Opinion ID: 181384
Heading Depth: 2
Heading Rank: 3

Heading: Claim Construction of the '645 and '413 Patents

Text: After the district court's claim construction order, Akamai Technologies, Inc. v. Limelight Networks, Inc., 494 F.Supp.2d 34, 39 (D.Mass.2007) (Claim Construction Order), Akamai stipulated that it could not prove infringement of the '645 patent under the district court's construction. The district court thus entered judgment of noninfringement. The district court subsequently entered summary judgment of noninfringement of claims 8, 18, and 20 of the '413 patent. Akamai appeals the district court's construction of several terms in the '645 and '413 patents. While Limelight does not concede that the '645 and '413 patents do not implicate a joint infringement issue similar to that found in the '703 patent above, both parties agree that even if such an issue does exist, it is not properly before the court in this appeal. Oral Arg. 10:35-11:10; 30:40-31:40 (Limelight's counsel stating that the joint infringement issues for the '645 and '413 patents were not developed at the trial court). Thus, we decide Akamai's appeal of the district court's construction of several terms in the asserted claims of the '645 and '413 patents independent of any potential joint infringement issues. We review claim construction de novo. Cybor Corp. v. FAS Techs., Inc., 138 F.3d 1448, 1451 (Fed.Cir.1998) (en banc). We begin a claim construction analysis by considering the language of the claims themselves. Edward Lifesciences LLC v. Cook Inc., 582 F.3d 1322, 1327 (Fed.Cir.2009). However, the written description can provide guidance as to the meaning of the claims, thereby dictating the manner in which the claims are to be construed, even if the guidance is not provided in explicit definitional format. SciMed Life Sys., Inc. v. Advanced Cardiovascular Sys., Inc., 242 F.3d 1337, 1344 (Fed.Cir.2001). A. The Technical Setting As part of a system for efficient content delivery, the '645 and '413 patents describe a framework including a set of hosting or ghost servers used to store and deliver a website's embedded objects. '703 patent col.3 ll.4-7. To determine the location of a hosting computer on which a particular object is stored, the framework includes a second set of servers that are configured with functionality that is similar to, but not exactly the same as, a typical Internet DNS server, such that the servers resolve URLs specifically for the CDN. The specification refers to this second set of servers as top-level DNS servers. Id. col.3 ll.17-21, 31. The specification also describes a third set of servers that provide low-level DNS functionality. Id. col.3 ll.22-24. Together, the top-level and low-level servers form an alternative domain name system. According to the patents' preferred embodiment, when a user's machine requests a web page from a content provider, the web page base document is delivered to the user's computer from the content server in the traditional manner described above. Id. col.3 ll.24-27. Any embedded objects in that web page that are stored on the CDN's hosting servers, however, are located using the invention's framework. First, the top-level DNS server determines the user's location in the network and uses that information to identify a list of low-level DNS servers. Id. col.3 ll.29-33, 60-61. The top-level DNS server then redirects the request for the embedded object to one of the identified low-level DNS servers that, in turn, resolves the request into an IP address for the appropriate hosting server that delivers the object to the user's computer. Id. col.3 ll.33-37. The specification does not limit the framework to two levels of DNS servers, but describes a hierarchy of DNS servers that consisting [sic] of several levels. Id. col.3 ll.37-41. In addition, the top-level and low-level DNS functionality may be combined into a single DNS level. Id. col.5 ll.54-57. The specification also describes load balancing across the set of hosting servers. Id. col.3 ll.66-67. Load balancing is the process of equalizing the workload on multiple computers. The specification describes a load balancing technique based on distributing the embedded object requests. This technique can be included in the tagging process by modifying the embedded object URL using the hostname of a virtual server. Id. col.4 ll.1-5. A virtual server is simply a reference to a hosting server whose physical location is not determined until a user attempts to access a specific object. This allows users to retrieve the objects stored on hosting servers efficiently based on a number of continually changing factors (e.g., network traffic, user location). Thus, upon retrieval of a modified web page by a user, the hosting framework maintained by the CDN will resolve the virtual server hostname in the modified URL into the IP address of the appropriate hosting server from which to retrieve the object. Claim 1 of the '645 patent provides: In a wide area network in which an Internet domain name system (DNS) is useable to resolve DNS queries directed to participating content provider content that is available from participating content provider sites, a method of content delivery wherein participating content providers identify content to be delivered by a service provider from a set of content servers that are distinct from the participating content provider sites and associated with the service provider, wherein a given object of a participating content provider is associated with an alphanumeric string, the method comprising: having the service provider establish an alternative domain name system (DNS), distinct from the Internet domain name system and any client local name server, and having authority to resolve the alphanumeric strings associated with the objects identified by the participating content providers so that the objects identified by the participating content providers are available to be served from the service