Patent Publication Number: US-10778756-B2

Title: Location of actor resources

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a divisional of U.S. patent application Ser. No. 15/469,776, filed Mar. 27, 2017, entitled “LOCATION OF ACTOR RESOURCES”, which is a divisional of U.S. patent application Ser. No. 14/076,815, filed Nov. 11, 2013, entitled “LOCATION OF ACTOR RESOURCES”, which is related to the following applications, each of which is hereby incorporated by reference in its entirety: U.S. patent application Ser. No. 14/076,718 filed Nov. 11, 2013, entitled “VIDEO ENCODING BASED ON AREAS OF INTEREST”; U.S. patent application Ser. No. 14/076,821 filed Nov. 11, 2013, entitled “ADAPTIVE SCENE COMPLEXITY BASED ON SERVICE QUALITY”; U.S. patent application Ser. No. 14/077,127 filed Nov. 11, 2013, entitled “SERVICE FOR GENERATING GRAPHICS OBJECT DATA”; U.S. patent application Ser. No. 14/077,136 filed Nov. 11, 2013, entitled “IMAGE COMPOSITION BASED ON REMOTE OBJECT DATA”; U.S. patent application Ser. No. 14/077,165 filed Nov. 11, 2013, entitled “MULTIPLE PARALLEL GRAPHICS PROCESSING UNITS”; U.S. patent application Ser. No. 14/077,084 filed Nov. 11, 2013, entitled “ADAPTIVE CONTENT TRANSMISSION”; U.S. patent application Ser. No. 14/077,180 filed Nov. 11, 2013, entitled “VIEW GENERATION BASED ON SHARED STATE”; U.S. patent application Ser. No. 14/077,186 filed Nov. 11, 2013, entitled “MULTIPLE STREAM CONTENT PRESENTATION”; U.S. patent application Ser. No. 14/077,149 filed Nov. 11, 2013, entitled “DATA COLLECTION FOR MULTIPLE VIEW GENERATION”; U.S. patent application Ser. No. 14/077,142 filed Nov. 11, 2013, entitled “STREAMING GAME SERVER VIDEO RECORDER”; U.S. patent application Ser. No. 14/077,146 filed Nov. 11, 2013, entitled “SESSION IDLE OPTIMIZATION FOR STREAMING SERVER”; U.S. patent application Ser. No. 14/077,023 filed Nov. 11, 2013, entitled “APPLICATION STREAMING SERVICE”; U.S. Patent Application No. 61/902,740 filed Nov. 11, 2013, entitled “EFFICIENT BANDWIDTH ESTIMATION”. 
    
    
     BACKGROUND 
     A computer computational environment can be set up as an actor system with programmed actors operating concurrently with respect to each other. Messages can be sent between actors to update a state of one of the actors, to request information about one of the actors, to create new actors and the like. The actors can operate independently of each other and the messages sent between actors can alter the way that the actors operate. The actor system can be hosted by a single computing device or hosted in a distributed system over multiple computing devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Throughout the drawings, reference numbers may be re-used to indicate correspondence between referenced elements. The drawings are provided to illustrate example embodiments described herein and are not intended to limit the scope of the disclosure. 
         FIG. 1  depicts an example of an actor system operating in a peer-to-peer computing environment. 
         FIGS. 2A and 2B  depict examples of a computing environment with a server-based actor system. 
         FIG. 3  depicts an embodiment of an actor server system that includes multiple servers in multiple server racks. 
         FIG. 4  depicts an actor server system that includes servers that can communicate with each other via communication link(s). 
         FIGS. 5A, 5B, 5C and 5D  depict an actor server system and examples of relocating actors within the actor server system. 
         FIGS. 6A and 6B  depict an example of moving an actor from one location to another when multiple destination locations are available. 
         FIG. 7  depicts a method that can be used by a management service to attempt to move one or more actors to another location. 
         FIG. 8  depicts a method of determining whether to move one or more actors after receiving degree of closeness of two actors. 
         FIG. 9  depicts a method of determining a degree of closeness for a first actor and a second actor. 
         FIG. 10  depicts a diagram illustrating an example computing system that may be used in some embodiments. 
         FIG. 11  depicts a diagram illustrating an example computing system that may be used in some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     An actor system in computer science is a mathematical model of concurrent computation that treats “actors” as the universal primitives of concurrent digital computation: in response to a message that it receives, an actor can make local decisions, create more actors, send more messages, and determine how to respond to the next message received. It has been used both as a framework for a theoretical understanding of computation, and as the theoretical basis for several practical implementations of concurrent systems. 
     The actor model typically operates under the notion that everything is an actor. This is similar to the philosophy used by some object-oriented programming languages, but differs in that object-oriented software is typically executed sequentially, while the actors in an actor system can operate concurrently. 
     An actor is a computational entity that, in response to a message it receives, can concurrently, among other actions, send messages to other actors, create new actors, or designate the behavior to be used for the next message it receives. There is no assumed sequence to these actions and they could be carried out in parallel. Messages sent within an actor system may not identify the sender of the message so that the actor system can call for asynchronous communication and control structures as patterns of passing messages. Instead, recipients of messages are identified by address, sometimes called a “mailing address.” One actor may be able to communicate only with other actors when it knows the other actors&#39; mailing addresses. An actor can be aware of an address of another actor by obtaining the address from a message, by creating the other actor, and the like. 
     The actor system can include concurrent computation within and among actors, dynamic creation of actors, inclusion of actor addresses in messages, and interaction through direct asynchronous message passing with no restriction on message arrival order. 
