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Finding cacheable areas in your Web Site using Python and Selenium

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Presentation Transcript

  1. Finding cacheable areas in your Web Site using Python and Selenium David Elfi Intel

  2. What does this session talk about? • Python • Performance • Web applications • Hands on session

  3. Caching • Hot topic in web applications because • Better response time across geo distribution • Better scalability • Difficult to focus at development time • Help developers to improve response time

  4. Source: Steve Souders– Cache is King!

  5. What to do • Find text areas repeated in a web resource (page, json response, other dynamic resources) in order to split them in different responses • Use Cache-Control, Expires and ETag HTTP Headers for caching control • Identify all the dependencies for a given URL • Even AJAX calls

  6. Proposed Solution • Take snapshots in different points in time • Use selenium for: • Download ALL the content • Needs to run JS code for Ajax • Compare the snapshots looking for similarities • Split the similar text in different HTTP responses

  7. Solution – Snapshots • Selenium through a forward proxy Proxy Twisted Web Server Store Content Data

  8. Running Selenium – Snapshots • Call Selenium from Python • Use of WebDriver >>> from selenium import webdriver >>> >>> br = webdriver.Firefox() >>> >>> br.get(“http://www.intel.com”) >>> >>> br.close()

  9. Twisted Proxy - Snapshots class CacheProxyClient(proxy.ProxyClient): defconnectionMade(self): # Connection Made. Prepare object properties defhandleHeader(self, key, value): # Save response header. defhandleResponsePart(self, buf): # Store response data. defhandleResponseEnd(self): # Finished response transmission. Store it class CacheProxyClientFactory(proxy.ProxyClientFactory): protocol = CacheProxyClient class CacheProxyRequest(proxy.ProxyRequest): protocols = dict(http=CacheProxyClientFactory) class CacheProxy(proxy.Proxy): requestFactory = CacheProxyRequest class CacheProxyFactory(http.HTTPFactory): protocol = CacheProxy

  10. Selenium + Twisted - Snapshots • Run Selenium using Proxy >>> from selenium import webdriver >>> fp = webdriver.FirefoxProfile() >>> fp.set_preference("network.proxy.type", 1) >>> fp.set_preference("network.proxy.http", "localhost") >>> fp.set_preference("network.proxy.http_port", 8080) >>> br = webdriver.Firefox(firefox_profile=fp)

  11. Selenium + Twisted - Snapshots • Configure Twisted and run Selenium in an internal Twisted thread from twisted.internetimport endpoints, reactor endpoint = endpoints.serverFromString(reactor, "tcp:%d:interface=%s" % (8080, "localhost")) d = endpoint.listen(CacheProxyFactory()) reactor.callInThread( runSelenium, url_str) reactor.run()

  12. All together running

  13. Comparison method Output = n = 2 = 1 2 3 n 1

  14. ''' Equal sequence searcher ''' defmatchingString(s1, s2): '''Compare 2 sequence of strings and return the matching sequences concatenated''' from difflibimport SequenceMatcher matcher = SequenceMatcher(None, s1, s2) output = "" for (i,_,n) in matcher.get_matching_blocks(): output += s1[i:i+n] return output defmatchingStringSequence( seq ): ''' Compare between pairs up to final result ''' try: matching = seq[0] for s in seq[1:len(seq)]: matching = matchingString(matching, s) return matching except TypeError: return "" Comparison

  15. Next Steps • Split similar texts in different HTTP responses • Set Cache-Control • Public • Private • No-cache • Set Expires • Depending on the time it should be cache • Set ETag • If response is big and does change too often

  16. Advanced Features to be done • Detect cache invalidation time from snapshots • SSL supports • Wait for all AJAX calls • Selenium Scripting • Authenticated URLs • Full feature sequence

  17. Summary • If caching areas has not been identified previous to development, this code could save time and effort in doing so • Caching areas need to be analyzed for looking best cache method (server cache, CDN, browser caching) • Refactoring for maximizing caching data is the next step

  18. Q & A

  19. Thank you! david.r.elfi@intel.com @elfoTech

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