provider's content servers, the service provider's alternative domain name system having one or more DNS levels, wherein at least one DNS level comprises a set of one or more name servers; for each of one or more participating content providers, delivering a given object on behalf of the participating content provider, wherein the given object is delivered by the following steps; responsive to a DNS query to the given object's associated alphanumeric string, the DNS query originating from a client local name server, receiving the DNS query at a given name server of a lowest level of the one or more DNS levels in the service provider's alternative domain name system, the given name server that receives the DNS query being close to the client local name server as determined by given location information; having the given name server that receives the DNS query resolve the alphanumeric string into an IP address that the given name server then returns to the client local name server, wherein the alphanumeric string is resolved without reference to a filename for the given object, wherein the IP address returned as a result of the resolution is associated with a content server within a given subset of the set of content servers, the subset of the set of content being associated with the given name server, the content server associated with the IP address returned by the given name server being selected according to a load sharing algorithm enforced across the subset of the set of content servers associated with the given name server; at the content server associated with the IP address, receiving a request for the given object, the request having the filename associated therewith; if the given object is available for delivery from the content server associated with the IP address, serving the given object from the content server. '645 patent col.17 ll.39-col.18 ll.29 (emphases added). Claim 8 is representative of the asserted claims of the '413 patent. It provides: A method of content delivery wherein participating content providers identify content to be delivered by a content delivery network service provider from a set of content servers associated with the content delivery network service provider, wherein a given object of a participating content provider is associated with a [URL] that includes, in addition to a filename, an alphanumeric string, comprising: having the content delivery network service provider establish a domain name system (DNS) having authority to resolve the alphanumeric strings in the URLs of the objects identified by the participating content providers, the content delivery network server provider's domain name system having one or more DNS levels, wherein at least one DNS level comprises a set of one or more name servers; for each of one or more participating content providers, delivering a given object on behalf of the participating content provider, wherein the given object is delivered by the following steps; responsive to a DNS query, selecting a given one of the name servers in the content delivery network service provider's domain name system; at the given one of the name servers, resolving the alphanumeric string to an IP address, wherein the alphanumeric string is resolved without reference to the filename for the given object; at a server associated with the IP address, the server being one of the set of content servers, receiving a request for the given object, the request having the filename associated therewith; from the server, serving the given object; and caching the given object at the server so that the given object is available for delivery from the server for a given time period in the event that a new DNS query to resolve the alphanumeric string is received at the domain name system and is resolved to the IP address of the server. '413 patent col.18 ll.14-51 (emphases added). B. Associated with an Alphanumeric String Akamai appeals the construction of the term a given object of a participating content provider is associated with an alphanumeric string in the preamble of claim 1 of the '645 patent. [4] The district court construed the limitation to require that the alphanumeric string include the embedded object's original URL (the URL including the hostname of the computer on which the actual object resided within the content provider's domain). Claim Construction Order at 39. The court reasoned that the written description portion of the '645 patent describes the invention as associating a particular object of a content provider with an alphanumeric string consisting of a virtual server hostname prepended onto the URL for the object. Id. at 40. The court found that [t]he specification discloses no other way that an object is associated with an alphanumeric string, nor is there any suggestion or teaching that an association which did not include the URL for the embedded object could be used in an embodiment of the invention. Id. The district court declined as overly broad Akamai's proposed construction of the term associated according to its dictionary definition of brought into some kind of relationship with. Akamai contends that the court imported a limitation from the specification into the claims and thereby improperly limited the scope of the claims to the specification's preferred embodiment. According to Akamai, nothing in the claim language supports requiring that the alphanumeric string include the original URL. Akamai relies on the parties' stipulation that alphanumeric string is a character string up to 24 characters drawn from the alphabet (a-z), digits (0-9), minus signs (-), and periods(.). Stipulated Order Establishing the Constructions for Certain Claim Terms as Agreed Upon by the Parties at 3, Akamai Techs., Inc. v. Limelight Networks, Inc ., No. 06-CV-11109 (D.Mass. Apr. 24, 2007). Akamai asserts that the specification and prosecution history do not define associated as having any meaning other than its ordinary meaning. Thus, Akamai