Using Web Services in Your Gadget/Widget

Using Web Services in your Gadget Alan Lewis – eBay Technical Evangelist NGW024

Hi

I lost my voice earlier this morning

:-(

I have some cool stuff to show you though

:-)

So, I’ll give it a try

Here goes…

Huh? What’s this presentation about???

Web Services

You may have heard of them

Yes, they are actually useful

No, you don’t have to use SOAP

Lots of services are out there for you to use (finally)

Gadgets

Or Widgets

Or Plugins

Or Panels

Definition: “mini-applications that let you perform common tasks and provide you with fast access to information”

Translation: They do cool stuff

Why Should I Care?

Gadgets are cool

Web services offer lots of reusable data and functionality

MIXing them up (nice plug) in your gadget saves you headaches

Alternative to doing it this way – server side coding

Need to scale your server to handle traffic from gadget

Different skill set required

Eww!!!

So, what sorts of web services are out there?

I’m so glad you asked… here is a totally random example:

eBay Web Services!!!

Please permit me a short detour to summarize

eBay Web Service Features

Search

Listing Items

Transaction/Order Management

My eBay

eBay Stores

Feedback Management

Watch List

Bidding (with signed agreement)

In short, almost everything you can do on the site

Different Flavors of eBay Web Services

SOAP

XML (HTTP POST)

Both support the same feature set (all calls)

Calls go over HTTPS

REST (HTTP GET)

supports GetSearchResults call

Sample Call Request

XML API:

<?xml version="1.0" encoding="utf-8"?>

<GetSearchResultsRequest xmlns="urn:ebay:apis:eBLBaseComponents">

<RequesterCredentials>

<eBayAuthToken>ABC123</eBayAuthToken>

</RequesterCredentials>

<Query>iPod Nano</Query>

</GetSearchResultsRequest>

REST API

http://rest.api.ebay.com/restapi?CallName=GetSearchResults&RequestToken=ABC123=&RequestUserId=alanlewis0&Query=iPod%20Nano&Schema=1

Sample Call Response

XML API and REST API (same response)

<?xml version="1.0" encoding="utf-8"?>

<GetSearchResultsRequest xmlns="urn:ebay:apis:eBLBaseComponents">

…

<Item>

<ItemID>4036874357</ItemID>

…

<SellingStatus>

<BidCount>31</BidCount>

<CurrentPrice currencyID="USD">80.0</CurrentPrice>

</SellingStatus>

<Site>US</Site>

<Title>Used Apple iPod Nano MP3 Player Good Condition</Title>

…

</Item>

…

</GetSearchResultsRequest>

And Now… Demo

Live.com

Supports RSS feeds and Gadgets

Gadgets are implemented in javascript + CSS

Still alpha feel – emerging feature set and very buggy at times (especially with CSS support)

Design Philosophy

Gadgets call for a fresh design approach

Sort of like code for mobile devices

Limited screen real-estate

Limited functionality/APIs

Except not

Still coding for the browser– multiple windows/tabs, cross-browser issues

Asynchronous interaction, more bandwidth

Challenge 1: Security Restrictions

Calls can’t go across domains

If the gadget was served up from www.mydomain.com, can’t call api.ebay.com

Live.com solution to this: proxy!

Supports XML data (except XHTML) and RSS feeds

Currently only supports HTTP GET (contrary to docs – support for POST will be added in the future)

Can’t proxy HTTPS yet, so only option for eBay is REST API

var r = Web.Network.createRequest(

Web.Network.Type.XML,

searchQuery,

{proxy:"generic"},

eBaySearchCallback);

Challenge 2: Namespaces

IE javascript engine can’t handle XML data in default namespaces

Solution: Use ugly RegEx hack to remove namespace:

var rootText = response.responseText;

var re = /xmlns="urn:ebay:apis:eBLBaseComponents"/g;

rootText = rootText.replace(re, "");

var responseWithoutNamespaces;

if (window.ActiveXObject) {

responseWithoutNamespaces = new ActiveXObject("Microsoft.XMLDOM");

responseWithoutNamespaces.async="false";

responseWithoutNamespaces.loadXML(rootText);

}

else {

responseWithoutNamespaces = document.implementation.createDocument("","",null);

responseWithoutNamespaces.loadXML(rootText);

}

And now…

ANNOUNCING:

The gadget is open sourced

Commercial software-friendly open source license: CDDL

Yeah!

http://searchgadget.codebase.ebay.com

Lets go check it out…

Now More Code

Here is the code, in-depth

Other Web Services

Lots to choose from: www.programmableweb.com

REST is very popular, but has limitations

RSS feeds are web services too

Building Commercial Apps

One issue to keep in mind is many Web services out there force non-commercial use

Shameless plug: that’s not the case with eBay Web services

One way to make money with your Gadget is to use an affiliate program like eBay’s: http://developer.ebay.com/affiliates

Other Gadget/Widget Platforms

Vista Sidebar

Bundled with Vista, but limited capabilities (thusfar)

Yahoo! Widget Engine (Konfabulator)

Multi-platform support, integration with Desktop still clumsy

Apple Dashboard

Best desktop integration, but only for OSX

Google Desktop – (Sidebar)

Information-rich widgets, but harder to build, bundled with a product IT departments hate

Google Personalized Home Page

Sorta like live.com – less functionality but better visibility

Learn More Stuff

More on eBay Web Services: http://developer.ebay.com Its totally free!

eBay Developers Conference, baby! June 10-12, Mandalay Bay, Las Vegas

Live.com eBay Gadget available in the Gallery: microsoftgadgets.com

Open sourced at: http://searchgadget.codebase.ebay.com

Sanaz Ahari’s presentation immediately following this one, in C/D

Using Web Services in Your Gadget/Widget

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