I often use Warren's rather excellent
Twitter for Umbraco package to display Twitter feeds on
websites. To save on hits to the Twitter server (especially on
busier sites) I cache the macro, often for about 20 minutes (unless
the feed is updated on a more regular basis). This has always
worked fine, until recently, when I had an issue on a client site
where the feed kept showing up empty.
I'd not come accross this before, so I did some digging and
found out that the Twiiter for Umbraco package was getting a 403
error, and therefore no Tweets, and the Macro was caching as empty.
After some digging around, I found out that Twitter have started
limiting access to the open feeds, to roughly 60 or so requests an
hour (this is called Rate Limiting, you can read about it here). This was still a bit
odd, as the site should only have been hitting the feed three times
an hour. Then I discovered that they had some other apps hitting
the feed as well, that was causing us to hit the limit.
The Twitter for Umbraco feed doesn't cache the response from
Twitter, so if it can't get a list of Tweets because you've fallen
foul of Rate Limiting (as we had), or if the Twitter feed is
unavailable (which also happens more than I realised), then you're
stuck with no Tweets.
I looked into a solution for this, and came up with the idea of
using Darren Ferguson's
Feed Cache package to download and cache the feed (as that way
if the feed was unavailable we'd still have a cached copy to read).
It turned out to be quite simple, with only a few tweaks needed, so
I thought I'd cover it here for anyone who's interested!
First, make sure you have the Twitter for Umbraco package
installed, and make sure that you have the Macro up and running on
a page and that it's pulling out Tweets and displaying them. Full
instructons for setting up the feed are on the
Twitter for Umbraco project page.
Next, install the
Feed Cache package, again, the setup instructions are included
on the project page.
Once both are installed, you can get everything set up. First
up, you need the URL that your Twitter Macro is using to get the
Tweets. This is pretty easy to get. Go into the developer section
in the back office, and open the XSLT file called
"cws_twitterStatus.xslt". Scroll down to the beginning of the
"match" part of the template, and you'll see a variable called
"twitterXMLUrl". Use an XSL value of just underneath this variable
to get the feed (don't forget to get rid of this once you've got
the feed URL!).
<xsl:value-of select="$twitterXMLUrl" />
Armed with the feed URL, you can now open the config file for
the feedCache package, which is called "feedcache2.config" and is
located in the "config" folder of the site. Below is an example of
the file, with a feed set up:
<?xml version="1.0" encoding="utf-8"?>
<Configuration xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<CachePath>C:\inetpub\wwwroot\mysite\App_Data\FeedCache</CachePath>
<Feeds>
<Feed>
<Url>[PLACE YOUR TWITTER URL HERE]</Url>
<LocalFile>mytwitter.xml</LocalFile>
</Feed>
</Feeds>
</Configuration>
Notice that we set a path to the feed to save its XML to (make
sure that App Pool identity can read, write and modify to the
location you specify, I normally use the "App_Data" folder). We
also set a file name for the twitter feed.
Now all we need to do is schedule the feed to run on a regular
basis. Open your "umbracoSettings.config" file from the config
folder of the website, and scroll down to the scheduled tasks
section. You can then add a scheduled task to the section for the
feed cache. The interval is in seconds, the example task below will
check the feed every 15 minutes. Here is an example of the
task:
<scheduledTasks>
<task log="true" alias="feedcache2" interval="1800" url="http://[ENTER YOUR URL HERE]/umbraco/plugins/FergusonMoriyama/FeedCache2/FmFeedCache.aspx" />
</scheduledTasks>
You can run the link from the task in a brower to make sure that
it's working. If it did, there should be an XML file with the name
you specified in the folder you specified. If there isn't, the main
things to check are that your Twitter URL is correct, and that the
permissions are set properly on the path you specified for the feed
to save to!
Once that's done, you just need to make a small change to the
"cws_twitterStatus.xslt" file in the developer section. First go
back to the section that sets the Twitter URL and comment it out.
Replace it with the folowing code:
<xsl:variable name="twitterXMLUrl" select="[RELATIVE PATH TO XML FILE HERE, e.g. '../App_Data/FeedCache/mytwitter.xml']"/>
Make sure that you set the path to the file that the feed is
saving to correctly! Once that's done, scroll slightly further down
the page, and you'll see two for-each loops that actually display
the Tweets. They're currently using an umbraco.library call, we
need to change that slightly. Change the first for-each to:
<xsl:for-each select="document($twitterXMLUrl)//statuses/status">
and the second for-each loop to:
<xsl:for-each select="document($twitterXMLUrl)//statuses/status [in_reply_to_screen_name = '']">
Save the macro, and you're done! You now have a Twitter feed
that's cached, so if the feed is unreachable, your site will still
display the tweets!