argues that the ordinary meaning of the words in the claim compel a broad interpretation without the limitation introduced by the district court. Akamai also argues that the specification very clearly indicates that including the object's original URL in the alphanumeric string is merely the preferred method. Akamai contends that one of ordinary skill in the art would understand that other tagging methods may be used to associate an alphanumeric string with the object. In addition, Akamai points to the prosecution history, other claim limitations in the '645 patent, and the use of alphanumeric string in claim 18 of the '413 patent as evidence contradicting the district court's construction. Akamai notes that (1) none of the examples of alphanumeric strings cited by Akamai during prosecution included the original URL; (2) other claim limitations of the '645 patent use the term alphanumeric string as a virtual server hostname, not a URL; and (3) the preamble of claim 18 of the '413 patent requires a URL to include an alphanumeric string, not the other way around. Limelight responds that the district court correctly limited the claim term to include the object's original URL because it reflects the '645 patent's explicit description of the invention. Reiterating the points made by the district court, Limelight asserts that the patents consistently describe the invention as associating an alphanumeric string with an object by prepending a virtual server hostname to the original URL that identifies the object in the absence of the CDN. Limelight adds that including the original URL in the alphanumeric string is not merely a preferred embodiment in the patents because all the examples in the patents contain the object's original URL. This court agrees with Limelight and the district court that the claim term a given object of a participating content provider is associated with an alphanumeric string limits tagged alphanumeric strings to those strings including the object's original URL. Here, as in Honeywell International, Inc. v. ITT Industries, Inc., 452 F.3d 1312, 1318 (Fed.Cir.2006), alphanumeric strings including the object's original URL were not merely discussed as a preferred embodiment. Instead, the written description specifically refers to strings including the object's original URL as the invention: According to the present invention, load balancing across the set of hosting servers is achieved in part through a novel technique for distributing the embedded object requests. In particular, each embedded object URL is preferably modified by prepending a virtual server hostname into the URL. More generally, the virtual server hostname is inserted into the URL. '645 patent col. 4 ll.13-19. According to the invention, the embedded object URL is first modified, preferably in an off-line process, to condition the URL to be served by the global hosting servers. Id. col.6 ll.54-57. Thus, according to the present invention, a virtual server hostname is prepended into the URL for a given embedded object.... Id. col.7 ll.36-38. With the above as background, the inventive global hosting framework is now described in the context of a specific example.... Instead of returning the usual page, according to the invention, the Web site returns a page with embedded object URLs that are modified according to the method illustrated in the flowchart of FIG. 4. Id. col.7 l.49-col.8 l.2 If, however, no copy of the data on the ghost exists, a copy is retrieved from the original server or another ghost server. Note that the ghost knows who the original server was because the name was encoded into the URL that was passed to the ghost from the browser. Id. col.12 ll.54-60. The specification does include language indicating that the patentee intended certain aspects of the description to represent preferred, rather than required, elements of the invention. See, e.g., '645 patent col.4 ll.15-17 ([E]ach embedded object URL is preferably modified by prepending a virtual server hostname into the URL.); id. col.6 ll.57-58 (A flowchart illustrating the preferred method for modifying the object URL is illustrated in FIG. 4.). This court also acknowledges that much of the language describing a string including a URL as the invention occurs within the section entitled Detailed Description of the Preferred Embodiment or in the description of Figure 4, which is referred to as a preferred method for modifying the object URL. However, the specification as a whole makes clear that including the object's original URL is the only method to achieve the claimed association between an alphanumeric string and the embedded object. Indeed, it is the only method described. Netword, LLC v. Centraal Corp., 242 F.3d 1347, 1352 (Fed.Cir.2001) (Although the specification need not present every embodiment or permutation of the invention and the claims are not limited to the preferred embodiment of the invention... neither do the claims enlarge what is patented beyond what the inventor has described as the invention.) (internal citations omitted). See also Bell Atl. Network Servs., Inc. v. Covad Commc'ns Grp., Inc., 262 F.3d 1258, 1271 (Fed.Cir.2001) ([W]hen a patentee uses a claim term throughout the entire patent specification, in a manner consistent with only a single meaning, he has defined that term `by implication.') (quoting Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582 (Fed.Cir.1996)). Moreover, the specification specifically limits the object's modified URL to either prepending or inserting a virtual server hostname into the URL. '645 patent col.4 ll.15-19 (In particular, each embedded object URL is preferably modified by prepending a virtual server hostname into the URL. More generally, the virtual server hostname is inserted into the URL.). Both of these methods include the original URL of the object in the modified string. Finally, the specification describes the proper functioning of the invention as motivation for including