Jayant's Blog

Moving to new blog platform...

2011-07-26T09:27:00.000-07:00

So much to do! So much unfinished!

2010-07-10T11:22:00.000-07:00

Software is never complete, period.

Of course its a good way to keep your job, but no project is ever complete. Even projects that get shipped have small quirks that need to put in because of some limitation of the platform or environment (or engineer). Sometimes there are things you want to come back to, but never do because there were other pressing issues. I've always tried to do the best I can and trying to use the best approach to solving a problem. But I know there's always a different way to get the same results and I'm always searching for it.

The good thing about iOS development in my opinion is that there are so many APIs that can do the job for you. The bad thing about iOS development is that there are so many APIs that can do the job for you. Yes, I know, its the same. iOS being HUGE, there's always a way to get something done. Its just a pain in the butt to look for it. Of course the more you use the SDK the easier it gets to find the correct API, but it does need a little searching and learning all the APIs.

I've always had a TODO list of things I want to try/play around with in the projects I've worked on. Its usually in my head, but I have made a conscious effort to maintain it in a todo list on my machine. Unfortunately, the TODO list is never without items that I have never done. For example Sqlite & XML were 2 that I had never worked with on iOS, but now I have used these APIs and feel pretty confident using these. Reachability is something that I should integrate, but just have not sat down to get cozy with. But my Achilles' heel in iOS development is OpenGL ES.

While working on the ArcGIS API for iOS, I found Quartz 2D to be sufficient for the job for drawing graphics. Its very performant and for the job at hand, perfect.

OpenGL ES... well. I've taken the time several times to start learning it, but have some how just not been able to go through the tutorials. I first started with iPhone OpenGL ES Tutorial Series a while ago, but left it after 3 tutorials. When I got back, the site was gone. Then I started looking at OpenGL ES from the Ground Up, which is really good. But now, I have other things on my plate, to it moves to the back burner... again!

So long story short: There's always some better way to do something. Seek it out. Find it. Learn it. Use it. It doesn't mean you're work will be always complete, but you will have the satisfaction of doing the best job possible with the right tools.

And time for change

2010-02-25T09:57:00.000-08:00

After 9 great years at ESRI, working on ArcIMS, MapObjects Java, Java ADF, JavaScript API & iPhone SDK, its time for change. Moving to Yahoo!

Inadvertently adding nil to NSArray

2009-12-05T07:44:00.000-08:00

In Cocoa, when populating a NSArray, you use nil to mark the end of the objects being added. So lets say you were populating an array using values from 2 UITextfields and a property, such that:


NSArray *array = [NSArray arrayWithObjects:self.textField1.text, self.textField2.text, self.nsnumberProperty, nil];

The values populated at runtime would look something like:


NSArray *array = [NSArray arrayWithObjects:"foo", "bar", 10, nil];

When you print out the array you get: { "foo", "bar", 10 }.

But what happens, if say self.textField2.text is nil? Now the code at runtime would look like:


NSArray *array = [NSArray arrayWithObjects:"foo", nil, 10, nil];

When you print the array now: { "foo" }

Ouch! Noticed what happened there? The array was terminated by the first nil, so you may have expected 3 values, but you only got 1. So beware of inadvertently adding a nil and terminating a NSArray. Use [NSNull null] if you want to add a null object in an array. Arrays: Ordered Collections.

This is definitely the case in NSDictionary also, but not sure if this is the case in NSSet.

Wow, need to post more often!

2009-08-09T17:56:00.001-07:00

Life has been quite busy for the past 5 months. Released v1.4 of the JSAPI and got done with UC and the sessions there, but the big news is iPhone development.

I have been working on developing iPhone apps for a few months now, finally convinced the appropriate people, built a prototype app in 2 weeks that was showcased during the plenary session of the recently concluded User Conference. Check out the video: Plenary Session - 2009 ESRI User Conference -> 'ArcGIS 9.4: Mobile GIS' -> about 2/3rds way into the video, presented by Chris Capelli.

