Can anyone familiar with creating podcast rss feeds please explain this one to me...
Q: What's the difference between <pubDate> and <lastBuildDate> for a podcast rss feed?
For context, <pubDate> and <lastBuildDate> are specific fields within an rss feed.
There are plenty of well-meaning descriptions available to research, e.g.
http://rssboard.org/rss-specification
What is the difference between <pubDate> and <lastBuildDate> in RSS?
Unfortunately, it is still confusing me.
Initially, I have tried to look at it from the point of view of a physical publication, e.g. a book.
Book gets written = <lastBuildDate>
Time elapses
Book gets published = <pubDate>
More time elapses, then, a new print run
Book gets republished = <pubDate>
More time elapes
Author decides to update content = <lastBuildDate>
Book gets republished = <pubDate>
This example makes perfect sense to me. It works well for something with a physical copy.
However, how does that work for an electronic resource like a podcast?
With a podcast, when you create a new episode, or update the description, i.e. lastBuildDate, you also update the feed, i.e. pubDate. Usually at the same time.
Therefore, there appears to be no difference between <pubDate> and <lastBuildDate> for a podcast?🤷♂️
Is there something I am missing / not understanding?
Thanks in advance for your thoughts and ideas.
Initially, I have tried to look at it from the point of view of a physical publication, e.g. a book.
This is an excellent way to think about it. And you're correct. I don't think you should be confused by anything.
To further clarify:
1. The lastBuildDate can also be modified by the content generator (the code that creates the feed markup) if it internally modifies any metadata known only to itself.
2. As both fields are optional, you should not rely directly on them for detecting new content if that's your purpose. HTTP Cache related headers are better suited for this.
3. Even for non-podcast feeds, pubDate when available should be used IMO. Additionally also check for pubdate. Some feeds publish the lower-cased variant of it as well.
Related
How's it going?
I've found a lot of more detailed answers relating to specific problems relating to RSS feeds, but I can't really figure out how you USE one, basically.
Could someone explain?
I see the RSS feed icon at the top of a lot of Wordpress sites, including my own, but when I click it, it just seems to be a long XML file. I don't know what to do with it, or even why it would be there.
How do you use this? Are you meant to hit it with an API request, or is there a particular kind of software that you use?
Cheers
Before telling you what RSS, let me describe you a common problem that many people have.
Say there is a bunch of sites that you really like and it's sort of a
daily routine for you to go thru them. They may be a news site, your
friend's blog, but also craigslist bcause you're currently looking for
a new house and maybe a weather site to know how late you should stay
at work :)
The first thing you do when you get to work, is open your web browser
and these sites in new tabs. It's not particularly cumbersome because
there are just 4 sites. But think about it: maybe there is a new blog
that you start to like and ho, these cartoons are really funny. Maybe
there is also a bit of financial info that you're interested in and
the pictures that your brother is posting to Flickr every couple day:
they just had a new baby! Also, as you're trying to buy a house, you'd
love a little raise and you've figured that your boss really likes it
when you tell her that you've read about your company in the news or
when you tell her about a new competing product... There is also
StackOverflow. You're desperately trying to get this "expert" badge
and boost up your reputation: this may help with your boss too or even
when you're looking for a new job.
Opening all these tabs is starting to take a toll and you keep
forgetting an important one. You're also slowly getting tired of the
different reading experience that all these sites have: small fonts,
large fonts, ads all over...etc. Now you have a problem.
Imagine there is a tool that does the following: you can tell it what sites you care about, and then, this tool will look up the new stuff for you. It will show everything in a nice looking format. It should also help you identify what's really worth seeing ASAP or maybe have some kind of "serendipity" mode that you can go into and find interesting stuff that you would have missed otherwise. The tool will obviously send you to the original sites should you need more info about any particular story or classified...
This tool exists. It's usually called a Reader, mostly because it lets your read more things online. Often times you'll see them called "RSS reader", because RSS is what they use to get the information from all these sites. RSS is the pipe. You as a user should probably not know about it, but that's what the readers depend on. In an ideal world, when you're on site you like, you should just hit "follow" on a button like this one and then you'd be redirected to your reader of choice. Later when new content is added, you'll get it straight in your reader.
To get a bit into more technical details, RSS (like Atom) is an XML flavor. It's a collection (mostly reverse chronological) of entries. Entries have at least a title and a link to the actual story. They should also include a unique identifier and could have other elements like a description, an image, tags, author information... etc.
RSS is great because it's content agnostic. It can be used to represent a lot of different things (as described in the little story) and decouples the publishing platform from the subscribing platform: they don't even know the other one exists. RSS is their lingua-franca.
I wrote a blog post about this very question not long ago. Here's the link if you're interested in reading my personal interpretation. https://www.rss.com/whatisrss
An XML file is all the content of a page, with no markup. The XML represents the data in its rawest, most descriptive form. Many readers can interpret XML sources from a variety of places, and format all of the data in its own unique way.
This question is coming from a non-technical person. I have asked a team to build a sort of RSS reader. In essence, its a news aggregator. What we had in mind at first was to source news directly from specific sources: ft.com, reuters.com, and bloomberg.com.
