Blog Posts by Erik Eldridge

  • YAP sample code: Image carousel w/ auto-rotation

    Ever want to automatically rotate through a series of images (or other content) in the small view of a Yahoo! Application Platform (YAP) app? Well, if so, here’s some code to do it.

    The top of the script gives instructions for usage, and defines an items array containing the content to display.

    Below that, we adjust the starting point for extracting the items to display from the array. A start param passed to the app defines the starting point. If this param exceeds the amount of elements in the array, the start point is set to zero.

    At the bottom, the script produces markup to display three of the items from the items array and a yml:include tag set to fire off a request back to the script for the next set of items after a brief delay.

    Please feel free to use derivations of this code in your work, but be sure to implement proper security and validation before exposing the code to live traffic.

    For the feed readers, here’s a link to the code on Github.

    Here's a screenshot of

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  • Open-Sourcing Traffic Server: 700k lines of code, 9 months

    The following is from a conversation with Andrew Hsu, a member of the Yahoo! team that prepared the Traffic Server code base for its open source release.

    What is Traffic Server (TS)?

    Traffic Server is a fast, scalable, and extensible HTTP/1.1 compliant caching proxy server. TS includes a low-latency, extensible framework that is based on a “plug-in” architecture. Developers can customize existing plug-ins or develop their own to accommodate specific application requirements, while benefiting from the built-in efficiency and performance of Traffic Server. Examples of plug-ins that are commonly developed by users: application specific load-balancers and URL mapping. Check out Miles Libbey’s description of TS’s usage at Yahoo!.

    What is TS’s history?

    Traffic Server was originally created by Inktomi and sold as a commercial product. The product was designed to run on every major operating system under the sun circa 1990: SunOS, DEC, IRIX, Windows, Linux, FreeBSD, etc. Yahoo! acquired

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  • YQL Open Tables for Google Social Graph API

    At some point, everyone has performed an ego search on their own name. Some may call this vain, but it's a good technique to see what information about you is discoverable across the web. The Google Social Graph API packages this information in a convenient format for developers and makes it accessible via a REST interface. This is a powerful tool for finding a user's connections and associations.

    Since we have so many social data sets in YQL (OpenSocial, Flickr, Twitter, Meme, Yelp, etc.), it was only natural to build an Open Table for the Google SocialGraph API. Now, connecting users with their connections is easier than ever.

    You can find the SocialGraph API tables in the yql-tables repository on Github. The google.socialgraph.lookup.xml table wraps the lookup endpoint. The google.socialgraph.otherme.xml table wraps the otherme endpoint.

    You can use these tables in your queries like this:
    USE ''

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  • Description of Yahoo! services used by The Huffington Post

    The Huffington Post announced its integration with a variety of Yahoo! services today. You can add these services to your site too.

    OpenID + OAuth (“Hybrid Auth”)

    Hybrid Auth enables you to let users log into your site using their Yahoo! IDs. By using Yahoo! for authentication, you free yourself from the work associated with building and maintaining a registration and authentication flow. It makes life easier for your users too because they won’t have to create yet another account, and they can import pre-existing social connections to your site from the Hybrid Auth provider.

    As a bonus, Hybrid Auth is composed entirely of open standards, as described in depth by Allen Tom in his YDN post Breaking News: Yahoo! OpenID on Huffington Post. OpenID forms the authentication half of Hybrid Auth. The second half is OAuth, which is used to authorize data access. In practical terms, this means your users can grant access to their data while they are logging in.

    You can get more

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  • YQL Open Table for Google Buzz now live

    We were seeing a lot of hype around Google Buzz today and we thought YQL would love to chew on the data. Fifteen or so minutes later we had an Open Table (the blog post took a bit longer :P ) wrapping the Google Buzz API. It's now live on GitHub:

    You can use it in your queries like this:
    USE "" AS; SELECT * FROM WHERE user="nakedtechnologist".

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  • CrisisCamp Haiti Silicon Valley 1/23/2010 Recap

    This past Saturday (Jan 23, 2010) Yahoo! hosted a CrisisCamp. CrisisCamp is a barcamp/hackday-like event focused on the goals of CrisisCommons, an international volunteer effort to “create technological tools and resources for responders to use in mitigating disasters and crises around the world” (according to the CrisisCommons “about” page).