     An actor system can be used as a framework for modeling, understanding and reasoning about a wide range of concurrent systems. In one example, an email system can be modeled as an actor system. Accounts can be modeled as actors and email addresses as actor addresses. Other aspects of the email system, such as an account&#39;s contact list, an account&#39;s settings and the like, can also be modeled as actors separate from the account actor. In another example, web services can be modeled with simple object access protocol endpoints modeled as actor addresses. In another example, programming objects with locks (such as in Java and C#) can be modeled as a serializer if their implementations permit messages to continually arrive. A serializer can be an actor defined by a property that it is continually available to the arrival of new messages (i.e., every message sent to a serializer is guaranteed to arrive). In yet another example, testing and test control notation (TTCN), such as TTCN-2 and TTCN-3, can follow actor systems rather closely. In TTCN, an actor can be a test component: either parallel test component (PTC) or main test component (MTC). Test components can send and receive messages to and from remote partners (peer test components or test system interface). 
     In a further example, a gaming system can be modeled as an actor system. Each of the characters in a gaming system can be an actor. The gaming system can include an environment in which multiple characters operate independently in a common environment, such as in WORLD OF WARCRAFT and other similar games. In this case, the characters can operate concurrently and independently and the corresponding actors (i.e., the programming actors) can be executing concurrently and independently of each other. The gaming system can also include other actors, such as an actor representing an inventory of items associated with each of the characters, an actor representing characteristics of each of the characters (e.g., skills, abilities, health, etc.), and the like. While a number of examples of actor systems are described below in the context of a gaming system, it should be understood that the examples can be similarly applied in any actor system. 
     Because actors in an actor system communicate messages to each other, the actor system will route messages between the actors. As the number of actors in the actor system increases, so too can the number of messages sent between actors. If every actor in an actor system communicated with every other actor in the actor system, a linear increase in the number of actors may result in an exponential increase in the number of messages handled within the actor system. The routing of large numbers of messages and the time that messages take to be sent between actors can cause latency in the actor system. 
       FIG. 1  depicts an example of an actor system operating in a peer-to-peer computing environment  100 . The computing environment  100  includes a number of computing devices  110 ,  120  and  130 . The computing environment  100  can include additional computing devices that are not depicted in  FIG. 1 . The computing device  110  can include one or more actors  112   a  to  112   n ; the computing device  120  can include one or more actors  122   a  to  122   n ; and the computing device  130  can include one or more actors  132   a  to  132   n . The computing devices  110 ,  120 , and  130  can be connected to a network  140  via communication links  114 ,  124 , and  134 , respectively. The network  140  can include one or more of the Internet, a local area network (LAN), a wide area network (WAN), a wireless network (e.g., a WiFi network, a cellular data network, etc.), and the like. 
     The computing device  110  includes a management service  111 . The management service  111  can manage the actors  112   a  to  112   n  located on the computing device  110 , manage the creation of new actors on the computing device  110 , manage the deletion of actors from computing device  110 , route communications to and from actors on the computing device  110 , transfer actors from the computing device  110  to another computing device or server, receive and host actors transferred from other computing devices or servers to the computing device  110  and the like. In the depiction shown in  FIG. 1 , computing devices  120  and  130  do not include management services. The actors  122   a  to  122   n  and  132   a  to  132   n  on computing devices  120  and  130  may be able to operate and send messages without the assistance of a management service. 
     In peer-to-peer computing environment  100 , when actors in different computing devices pass messages between each other, the messages are routed via the network  140 . For example, a message sent from actor  112   a  to actor  122   n  will be sent from computing device  110  to network  140  via communication link  114  and then from the network  140  to the computing device  120  via the communication link  124 . In another example, a message sent from actor  132   a  to actor  112   n  will be sent from computing device  130  to network  140  via communication link  134  and then from the network  140  to the computing device  110  via the communication link  114 . In yet another example, a message sent from actor  112   a  to actor  112   n  will be passed within the computing device  110 . 
     Using the examples from the preceding paragraph, it is apparent that certain pairs of actors can be “closer” to each other than other pairs of actors. In this context, actors are considered “close” or “far” depending on the speed with which messages can be communicated between them. Among the three examples described in the preceding paragraph, actors  112   a  and  112   n  may be considered the closest of the three examples if communicating messages within computing device  110  is faster than communicating messages via the network  140 . If both of the communication link  114  and the communication link  124  are high-speed communication links and communication link  134  is a low-speed communication link, then actors  112   a  and  122   n  may be closer to each other than actors  132   a  and  112   n  because messages communicated between actors  112   a  and  122   n  may be faster via the high-speed communication links  114  and  124  than messages communicated via high-speed communication links  114  and low-speed communication link  134 . 
     One issue with the messages sent between actors in the peer-to-peer computing environment  100  is the latency incurred by communicating messages between different computing devices. While delays due to communicating messages across network(s)  140  may be on the order of a few seconds, such delays can be noticeable to users of the various computing devices. Moreover, while only three computing devices  110 ,  120 , and  130  are depicted in  FIG. 1 , a similar system could include significantly more computing devices, such as hundreds, thousands or more. As actors on a significant number of computing devices need to communicate with each other, the latency in sending and receiving messages can increase. Although an actor system operates on the premise that all of the actors are operating concurrently and independently of each other and messages are passed asynchronously, delays in interactions between actors can be perceptible to users of the computing device and lower the users&#39; experience. 
       FIG. 2A  depicts a computing environment  200  with a server-based actor system. The computing environment  200  includes a number of computing devices  210 ,  220  and  230 . The computing devices  210 ,  220  and  230  can be operated by different users to interact with the actor system. Each of the computing devices  210 ,  220  and  230  can be connected to a network  240  via communication links  214 ,  224  and  234 , respectively. While three computing devices  210 ,  220  and  230  are depicted in  FIG. 2 , any number of computing devices could be communicatively coupled to the network  240 . 