Now, the development team has proposed a certain way of doing it (because it'll be easier)... which is to use news.google.com and return whatever is the result. Now I know this has questionable legality and we are not really that comfortable with that fact, but while the legal department is checking that.. we have proceeded working with a prototype.
Now comes the technical problem... because the method was actually simulating search via news.google.com, after a period of time it returns a captcha. I'm suspicious that its because the method was SEARCHING WITH RESULTS SHOWN AS RSS as opposed to an outright RSS... however the dev team says RSS is exactly the same thing... and that it will give captcha as well.
I have my doubts. If thats the case, how have the other news aggregator sites done their compilation of feeds from different sources?
For your reference, here is the same of the URL that eventually gives the CAPTCHA
https://news.google.com/news/feeds?hl=en&gl=sg&as_qdr=a&authuser=0&q=dbs+bank+singapore&bav=on.2,or.r_gc.r_pw.r_cp.,cf.osb&biw=1280&bih=963&um=1&ie=UTF-8&output=rss
"Searching" is usually behind a captcha because it is very resource intensive, thus they do everything they can to prevent bots from searching. A normal RSS feed is the opposite of resource intensive. To summarize: normal RSS feeds will probably not trigger CAPTCHA's.
Since Google declared their News API deprecated as of May 26, 2011, maybe using NewsCred as suggested in this group post http://productforums.google.com/forum/#!topic/news/RBRH8pihQJI could be an option for your commercial use.
So I have played with the idea of making a specialized RSS-reader for some time now, but I have never gotten around to it. I have several project that could benefit from reading feeds in one way or another.
One project for this is an RSS-bot for an IRC-channel I'm on. But I havent quite wrapped my mind around how I can "mark as read" a story, so that it doesn't spit out all the stories in the feed everytime it runs.
Now, I haven't read the specs extencively yet either, so there might be some kind of unique ID I could use to mark the entry as read using a database of some kind. But is this the right way to do it?
From reading the specs for RSS 2.0 at ttp://cyber.law.harvard.edu/rss/rss.html#hrelementsOfLtitemgt it seems each item has a GUID which you can use to know which articles have been read or not.
I've been experimenting with writing my own RSS reader. I can handle the "parse XML" bit. The thing I'm getting stuck on is "How do I fetch older posts?"
Most RSS feeds only list the 10-25 most recent items in their XML file. How do I get ALL the items in a feed, and not just the most recent ones?
The only solution I could find was using the "unofficial" Google Reader API, which would be something like
http://www.google.com/reader/atom/feed/http://fskrealityguide.blogspot.com/feeds/posts/default?n=1000
I don't want to make my application dependent on Google Reader.
Is there any better way? I noticed that on Blogger, I can do "?start-index=1&max-results=1000", and on WordPress I can do "?paged=5". Is there any general way to fetch an RSS feed so that it gives me everything, and not just the most recent items?
RSS/Atom feeds does not allow for historic information to be retrieved. It is up to the publisher of the feed to provide it if they want such as in the blogger or wordpress examples you gave above.
The only reason that Google Reader has more information is that it remembered it from when it came up the first time.
There is some information on something like this talked about as an extension to the ATOM protocol, but I don't know if it is actually implemented anywhere.
As the other replies here mentioned, a feed may not provide archival data but historical items may be available from another source.
Archive.org’s Wayback Machine has an API to access historical content, including RSS feeds (if their bots have downloaded it). I’ve created the web tool Backfeed that uses this API to regenerate a feed containing concatenated historical items. If you'd like to discuss the implementation in detail please get in touch.
In my experience with RSS, the feed is compiled by the last X items where X is a variable. Certain Feeds may have the full list, but for bandwidth sake most places are likely limiting to just the last few items.
The likely answer for google reader having the old info, is that it is storing it on its side for users later.
Further to what David Dean said the RSS/Atom feeds will only contain what the publisher of the feed has up at that moment and someone would need to be actively collecting this informaton in order to have any historical information. Basically Google Reader was doing this for free and when you interacted with it you could retrieve this stored informaton from the google database servers.
Now that they have retired the service, to my knowledge you have two choices. You either have to start collection of this information from your feeds of interest and store the data using XML or some such, or you could pay for this data from one of the companies who sell this type of archived feed information.
I hope this information helps somebody.
Seán
Another potential solution that might not have been available when the question was originally asked and shouldn't require any specific service.
Find the URL of the RSS feed you want and use waybackpack to get the archived urls for that feed.
Use FeedReader or a similar library to pull down the archived RSS feed.
Take the URLs from each feed and scrape them as you wish. If you're going way back in time it's possible there might be some dead links.
All previous answers more or less relied on existing services to still have a copy of that feed or the feed engine to be able to provide older items dynamically.
There's though another, admittedly pro-active and rather theoretical way to do so: Let your feedreader use a caching proxy which semantically understands RSS and/or Atom feeds and caches them on a per-item base up to as many items as you configure.
