Patent Publication Number: US-8533333-B2

Title: Shared hosting using host name affinity

Description:
BACKGROUND 
     The Internet allows access to a wide variety of web sites. Some sites experience heavy traffic and may use large server farms dedicated to servicing a large number of concurrent requests. Examples of such sites might include large on-line book stores, world-wide bidding services, large corporate sites, and so forth. However, lower-traffic (hereinafter also called “smaller”) sites also contribute to the wealth and depth of the internet. Those smaller sites may encounter less traffic and may not be actively processing requests all the time. Perhaps such smaller sites may even be inactive most of the time. Examples of such smaller sites include, for example, a family blog that has a very limited number of authors and viewers. 
     For smaller sites, it is often economically and technically infeasible or at least inconvenient for the site owner to set up a server to actually host the web site. Accordingly, shared hosting service companies have come into being. Smaller web site owner may now hire the hosting service to host the web site. The hosting service will typically have one or more servers that serve a large number of web sites. It is possible, if not likely, to host a large number of web sites on a single server. Given that the shared hosting service provides services to a large number of smaller web sites that are not active all the time, the shared hosting service can have a single server host more web sites than the server would be capable of if the web sites were always active. 
     For instance, suppose the hosted web sites were on average active less than ten percent of the time. Also, suppose that a given server is capable of hosting 200 active web sites at a time. The shared hosting service might choose to deploy 2000 total web sites on the server in the hopes that the active web sites always stay less than the ten percent amount, thereby allowing the server to effectively service 2000 web sites in an acceptable manner. The success of this approach is dependent on the usage pattern of the host web sites, which may not be predictable in some cases. 
     However, shared hosting services recognize that trends sometimes change. Accordingly, shared hosting services perform a sort of manual load balancing by periodically checking each of their servers to be verify that the servers are effectively meeting the demands of the ever changing active web sites. In the case where the server is meeting demand by a significant margin and safety factor where the server is meeting demand and still has additional unconsumed resources, the service might choose to deploy additional web sites on that server to effectively maximize the server resources. In the case where the server is not meeting demand, this means that the server is at least at risk of failing to adequately respond to web site requests. In such a case, the hosting service might remove some web sites off of the server, and redeploy them on another, perhaps new, server. As the total number of web sites and/or the average percentage of active web sites increase, the shared hosting service will add new servers. A shared hosting service may have hundreds or even thousands of such servers, each having deployed thereon a large number of web sites. Each of these servers may have a configuration file that is managed by the service. 
     BRIEF SUMMARY 
     Embodiments described herein related to the routing of requests in a shared hosting environment. The shared hosting environment includes a network farm of servers, each capable of processing the request corresponding to the host name. When a request is received, a router determines whether or not there is already a host name affinitization of subset of the servers to the host name corresponding to the request. If so, the message is dispatched to one of those affinitized servers. If not, one or more of the servers are affinitized to the host name to create a subset of affinitized server(s) for that host name. Different host names may have different subsets of servers that they are affinitized to. 
     This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to describe the manner in which the above-recited and other advantages and features can be obtained, a more particular description of various embodiments will be rendered by reference to the appended drawings. Understanding that these drawings depict only sample embodiments and are not therefore to be considered to be limiting of the scope of the invention, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG. 1A  illustrates a message processor in the form of a computing system that may implement one or more features described herein; 
         FIG. 1B  illustrates a message processor in the form of a state machine that may implement one of more features described herein; 
         FIG. 2  illustrates a shared hosting environment in which host name affinitization may be employed; and 
         FIG. 3  illustrates a flowchart of a method for responding to a request corresponding to a host name in a shared hosting environment that performs host name affinitization. 
     
    
    
     DETAILED DESCRIPTION 
     In accordance with embodiments described herein, the principles described herein provide efficient mechanisms to affinitize processing on the basis of host name in a shared hosting environment. First, various embodiments of message processors will be described with respect to  FIGS. 1A and 1B . Then, various embodiments of the host name-based affinitization will be described with respect to  FIGS. 2 and 3 . 