     The computing environment  200  also includes an actor server system  250  in communication with network  240 . The actor server system  250  can include one or more servers that host actors in the server-based actor system. In the specific example depicted in  FIG. 2 , the actor server system  250  hosts actors  212   a  to  212   n , actors  222   a  to  222   n  and actors  232   a  to  232   n . In one example, the actors  212   a  to  212   n ,  222   a  to  222   n  and  232   a  to  232   n  may be associated with users of computing devices  210 ,  220  and  230 , respectively. For example, actors  212   a  to  212   n  can be associated with an email account of a user of the computing device  210  in an actor-based email system, actors  212   a  to  212   n  can be associated with a character of a user of the computing device  210  in an actor-based gaming system, and the like. In another example, the actors  212   a  to  212   n ,  222   a  to  222   n  and  232   a  to  232   n  may not be associated with any one user or computing device, but merely actors in an actor-based system. 
     Placing actors of an actor system within an actor server system can reduce latency in sending messages between the actors. For example, with actors  212   a  to  212   n ,  222   a  to  222   n  and  232   a  to  232   n  hosted by the actor server system  250 , messages sent between any two of the actors  212   a  to  212   n ,  222   a  to  222   n  and  232   a  to  232   n  will be sent within the actor server system  250 . While it may take some time to send and receive messages between actors in the actor server system  250 , the latency from sending messages can be reduced. For example, messages sent by actors within the actor server system  250  do not need to be sent via the network  240 . In this way, the speed of sending messages is not limited by the speed of any communication link with the network  240  or the speed of communicating within network  240 . 
     While all of the messages sent between actors  212   a  to  212   n ,  222   a  to  222   n  and  232   a  to  232   n  can be sent within the actor server system  250 , computing devices  210 ,  220  and  230  can still interact with the actor system. For example, in the case where the actor system is a gaming system and one of the actors hosted by the actor server system  250  may be associated with a character of a user of computing device  210 . The user may input controls and commands into the remote computing device which are communicated from the computing device  210  to the actor server system  250  via the network  240 . The actor server system  250  can modify the actor associated with the user&#39;s character based on those controls and commands. The actor server system  250  can also modify other actors based on those controls and commands (e.g., modify an actor associated with an inventory of the user&#39;s character, modify an actor associated with another character that is interacting with the user&#39;s character, etc.). Similarly, the actor server system  250  can send back information about the actor system environment back to the computing device  210 . The information sent back to the computing device  210  from the actor server system  250  can include information for the computing device  210  to be able to render updated actors properly (e.g., updates in particular characters, changes in a character&#39;s inventory, etc.). The actor server system  250  may also perform all of the processing needed to update the environment from the perspective of the user, and the information sent back to the computing device  210  from the actor server system  250  can include information for the computing device  210  to render the environment to the user. 
       FIG. 2B  depicts anther embodiment of the computing environment  200  with a server-based actor system. The example in  FIG. 2B  includes actors  212   z ,  222   z  and  232   z  located on computing device  210 , computing device  220  and computing device  230 , respectively, and a security service  260  located between the actor server system  250  and the network  240 . While the example depicted includes one actor on each of computing devices  210 ,  220  and  230 , the computing devices  210 ,  220  and  230  could include any number of actors. The actors  212   z ,  222   z  and  232   z  located on computing devices  210 ,  220  and  230  can send messages to and receive messages from the actors in the actor server system  250 . 
     The security service  260  can ensure that messages passed between actors across the network  240  are communicated in a secure fashion, such as by encrypting the messages using a security protocol. The security service  260  can also ensure that the messages sent by actors on the computing devices  210 ,  220  and  230  do not perform an actions that are not allowed by the actor system. Because the actors on the computing devices  210 ,  220  and  230  are not under the control of the actor server system  250 , there could be concern that those actors could be programmed to perform malicious functions or other functions that would be improper. For example, in an gaming scenario where characters can earn money, an actor  212   z  on computing device  210  may send a message to an actor in the actor server system  250  that would attempt to give a character money that was not earned by that character. Since it would be improper to for the actor  212   z  to perform such a money-transfer function, the security service  260  can intercept such messages to prevent the money-transfer function from occurring. In the depiction of  FIG. 2B , the security services is located outside of the actor server system  250 , the security service  260  could also be hosted inside of the actor server system. In this case, the security service  260  located inside of the actor server system  250  could monitor and secure messages coming out of and into the actor server system  250  to and from actors on computing devices  210 ,  220  and  230 . 
       FIG. 3  depicts an embodiment of an actor server system  300  that includes multiple servers in multiple server racks. The actor server system  300  includes a server rack  310  and a server rack  350 . Server racks  310  and  350  can be a structure that can accommodate a number of servers in a modular manner. One or more servers can be added to or removed from server racks  310  and  350  without disrupting operation of the other servers in the server racks  310  and  350 . A server rack can provide a number of functions to each of the servers in the server rack, such as providing power, cooling, networking communication links and the like. Some advantages to using a server rack include the ability to provision additional server(s) in a server rack if demand for computing resources increases and the ability to remove server(s) from the server rack if demand for computing resources decreases. 
     In the particular embodiment shown in  FIG. 3 , the server rack  310  includes servers  320 ,  330  and  340 , and the server rack  350  includes servers  360 ,  370  and  380 . While three servers are depicted in each of server rack  310  and server rack  350 , server rack  310  and server rack  350  could include any number of servers. Server  320  hosts actors  321   a  to  321   n , server  330  hosts actors  331   a  to  331   n , server  340  hosts actors  341   a  to  341   n , server  360  hosts actors  361   a  to  361   n , server  370  hosts actors  371   a  to  371   n  and server  380  hosts actors  381   a  to  381   n . The actors  321 ,  331 ,  341 ,  361 ,  371  and  381  may all be part of the same actor system. While the actors  321 ,  331 ,  341 ,  361 ,  371  and  381  could all be hosted by the same server, it may be desirable to host the actors  321 ,  331 ,  341 ,  361 ,  371  and  381  on different servers, such as in the way depicted in  FIG. 3 . It may be that the number of actors  321 ,  331 ,  341 ,  361 ,  371  and  381  is too great to be hosted by a single server and that multiple servers can be used, such as in the way depicted in  FIG. 3 . 