the object's original URL in the modified string, the ghost knows who the original server was because the name was encoded into the URL that was passed to the ghost from the browser. Id. col.12 ll.56-58. This court is not persuaded by Akamai's argument that the patentee established a broader scope during prosecution or that other uses of the term alphanumeric string compel a broader interpretation. Akamai argues that during prosecution the patentee made it clear that an alphanumeric string can be comprised of just a hostname as opposed to requiring the inclusion of an entire URL. Akamai refers to the patentee's description of an examiner interview in a preliminary amendment. The remarks describe the interpretation of the phrase alphanumeric string and cite numerous examples of such strings, such as ... `a1234.g.akamaitech.net,' in the written description. Id. col.7 ll.14-15. However, in the specification, the reference to the indicated hostname is in the context of determining a virtual server hostname for ultimate inclusion in the tagged string. The specification does not indicate that this virtual hostname can eventually be the entire string. Instead, the specification clearly describes that the hostname will be prepended into the URL for the given embedded object once the hostname is determined. See, e.g., id. col.6 ll.63-64. In fact, all the examples in the specification indicate that the ultimate tagged string contains the object's original URL. '645 patent col.8 ll.24-25; id. col.8 ll.56-57; id. col.9 ll.25-26. Even if we agreed with Akamai that the patentee indicated in the prosecution history that the alphanumeric string associated with an object could include only a hostname, this is not enough to overcome the clear description of the invention in the specification. See Honeywell, 452 F.3d at 1319 (Where, as here, the written description clearly identifies what his invention is, an expression by a patentee during prosecution that he intends his claims to cover more than what his specification discloses is entitled to little weight.); Biogen, Inc. v. Berlex Labs., 318 F.3d 1132, 1140 (Fed.Cir.2003) (stating that [r]epresentations during prosecution cannot enlarge the content of the specification.). Akamai's arguments that other uses of alphanumeric string in the '645 and '413 patents require a broad interpretation such that the string may include only a hostname are likewise not persuasive. None of the uses of alphanumeric string in either patent clearly limits the contents to just a hostname. In fact, Akamai does not explain how a string made up of just a virtual server hostname would be associated with the original object even under the broadest definition of that term. Akamai argues that the district court's requirement that the alphanumeric string include an entire URL is nonsensical because DNS servers resolve hostnames, not URLs. Akamai also asserts that the district court's statement that [t]he URL of the object is necessary to the inventive global framework in order to retrieve the object from the content provider's server if no copy exists on a ghost [i.e., content] server in its claim construction order, Claim Construction Order at 40, demonstrates a fundamental misunderstanding of the requirements of the invention. Akamai's Principal Br. at 57. According to Akamai, this statement ignores that the specification describes retrieving any missing content from either the content provider's original server or another content server in the CDN. None of these arguments are persuasive. At no place does the specification indicate that the entire string must be used by the DNS server. Even if only the hostname is used by the DNS during the resolving step, this does not mean that an alphanumeric string cannot contain other information not used by the DNS during this step. Indeed, this must be the case since the specification explicitly notes that the ghost knows who the original server was because the name was encoded into the URL that was passed to the ghost from the browser. '645 patent col.12 ll.56-58. C. Selection by the Alternative Domain Name System Akamai also appeals the district court's construction of the given name server that receives the DNS query being close to the client local name server as determined by given location information in claim 1 of the '645 patent and selecting a given one of the name servers in the content delivery network in claims 8, 18, and 20 of the '413 patent. The district court interpreted both limitations to require that the name server be selected by the alternative domain name system. [5] Claim Construction Order, at 42, 45. The court found that the specification compelled this interpretation because [r]ead in light of the specification, the invention claims an alternate DNS system that selects a DNS server in response to a user request based on the location of the user. Id. at 43. Akamai, citing DSW, Inc. v. Shoe Pavilion, Inc., 537 F.3d 1342, 1347 (Fed.Cir.2008), argues that the district court improperly incorporated a structural limitationthe alternative domain name systeminto method claims. Moreover, Akamai asserts that claim 1 of the '645 patent does not use the term selecting at all. Akamai points out that claim 1 only requires that the CDN's DNS server receiving a DNS query be close to the client's local name server. In addition, Akamai argues that nothing in the '413 patent claim language, specification, or prosecution history supports the court's requirement of selection by the alternative domain name system. Limelight responds that the district court did not import a new structural limitation because claim 1 expressly requires an alternative domain name system. This court is not persuaded by Akamai's argument. DSW is inapposite. In DSW this court reversed the district court's claim construction importing a limitation from a preferred embodiment because the claim language was unambiguously broader than the preferred embodiment, not because