       FIG. 1A  illustrates a message processor in the form of a computing system  100 A. In its most basic configuration, a computing system  100 A typically includes at least one processing unit  102  and memory  104 . The memory  104  may be physical system memory, which may be volatile, non-volatile, or some combination of the two. The term “memory” may also be used herein to refer to non-volatile mass storage such as physical storage media. If the computing system is distributed, the processing, memory and/or storage capability may be distributed as well. 
     As used herein, the term “module” or “component” can refer to software objects or routines that execute on the computing system. The different components, modules, engines, and services described herein may be implemented as objects or processes that execute on the computing system (e.g., as separate threads). However, as will be described further below with respect to  FIG. 1B , the message processor may be implemented as a state machine as well, perhaps even fully in hardware. 
     In the description that follows, embodiments are described with reference to acts that are performed by one or more computing systems. If such acts are implemented in software, one or more processors of the associated computing system that performs the act direct the operation of the computing system in response to having executed computer-executable instructions. An example of such an operation involves the manipulation of data. The computer-executable instructions (and the manipulated data) may be stored in the memory  104  of the computing system  100 A. 
     Computing system  100 A may also contain communication channels  108  that allow the computing system  100 A to communicate with other message processors over, for example, network  110 . Communication channels  108  are examples of communications media. Communications media typically embody computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism and include any information-delivery media. By way of example, and not limitation, communications media include wired media, such as wired networks and direct-wired connections, and wireless media such as acoustic, radio, infrared, and other wireless media. The term computer-readable media as used herein includes both storage media and communications media. 
     Embodiments within the scope of the present invention also include computer-readable media for carrying or having computer-executable instructions or data structures stored thereon. Such computer-readable media can be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise physical storage and/or memory media such as RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of computer-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a computer, the computer properly views the connection as a computer-readable medium. Thus, any such connection is properly termed a computer-readable medium. Combinations of the above should also be included within the scope of computer-readable media. 
     Computer-executable instructions comprise, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described herein. Rather, the specific features and acts described herein are disclosed as example forms of implementing the claims. 
       FIG. 1B  illustrates a message processor in the form of a state machine  120 . A state machine  120  may be implemented entirely in hardware, although that need not be the case. The state machine  120  receives input signal(s)  121 , and deterministically generates output signal(s)  122 . Optionally, the deterministic function may depend on one or more optional configuration settings  123 . In one embodiment, the state machine  120  may be implemented using logic gates and potentially other circuit components such as perhaps registers and clocks. When implemented as a message processor, the state machine  120  may perform the message dispatch described herein. 
     Now that example message processors have been described,  FIG. 2  will now be described, which illustrates a particular messaging processing environment  200 . The various illustrated components may be implemented in software or hardware. For instance, if a given component is implemented in software, the computing system  100 A of  FIG. 1A  may cause the components to be created and operated as a result of the processor(s)  102  executing computer-executable instructions from the memory  104 . If implemented in hardware, the component may be a computing system or device such as that illustrated with respect to  FIG. 1B . 
       FIG. 2  illustrates a shared hosting environment  200  that includes a number of clients  210  communicating over a network (such as the Internet) with a shared hosting network farm  220 . The shared hosting network farm  220  has deployed thereon numerous web sites, each having a corresponding host name. Whenever a client browser navigates to one of the host names that is served by the shared hosting network farm, the client issues a request corresponding to the host name to the shared hosting network farm  220 . 
     In  FIG. 2 , there are only four clients  211  through  214  shown. However, the ellipses  215  represents that there may be many clients that interface with the shared hosting network farm  220 . The set of clients  200  that interface with the network farm  220  may change dynamically as each client, or its user, decides which host names to navigate to in their browser. 
