Infrastructure Architecture: Whitelisting with JSON and API Keys
Application delivery infrastructure can be a valuable partner in architecting solutions …. AJAX and JSON have changed the way in which we architect applications, especially with respect to their ascendancy to rule the realm of integration, i.e. the API. Policies are generally focused on the URI, which has effectively become the exposed interface to any given application function. It’s REST-ful, it’s service-oriented, and it works well. Because we’ve taken to leveraging the URI as a basic building block, as the entry-point into an application, it affords the opportunity to optimize architectures and make more efficient the use of compute power available for processing. This is an increasingly important point, as capacity has become a focal point around which cost and efficiency is measured. By offloading functions to other systems when possible, we are able to increase the useful processing capacity of an given application instance and ensure a higher ratio of valuable processing to resources is achieved. The ability of application delivery infrastructure to intercept, inspect, and manipulate the exchange of data between client and server should not be underestimated. A full-proxy based infrastructure component can provide valuable services to the application architect that can enhance the performance and reliability of applications while abstracting functionality in a way that alleviates the need to modify applications to support new initiatives. AN EXAMPLE Consider, for example, a business requirement specifying that only certain authorized partners (in the integration sense) are allowed to retrieve certain dynamic content via an exposed application API. There are myriad ways in which such a requirement could be implemented, including requiring authentication and subsequent tokens to authorize access – likely the most common means of providing such access management in conjunction with an API. Most of these options require several steps, however, and interaction directly with the application to examine credentials and determine authorization to requested resources. This consumes valuable compute that could otherwise be used to serve requests. An alternative approach would be to provide authorized consumers with a more standards-based method of access that includes, in the request, the very means by which authorization can be determined. Taking a lesson from the credit card industry, for example, an algorithm can be used to determine the validity of a particular customer ID or authorization token. An API key, if you will, that is not stored in a database (and thus requires a lookup) but rather is algorithmic and therefore able to be verified as valid without needing a specific lookup at run-time. Assuming such a token or API key were embedded in the URI, the application delivery service can then extract the key, verify its authenticity using an algorithm, and subsequently allow or deny access based on the result. This architecture is based on the premise that the application delivery service is capable of responding with the appropriate JSON in the event that the API key is determined to be invalid. Such a service must therefore be network-side scripting capable. Assuming such a platform exists, one can easily implement this architecture and enjoy the improved capacity and resulting performance boost from the offload of authorization and access management functions to the infrastructure. 1. A request is received by the application delivery service. 2. The application delivery service extracts the API key from the URI and determines validity. 3. If the API key is not legitimate, a JSON-encoded response is returned. 4. If the API key is valid, the request is passed on to the appropriate web/application server for processing. Such an approach can also be used to enable or disable functionality within an application, including live-streams. Assume a site that serves up streaming content, but only to authorized (registered) users. When requests for that content arrive, the application delivery service can dynamically determine, using an embedded key or some portion of the URI, whether to serve up the content or not. If it deems the request invalid, it can return a JSON response that effectively “turns off” the streaming content, thereby eliminating the ability of non-registered (or non-paying) customers to access live content. Such an approach could also be useful in the event of a service failure; if content is not available, the application delivery service can easily turn off and/or respond to the request, providing feedback to the user that is valuable in reducing their frustration with AJAX-enabled sites that too often simply “stop working” without any kind of feedback or message to the end user. The application delivery service could, of course, perform other actions based on the in/validity of the request, such as directing the request be fulfilled by a service generating older or non-dynamic streaming content, using its ability to perform application level routing. The possibilities are quite extensive and implementation depends entirely on goals and requirements to be met. Such features become more appealing when they are, through their capabilities, able to intelligently make use of resources in various locations. Cloud-hosted services may be more or less desirable for use in an application, and thus leveraging application delivery services to either enable or reduce the traffic sent to such services may be financially and operationally beneficial. ARCHITECTURE is KEY The core principle to remember here is that ultimately infrastructure architecture plays (or can and should play) a vital role in designing and deploying applications today. With the increasing interest and use of cloud computing and APIs, it is rapidly becoming necessary to leverage resources and services external to the application as