     The actor server system  300  can also include a number of communication links. Server rack  310  includes a number of intra-rack communication link(s)  311  that permit communication between each of the servers  320 ,  330  and  340  that are located on the server rack  310 . Server rack  350  includes a number of intra-rack communication link(s)  351  that permit communication between each of the servers  360 ,  370  and  380  that are located on the server rack  350 . The actor server system  300  also includes inter-rack communication link(s)  301  that permit communication between different server racks and permit communication between the server racks and an external network  390 . The external network  390  can include a local area network (LAN), the Internet or any other type of network. In some embodiments, actors in the actor system can also be hosted by servers that are outside of the actor server system  300 . In this case, actors can be hosted by an external system  395 . The external system  395  can be a computing device, server or another actor server system that is in communication with the external network  390 . 
     Communicating messages between two actors in the actor system shown in  FIG. 3  may take different amounts of time depending on the network location between the two actors. For example, a message can be sent between actors in the same server at a first rate. Messages sent within a server, such as a message sent from actor  321   a  to actor  321   n  may be sent at the first rate. In another example, intra-rack communication link(s)  311  may allow communications at a second rate, such as a rate of 100 gigabits per second (e.g., via a 100 Gigabit Ethernet (100GbE) link). The second rate can be slower than the first rate. Messages sent via the intra-rack communication link(s)  311 , such as a message sent from actor  321   a  to actor  331   a , can be communicated at the second rate. In another example, inter-rack communication link(s)  301  may allow communications at a third rate, such as a rate of 10 gigabits per second (e.g., via a 10 Gigabit Ethernet (10GbE) link). The third rate can be slower than the second rate. Messages sent via the inter-rack communication link(s)  301 , such as a message sent from actor  321   a  to actor  361   a , can be communicated at the third rate. In another example, external network  390  may allow communications at a fourth rate. The fourth rate can be slower than the third rate. Messages sent via the external network  390 , such as a message sent from actor  321   a  to an actor in external system  395 , can be communicated at the fourth particular rate. 
     Using the examples from the previous paragraph, the closeness of one actor to other actors can be understood. Closeness of one actor to other actors can be determined based on the time taken to communicate messages from the one actor to the other actors or the rate of communication between one actor and the other actors. The actor  321   a  is closest to the other actor(s) on server  320 , such as actor  321   n , because communications between the actor  321   a  and the other actor(s) on server  320  occur at the fastest rate in this example. The actor  321   a  is next closest to the actor(s) on other server(s) within the server rack  310 , such as actor  331   a  on server  330  and actor  341   a  on server  340 , because communications between the actor  321   a  and the other actor(s) on other server(s) within the server rack  310  occur at the second fastest rate in this example. The actor  321   a  is next closest to the actor(s) on other server(s) within other server rack(s) within the actor server system  300 , such as actor  361   a  on server  360  and actor  371   a  on server  370  in server rack  350 , because communications between the actor  321   a  and the other actor(s) on other server(s) within other server rack(s) within the actor server system  300  occur at the third fastest rate in this example. The actor  321   a  is furthest from the actor(s) on the external system  395  because communications between the actor  321   a  and actor(s) on the external system  395  occur at the slowest rate in this example. 
     The closeness of actors to each other and the differences in communication speeds are not limited to those depicted in  FIG. 3 . Many other configurations could place actors near or close to each other. In one example, actors could be located in different rooms of a data center and actors in different rooms of a data center could be further apart than actors in different server racks in the same room. In another example, actors could be located in different data centers which could be further apart than actors in different rooms within a single data center. In yet another example, actors could be located in data centers in different availability zones which could be further apart than actors in different data centers within a single availability zone. Many other conditions could exist that would place actors near or far from each other. 
       FIG. 4  depicts an actor server system  400  that includes servers  410 ,  420 , and  430  that can communicate with each other via communication link(s)  440 . The communication links  440  shown in  FIG. 4  show a fairly simple topology with one connection between each pair of servers  410 ,  420 , and  430 . However, such a topology could be difficult to implement should additional servers be added to the system  400 . Many other topologies could be used to implement communication links  440 , and communication links  440  are not limited to this one example depicted in  FIG. 4 . For example, communication links  440  could have a hierarchical topology or a ring topology. The communication links  440  could also be replaced by a network, such as a local area network (LAN), or a communication hub, such as a WiFi router. 
     The server  410  includes a management service  411  and actors  412 - 414 . The management service  411  can manage the actors  412 - 414  located within server  410 , manage the creation of new actors within server  410 , manage the deletion of actors from server  410 , route communications to and from actors on the server  410 , transfer actors from the server  410  to another server, receive and host actors transferred from other servers to the server  410  and the like. The server  420  includes a management service  421  and actors  422 - 424 . The server  430  includes a management service  431  and actors  432 - 434 . The management services  421  and  431  can provide similar functionality for their respective servers  420  and  430 , as was described with respect to the functionality of management service  411  for its server  410 . 
     The management services  411 ,  421  and  431  can maintain a log of the messages sent from and received by the actors on their respective servers  410 ,  420  and  430 . For example, management service  411  can maintain a log that includes an indication of the number of times that actor  412  has received a message from each of the actors  413 ,  414 ,  422 - 424  and  432 - 434 , and the number of times that the actor  412  has sent a message to each of the actors  413 ,  414 ,  422 - 424  and  432 - 434 . Such a log can be used to determine a message frequency of messages sent between the actor  412  and each of the other actors in the actor server system  400 . A message frequency can be based on the overall number of messages sent during a particular period of time, based on sizes of messages sent during a particular period of time, or based on a combination of the number of overall messages and the sizes of messages sent during a particular period of time. Message frequencies can indicate how “talkative” the actor  412  is with the other actors in the actor server system  400 . If two actors are more talkative with each other than with other actors, it may be advantageous to place the two actors closer to each other within the actor server system  400  to reduce the time that messages take to pass between the two talkative actors. 