     At the back-end, the shared hosting environment includes a number of content servers  230 . In the illustrated embodiment, there are five content servers  231  through  235  shown. However, the ellipses  236  represents that there may be more or less than this number, and that the number may change dynamically. Indeed, some embodiments described herein permit for quite efficient scaling in the number of content servers. 
     Conventional shared hosting network farms also can include multiple content servers. However, in  FIG. 2 , the content servers  230  are each independently capable of processing requests corresponding to a common set of host names. In one specific example that will be frequently referred to herein, the common set of host names includes 10,000 host names including yyy.hostname1.com through yyy.hostname10000.com. Of course, these are not real navigatable host names. For one thing, the term “www” has been changed to “yyy” in this description in order to avoid automatic hyperlinking of the electronic text of published versions of the patent application, which automatic hyperlinking is contrary to the rules of at least one patent office. In addition, the hostnames “hostname1” through “hostname10000” are clearly made up for purposes of discussion only. In a real deployment, the host names would correspond to actual operational and navigatable web sites. 
     The broader principles described herein are not limited to the specific manner in which each of the content servers  230  is made capable of independently processing requests for the common set of host names. For instance, in one embodiment, each of the content servers  230  includes its own data server that provides files as needed to render each of the web sites corresponding to each of the corresponding host names in the common set of host names. Nevertheless, for improved efficiency and lower cost of deployment, the content servers  230  may share a single data server  240  that includes all files necessary to render each of the web sites of the common set of host names. As each content server  230  processes a request corresponding to a particular host name, the content server will request and receive the corresponding files from the data server  240 . Of course, as the number of content servers  230  increases, the number of data servers  240  may likewise be scaled up if needed to handle the increased demand. 
     As a side note, the content servers  230  and the various other servers illustrated in  FIG. 2  will be described as having a certain function. That is not to say that the server is limited to that function. For instance, although each of the content servers is capable of independently processing requests corresponding to a common set of host names, that does not imply that all of the content servers are only able to process host names corresponding to that common set. For instance, a subset of the content servers might be able to process requests corresponding to additional common set of host names. For example, content servers  231  through  233  might be capable of processing request corresponding to the common set yyy.hostname1.com through yyy.hostname10000.com as well as to an addition set of hostnames yyy.hostname10001 through yyy.hostname11000.com. Furthermore, there may be content servers able to process request corresponding to host names that no other content server is capable of processing. For instance, perhaps, content server  231  is also capable of processing requests corresponding to host names yyy.hostname11001.com through yyy.hostname12000.com. 
     As one final note before returning to the description of  FIG. 2 , although there are five content servers  231  through  235  illustrated that are capable of processing requests corresponding to the common set of content servers, the shared hosting network farm  220  may, for whatever reason, include other content servers that are not capable of processing requests corresponding to all of the common set of host names. For instance, the five content servers  231  through  235  may process requests for one common set of host names yyy.hostname1.com through yyy.hostname10000.com, while there might be another set of one or more content servers that process requests corresponding to another set of host names, perhaps yyy.hostname10001.com through yyy.hostname20000.com. Nevertheless, for clarity in avoiding such complications, this description will now turn to the simplified example in which the content servers  231  through  235  are described as responding to requests corresponding to the common set of host names yyy.hostname1.com through yyy.hostname10000.com. Responses to other requests will not be described further. 
     The shared hosting network farm  220  includes a routing server  221  that receives client requests that are to be processed by the shared hosting network farm  220 . While the routing server  221  might receive request corresponding to host names that extend out of the common set of host names, it is only the processing of requests corresponding to the common set of host names that will be described in further detail here. The routing server  221 , the content servers  230  and the data server  240  may, but need not, be structured as described above for the computing system  100 A of  FIG. 1A  and/or the state machine  120  of  FIG. 1B . 
     When the routing server  221  receives a request corresponding to a host name of the common set of host names, the routing server  221  identifies a content server  230  that will process the request, and dispatches the request to the identified content server. This identification and dispatch occurs in a way that enforces host name affinitization in which at least some of the common set of host names are affinitized. Because of this, the routing server  221  may also be referred to in this description as a routing and affinitization server  221 . The routing and affinitization server  221  may also serve to identify an appropriate server based on a load balancing algorithm. 
