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I am using Google App Engine BLOBSTORE. I already have some images saved on the server now I would like to consume them via browser (HTML5, JAVASCRIPT etc...) It turns out that I have only the link that apparently is not the image itself, as follows:
Note that there is no extension in the URL...
What is the correct way to consume these blobs in the browser? Can I simply use this URL in the IMG SRC parameter?
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Yes you can use with the HTML5 img tag, follow the example:
<div>
<img src="https://filiperebollo1986.appspot.com/serve?blob-key=AMIfv967H0sWgJttreCFsuGZ57JmaXCkhFPC4QoHcPPxLBN2JhGkOGsY34rdD4ebvqNtdYfTmf_utULqUjdP_9mkjJQ91jkwkcDMlxlU7PZwrC-r0W-eIa3r8YaTWPKd7hAzuTcftyiUg8Ho2k9g1k4JV4Yx2MzdTwe_HeCHKGCvxnH3sm_WWN0" />
</div>
But when it comes to good practices, here are some considerations: There are some good practices to be followed when it comes to serving web images, most consist of optimizing the image itself to decrease its weight, and thus decreasing its size which would result in a shorter time for the user to be able to view it on your site, there is a guide of own google in pt-br to teach on the subject, I will be leaving the link at the end of the reply, besides it is also always indicated the use of a CDN service to serve the images and also use caching strategies.
link to the optimization guide: https://developers.google.com/web/fundamentals/performance/optimizing-content-efficiency/image-optimization?hl=pt-br
Browser other questions tagged javascript servlet blob google-app-engine
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jsfidle link, with an "executable" example https://jsfiddle.net/brz4g3c1/
– Leonardo Villela
But is that best practice? What would be the best way to consume these blobs? Won’t I have performance problems using this url directly? Because I realize it takes a while to load in the browser..
– Filipe Rebollo
changed the answer to contemplate this question, beauty?
– Leonardo Villela
I’m not seeing the change only the HTML tags as you had responded at the beginning..
– Filipe Rebollo
Opa Felipe, check now.
– Leonardo Villela
You mean the URL generated is as much as a *.jpeg type URL?
– Filipe Rebollo
Yes, so that your server sent the content-type of your image in Sponse, it makes no difference, now as for the best type of extension to be used is another story, this is very detailed in this guide that I put, in the case of your image, it is sending the containstype image/png, in general the format that more Performa and has high compatibility with the browser is JPEG, however its quality is lower.
– Leonardo Villela
I was able to clear your doubts?
– Leonardo Villela
Perfect, thank you very much!
– Filipe Rebollo
Nothing Felipe, glad I could help, good studies, just be sure to prioritize the relevant comments, mark the answer as useful and the question as solved, so other users can view better, :)
– Leonardo Villela
In my backend I created a Serve.java plus upload... What is the need to use it if I can consume directly through the URL? And how I can use it via browser, JAVASCRIPT, HTML5.. 

public class Serve extends HttpServlet {
 private BlobstoreService blobstoreService = BlobstoreServiceFactory.getBlobstoreService();

 @Override
 public void doGet(HttpServletRequest req, HttpServletResponse res)
 throws IOException {
 Blobkey blobKey = new Blobkey(req.getParameter("blob-key")); blobstoreService.serve(blobKey, res); } }
– Filipe Rebollo
In my view given your restrictions, I see no reason for you not to use the URL directly, just remember to upload the optimized images to your google service if you are focusing on performance.
– Leonardo Villela