     Based on the message frequencies of messages being sent between actors, a degree of closeness can be determined for two or more actors. A degree of closeness can be a binary option (e.g., either actors should be close or actors do not need to be close), a range of values (e.g., a range of value from 1 to 10 where 1 is associated with a lowest need for the actors to be close and 10 is associated with the highest indicator that the actors should be close), and/or any other indication of a degree. In another embodiment, a degree of closeness for two or more actors can be set by a developer of the actor system hosted by actor server system  400 , by an operator of the actor system hosted by actor server system  400 , or by any other group or individual. As is discussed in greater detail below, the degree of closeness—whether determined based on a message frequency of messages sent or set by a person or group—can be used to locate one or more actors within the actor server system  400 . 
       FIGS. 5A to 5D  depict an actor server system  500  and examples of relocating actors within the actor server system  500 . The actor server system  500  includes servers  510 ,  520  and  530  that are in communication with each other via communication link(s)  540 . Servers  510 ,  520  and  530  include management services  511 ,  512  and  513 , respectively. At the time depicted in  FIG. 5A , server  510  hosts actors  512 - 519 , server  520  hosts actors  522  and  523  and server  530  hosts actors  532 - 535 . The management service  511  may determine to move actors  518  and  519  to one or more of the other servers  520  and  530 . Such a determination may be made on one or more of a number of factors, such as server  510  reaching or nearing a capacity of actors, management service  511  determining that actors  518  and  519  are more talkative with actors that are not on server  510  than with actors on server  510  or the like. Each of the times depicted in  FIGS. 5B to 5D  represents a different way that management server  511  can move actors  518  and  519  from the server  510  to one or more of the other servers  520  and  530 . 
       FIG. 5B  depicts a load-balancing approach to move actors  518  and  519  from the server  510 . At the time depicted in  FIG. 5A , management service  511  may determine to attempt to move actors  518  and  519  from server  510  to another server. This determination may be made because usage of computing resources in server  510  are at or nearing a maximum level, because the message frequency between each of actors  518  and  519  and other actors outside of server  510  are above a threshold, or for any other reason. 
     Management server  511  can send an availability inquiry to each of management service  521  and management service  531  requesting an availability of the server  520  and the server  530 , respectively, to host additional actors. Responses from the management service  521  and management service  531  can be sent to management service  511  indicating a level of availability of the server  520  and the server  530  to host additional actors. In the particular embodiment shown in  FIG. 5A , based on the responses from management service  521  and from management service  531  to management service  511  can indicate that both the server  520  and the server  530  have availability to host additional actors. The responses can also indicate that the server  520  has greater availability than server  530  to host additional resources. In the particular instance shown in  FIG. 5B , the management service  511  sent the actors  518  and  519  to the server  520 . Such a decision may be made based, at least in part, on an intent to balance the load among the servers  510 ,  520  and  530 . 
       FIG. 5C  depicts an approach to move actors  518  and  519  from the server  510  based on message frequencies between actors. At the time depicted in  FIG. 5A , management service  511  may determine that actors  518  and  519  are sending messages to actors outside of server  510  more frequently that they send messages to actors within the server  510 . For example, management service  511  can determine that actors  518  and  519  send messages to actors located on server  530  at a message frequency that is above a threshold message frequency. Because the message frequency between actors  518  and  519  and actors located on server  530  is above the message threshold frequency, the management service  511  can send an availability inquiry to management service  531  and the management service  531  can respond with an indication that server  530  has availability to host additional actors. In the particular instance shown in  FIG. 5C , the management service  511  sent the actors  518  and  519  to the server  530 . 
       FIG. 5D  depicts an approach to move actors  518  and  519  from the server  510  based on a degree of closeness received by the actor server system  500 . The actor server system  500  can receive an indication of a degree of closeness for actor  518  and a degree of closeness for actor  519 . The degree of closeness for actor  518  can indicate that actor  518  should be located close to actor  522 . The degree of closeness for actor  519  can indicate that actor  519  should be located close to actor  532 . The degrees of closeness for actors  518  and  519  can be submitted by a developer of the actor system, an operator of the actor system, or any other group or individual. Based on the degree of closeness for actor  518 , management service  511  can send an availability inquiry to management service  521  about an availability of the server  520  to host actor  518  and the management service  521  can respond with an indication that server  520  has availability to host actor  518 . Based on the degree of closeness for actor  519 , management service  511  can send an availability inquiry to management service  531  about an availability of the server  530  to host actor  519  and the management service  531  can respond with an indication that server  530  has availability to host actor  519 . In the particular instance shown in  FIG. 5D , the management service  511  sent the actor  518  to the server  520  and the management service  511  sent the actor  519  to the server  530 . 
       FIGS. 6A and 6B  depict an example of moving an actor from one location to another when multiple destination locations are available.  FIGS. 6A and 6B  depict an actor server system  600  that includes a server rack  610  and a server rack  640 . The server rack  610  includes server  620  and server  630 . Server  620  includes a management service  621  and hosts actors  622 - 627 . Server  630  includes a management service  631  and hosts actors  632  and  633 . The servers  620  and  630  within server rack  610  can communicate with each other via intra-rack communication link(s)  611 . The server rack  640  includes server  650  and server  660 . Server  650  includes a management service  651  and hosts actors  652 - 657 . Server  660  includes a management service  661  and hosts actors  662 - 664 . The servers  650  and  660  within server rack  640  can communicate with each other via intra-rack communication link(s)  641 . Communications between server racks  610  and  640  can be carried via inter-rack communication link(s)  601 . The intra-rack communication link(s)  611  and  641  may communicate messages at a faster rate than the inter-rack communication link(s)  601  may communicate messages. 