a means to rapidly deploy new functionality and support for new features. The abstraction offered by application delivery services provides an effective, cross-site and cross-application means of enabling what were once application-only services within the infrastructure. This abstraction and service-oriented approach reduces the burden on the application as well as its developers. The application delivery service is almost always the first service in the oft-times lengthy chain of services required to respond to a client’s request. Leveraging its capabilities to inspect and manipulate as well as route and respond to those requests allows architects to formulate new strategies and ways to provide their own services, as well as leveraging existing and integrated resources for maximum efficiency, with minimal effort. Related blogs & articles: HTML5 Going Like Gangbusters But Will Anyone Notice? Web 2.0 Killed the Middleware Star The Inevitable Eventual Consistency of Cloud Computing Let’s Face It: PaaS is Just SOA for Platforms Without the Baggage Cloud-Tiered Architectural Models are Bad Except When They Aren’t The Database Tier is Not Elastic The New Distribution of The 3-Tiered Architecture Changes Everything Sessions, Sessions Everywhere
HTML5 WebSocket rewriting
I am having an issue with rewriting my WebSocket connection. Let me explain my scenario, and then I will explain the issue I am experiencing. On my Internal network (192.168.252.x) I have a HTML5 gateway device(252.100), that is used to establish an HTML5 RDP session. This component is setup correctly, from the internal network I am able to log into the web based interface and successfully establish an HTML5 based RDP connection from my HTML5 gateway device (252.100) to my target machine 252.101. What I am trying to accomplish is to do this HTML5 RDP connection going through the F5. From the webtop, my user will click on a portal access link. This portal access link takes the user to the web based front-end of my HTML5 gateway device via and https webpage. My user is able to successfully go through the webtop, and log into my web front end. The issue occurs when starting the HTML5 RDP session from the webtop. My HTML5 proxy machine is throwing an error saying Websocket closed. Tracing the network traffic between all components, there is no traffic flow from the HTML gateway and the Target machine, and no traffic flows into the HTML gateway. This is due to the fact that the Websocket is not being rewritten by the F5. I will try to attach an image with the Chrome dev console that shows this websocket address: In short: when a new websocket is created I get the following: WebSocket connection to 'wss://192.168.252.100/myservice?mypage.hsl_mode=DIRECT&servicename_name=encodedlinkname failed: Error in connection establishment net::ERR_CONNECTION_TIMED_OUT. What I would expect to see is not the direct Internal IP address of the HTML5 gateway but some External IP from the F5 since the websocket should be rewritten by F5. My External net address is 192.168.210.x. I am testing from 192.168.210.100 and my F5 External self IP is 192.168.210.22. So I would expect to see that the websocket address would the External SelfIP. I have attempted playing around with the HTTP profile, Redirect Rewrite settings (None, All, Matching, and Nodes). But this didn't seem to help. I have also tried creating a WebSocket profile and tested all the Masking settings, (Preserve, Unmask, Selective, and Remmask) Also no dice. I have tested quite a few settings on the other profiles as well without any luck. Any suggestions would be helpful. As a side note: I was able to get this successfully running on Big-ip 11.4. With the same configuration, I am not able to get this working on our newer 12.1 implementation. I am also currently unable to observe the 11.4 websocket creation behavior as this VE install has eaten itself while trying to do a version update.. But that is another story.
APM :: VMware View :: Blast HTML5
I'm trying to get the APM functioning with VMware View Blast client - and I am having quite the time. I have tried the iApp (1.5) but haven't been able to get that to function either. At the moment, I have a manual configuration based-off of the deployment guide. The deployment guide says to create a forwarding virtual server, and the iApp does the same thing. Neither of which seem to be working for me. So with the forwarding VS above created… I can log-in fine, the webtop displays, the RDP link I have works great... the Blast HTML5 link... not so much. If I click on the VMware View desktop shown above, it brings me to the following: The error shown above is thrown-around a lot by View, so it’s hard to say what the real problem is. I’ve seen that error displayed for straight-up communications issues in the past… which I think this is. If I do a tcpdump on the BIG-IP, I can see it trying to connect to 8443, but it cannot connect (SYNs… no SYN/ACKs). 11:27:30.022625 IP x.x.x.10.28862 > x.x.x.252.8443: Flags [S], seq 2246191783, win 4140, options [mss 1380,sackOK,eol], length 0 out slot1/tmm0 lis=/Common/xxxxxxxxxxxxxxxxxxxx-https Source is the floating IP, destination is the VS. I know 8443 is listening on the VMware View server because I can connect to it locally. And I know the VMware View server knows how to get back to the F5 because it populates the webtop with my available desktop(s) shown above. I tried converting the forwarding VS to standard, assigned a pool, etc… and it still did the same thing. SYNs… no SYN/ACKs. What might be telling though is the lis= above. It lists my main virtual server with the APM policy assigned. That makes me think though… Why is it trying to connect to that VS and not the forwarding VS? The forwarding virtual server is a better match no? In any event, yeah if the virtual server isn’t listening on 8443, of course it won’t reply back (my thought-process anyway). So I figure… welp, why not just try an “any” port VS… yeah not so much. If I manually remove the :0 and submit, it loads the same error about the certificate. Nothing shows-up in tcpdump trying to connect to 8443 either - so, a step back. If anybody happen to have any ideas for me, I would be really appreciative. Thanks!HTML5 Web Sockets Changes the Scalability Game
