Size of RSS feed

Question

I'm using ROME to generate a feed from data in my database.

In all the samples I found, the Servlet extracts all the data from the database, and sends it as a feed.

Now, if the database contains thousands of entries, how many entries should I send?

protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    try {
        SyndFeed feed = getFeed(request);

        String feedType = request.getParameter("type");
        feedType = feedType != null ? feedType : defaultType;
        feed.setFeedType(feedType);

        response.setContentType("application/xml; charset=UTF-8");
        SyndFeedOutput output = new SyndFeedOutput();
        output.output(feed, response.getWriter());
    } catch (FeedException ex) {
        String msg = "Could not generate feed";
        log(msg, ex);
        response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, msg);
    }
}


protected SyndFeed getFeed(HttpServletRequest request) {

    // **** Here I query the database for posts, but I don't know how many
    // I should fetch or where should I stop?  ***
    List<Post> posts = getPosts(); 

    SyndFeed feed = new SyndFeedImpl();
    feed.setTitle("My feed");
    feed.setLink("http://myurl");
    feed.setDescription("my desc");

    // create the feeds.Each tutorial will be a feed entry
    List<SyndEntry> entries = new ArrayList<SyndEntry>();
    for (Post post : posts) {
        SyndEntry entry = new SyndEntryImpl();
        SyndContent description;
        String title = post.getTitle();
        String link = post.getLink();
        entry.setTitle(title);
        entry.setLink(link);

        // Create the description of the feed entry
        description = new SyndContentImpl();
        description.setType("text/plain");
        description.setValue(post.getDesc());
        entry.setDescription(description);
        entries.add(entry);
    }
    feed.setEntries(entries);
    return feed;
}

score 1 · Answer 1 · edited Oct 07 '21 at 11:19

1

There really isn't a single way to do this that all rss clients will support, but i would recommend checking out rfc 5005 appendix B, you'll at least have a referenxe to give to clients. https://www.rfc-editor.org/rfc/rfc5005#appendix-B

so long as your default query always shows the latest (page length you define) items, sorted descending, all clients will appear correct. Clients that need to be able to page can implement this standard.

edited Oct 07 '21 at 11:19

Community

1
1

answered Nov 04 '14 at 02:58

Steve Siebert

1,874
12
18

So I just present the latest N posts and it's up to the client to adjust the fetching frequency? – Majid Laissi Nov 04 '14 at 09:43
Yep - honestly, that's the nature of ATOM/RSS (especially RSS). That RFC helps, but there really isn't any descriptor file (like WSDL or WADL) or otherwise to go along with it to aid users to know if you support standard (RFC) or non-standard query parameters. The closest thing you can do is add an OpenSearch descriptor file to help. – Steve Siebert Nov 04 '14 at 09:45

score 0 · Answer 2 · answered Nov 04 '14 at 02:31

I suggest a paging system. the user makes a request for page 0 to take 30 items. then the user makes a request for page 1 to take the next 30 items. first request: items 0->29, second request: items 30->59. to model this have a integer variable called skip keep track of what position to start at, for instance:

int skip = page * numItems; // first request: 0 * 30 (starts at 0), sec request: 1 * 30 (starts at 30)

So you will skip so many items and take only the value of numItems. Then the client requests for however many feed items the client wants at once.

thanks for the reply but RSS feed does not work that way. I don't know who's calling my Servlet so I must always send the latest posts in descending order. — Majid Laissi, Nov 04 '14 at 09:47

Size of RSS feed

2 Answers2