (data, isPartial, xmlhttp)
* `error` callback on HTTP error ou incorrect JSON response. Parameters: (data, isPartial, xmlhttp)
* `exception` callback on caught server side exception: Parameters: (data, xmlhttp)
* `partialSlices` The size of partial response slices. Default to :[100,100,100,100,100,500] meaning 5 times each 100 rows, then each 500 rows until loading ended. Slices should not be too small to avoid too frequent updates that might be not needed. Lower CPU usage
* `partialMinInterval` The minimum interval between partial responses. Default to 200 millis. Allows to reduce client CPU by avoiding too frequent updates, and less frequent xmlhttp.responseText access


## Example

```jsx
import lightlink from "lightlink";

...
lightlink("/lightlink/my/service",{firstName:"John", lastName:"Smith"},{
    successOrPartial:function(data, isPartial, xmlhttp){...},
    error:function(xmlhttp){
        if (xmlhttp.status!=200)
           console.log("HTTP Error : "+xmlhttp.status)
        else
           console.log("HTTP Error : "+xmlhttp.status)
    },
    exception:function(data, xmlhttp){
       console.log(
        data.error,     // exception.toString() from the server side
        data.stackTrace // will be available in debug mode only
       )
    }
})

```

That was a verbose (full) syntax.
In real application you will probably wrap `lightlink` function for default error handling, if any.

Something like this:
```jsx
import lightlink from "lightlink";
...
function myLightLink(url,params,successOrPartial){
    lightlink(url,params,{
        error:function(xmlhttp){
            if (xmlhttp.status!=200)
               console.log("HTTP Error : "+xmlhttp.status)
            else
               console.log("HTTP Error : "+xmlhttp.status)
        },
        exception:function(data, xmlhttp){
           console.log(
            data.error,     // exception.toString() from the server side
            data.stackTrace // will be available in debug mode only
           )
        },
        successOrPartial:successOrPartial
    });
}

...
myLightLink("/lightlink/my/service1",params1,
    (data, isPartial)=>{...}
);

myLightLink("/lightlink/my/service2",params2,
    (data, isPartial)=>{...}
);

```