#HTML5 Web Sockets are poised to completely change scalability models … again. Using Web Sockets instead of XMLHTTPRequest and AJAX polling methods will dramatically reduce the number of connections required by servers and thus has a positive impact on performance. But that reliance on a single connection also changes the scalability game, at least in terms of architecture. Here comes the (computer) science… If you aren’t familiar with what is sure to be a disruptive web technology you should be. Web Sockets, while not broadly in use (it is only a specification, and a non-stable one at that) today is getting a lot of attention based on its core precepts and model. Web Sockets Defined in the Communications section of the HTML5 specification, HTML5 Web Sockets represents the next evolution of web communications—a full-duplex, bidirectional communications channel that operates through a single socket over the Web. HTML5 Web Sockets provides a true standard that you can use to build scalable, real-time web applications. In addition, since it provides a socket that is native to the browser, it eliminates many of the problems Comet solutions are prone to. Web Sockets removes the overhead and dramatically reduces complexity. - HTML5 Web Sockets: A Quantum Leap in Scalability for the Web So far, so good. The premise upon which the improvements in scalability coming from Web Sockets are based is the elimination of HTTP headers (reduces bandwidth dramatically) and session management overhead that can be incurred by the closing and opening of TCP connections. There’s only one connection required between the client and server over which much smaller data segments can be sent without necessarily requiring a request and a response pair. That communication pattern is definitely more scalable from a performance perspective, and also has a positive impact of reducing the number of connections per client required on the server. Similar techniques have long been used in application delivery (TCP multiplexing) to achieve the same results – a more scalable application. So far, so good. Where the scalability model ends up having a significant impact on infrastructure and architectures is the longevity of that single connection: Unlike regular HTTP traffic, which uses a request/response protocol, WebSocket connections can remain open for a long time. - How HTML5 Web Sockets Interact With Proxy Servers This single, persistent connection combined with a lot of, shall we say, interesting commentary on the interaction with intermediate proxies such as load balancers. But ignoring that for the nonce, let’s focus on the “remain open for a long time.” A given application instance has a limit on the number of concurrent connections it can theoretically and operationally manage before it reaches the threshold at which performance begins to dramatically degrade. That’s the price paid for TCP session management in general by every device and server that manages TCP-based connections. But Lori, you’re thinking, HTTP 1.1 connections are persistent, too. In fact, you don’t even have to tell an HTTP 1.1 server to keep-alive the connection! This really isn’t a big change. Whoa there hoss, yes it is. While you’d be right in that HTTP connections are also persistent, they generally have very short connection timeout settings. For example, the default connection timeout for Apache 2.0 is 15 seconds and for Apache 2.2 a mere 5 seconds. A well-tuned web server, in fact, will have thresholds that closely match the interaction patterns of the application it is hosting. This is because it’s a recognized truism that long and often idle connections tie up server processes or threads that negatively impact overall capacity and performance. Thus the introduction of connections that remain open for a long time changes the capacity of the server and introduces potential performance issues when that same server is also tasked with managing other short-lived, connection-oriented requests. Why this Changes the Game… One of the most common inhibitors of scale and high-performance for web applications today is the deployment of both near-real-time communication functions (AJAX) and traditional web content functions on the same server. That’s because web servers do not support a per-application HTTP profile. That is to say, the configuration for a web server is global; every communication exchange uses the same configuration values such as connection timeouts. That means configuring the web server for exchanges that would benefit from a longer time out end up with a lot of hanging connections doing absolutely nothing because they were used to grab standard dynamic or static content and then ignored. Conversely, configuring for quick bursts of requests necessarily sets timeout values too low for near or real-time exchanges and can cause performance issues as a client continually opens and re-opens connections. Remember, an idle connection is a drain on resources that directly impacts the performance and capacity of applications. So it’s a Very Bad Thing™. One of the solutions to this somewhat frustrating conundrum, made more feasible by the advent of cloud computing and virtualization, is to deploy specialized servers in a scalability domain-based architecture using infrastructure scalability patterns. Another approach to ensuring scalability is to offload responsibility for performance and connection management to an appropriately capable intermediary. Now, one would hope that a web server implementing support for both HTTP and Web Sockets would support separately configurable values for communication