So now I am leading the development of the iPhone API, similar to the JavaScript API, and have handed over the reins to the JSAPI to Praveen. So finally I am getting to make my move into mobile computing.

ArcGIS JavaScript API v1.3 OUT

2009-02-27T09:46:00.000-08:00

This is a developer centric release. The enhancements include custom layers, error handling and more layer management in the Map which have been requested time & time again. Check out the full list of What's New.

At the Dev Summit in March, Jeremy & I will be presenting the 'An overview of the ArcGIS JavaScript APIs' and 'Developing Advanced Applications with the ArcGIS JavaScript API' sessions. Jeremy will also be presenting 'Patterns and Best Practices for Building Applications with ArcGIS API for JavaScript' and finally 'Using the ArcGIS Server REST API' with Keyur. To see when these sessions are offered, go to the session search page and search by session name.

We will take an in-depth look into the v1.3 developer features in the advanced sessions. In depth looks into error handling, using esri.request, custom layer, etc. You can hear a podcast about our sessions too.

In case you are interested in attending for the ESRI Developer Summit, check out the website.

Google Latitude & the iPhone

2009-02-07T14:21:00.000-08:00

I'm sure everyone has heard about Google Latitude, essentially a mobile app that lets you share and find friends in the vicinity, with caveats. Well, what it may potentially tell us about the next iPhone OS release is that the OS will probably have background processes. I know its a long shot, but here goes:

The google latitude page states: http://google.com/latitude -> Will it work with my phone? -> iPhone and iPod touch devices (coming soon).

In the FAQ for Latitude: http://www.google.com/support/mobile/bin/answer.py?answer=136647&topic=20071, the page states:

... Latitude can automatically detect and update your location in the background ...

... you will have the option to continue sharing your location in the background even with Maps for mobile closed.

So in order for Latitude to truly work on the iPhone, they need background process support in the SDK. And guess what, it may be 'coming soon'. Fingers crossed & hoping so...

Integrating SVG in blogger post

2008-12-31T12:16:00.000-08:00

This is in response to a comment to my earlier post Integrating Dojo in blogger post.

If you want to just use SVG, the following sample works. It uses 2 external JavaScript files, one for basic SVG context and drawing (also used in the Simple SVG Shapes post) and the 2nd one for actually drawing the content.

Here is the HTML markup:

I also tried with Dojo GFX. GFX is a nice abstraction layer to SVG/VML graphics. I tried integrating it into the blogger page, but that didn't worry, it kept throwing a console not found error. Here's the external JavaScript file incase you would like to try it.

ArcGIS JavaScript API v1.2 OUT

2008-11-21T09:01:00.000-08:00

We've worked on this for the last 3-4 months or so. Its a major release for us with a LOT of new features & updates.

We have tried to keep the backward compatibility and we pretty much have it. Just a few minor things which are stricter, for example, setting an Extent in the Map constructor should have a SpatialReference and the SR and extent values should be in sync.

Go check it out... the ArcGIS Server Blog post

Integrating Dojo in blogger post

2008-10-22T20:16:00.000-07:00

So I have been working on integrating Dojo within my blog... so here goes.

Open lightbox

So first, I should thank this blog post on integrating an external JavaScript module within a blogger post. So essentially all the work is done in an external file. But this document still contains the markup that the dojo parser parses to render the light box.

Click on the 'Open lightbox' link below and it will open up a dojo lightbox. These are photos of a sunset I took while in Vancouver in August. Use the keyboard cursor keys to navigate through the photos.

<a href="..." dojoType="dojox.image.Lightbox" group="sunset" title="A beautiful sunset">Open lightbox</a>
<a href="..." dojoType="dojox.image.Lightbox" group="sunset" title="The colors where AMAZING"></a>
<a href="..." dojoType="dojox.image.Lightbox" group="sunset" title="Taken from my friend's apartment"></a>
<script type="text/javascript" src="http://ecodevil.net/dev/blog/blogger_lightbox.js"></script>

</div>

Thats it.