     At the time depicted in  FIG. 6A , the management service  621  may determine that actor  627  should be moved to another server. The determination that actor  627  should be moved can be based on one or more of server  620  nearing a capacity of hosted actors, a degree of closeness of actor  627  to another actor being determined, a degree of closeness of actor  627  to another actor being received and the like. The management service  621  can send an availability inquiry to each of the other management services  631 ,  651  and  661  in the actor server system  600 . At the particular time depicted in  FIG. 6A , the management service  651  may respond with an indication that the server  650  is unavailable to host another actor and the management services  631  and  661  may respond with an indication that the servers  630  and  660  are available to host another actor. 
     The determination that actor  627  should be moved can be based can also be based on a determination of optimization of computing resources within the actor system. In one embodiment, if computing resources within the actor system are underutilized, it may be more optimal for the underutilized computing resources to be shut down instead of moving actor  627 . For example, it may be possible to move the actors  632  and  633  on server  630  to server  660  and remove server  630  from service. In this embodiment, the termination may be made to leave actor  627  on server  620  so that server  630  could be removed to save computing resources. In another embodiment, the determination of optimization of computing resources within the actor system can be based on a local, regional or global view of the actor system. A global view of the actor system can provide a complete analysis of the actor system, but it may take a significant about of time to analyze the entire actor system. A local view of the actor system can provide an analysis of the actors close to one or more actors; however, a local analysis may not provide enough information about the actor system. A regional view may provide an analysis that is somewhere between the local view and the global view of the actor system. One way to approximate a global view of the actor system would be to combine multiple regional views of the actor system to approximate the global view of the actor system. Such an approximation of the global view of the actor system may not take as much time to perform as performing a full global view of the actor system. 
     The management service  621  may determine which of the available servers  630  and  660  to which the actor  627  should be transferred based on the degree of closeness between actor  627  and another actor in the actor server system  600 . For example, the management service  621  may be aware of a degree of closeness between actor  627  and actor  656  on server  650 . The degree of closeness between actor  627  and actor  656  can be based on a message frequency of messages sent between actor  627  and actor  656 , based on a received degree of closeness between actor  627  and actor  656 , or based on any other information. Placing the actor  627  on server  650  would place the actor  627  in the closest location to actor  656 . However, server  650  is not available to host actor  627 . Between the available servers  630  and  660 , the management service  621  can determine that the actor  627  will be closer to actor  656  if it is moved to server  660  than if it is moved to server  630  because the intra-rack communication link(s)  641  communicate messages between server  660  and server  650  at a faster rate than the inter-rack communication link(s)  601  communicate messages between server  630  and server  650 . At the time shown in  FIG. 6B , the actor  627  has been moved to server  660 . 
       FIG. 7  depicts a method  700  that can be used by a management service to attempt to move one or more actors to another location. At block  701 , the management service can determine that one or more actors should be moved to another location. As discussed above, such a decision can be based on a usage of a computing device or server on which the one or more actors are hosted, based on a degree of closeness of the one or more actors, or based on any other information or reason. The decision can also be based on a determination of optimization of computing resources within the actor system. At block  702 , an inquiry can be made about availability of other locations to accept the one or more actors. The inquiry can include an inquiry message sent from one management service on a server or computing device to another management service on another server or computing device. At block a  703 , a determination can be made as to how many locations are available to host the one or more actors. 
     If, at block  703 , it is determined that there are no locations available to host the one or more actors, then, at block  704 , the one or more actors can be left in their original location. At block  705 , a signal can be sent that additional locations may need to be provisioned. Such a signal can include one or more of a signal sent to a developer or operator of the actor system to purchase additional computing resources available in a server system, a signal for a network technician to install an additional server within a server rack, a signal to automatically provision an additional server to host actors and the like. If additional locations are provisioned, the one or more actors can then be transferred to the newly-provisioned locations. 
     If, at block  703 , it is determined that only one location is available, then, at block  706 , the one or more actors can be sent to that available location. In an embodiment not depicted in  FIG. 7 , an additional decision can be made after block  703  and before block  703 . In that embodiment, a decision can be made whether the one or more actors will be closer to other actors with which the one or more actors frequently send or receive messages. If the one or more actors would be closer to those other actors at the available location, then the method could proceed to block  706  where the one or more actors are sent to the available location. However, if the one or more actors would not be closer to those other actors at the available location, then the one or more actors can be left at their original location. 
     If, at block  703 , it is determined that more than one location is available, then, at block  707 , a degree of closeness can be determined between the one or more actors and other actors in the actor system. At block  708 , a destination location from the available locations can be determined based at least in part on the degree of closeness. The destination location may not be the closest location of the one or more actors to other actors with which the one or more actors frequently send messages, but the destination location may be the closest available location. Additionally, in the case where there are more than one actors being moved, more than one destination location may be determined. At block  709 , the one or more actors are sent to the destination location determined at block  708 . 
       FIG. 8  depicts a method  800  of determining whether to move one or more actors after receiving degree of closeness of two actors. At block  801 , an indication of a degree of closeness between two actors can be received. The degree of closeness can be a binary option (e.g., either actors should be close or actors do not need to be close), a range of values (e.g., a range of value from 1 to 10 where 1 is associated with a lowest need for the actors to be close and 10 is associated with the highest indicator that the actors should be close), and/or any other indication of a degree. For example, the indication of the degree of closeness can indicate that a first actor and a second actor should be located close to each other within an actor system. At block  802 , an inquiry can be made whether any possible new locations for the first and/or second actor exist. A new location can be a server, a server rack, a computing device and the like. 
