RserveLink Eval Failed Even When Successful

I have been playing with RserveLink and Rserve recently and found that it worked very well, except in one case (which is not really a fringe case) where it reliably returns an "Eval Failed" exception when the command actually succeeded. I was able to run the command in RStudio (Awesome R IDE) and RGUI successfully.

I am not going to include the R statement that generated the issue because it is large, but suffice it to say that it reliably works with much larger statements.

The response we get for the 4th index is 0 and the library jumps over the if statement. However, dragging the debug arrow onto the DataLength line and run the code, it continues without error.

if (response[4] != 0)
{
    Int32 DataLength = BitConverter.ToInt32(response, 4);

I changed the section of code converting the code to the following. Essentially, just getting the response data length and assume that a data length greater than 0 is successful.

Int32 DataLength = BitConverter.ToInt32(response, 4);
if (DataLength != 0)
{

The original code was posted in a zip file on SourceForge and posted back in 2007. I have emailed the author (awaiting reply) and posted my change on my RserveLink GitHub repository. The binary library targeting 4.0 Client and 4.5.1 can be found in the releases section.

I have also published an RserveLink Nuget package for ease of adding to .Net projects.

AngularJS UTC to Local Time Filter

In a previous post I detailed how to to implement the UTC time to local time conversion in Vanilla JS. Now let's take it a step further and utilize it in an AngularJS application. The best path forward will be to create a filter which will format the string being rendered. The end result will allow us to do something like the following:

<div class="row" ng-repeat="time in viewModel.times">
  <div class="col-md-6">
    <time datetime="{{time}}">{{ time | utctolocal }}</time>
  </div>
</div>

Basic usage is thus: create the filter, add the script tag to load the filter, add the module to be a dependency on the app.

angular.module('intPonfilters', [])
 .filter('utctolocal', function () {

 var LeadingZero = function (val) {
  return (val < 10) ? "0" + val : val;
 },
 ToDateString = function (dateObj, dateFormat) {
  var curr_year = dateObj.getFullYear(),
   curr_month = LeadingZero(dateObj.getMonth() + 1),
   curr_date = LeadingZero(dateObj.getDate()),
   curr_hour = LeadingZero(dateObj.getHours()),
   curr_min = LeadingZero(dateObj.getMinutes()),
   curr_sec = LeadingZero(dateObj.getSeconds()),
   curr_ampm = "AM";
  if (curr_hour > 11) {
   curr_ampm = "PM";
   curr_hour = (curr_hour == 12) ? 12 : curr_hour - 12;
  }
    var timestamp = curr_year + "-" + curr_month + "-" + curr_date + " " + curr_hour + ":" + curr_min + ":" + curr_sec + " " + curr_ampm + " " + LocalTimeZone();
  return timestamp;
 },
  LocalTimeZone = function() {
    // From http://stackoverflow.com/questions/2897478/get-client-timezone-not-gmt-offset-amount-in-js
    var now = new Date().toString(),
        timezone = now.indexOf('(') > -1 ?
          //now.match(/\([^\)]+\)/)[0] :  // Uncomment this line to return the full time zone text
          now.match(/\([^\)]+\)/)[0].match(/[A-Z]/g).join('') :  // Uncomment this line to return the full time zone abbreviation
          now.match(/[A-Z]{3,4}/)[0];
    if (timezone == "GMT" && /(GMT\W*\d{4})/.test(now))
      timezone = RegExp.$1;
    return timezone;
  };

 return function (input) {
  var inputDate = new Date(input);
  var dateString = ToDateString(inputDate);
  return dateString;
 };
});

An example can be found in my UTCtoLocalAngularJS GitHub repository.

Javascript UTC to Local Time for Display

If you are developing an application which will only be used by a people in one timezone, then DateTime.Now with the current time zone will work for you. This is a rather short sighted. As the userbase grows, users will have to translate the dates manually. Additionally, if you have migrate the application to servers in different locations which have a different time zone set or a time zone that you can't control, the date and times generated will be off. This is especially true when developing applications for the cloud (which by and large use UTC).

There are a couple options:

1. Have a setting per users which indicates the users timezone and convert the times on every view/page render
2. Have the user's browser handle the conversion
   
3. 
   

The former requires significantly more development, user interaction, and more processing time. The latter requires a bit of HTML5 and javascript. So let's see what it takes to do it in javascript. There are javascript libraries like Moment.js which do this with potentially more robustness, but it is more than 12KB minified and gzipped. If it can be done in 1-2KB's, why tote the rest around. When page load times are so important, every kilobyte saved is time spent loading your page. Lets say we want to render the following render the following HTML to the browser.

<time datetime="@Html.DisplayFor(modelItem => item.Created) UTC">
 @Html.DisplayFor(modelItem => item.Created) UTC
</time>

We can iterate over all of the time elements and convert the UTC times and leverage javascript to translate the times to local with the following code.

function UtcTimesToLocal() {
 $("time").each(function (index, element) {
  var el = $(element),
   time = el.attr("datetime"),
   converted = new Date(time);
  var dateString = ToDateString(converted);
  el.text(dateString);
 });
}

function ToDateString(dateObj, dateFormat) {
 var curr_year = dateObj.getFullYear(),
  curr_month = LeadingZero(dateObj.getMonth() + 1),
  curr_date = LeadingZero(dateObj.getDate()),
  curr_hour = LeadingZero(dateObj.getHours()),
  curr_min = LeadingZero(dateObj.getMinutes()),
  curr_sec = LeadingZero(dateObj.getSeconds()),
  curr_ampm = "AM";
 if (curr_hour > 11) {
  curr_ampm = "PM";
  curr_hour = (curr_hour == 12) ? 12 : curr_hour - 12;
 }
 var timestamp = curr_year + "-" + curr_month + "-" + curr_date + " " + curr_hour + ":" + curr_min + ":" + curr_sec + " " + curr_ampm + " " + LocalTimeZone();
 return timestamp;
}

function LeadingZero(val) {
 return (val < 10) ? "0" + val : val;
}

function LocalTimeZone () {
  // From http://stackoverflow.com/questions/2897478/get-client-timezone-not-gmt-offset-amount-in-js
  var now = new Date().toString(),
      timezone = now.indexOf('(') > -1 ?
        //now.match(/\([^\)]+\)/)[0] :  // Uncomment this line to return the full time zone text
        now.match(/\([^\)]+\)/)[0].match(/[A-Z]/g).join('') :  // Uncomment this line to return the full time zone abbreviation
        now.match(/[A-Z]{3,4}/)[0];
  if (timezone == "GMT" && /(GMT\W*\d{4})/.test(now))
    timezone = RegExp.$1;
  return timezone;
}

Then at the bottom of the page, run the UtcTimesToLocal function.

<script>
 $(function() { UtcTimesToLocal(); });
</script>

An example project can be found on my UTCtoLocalJS GitHub repository.