The Mobile Web

2008-10-21T22:52:00.000-07:00

So recently the guys in the ArcGIS Mobile team (Fred, Jeff & Myles) asked me whether I could put together a blog posting about integrating the JSAPI to work in mobile browsers. So here's a first of several blog posts on The Mobile Web. If you're interested in the bringing your ArcGIS Server content to mobile devices, watch the the ArcGIS Mobile Blog.

This particular post simply shows how to make REST calls and doesn't have any JSAPI, but this one will work on any mobile browser, even IE Mobile.

You can find the page hosted here. So whip out that mobile phone of yours and go to http://ecodevil.net/dev/blog/basicMap.php and check it out. Click the +/- to zoom in/out and the N/E/S/W to pan in the specific direction.

DDD & AjaxExperiece

2008-10-14T20:23:00.000-07:00

A couple of weeks ago the Dojo guys gave me the opportunity to present the ArcGIS JavaScript API at the Dojo Developer Day and Ajax Experience. Here's a wrap up on the proceedings from both at Uxebu's blog and Sitepen's blog. Btw, I'm in the right corner in the red shirt in the group photo. I wore my Dojo shirt the previous day and didn't wear it that morning.

SVG events in Safari vs FF3/Opera

2008-10-08T22:40:00.000-07:00

So don't get me wrong... FF3 is awesome, but when it comes to rendering HTML/SVG/JavaScript... I think WebKit kicks Gecko's butt! So recently while doing some R&D, where I wanted to layer 2 SVG containers on top of each other, I noticed that the events actually work differently. So check out this sample.

So this is a really simple test page. The code essentially creates and adds an svg element (z-index:0) to the root div. To this new surface, a rectangle is added to it. Next an image to the root div (z-index:1). Finally another svg element (z-index:2) is created and added to the root div and a circle added to it.

Now to test this out, make sure to have Safari/WebKit's console open and in Firefox, Firebug. Click on the 'green rect', 'image', the 'red circle' & finally the 'white background' div.

In Safari, the output looks like:

rect : rect
IMG : image
circle : circle
DIV : div

Where as in Firefox (and Opera)

svg : surface2
svg : surface2
circle : circle
svg : surface2

So basically you can see that, since the 2nd surface is above in z-ordering, it traps all events outside the itself and doesn't let it go through. But Safari seems to have a different algorithm for determining the event source/target. Googling around, I have not been able to find more details on how the each rendering engine determines the event source/target.

iPhone SVG Events

2008-09-16T20:05:00.000-07:00

The way the events work on a browser is pretty simple. If you want to listen to a particular event (say mousedown) on the whole document, you simply add an event listener to the document: document.addEventListener("mousedown", listenerFunction, false);. Setting 'false' for the 'useCapture' argument sets the event to bubble, which is the preferred event flow.

The test that we have is really simple. On your iPhone, the page renders a circle, a rectangle & of course these are rendered within a SVG container which is created within a background div. Tap on the circle, then rect and finally the background div. The test pages have 'touchstart' or 'click' event listeners registered by default. Click the 'Add'/'Remove' buttons to add/remove event listeners from the SVG element. There are 2 listener functions, one for logging document events and one for svg events. The events are logged with 'short function name: event.type : event.target'.

If you didn't know this already, you can enable the debug console in Safari on the iPhone.

Now, on the iPhone, the 'touchstart' event is similar to the 'mousedown' on a browser. Go to http://ecodevil.net/dev/blog/events_touch.html using your iPhone. Click on the circle, then rect and finally the white background. You should see 3 events logged.

Now click on the 'Add' button and as expected you will see 1 event (for the button). Now clear the console and click the circle, rect & background again. This time, you will have 5 events logged.

This is actually the expected behavior.

Now from your desktop Safari, go to http://ecodevil.net/dev/blog/events_click.html. You can enable your developer menu as well, see 'Safari Developer FAQ'. You will notice that you have 3 click events logged.