     At block  803 , a determination can be made whether any additional locations are available to host one or both of the first and second actors. The determination can be made based on responses to the inquiries sent at block  802 . If, at block  803 , it is determined that no new locations are available to host one or both of the first and second actors, then, at block  804 , a signal can be raised regarding a possible need for additional locations. Additional locations can be made by provisioning an additional server, by purchasing access to additional resources within an actor server system and the like. At block  805 , the first and second actors can be left in their original locations. 
     If, at block  803 , it is determined that one or more new locations are available to host one or both of the first and second actors, then, at block  806 , a determination is made whether the possible one or more new locations would permit the first and second actors to be located closer to each other. For example, if one of the possible new locations is a server that already hosts the second actor, then placing the first actor on the same server would locate the first and second actors closer to each other. In another example, if the first and second actors are located on different servers within the same server rack and the only possible new location is a server in another server rack, then moving one of the first and second actors to the server in the other server rack would not locate the first and second actors closer to each other. If, at block  806 , it is determined that the possible new locations would not locate the first and second actors closer to each other, then the method can proceed to block  805  where the first and second actors are left in their original locations. However, if, at block  806 , it is determined that the possible new locations would locate the first and second actors closer to each other, then, at block  807 , one or both of the first and second actors can be moved to one or more of the new locations. 
       FIG. 9  depicts a method  900  of determining a degree of closeness for a first actor and a second actor. At block  901 , the addresses of messages sent from and received by a first actor can be monitored. Monitoring the messages can include creating a log of the destinations of each message sent by the first actor and the origins of each message received by the first actor. At block  902 , a message frequency sent between the first actor and a second actor can be determined. The message frequency can be based on the overall number of messages sent between the first actor and a second actor during a particular period of time, based on sizes of messages sent between the first actor and a second actor during a particular period of time, or based on a combination of the number of overall messages and the sizes of messages sent between the first actor and a second actor during a particular period of time. The message frequency can be determined based on information from a log created during the monitoring in block  902 . At block  903 , a determination can be made whether the message frequency exceeds a threshold. The threshold can be a static threshold, such as a predetermined frequency. The threshold can also be a variable threshold, such as a threshold based on a message frequency between the first actor and other actors in the same server. 
     If, at block  903 , it is determined that the message frequency between the first actor and the second actor exceeds the threshold, then, at block  904 , a degree of closeness between the first and second actors can be determined. The degree of closeness between the first and second actors can be based on the message frequency between the first and second actors. At block  905 , a determination can be made, based at least in part on the degree of closeness between the first and second actors, whether one or both of the first and second actors should be moved to a new location. However, if, at block  903 , it is determined that the message frequency between the first actor and the second actor does not exceed the threshold, then, at block  906 , the first and second actor can be left in their original locations. 
       FIG. 10  illustrates an example computing environment in which the embodiments described herein may be implemented.  FIG. 10  is a diagram schematically illustrating an example of a data center  1010  that can provide computing resources to users  1000   a  and  1000   b  (which may be referred herein singularly as user  1000  or in the plural as users  1000 ) via user computers  1002   a  and  1002   b  (which may be referred herein singularly as computer  1002  or in the plural as computers  1002 ) via a communications network  1030 . Data center  1010  may be configured to provide computing resources for executing applications on a permanent or an as-needed basis. The computing resources provided by data center  1010  may include various types of resources, such as gateway resources, load balancing resources, routing resources, networking resources, computing resources, volatile and non-volatile memory resources, content delivery resources, data processing resources, data storage resources, data communication resources and the like. Each type of computing resource may be general-purpose or may be available in a number of specific configurations. For example, data processing resources may be available as virtual machine instances that may be configured to provide various web services. In addition, combinations of resources may be made available via a network and may be configured as one or more web services. The instances may be configured to execute applications, including web services, such as application services, media services, database services, processing services, gateway services, storage services, routing services, security services, encryption services, load balancing services, application services and the like. These web services may be configurable with set or custom applications and may be configurable in size, execution, cost, latency, type, duration, accessibility and in any other dimension. These web services may be configured as available infrastructure for one or more clients and can include one or more applications configured as a platform or as software for one or more clients. These web services may be made available via one or more communications protocols. These communications protocols may include, for example, hypertext transfer protocol (HTTP) or non-HTTP protocols. These communications protocols may also include, for example, more reliable transport layer protocols such as transmission control protocol (TCP) and less reliable transport layer protocols such as user datagram protocol (UDP). Data storage resources may include file storage devices, block storage devices and the like. 
     Each type or configuration of computing resource may be available in different sizes, such as large resources—consisting of many processors, large amounts of memory and/or large storage capacity—and small resources—consisting of fewer processors, smaller amounts of memory and/or smaller storage capacity. Customers may choose to allocate a number of small processing resources as web servers and/or one large processing resource as a database server, for example. 
     Data center  1010  may include servers  1016   a - b  (which may be referred herein singularly as server  1016  or in the plural as servers  1016 ) that provide computing resources. These resources may be available as bare metal resources, or as virtual machine instances  1018   a - d  and (which may be referred herein singularly as virtual machine instance  1018  or in the plural as virtual machine instances  1018 ). Virtual machine instances  1018   c  and  1018   d  are interest virtual machine instances. The interest virtual machine instances  1018   c  and  1018   d  may be configured to perform all or any portion of the encoding techniques based on areas of interest in accordance with the present disclosure and described in detail below. As should be appreciated, while the particular example illustrated in  FIG. 10  includes one interest virtual machine in each server, this is merely an example. A server may include more than one interest virtual machine or may not include any interest virtual machines. 