    This was the second CrisisCamp in support of disaster relief for post-earthquake Haiti, and in addition to Yahoo!’s camp, there were ten other satellite camps hosted across North and South America. Attendees came from various companies and NGOs. 121 people participated in the Silicon Valley camp. Somewhere between 700 and 1,000 people participated overall.

    You can see photos of the various camps on Flickr. Here's one showing some of the CrisisCamp volunteers at work in Sunnyvale:

    CrisisCamp volunteers a work
    Credit: YDN

    Unlike a hackday, where the focus is on developing an idea in 24 hours and competing for prize at the end, the projects created and developed at a

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  • Photos and notes from San Diego BarCamp 6

    The sixth annual BarCamp San Diego last weekend was great. Dan Tentler (@Viss), Phelan Riessen (@imagium), and crew did an excellent job pulling it together.

    Around 325 people came for two days of talks on a variety of subjects. A few of my favorites were: “massively-multi player rock paper scissors,” @mrgunn’s “disrupting academic reputation,” and @nerdkits’ “aluminum foil + paper clip + C code = proximity sensor.” Check out photos from the event in the barcampsd flickr pool.

    BarCamp San Diego 6
    Photo credit: vissago

    Big thanks to Intuit for hosting the event at their beautiful TurboTax headquarters.

    Intuit's TurboTax headquarters
    Photo credit: YDN

    If you’re organizing a barcamp or other tech event and you’d like the Yahoo Developer Network to be involved, please let let us know: @ydn


    Erik Eldridge (@erikErik Eldridge)
    Yahoo! Developer Network

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  • Setting an Open App’s detail images in 8 easy steps

    If you’re just getting started with the Yahoo! Application Platform (YAP), you should be aware that you’ll need to define a few parameters in the YAP dashboard before your app can be pushed live. Four of these required fields concern the images that represent the app in various contexts. This brief tutorial walks through the steps for defining these images and clarifies the requirements.

    screenshot showing application icons

    Screenshot showing icons. Image credit: YDN


    • An Open App. You can easily create one of these using the YAP dashboard
    • 4 images for your app (all dimensions in pixels):
      • Application Icon: 64 x 64 jpg, gif, or png. This is the image that appears in the top left of an app’s border on
      • Favicon: 16 x 16 jpg, gif, png, or ico. This image represents your app in event notifications
      • icon: 20 x 20 gif. This is the image that appears in the list of applications on the Yahoo! homepage (see screenshot above)
      • Screenshot: 300 x 250 jpg, gif, or png. This image is
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  • Yahoo! Developer Network supports U.S. National Computer Science Education Week

    California State University Monterey Bay (CSUMB) commemorated the U.S. National Computer Science Education Week yesterday with a panel discussion (press release). I had the pleasure of participating along with Sue Higgens from the Naval Postgraduate School, Andrès Ornelas from Google, and Srikar Kandaswamy from Cisco. One of the goals of the CS Education Week is to drive enrollment in CS education, which has, unfortunately, been in decline in the US over the past few years. To this end, we were invited to talk about what we do at our jobs, the role a CS degree plays in our careers, and our experiences in school.

    Among other things, I learned more about the raw computing power employed by the US Department of Defense, and how it isn’t all used for war. There is a lot of buzz around scalability in the Web world, but scalability is also an important issue for the Navy developers down the road from CSUMB that calculate global maritime weather forecasts. As a side note, Ms. Higgens

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  • Yahoo! Application Platform (YAP) search box code example

    Putting a search box in your YAP app

    Want to add a search box to your Yahoo application (YAP app)? Here’s some sample PHP code to help you get started. It consists of a single file that calls itself to perform a search and output the results. If the file is requested without a search_term parameter, it will output a form consisting of:

    • yml:form tags defining a form that will make an asynchronous Get request when submitted. Because no param attribute is defined for the yml:form tag, it will call back to the application URL by default. The replace attribute specifies that output of the callback file will replace a DOM element in the app with the id matching the value of the attribute, which in this example is “results”.
    • an input field and submit button

    When the form submits back to this file with the search_term defined, the file outputs HTML for an unordered list containing the results of a search. This HTML is then placed on the page by the yml:form tag.


    • PHP 5.2
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