Now click on the 'Add' button and try the test again. You will once again have 1 + 5 events.

Again try http://ecodevil.net/dev/blog/events_click.html using your iPhone 2.1. When you run through the first set of tests, you will see no events logged.

Now click on the 'Add' button and try the test again. You will now see 4 events logged, but there is no click event on the background div.

So What?
So basically, events don't work exactly the same on the iPhone as the desktop browser. On a desktop browser, if an event listener is registered to listen to a particular event on the document, any event of the same type, on any element on the document bubbles up and will be logged, unless the event is stopped from propagating. But seems like on the iPhone, the touch/gesture events work by default on the document as well as the SVG element. But for the click/mouse* events to work on the document, there needs to be an event listener registered to listen to the SVG element. And removing this event listener will stop all click/mouse* events on the document.

Simple SVG Shapes

2008-09-15T21:19:00.000-07:00

Here's a simple test page which will draw different SVG shapes on your canvas. Of course if your iPhone OS is not 2.1, go get it and try out http://ecodevil.net/dev/blog/shapes.html. So lets looks at the code for http://ecodevil.net/dev/blog/svg.js.

Firstly, I have 3 JavaScript functions. The createNode is the main one which creates the appropriate SVG node using the node type and applies all properties from the argument hash to the new node. The createImage & createText are just specialized uses of this function.

<javascript>

</javascript>

The next is the test function which is called on document.onload. It creates a rect, circle, ellipse, line, polyline, polygon, image, text & path. I've found the Pike's SVG Tutorial to be a good quick reference for SVG syntax.

<javascript>

</javascript>

Thats it. You can try this page using Safari/Firefox/Opera or Chrome... not IE.

iPhone 2.1 now supports SVG

2008-09-12T13:12:00.000-07:00

At iPhone 2.0, SVG was to be supported but when trying using the iPhone safari browser, even simple stuff it didn't work. So it was promised that the support would be there at the next major release and well its here. There's not too much noise about it in the blogs... but this is HUGE.

Currently dojox.gfx defaults to canvas on the iPhone but the following bug will fix that, hopefully in time for v1.2.

The iPhone has had touch & gesture events since iPhone 2.0 for handling single & double-touch events respectively. With this release, there should be support for drawing vector geometry using SVG and also events on SVG elements.

More to come...

YouTube video

2008-09-06T22:51:00.000-07:00

ESRI puts videos about its software online, including on youtube. Recently Andy stopped by to have a chat with Jeremy & me about the ArcGIS JavaScript API. You can see my office, with my Colts cap, the Dilbert head, my miniature planes and my Star Wars fighter models. I forgot about the chat that morning and forgot to shave and wear a good shirt. Oh well! Link to the video

Using Php with ArcGIS Server 9.3 REST (v0.03)

2008-08-13T21:48:00.000-07:00

So here's another sample. I have a pre-populated JSON file (addresses.txt) with a bunch of addresses to be geocoded.

{
"addresses": [
{ "name":"ESRI", "street":"380 New York St", "city":"Redlands", "state":"CA", "zip":92373 },
{ "name":"Google", "street":"1600 Amphitheatre Parkway", "city":"Mountain View", "state":"CA", "zip":94043 },
{ "name":"Yahoo", "street":"701 First Avenue", "city":"Sunnyvale", "state":"CA", "zip":94089 },
{ "name":"Microsoft", "street":"One Microsoft Way", "city":"Redmond", "state":"WA", "zip":98052 }
]
}

This code shows how to load up the address list from the JSON file. I tried naming the file as .json, but am guessing since my json mime-type has not been set correctly, it wasn't loaded properly.

<?php

$url = "addresses.txt";
$response = file_get_contents($url);
$json = json_decode($response);

?>

Next is the code to take the address, build the request and use the geocoding service on sample server to geocode the addresses.