settings on at least the protocol level. Today there are very few web servers that support both HTTP and Web Sockets. It’s a nascent and still evolving standard so many of the servers are “pure” Web Sockets servers, many implemented in familiar scripting languages like PHP and Python. Which means two separate sets of servers that must be managed and scaled. Which should sound a lot like … specialized servers in a scalability domain-based architecture. The more things change, the more they stay the same. The second impact on scalability architectures centers on the premise that Web Sockets keep one connection open over which message bits can be exchanged. This ties up resources, but it also requires that clients maintain a connection to a specific server instance. This means infrastructure (like load balancers and web/application servers) will need to support persistence (not the same as persistent, you can read about the difference here if you’re so inclined). That’s because once connected to a Web Socket service the performance benefits are only realized if you stay connected to that same service. If you don’t and end up opening a second (or Heaven-forbid a third or more) connection, the first connection may remain open until it times out. Given that the premise of the Web Socket is to stay open – even through potentially longer idle intervals – it may remain open, with no client, until the configured time out. That means completely useless resources tied up by … nothing. Persistence-based load balancing is a common feature of next-generation load balancers (application delivery controllers) and even most cloud-based load balancing services. It is also commonly implemented in application server clustering offerings, where you’ll find it called server-affinity. It is worth noting that persistence-based load balancing is not without its own set of gotchas when it comes to performance and capacity. THE ANSWER: ARCHITECTURE The reason that these two ramifications of Web Sockets impacts the scalability game is it requires an broader architectural approach to scalability. It can’t necessarily be achieved simply by duplicating services and distributing the load across them. Persistence requires collaboration with the load distribution mechanism and there are protocol-based security constraints with respect to incorporating even intra-domain content in a single page/application. While these security constraints are addressable through configuration, the same caveats with regards to the lack of granularity in configuration at the infrastructure (web/application server) layer must be made. Careful consideration of what may be accidentally allowed and/or disallowed is necessary to prevent unintended consequences. And that’s not even starting to consider the potential use of Web Sockets as an attack vector, particularly in the realm of DDoS. The long-lived nature of a Web Socket connection is bound to be exploited at some point in the future, which will engender another round of evaluating how to best address application-layer DDoS attacks. A service-focused, distributed (and collaborative) approach to scalability is likely to garner the highest levels of success when employing Web Socket-based functionality within a broader web application, as opposed to the popular cookie-cutter cloning approach made exceedingly easy by virtualization. Infrastructure Scalability Pattern: Partition by Function or Type Infrastructure Scalability Pattern: Sharding Sessions Amazon Makes the Cloud Sticky Load Balancing Fu: Beware the Algorithm and Sticky Sessions Et Tu, Browser? Forget Hyper-Scale. Think Hyper-Local Scale. Infrastructure Scalability Pattern: Sharding Streams Infrastructure Architecture: Whitelisting with JSON and API Keys Does This Application Make My Browser Look Fat? HTTP Now Serving … EverythingAPM SSO with Atlassian Jira, Confluence and Sharepoint
Hi, For one of our clients we are trying to realize a single sign on solution on our F5 for Atlassian Jira, Confluence, Stash and Sharepoint. To this end we have created a virtual server with an APM policy of type LTM-APM. All websites are published through one and the same Virtual Server. We filter host-headers (HTTP::host) in order to decide which backend server traffic needs to be forwarded to and use different SSO Configurations for connecting to the backend. In addition we used a community iRule to provide for Sharepoint-office integration SSO (as provided here: https://devcentral.f5.com/codeshare/apm-sharepoint-authentication) with some tweaks. Although SSO works we're still struggling with issues that we've not yet been able to resolve and we think are related to the fact that especially Jira and Confluence are stateful HTML5 applications with ajax. This in combination with the fact that there is no integration between the F5 and the backend webservers. These problems are giving me a headache. I've already searched devcentral but have been unable to find a solution for our problems. Amongst others the following problems are encountered: When a logged on user is inactive for some time he runs into an APM session inactivity timeout (F5 side) and the session is deleted from the session table; This shouldn't be a problem in a normal situation, but the webapplication clientside does not signal the user that the session expired. Now when the user comes back again and clicks somewhere on the webpage 1 of 2 things may happen: a. The user clicks a link which fires a javascript/ajax/restapi-call; this script may perform a call to the backend server, is blocked by the F5 and redirected to a login page in the background. For the user this means an unresponsive webapplication with a doughnut or an error on the screen (without the F5 in between the user would also get an 'error', but with a possibility to copy data that will be lost and a link to the logon page). For the user the webapplication is broken at this point. b. The user clicks a link