     For instance, when the first request for hostname1 is received, or at least when a request for hostname1 is received and there is no active host name affinitization for hostname1, the routing server  221  might select one or more content servers to affinitize the hostname to. As an example, if there are two content servers that are to be affinitized, the routing server  221  might affinitize content servers  231  and  232  to hostname1. These two affinitized content servers may be selected based on a load balancing algorithm. When subsequent requests for hostname1 are received, unless the affinitization has been terminated in the meantime, the request will be dispatched to the affinitized set of content servers  231  and  232 . The appropriate one server of the affinitized set of content servers  231  and  232  may also be selected based on the load balancing algorithm. 
     If a request for hostname2 is received, the affinitization for hostname1 is not relevant, unless the routing server were to affinitize clusters of host names at the same time and hostname1 and hostname2 happened to be in the same cluster of host names. However, in the embodiment described further herein, affinitization occurs on an individual host name basis, although the principles of the present invention are not limited to that. When the request for hostname2 is received, if there was not already an affinitization for hostname2, then the routing server  221  decides an affinitization. In this case, perhaps only one server is affinitized, say content server  233 . Subsequently, unless the affinitization is terminated, the content server  223  will process requests for hostname2. 
     Note that in this example, hostname1 was affinitized to two content servers, whereas hostname2 was affinitized to only one. In one embodiment, each host name may have a different number of affinitizations. Perhaps this is due to the host name provider of hostname1 subscribing to a higher level of service (e.g., two affinitization units) than the host name provider for hostname2. This might be appropriate if, for example, the provider of hostname1 expects somewhat more network traffic than the provider of hostname2, or would like more reliable service. At some point, as the provider of hostname2 experiences even more network traffic, the provider may simply subscribe to yet even more units of affinitization with perhaps an increase in compensation paid to the shared hosting service. Thus, the host provider may stay the decision to implement alternative and perhaps more expensive hosting arrangements such as dedicated hosting services or perhaps even purchasing and setting up their own hosting network. Accordingly, the shared hosting service can tailor shared hosting to a wide variety of customers who have different traffic and reliability needs, creating an expanded business opportunity and customer base for shared hosting services. 
     While the precise method by which this host name affinitization occurs is not critical to the broader principles described herein, a specific example method will now be described.  FIG. 3  illustrates a flowchart of a method  300  for affinitizing a request corresponding to a host name. The method  300  may be initiated by the routing server  221  each time a request corresponding to a host name of the common set of host names is received (act  301 ). 
     Upon receiving the request (act  301 ), the routing server identifies the corresponding host name for the request (act  302 ). For example, the routing server might identify that the request corresponds to the host name yyy.hostname1.com. The routing server then determines whether or not the corresponding host name is affinitized to any of the content servers  230  (decision block  303 ). 
     If there is not already a host name affinitization for the host name to one or more content servers (No in decision block  303 ), the routing server selects the subset of server(s) to which to affinitize to the host name (act  304 ). In one embodiment, there may be a cluster of host names that are associated together. For instance, for marketing purposes, an owner of a site may have multiple host names for that site. For instance, a seller of office chairs might have two host names “yyy.comfychairs.com” as well as “yyy.comfortablechairs.com”. These two host names may actually be the same site in that the Domain Name Server (DNS) server resolves both names to the same Internet Protocol (IP) address. In such an example, there is no reason to treat them differently. Accordingly, if the request was associated with host name “yyy.comfychairs.com”, the act  304  might not only affinitize a set of servers to that host name, but might also affinitize the same set of servers to the associated host name “yyy.comfortablechairs.com” since they are effectively the same site. 
     As mentioned above, the subset of host name affinitized content servers could be a single affinitized content server, or it could include multiple host name affinitized content servers. If, for example, there is only one content server to be selected for affinitization, the routing server might perform a load balancing algorithm to select the content server that it deems most suitable for processing the request. 