<?php

$geocodeUrl = "http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/" . "Locators/ESRI_Geocode_USA/GeocodeServer/" . "findAddressCandidates?f=json";
foreach($json->addresses as $address) {
$url = str_replace(" ", "+", $geocodeUrl . "&Address=" . $address->street . "&City=" . $address->city . "&State=" . $address->state . "&Zip=" . $address->zip);

$response = file_get_contents($url);
$candidates = json_decode($response);

?>

Next filter the address candidates and display only those candidates who's score is 100. We simply print these.

<?php

$html = "Address candidate(s) for (" . $address->name . "\n<ul>\n";
foreach($candidates->candidates as $candidate) {
if ($candidate->score == 100) {
$html .= "<li>" . $candidate->address . " (" . $candidate->location->x . ", " . $candidate->location->y . ")</li>";
}
}
$html .= "</ul>\n";
echo $html;
}

Using Php with ArcGIS Server 9.3 REST (v0.02)

2008-08-09T22:56:00.000-07:00

One of the powers of using GIS is that in addition to tabular data you also have access to spatial data as part of each record. So in the following Php code, I will query to find 'Los Angeles' and simple display the result with the coordinates of the city.

<?php

$url = "http://sampleserver1.arcgisonline.com/ArcGIS/rest/services" . "/Specialty/ESRI_StatesCitiesRivers_USA/MapServer/0/query" . "?f=json&where=CITY_NAME='Los+Angeles'";
$response = file_get_contents($url);
$json = json_decode($response);

$la = $json->features[0];
echo $la->attributes->CITY_NAME . " (" . $la->geometry->x . ", " . $la->geometry->y . ")";

Using Php with ArcGIS Server 9.3 REST

2008-08-09T14:55:00.000-07:00

The latest release of ArcGIS Server now supports REST access to the services. The best thing, it returns JSON. And at Php 5.2, there is support for JSON. So how simple is it to request an process a response?

Well, first use file_get_contents to call the REST endpoint. Next decode the JSON response as an object using json_decode. So here's a really simple sample to get a map image. Although I can't really see why you would use this rather than using the ArcGIS JavaScript API.

<?php

$url = "http://sampleserver1.arcgisonline.com/ArcGIS/rest/services" . "/Specialty/ESRI_StateCityHighway_USA/MapServer/export?f=json";
$response = file_get_contents($url);
$json = json_decode($response);

echo "<img src='" . $json->href . "' width='" . $json->width . "' height='" . $json->height . "' />";

The ArcGIS JavaScript API on dojotoolkit.org

2008-08-02T10:09:00.000-07:00

The Dojo Toolkit website has added a section in their spotlight page about the ArcGIS JavaScript API page. Check it out http://dojotoolkit.org/spotlight. Click on the ESRI link to see the details page. Dylan also added a blog entry on the website as well ESRI Launches Dojo-based GIS JavaScript API.

Thanks to Dylan for spending the time putting this page up despite his busy schedule.

Presenting the ArcGIS JavaScript API

2008-07-28T21:30:00.000-07:00

For the last couple of years, I've been working hard on TONS of client side JavaScript for the ArcGIS Server product. The first year and a half was working on the ArcGIS JavaADF client side code (JavaScript/CSS/Ajax) and for the last year and a half, its been the ArcGIS JavaScript API.

The ArcGIS JavaScript API is basically a lightweight API for doing GIS on the web. It works with ESRI's ArcGIS 9.3 new REST serivices. Its been a GREAT experience working with Jeremy (The Bartley), Keyur and Praveen.

The API is now available so check out ESRI's new Resource Center.

More posts coming now that I have time to do other things than just work all the time... :)

Moving to Java dev team @ ESRI

2006-03-23T13:50:00.000-08:00

Well I am formally moving to the Java development team at ESRI, and one of the popular trends here is blogging... well in keeping with the trend, I will join my piers in doing the same...

My work is primarily on the client side web libraries and some server side, AJAX integration and some other stuff... I plan on using this blog to talk about what we're working on, show code bits, tips, tricks, hooks, etc and hopefully get input on how to improve the client side web libraries that we are working on... and will ship in our products.