that will actively fire a redirect to the F5 login page. This is desirable behaviour from our point of view, but... In comes the next issue... After a re-login via APM the user is redirected back to the landing-page that initiated the APM_SESSION_STARTED event. Because the webapplication fires all kinds of requests from the client to the server more often than not this process erroneously redirects the user to some page belonging to the rest api or a javascript on the webserver. When redirected to javascript the user sees javascript, when to the rest api it's even more jibberish. There some other issues too but my post is getting too long i guess so i'll leave them for a different post. We thought of several solutions but up until now none of them really seem to work satisfactory: Javascript injection (something like this: https://devcentral.f5.com/questions/ltm-apm-session-expired-detection) to detect APM session timeout and actively redirect the user. This however would not solve incorrect redirect behaviour mentioned in my second statement; in addition Auto redirect on inactivity would eventually also timeout on the APM loginform after which the original landing page is no longer available; Auto logout on serverside; This is a problem however if user is still working in different browser-tab in another application and the application timing out redirects the user to the logon page, which in turn is being detected by the F5, hereby unintentionally killing the APM session altogether and requiring an 'active' user to re-login and potentially losing work; Redirect to a default page (for the second issue); this solution is not acceptable to our client; Sending heartbeats to always keep the session alive; this would however circumvent active security policies and therefore is not acceptable; Using Client Initiated forms based auth and only enable APM for login pages; this seems to work somewhat (inactivity timeout on the serverside provides for the desired behaviour), however, after the first login APM is never being hit again causing an inactivity timeout in no time. The main goal is to provide a seamless SSO-experience for the users. Any thoughts to resolve these issues would really be appreciated. Thanks, MarkBIG-IP APM with Horizon 7.x HTML5 gets a Hotfix For Updated Code
Technical update on some new hotfixes that were rolled out to resolve some issues with HTML5 connectivity with VMware Horizon 7.1/7.2 with BIG-IP Access Policy Manager. What is VMware Horizon HTML Access? VMware Horizon HTML Access provides the ability for employees to access applications and desktops via web browsers (HTML5 compliant) and without the need for additional plugins or native client installations. This method of access provides advantages to customers who utilize very strict software installation requirements and require access to their internal resources, as well as customers who utilize BYOD based implementations. VMware Horizon HTML Access is an alternative way of accessing company internal resources without the requirement of software installation. What does the Hotfix Do? The Hotfix is designed to allow the newer version of the VMware Horizon HTML Access Clients which were upgraded with new URI information to be accessible via APM. Without this hotfix, customers who upgrade to the Horizon 7.1/7.2 code may experience an issue where HTML5 will not connect to the VDI Resource (blank or grey screen.) The easiest way to determine if you are affected by the issue is within the URL. If you do not see the string f5vdifwd within the URL then you are most likely affected by this issue. Here is an example of a working configuration. Notice the f5vdifwd string in the URL: https://test.test.local/f5vdifwd/vmview/68a5058e-2911-4316-849b-3d55f5b5cafb/portal/webclient/index.html#/desktop The Hotfix Information Details Note that the fixes are incorporated into Hotfixes. F5 recommends to use the Hotfix builds over the iRules listed in the below article. If the iRules are in place when upgrading to a build with the incorporated fix, make sure that the iRule is removed. Version 12.1.2 HF1 Release Notes Version 13.0 HF2 Release Notes 638780-3 Handle 302 redirects for VMware Horizon View HTML5 client Component Access Policy Manager Symptoms Starting from v4.4, Horizon View HTML5 client is using new URI for launching remote sessions, and supports 302 redirect from old URI for backward compatibility. Conditions APM webtop with a VMware View resource assigned. HTML5 client installed on backend is of version 4.4 or later. Impact This fix allows for VMware HTML5 clients v4.4 or later to work properly through APM. Workaround for versions 11.6.x and 12.x priority 2 when HTTP_REQUEST { regexp {(/f5vdifwd/vmview/[0-9a-f\-]{36})/} [HTTP::uri] vmview_html5_prefix dummy } when HTTP_RESPONSE { if { ([HTTP::status] == "302") && ([HTTP::header exists "Location"]) } { if { [info exists vmview_html5_prefix] } { set location [HTTP::header "Location"] set location_path [URI::path $location] if { $location_path starts_with "/portal/" } { set path_index [string first $location_path $location] set new_location [substr $location $path_index] regsub "/portal/" $new_location $vmview_html5_prefix new_location HTTP::header replace "Location" $new_location } unset vmview_html5_prefix } } } Workaround for version 13.0 priority 2 when HTTP_REQUEST { regexp {(/f5vdifwd/vmview/[0-9a-f\-]{36})/} [HTTP::uri] dummy vmview_html5_prefix } when HTTP_RESPONSE { if { ([HTTP::status] == "302") && ([HTTP::header exists "Location"]) } { if { [info exists vmview_html5_prefix] } { set location [HTTP::header "Location"] set location_path [URI::path $location] if { $location_path starts_with "/portal/" } { set path_index [string first $location_path $location] set new_location "$vmview_html5_prefix[substr $location $path_index]" HTTP::header replace "Location" $new_location } unset vmview_html5_prefix } } }
HTML5 Remote Desktop client for APM Webtop?