it imported structural limitations into a method claim. Id. at 1347. Method claims often include structural details. See e.g., Microprocessor Enhancement Corp. v. Tex. Instruments, Inc., 520 F.3d 1367, 1374 (Fed.Cir.2008) (Method claim preambles often recite the physical structures of a system in which the claimed method is practiced, and claim 1 is no different.); Eaton Corp. v. Rockwell Int'l Corp., 323 F.3d 1332, 1342 (Fed.Cir.2003) (construing a method claim as including steps that require the operation or manipulation of the particular structure identified and described by the preamble). All of the asserted claims in both the '645 patent and the '413 patent explicitly refer to the alternative domain name system as a detail associated with the claimed method. '645 patent col.17 ll.50-51 (having the service provider establish an alternative domain name system (DNS)); '413 patent col.18 ll.22-23, col.19 ll.44-45, col.20, ll.25-26 (having the content delivery network service provider establish an alternative domain name system (DNS)). Therefore, the structural element of the alternative DNS framework was explicitly and properly included in the claims. Akamai also asserts that the district court's interpretation improperly limits the inventive framework to a multi-level DNS system. Akamai points out that because the patents explicitly allow for a framework with a one-level DNS framework, a multi-level restriction is unduly limiting. '703 patent col.5 ll.56-57 (Alternatively, there may be a single DNS level that combines the functionality of the top-level and low-level servers.). The district court responded to this exact argument in its claim construction order. Specifically, the court explained that because the specification states that the functionality of the top and low-level servers may be combined in a single DNS level, the specification requires that a single-level DNS system accomplish the same steps as the two-level system described in the preferred embodiment. Claim Construction Order at 45. Thus, the district court's construction does support a single-level DNS system, and is not limited to a multilevel DNS system. As the district court recognized, the steps described in the preferred embodiment(1) a top-level DNS server of the CDN selects a close-by low-level DNS server and redirects the user to that server and (2) the user's local DNS server requests the object's IP address from the low-level servercan be accomplished by one DNS server. Id. at 46 (citing '413 patent col.9 ll.44-50). Specifically, the district court explained: In a single-level DNS embodiment, as suggested by the specification, the user's local name server would still contact a content delivery provider's top-level name server to resolve the IP address of a server to serve an object. This name server, however, would then directly communicate with a particular local name server, based on the user's location, to resolve the server's IP address and return it to the user, rather than require the user to conduct a second lookup. Thus, the user would obtain the IP address of the appropriate ghost server with only a single DNS request, however the selection of a particular name server would still be the result of a DNS lookup by the service provider's DNS system. Such an embodiment would satisfy the claimed one level of DNS, yet not be in conflict with [the district court's adopted] claim construction. Id. at 45-46. This explanation is entirely consistent with the specification's description of the invention and effectively counters Akamai's argument that the court's construction improperly limits the invention to a multi-level DNS system. Akamai also asserts, however, that one of these other techniques could be substituted for the top-level DNS servers in order to implement a one-level DNS framework. Thus, according to Akamai, the patent, but not the district court's construction, allows for a one-level DNS framework in which other techniques, such as Anycasting, would be used to select the ultimate CDN DNS serverinstead of a top-level DNS serverbecause the specification encompassed techniques known in the prior art. Akamai's Br. at 61 (citing BJ Servs. Co. v. Halliburton Energy Servs., Inc., 338 F.3d 1368, 1372 (Fed.Cir.2003)). This court does not agree that the patent's description allows for such a broad reading of the claims. The patent disclosure supports only one method for choosing the ultimate CDN DNS serverthe alternative DNS system. There is no support in the specification for any method of choosing a particular name server other than by a DNS lookup and no disclosure that would have suggested to a person of ordinary skill in the art that anything other than a DNS lookup should be contemplated. There is no evidence that, given the lack of detailed disclosure in the patent's language, a person of skill in the art would have looked to other known techniques to implement this portion of the claimed invention. In fact, the patent repeatedly defines using DNS lookup for choosing the ultimate CDN DNS server as the invention. As noted by the district court, the specification describes the present invention as manipulat[ing] the DNS system so the name is resolved to one of the ghosts that is near the client. '703 patent col.9 ll.26-28. In addition, under the heading entitled Brief Summary of the Invention, the specification states that [t]o locate the appropriate hosting servers to use, the top-level DNS server determines the user's location in the network to identify a given low-level DNS server to respond to the request for the embedded object. '703 patent col.3 ll.29-33. Akamai conceded that under the district court's construction, Limelight does not infringe the '645 patent. Akamai also does not argue that Limelight would infringe the '413 patent under this construction. Therefore, this court is left to conclude that the district court properly entered judgment in favor of Limelight on the issue of infringement.