If the feedreader doesn't poll feeds regularily, the proxy could fetch known feeds time-based on its own to not miss an item in highly volatile feeds like the one from User Friendly which has only one item and changes every day (or at least used to do so). Hence if the feedreadere.g. crashed or lost network connection while you are away for a few days, you might loose items in your feedreader's cache. Having the proxy to fetch those feeds regularily (e.g. from a data center instead from at home or on a server instead of a laptop) allows you to easily run the feedreader only then and when without loosing items which were posted after your feedreader fetched feeds the last time but rotated out again before you fetch them the next time.
I call that concept a Semantic Feed Proxy and I've implemented a proof of concept implementation called sfp. It's though not much more than a proof of concept and I haven't developed it further. (So I'd be happy about hints to projects with similar ideas or purposes. :-)
Why does this problem exist?
Most RSS readers need to import feeds through a live URL, which makes things harder for sites that are unindexed on Wayback Machine.
The reason why Wayback Machine feeds can be imported is that the reader can regularly poll the server for updates according to its defined TTL configuration. The reader compares the current datetime with the RSS feed posts pubDate or lastBuildDate keys in the XML response. We can't hack the machine datetime to work around the datetime resolution because the current datetime is fetched live.
I've outlined an alternative solution without Wayback below. Unfortunately, I have not been able to find a universal solution for all feed sources.
Alternative Solution(s)
In my experience, NOT ALL feeds are partial though. The XML doesn't have to specify the datetime of each post. This means the RSS Reader doesn't have a datetime to filter the feed with. An example of this feed type can be found here.
This kind of reading experience is useful when chronological order is irrelevant, and the content doesn't need to be sorted. This approach is useful for sites where ALL the content is valuable, and the linked Essays of Paul Graham is a good example.
If the site has a generic, non-chronological feed option, subscribe to that RSS instead (the preferred option).
Download the linked timestamped .rss file, strip datetimes and host the file on your own server. Note, we can implement this via an AWS Lambda.
Set up a server that fetches the RSS from live.
Strip the pubDate tags from the XML file on fetch.
Host the modified RSS on your own server.
Note
These are suboptimal solutions due to loss of orders, however, I wanted to provide a potential alternative to WaybackMachine.
In addition, some existing answers require advanced SysDesign workarounds, more prework and in some cases are outdated (Google Reader is shut down). I hope it's helpful for those who really need a solution for a complete feed list. Constructing new RSS feeds is not too hard from the original RSS file.
I wondered if anyone can give an example of a professional use of RSS/Atom feeds in a company product. Does anyone use feeds for other things than updating news?
For example, did you create a product that gives results as RSS/Atom feeds? Like price listings or current inventory, or maybe dates of training lessons?
Or am I thinking in a wrong way of use cases for RSS/Atom feeds anyway?
edit #abyx has a really good example of a somewhat unexpected use of RSS as a way to get debug information from program transactions. I like the idea of this process. This is the type of use I was thinking of - besides publishing search results or last changes (like mediawiki)
Some of my team's new systems generate RSS feeds that the developers syndicate.
These feeds push out events that interest the developers at certain times and the information is controlled using different loggers. Thus when debugging you can get the debugging feed, when you want to see completed transactions you go to the transactions feeds etc.
This allows all the developers to get the information they want in a comfortable way and without any need to mess a lot with configuration. If you don't want to get it there's no need to remove yourself from a mailing list or edit a configuration file - simply remove the feed and be done with it.
Very cool, and the idea was stolen from Pragmatic Project Automation.
Most of the digital libraries uses RSS/ATOM to display their search/results, data update, according to the OAI-PMH protocol
With our internal TRAC server, I'm subscribed to the timeline view for each project that I work on. It's great for keeping track of checkins and bug tickets. This is pretty exclusive to a developer position though.
I also am subscribed to the recent changes for our installation of MediaWiki that we use for our intranet. That way it's easy to see if documents that I need have been changed, or if there's new policies etc.
Our website has a news page that I wrote an RSS feed for as well. While you mentioned that you weren't really interested in recent news, it is nice to keep up with our press releases.
I have seen RSS used to syndicate gas prices from a service for a specific zip code.
there are many examples. Here are a couple.
SharePoint provides RSS feeds from its lists.
Many faceted navigation products allow you to get an RSS feed based on a selected filter. For example, you can navigate to view 24" LCD Monitors on newegg.com and then get an RSS feed of that view.
Mantis bug tracker includes RSS feeds although I wish they were more configurable. Also we use MediaWiki for documentation which has all sorts of RSS Feeds including a per page watch, and recent changes.
I just added RSS feeds to the ticketing system I use at work (TicketDesk) and that feature should be in the next release of the product.
It's nice because it basically provides me a custom search view of outstanding trouble tickets or work requests that comes to me rather then me having to go to the application. It also allows users to get feeds of issues they may be interested in, but not require them to get emails on each update.
I'm looking at implementing an RSS feed for calls for service that our agency takes, to provide the administrators a quick and easy way to see what has been going on.
Atom feed documents and Atom entry documents are used as the representation format for RESTful web services that follow the Atom Publication Protocol (AtomPub).
I personally have used syndication feeds to expose a sub-set of the Windows Event Log information so that I could subscribe and be notified of critical events on a server.
immobilienscout24
they use RSS feeds for updates on your search.