We're currently running BIG-IP 11.4 Hotfix 3. I'm trying to publish a Remote Desktop via a Webtop (RDP) and it either needs a browser plugin (no good for Internet Explorer 10+) or when I turn on Java it is very fussy with the versions. Has the later versions of BIG-IP included a HTML5 viewer? Updating the F5 environment here is not an easy task so I can't update to find out.F5 Friday: Domain Sharding On-Demand
Domain sharding is a well-known practice to improve application performance – and you can implement automatically without modifying your applications today. If you’re a web developer, especially one that deals with AJAX or is responsible for page optimization (aka “Make It Faster or Else”), then you’re likely familiar with the technique of domain sharding, if not the specific terminology. For those who aren’t familiar with the technique (or the term), domain sharding is a well-known practice used to trick browsers into opening many more connections with a server than is allowed by default. This is important for improving page load times in the face of a page containing many objects. Given that the number of objects comprising a page has more than tripled in the past 8 years, now averaging nearly 85 objects per page, this technique is not only useful, it’s often a requirement. Modern browsers like to limit browsers to 8 connections per host, which means just to load one page a browser has to not only make 85 requests over 8 connections, but it must also receive those requests over those same, limited 8 connections. Consider, too, that the browser only downloads 2-6 objects over a single connection at a time, making this process somewhat fraught with peril when it comes to performance. This is generally why bandwidth isn’t a bottleneck for web applications but rather it’s TCP related issues such as round trip time (latency). Here are the two main points that need to be understood when discussing Bandwidth vs. RTT in regards to page load times: 1.) The average web page has over 50 objects that will need to be downloaded (reference: http://www.websiteoptimization.com/speed/tweak/average-web-page/) to complete page rendering of a single page. 2.) Browsers cannot (generally speaking) request all 50 objects at once. They will request between 2-6 (again, generally speaking) objects at a time, depending on browser configuration. This means that to receive the objects necessary for an average web page you will have to wait for around 25 Round Trips to occur, maybe even more. Assuming a reasonably low 150ms average RTT, that’s a full 3.75 seconds of page loading time not counting the time to download a single file. That’s just the time it takes for the network communication to happen to and from the server. Here’s where the bandwidth vs. RTT discussion takes a turn decidedly in the favor of RTT. -- RTT (Round Trip Time): Aka – Why bandwidth doesn’t matter So the way this is generally addressed is to “shard” the domain – create many imaginary hosts that the browser views as being separate and thus eligible for their own set of connections. This spreads out the object requests and responses over more connections simultaneously, allowing what is effectively parallelization of page loading functions to improve performance. Obviously this requires some coordination, because every host name needs a DNS entry and then you have to … yeah, modify the application to use those “new” hosts to improve performance. The downside is that you have to modify the application, of course, but also that this results in a static mapping. On the one hand, this can be the perfect time to perform some architectural overhauls and combine domain sharding with creating scalability domains to improve not only performance but scalability (and thus availability). You’ll still be stuck with the problem of tightly-coupled hosts to content, but hey – you’re getting somewhere which is better than nowhere. Or the better way (this is an F5 Friday so you knew that was coming) would be to leverage a solution capable of automatically sharding domains for you. No mess, no fuss, no modifying the application. All the benefits at one-tenth the work. DOMAIN SHARDING with BIG-IP WebAccelerator What BIG-IP WebAccelerator does, automatically, is shard domains by adding a prefix to the FQDN (Fully Qualified Domain Name). The user would initiate a request for “www.example.com” and WebAccelerator would go about its business of requesting it (or pulling objects from the cache, as per its configuration). Before returning the content to the user, however, WebAccelerator then shards the domain, adding prefixes to objects. The browser then does its normal processing and opens the appropriate number of connections to each of the hosts, requesting each of the individual objects. As WebAccelerator receives those requests, it knows to deshard (unshard?) the hosts and make the proper requests to the web or application server, thus insuring that the application understands the requests. This means no changes to the actual application. The only changes necessary are to DNS to ensure the additional hosts are recognized appropriately and to WebAccelerator, to configure domain sharding on-demand. This technique is useful for improving performance of web applications and is further enhanced with BIG-IP platform technology like OneConnect which multiplexes (and thus reuses) TCP connections to origin servers. This reduces the round trip time between WebAccelerator and the origin servers by keeping connections open, thus eliminating the overhead of TCP connection management. It improves page load time by allowing the browser to request more objects simultaneously. This particular feature falls into the transformative category of web application acceleration as it transforms content as a means to improve performance. This is also called FEO (Front End Optimization) as opposed to WPO (Web Performance Optimization) which focuses on optimization and acceleration of delivery channels, such as the use of compressing and caching. Happy Sharding! Fire and Ice, Silk and Chrome, SPDY and HTTP F5 Friday: The Mobile Road is Uphill. Both Ways. F5 Friday: Performance, Throughput and DPS F5 Friday: Protocols are from Venus. Data is from Mars. Acceleration is strategic, optimization is a tactic. Top-to-Bottom is the New End-to-End As Time Goes By: The Law of Cloud Response Time" (Joe Weinman) All F5 Friday Entries on DevCentral Network Optimization Won’t Fix Application Performance in the CloudWho Took the Cookie from the Cookie Jar … and Did They Have Proper Consent?