     In one embodiment, the load balancing algorithm may take into consideration any client affinitizations that might already exist for the client that made the request. Here, we introduce a different type of affinitization called “client affintization”, which is not to be confused with “host name affinitization”. Client affinitization means that content servers may be selected to process a request based on the client that made the request, whereas host name affinitization means that content servers may be selected to process a request based on the host name corresponding to the request. 
     Once the set of content server(s) is selected (act  304 ), the selected content server(s) are host name affinitized to the corresponding host name of the request (act  305 ). Thus, from that time forward, unless and until the host name affinitization for the affinitized set of content servers is terminated, requests corresponding to that host name will continue to be processed only by one of the affinitized set of content servers. 
     There might be a number of reasons why a host name affinitization of a particular content server is terminated, one reason is that the associated worker process simply times out. That is, a request corresponding to a host name is not received in a particular configurable amount of time. Since the web sites for the host names are perhaps not used most of the time, this means that affinitization of content servers to host names may often be terminated due to the worker process timing out. Another reason for terminating affinitization is that perhaps the content server has lost its health sufficient to process further requests. In one embodiment, the host name affinitization for a content server is terminated upon the occurrence of the earlier of some configurable time out, and the loss of health of the content server. 
     If a host name affinitization for a content server is lost, for example, due to loss of health of that content server, and if there are still content servers in the affinitized set for a particular host name, the routing server may actively search for the best suited content server outside of the affinitized set even before the next request corresponding to the host name is received. Alternatively, the routing server may await the determination until the next request for the host name is received. 
     For instance, if a host name is allotted three unit affinitization units, and a request for the host name is then received. If the set of affinitized content servers has dwindled to just one in that two prior affinitized servers have lost their affinitization to that host name, then the routing server will select two more content servers to affinitize to the host name to thereby restore the allotted total of three host name affinitized content servers. 
     On the other hand, after the request is received (act  301 ), and the host name is identified (act  302 ), if it turns out that there is already an affinitized set of content servers (Yes in decision block  303 ), then the affinitized set of content servers is identified (act  306 ). As noted previously, however, if the affinitized set of content servers has dropped below the allotted number of content servers for that particular host name, additional content servers may be selected and affinitized to the host name. 
     Once the affinitized set of content servers is identified (act  306 ), a particular one affinitized content server is identified that is to process the request and to which the request corresponding to the host name will be dispatched (act  307 ). In the trivial case where there is but one affinitized content server in the set, that content server will be the one that processes the request. In the more difficult case where there are multiple affinitized content servers for that host name, the routing server selects one to process the request. 
     The routing server may make the selection based again on a load balancing algorithm, perhaps selecting the most healthy or available content server in the affinitized set of content servers. In one embodiment, however, the routing server may impose client affinitization. For instance, if there is one server that previously processed a request from a particular client and that corresponded to a host name, the routing server might select that one server again to process another request corresponding to that same host name and corresponding to the same client, even if there are multiple content servers affinitized to that host name. 
     Accordingly, the principles described herein provide an efficient and perhaps easily scalable mechanism for affinitizing requests in a shared hosting environment. For instance, in order to scale, perhaps all that is performed to add a content server is to allow the content server access to the common data server, and let the routing server know of the existence of the additional content server. 
     In addition, configuration information may be shared amongst multiple servers since they are all capable of responding to requests for each of the common set of hostnames. This can simplify the configuration management of the shared hosting service. For instance, if an additional content server is added, one may simply give the additional content server access to the common configuration file. 
     Furthermore, load balancing need not be manually performs since all content servers are capable of responding to requests for web sites in the common set of host names, and a suitable content server is selected at the time a request is received. Finally, reliability can be improved since each content server is capable of responding to requests corresponding to any of the host names in the common set. If one content server goes down, another may also handle the same requests. 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.