Cookies as a service enabled via infrastructure services provide an opportunity to improve your operational posture. Fellow DevCentral blogger Robert Haynes posted a great look at a UK law regarding cookies. Back in May a new law went info effect regarding “how cookies and other “cookie-like” objects are stored on users’ devices.” If you haven’t heard about it, don’t panic – there’s a one-year grace period before enforcement begins and those £500 000 fines are being handed out. The clock is ticking, however. What do the new regulations say? Well essentially whereas cookies could be stored with what I, as a non-lawyer, would term implied consent, i.e. the cookies you set are listed along with their purpose and how to opt out in some interminable privacy policy on your site, you are now going to have to obtain a more active and informed consent to store cookies on a user’s device. -- The UK Cookie Law – Robert goes on to explain that the solution to this problem requires (1) capturing cookies and (2) implementing some mechanism to allow users to grant consent. Mind you, this is not a trivial task. There are logic considerations – not all cookies are set at the same time – as well as logistical issues – how do you present a request for consent? Once consent is granted, where do you store that? In a cookie? That you must gain consent to store? Infinite loops are never good. And of course, what do you if consent is not granted, but the application depends on that cookie existing? To top it all off, the process of gathering consent requires modification to application behavior, which means new code, testing and eventually deployment. Infrastructure services may present an alternative approach that is less disruptive technologically, but does not necessarily address the business or logic ramifications resulting from such a change. COOKIES as a SERVICE Cookies as a Service, a.k.a. cookie gateways, wherein cookie authorization and management is handled by an intermediate proxy, is likely best able to mitigate the expense and time associated with modifying applications to meet the new UK regulation. As Robert describes, he’s currently working on a network-side scripting solution to meet the UK requirements that leverages a full-proxy architecture’s ability to mediate for applications and communicate directly with clients before passing requests on to the application. Not only is this a valid approach to managing privacy regulations, it’s also a good means of providing additional security against attacks that leverage cookies either directly or indirectly. Cross-site scripting, browser vulnerabilities and other attacks that bypass the same origin policy of modern web browsers – sometimes by design to circumvent restrictions on integration methods – as well as piggy-backing on existing cookies as a means to gain unauthorized access to applications are all potential dangerous of cookies. By leveraging encryption of cookies in conjunction with transport layer security, i.e. SSL, organizations can better protect both users and applications from unintended security consequences. Implementing a cookie gateway should make complying with regulations like the new UK policy a less odious task. By centralizing cookie management on an intermediate device, they can be easily collected and displayed along with the appropriate opt-out / consent policies without consuming application resources or requiring every application to be modified to include the functionality to do so. AN INFRASTRUCTURE SERVICE This is one of the (many) ways in which an infrastructure service hosted in “the network” can provide value to both application developers and business stakeholders. Such a reusable infrastructure-hosted service can be leveraged to provide services to all applications and users simultaneously, dramatically reducing the time and effort required to support such a new initiative. Reusing an infrastructure service also reduces the possibility of human error during the application modification, which can drag out the deployment lifecycle and delay time to market. In the case of meeting the requirements of the new UK regulations, that delay could become costly. According to a poll of CIOs regarding their budgets for 2010, The Society for Information Management found that “Approximately 69% of IT spending in 2010 will be allocated to existing systems, while about 31% will be spent on building and buying new systems. This ratio remains largely the same compared to this year's numbers.” If we are to be more responsive to new business initiatives and flip that ratio such that we are spending less on maintaining existing systems and more on developing new systems and methods of management (i.e. cloud computing ) we need to leverage strategic points of control within the network to provide services that minimize resources, time and money on existing systems. Infrastructure services such as cookie gateways provide the opportunity to enhance security, comply with regulations and eliminate costs in application development that can be reallocated to new initiatives and projects. We need to start treating the network and its unique capabilities as assets to be leveraged and services to be enabled instead of a fat, dumb pipe. Understanding network-side scripting This is Why We Can’t Have Nice Things When the Data Center is Under Siege Don’t Forget to Watch Under the Floor IT as a Service: A Stateless Infrastructure Architecture Model You Can’t Have IT as a Service Until IT Has Infrastructure as a Service F5 Friday: Eliminating the Blind Spot in Your Data Center Security Strategy The UK Cookie Law –SPDY versus HTML5 WebSockets
#HTML5 #fasterapp #webperf #SPDY So much alike, yet so vastly a different impact on the data center … A recent post on the HTTP 2.0 War beginning garnered a very relevant question regarding WebSockets and where it fits in (what might shape up to be) an epic battle. The answer to the question, “Why not consider WebSockets here?” could be easily answered with two words: HTTP headers. It could also be answered with two other words: infrastructure impact. But I’m guessing Nagesh (and others) would like a bit more detail on that, so here comes the (computer) science. Different Solutions Have Different Impacts Due to a simple (and yet profound) difference between the two implementations, WebSockets is less likely to make an impact on the web (and yet more likely to make an impact inside data centers, but more on that another time). Nagesh is correct in that in almost all the important aspects, WebSockets and SPDY are identical (if not in implementation, in effect). Both are asynchronous, which eliminates the overhead of “polling” generally used to simulate “real time” updates a la Web 2.0 applications. Both use only a single TCP connection. This also reduces overhead on servers (and infrastructure) which can translate into better performance for the end-user. Both can make use of compression (although only via extensions in the case of WebSockets) to reduce size of data transferred resulting, one hopes, in better performance, particularly over more constrained mobile networks. Both protocols operate “outside” HTTP and use an upgrade mechanism to initiate. While WebSockets uses the HTTP connection header to request an upgrade, SPDY uses the Next Protocol Negotiation (proposed enhancement to the TLS specification). This mechanism engenders better backwards-compatibility across the web, allowing sites to support both next-generation web applications as well as traditional HTTP. Both specifications are designed, as pointed out, to solve the same problems. And both do, in theory and in practice. The difference lies in the HTTP headers – or lack thereof in the case of WebSockets. Once established, WebSocket data frames can be sent back and forth between the client and the server in full-duplex mode. Both text and binary frames can be sent full-duplex, in either direction at the same time. The data is minimally framed with just two bytes. In the case of text frames, each frame starts with a 0x00 byte, ends with a 0xFF byte, and contains UTF-8 data in between. WebSocket text frames use a terminator, while binary frames use a length prefix. -- HTML5 Web Sockets: A Quantum Leap in Scalability for the Web WebSockets does not use HTTP headers, SPDY does. This seemingly simple difference has an inversely proportional impact on supporting infrastructure. The Impact on Infrastructure The impact on infrastructure is why WebSockets may be more trouble than its worth – at least when it comes to public-facing web applications. While both specifications will require gateway translation services until (if) they are fully adopted, WebSockets has a much harsher impact on the intervening infrastructure than does SPDY. WebSockets effectively blinds infrastructure. IDS, IPS, ADC, firewalls, anti-virus scanners – any service which relies upon HTTP headers to determine specific content type or location (URI) of the object being requested – is unable to inspect or validate requests due to its lack of HTTP headers. Now, SPDY doesn’t make it easy – HTTP request headers are compressed – but it doesn’t make it nearly as hard, because gzip is pretty well understood and even intermediate infrastructure can deflate and recompress with relative ease (and without needing special data, such as is the case with SSL/TLS and certificates). Let me stop for a moment and shamelessly quote myself from a blog on this very subject, “Oops! HTML5 Does it Again”: One of the things WebSockets does to dramatically improve performance is eliminate all those pesky HTTP headers. You know, things like CONTENT-TYPE. You know, the header that tells the endpoint what kind of content is being transferred, such as text/html and video/avi. One of the things anti-virus and malware scanning solutions are very good at is detecting anomalies in specific types of content. The problem is that without a MIME type, the ability to correctly identify a given object gets a bit iffy. Bits and bytes are bytes and bytes, and while you could certainly infer the type based on format “tells” within the actual data, how would you really know? Sure, the HTTP headers could by lying, but generally speaking the application serving the object doesn’t lie about the type of data and it is a rare vulnerability that attempts to manipulate that value. After all, you want a malicious payload delivered via a specific medium, because that’s the cornerstone upon which many exploits are based – execution of a specific operation against a specific manipulated payload. That means you really need the endpoint to believe the content is of the type it thinks it is. But couldn’t you just use the URL? Nope – there is no URL associated with objects via a WebSocket. There is also no standard application information that next-generation firewalls can use to differentiate the content; developers are free to innovate and create their own formats and micro-formats, and undoubtedly will. And trying to prevent its use is nigh-unto impossible because of the way in which the upgrade handshake is performed – it’s all over HTTP, and stays HTTP. One minute the session is talking understandable HTTP, the next they’re whispering in Lakota, a traditionally oral-only language which neatly illustrates the overarching point of this post thus far: there’s no way to confidently know what is being passed over a WebSocket unless you “speak” the language used, which you may or may not have access to. The result of all this confusion is that security software designed to scan for specific signatures or anomalies within specific types of content can’t. They can’t extract the object flowing through a WebSocket because there’s no indication of where it begins or ends, or even what it is. The loss of HTTP headers that indicate not only type but length is problematic for any software – or hardware for that matter – that uses the information contained within to extract and process the data. SPDY, however, does not eliminate these Very-Important-to-Infrastructure-Services HTTP headers, it merely compresses them. Which makes SPDY a much more compelling option than WebSockets. SPDY can be enabled for an entire data center via the use of a single component: a SPDY gateway. WebSockets ostensibly requires the upgrade or replacement of many more infrastructure services and introduces risks that may be unacceptable to many organizations. And thus my answer to the question "Why not consider WebSockets here” is simply that the end-result (better performance) of implementing the two may be the same, WebSockets is unlikely to gain widespread acceptance as the protocol du jour for public facing web applications due to the operational burden it imposes on the rest of the infrastructure. That doesn’t mean it won’t gain widespread acceptance inside the enterprise. But that’s a topic for another day… HTML5 Web Sockets: A Quantum Leap in Scalability for the Web Oops! HTML5 Does it Again The HTTP 2.0 War has Just Begun Fire and Ice, Silk and Chrome, SPDY and HTTP Grokking the Goodness of MapReduce and SPDY Google SPDY Protocol Would Require Mass Change in Infrastructure