     The availability of virtualization technologies for computing hardware has provided benefits for providing large scale computing resources for customers and allowing computing resources to be efficiently and securely shared between multiple customers. For example, virtualization technologies may allow a physical computing device to be shared among multiple users by providing each user with one or more virtual machine instances hosted by the physical computing device. A virtual machine instance may be a software emulation of a particular physical computing system that acts as a distinct logical computing system. Such a virtual machine instance provides isolation among multiple operating systems sharing a given physical computing resource. Furthermore, some virtualization technologies may provide virtual resources that span one or more physical resources, such as a single virtual machine instance with multiple virtual processors that spans multiple distinct physical computing systems. 
     Referring to  FIG. 10 , communications network  1030  may, for example, be a publicly accessible network of linked networks and possibly operated by various distinct parties, such as the Internet. In other embodiments, communications network  1030  may be a private network, such as, a corporate or university network that is wholly or partially inaccessible to non-privileged users. In still other embodiments, communications network  1030  may include one or more private networks with access to and/or from the Internet. 
     Communication network  1030  may provide access to computers  1002 . User computers  1002  may be computers utilized by users  1000  or other customers of data center  1010 . For instance, user computer  1002   a  or  1002   b  may be a server, a desktop or laptop personal computer, a tablet computer, a wireless telephone, a personal digital assistant (PDA), an e-book reader, a game console, a set-top box or any other computing device capable of accessing data center  1010 . User computer  1002   a  or  1002   b  may connect directly to the Internet (e.g., via a cable modem or a Digital Subscriber Line (DSL)). Although only two user computers  1002   a  and  1002   b  are depicted, it should be appreciated that there may be multiple user computers. 
     User computers  1002  may also be utilized to configure aspects of the computing resources provided by data center  1010 . In this regard, data center  1010  might provide a gateway or web interface through which aspects of its operation may be configured through the use of a web browser application program executing on user computer  1002 . Alternately, a stand-alone application program executing on user computer  1002  might access an application programming interface (API) exposed by data center  1010  for performing the configuration operations. Other mechanisms for configuring the operation of various web services available at data center  1010  might also be utilized. 
     Servers  1016  shown in  FIG. 10  may be standard servers configured appropriately for providing the computing resources described above and may provide computing resources for executing one or more web services and/or applications. In one embodiment, the computing resources may be virtual machine instances  1018 . In the example of virtual machine instances, each of the servers  1016  may be configured to execute an instance manager  1020   a  or  1020   b  (which may be referred herein singularly as instance manager  1020  or in the plural as instance managers  1020 ) capable of executing the virtual machine instances  1018 . The instance managers  1020  may be a virtual machine monitor (VMM) or another type of program configured to enable the execution of virtual machine instances  1018  on server  1016 , for example. As discussed above, each of the virtual machine instances  1018  may be configured to execute all or a portion of an application. 
     It should be appreciated that although the embodiments disclosed above discuss the context of virtual machine instances, other types of implementations can be utilized with the concepts and technologies disclosed herein. For example, the embodiments disclosed herein might also be utilized with computing systems that do not utilize virtual machine instances. 
     In the example data center  1010  shown in  FIG. 10 , a router  1014  may be utilized to interconnect the servers  1016   a  and  1016   b . Router  1014  may also be connected to gateway  1040 , which is connected to communications network  1030 . Router  1014  may be connected to one or more load balancers, and alone or in combination may manage communications within networks in data center  1010 , for example by forwarding packets or other data communications as appropriate based on characteristics of such communications (e.g., header information including source and/or destination addresses, protocol identifiers, size, processing requirements, etc.) and/or the characteristics of the private network (e.g., routes based on network topology, etc.). It will be appreciated that, for the sake of simplicity, various aspects of the computing systems and other devices of this example are illustrated without showing certain conventional details. Additional computing systems and other devices may be interconnected in other embodiments and may be interconnected in different ways. 
     In the example data center  1010  shown in  FIG. 10 , a server manager  1015  is also employed to at least in part direct various communications to, from and/or between servers  1016   a  and  1016   b . While  FIG. 10  depicts router  1014  positioned between gateway  1040  and server manager  1015 , this is merely an exemplary configuration. In some cases, for example, server manager  1015  may be positioned between gateway  1040  and router  1014 . Server manager  1015  may, in some cases, examine portions of incoming communications from user computers  1002  to determine one or more appropriate servers  1016  to receive and/or process the incoming communications. Server manager  1015  may determine appropriate servers to receive and/or process the incoming communications based on factors such as an identity, location or other attributes associated with user computers  1002 , a nature of a task with which the communications are associated, a priority of a task with which the communications are associated, a duration of a task with which the communications are associated, a size and/or estimated resource usage of a task with which the communications are associated and many other factors. Server manager  1015  may, for example, collect or otherwise have access to state information and other information associated with various tasks in order to, for example, assist in managing communications and other operations associated with such tasks. 
     It should be appreciated that the network topology illustrated in  FIG. 10  has been greatly simplified and that many more networks and networking devices may be utilized to interconnect the various computing systems disclosed herein. These network topologies and devices should be apparent to those skilled in the art. 
     It should also be appreciated that data center  1010  described in  FIG. 10  is merely illustrative and that other implementations might be utilized. Additionally, it should be appreciated that the functionality disclosed herein might be implemented in software, hardware or a combination of software and hardware. Other implementations should be apparent to those skilled in the art. It should also be appreciated that a server, gateway or other computing device may comprise any combination of hardware or software that can interact and perform the described types of functionality, including without limitation desktop or other computers, database servers, network storage devices and other network devices, PDAs, tablets, cellphones, wireless phones, pagers, electronic organizers, Internet appliances, television-based systems (e.g., using set top boxes and/or personal/digital video recorders) and various other consumer products that include appropriate communication capabilities. In addition, the functionality provided by the illustrated modules may in some embodiments be combined in fewer modules or distributed in additional modules. Similarly, in some embodiments the functionality of some of the illustrated modules may not be provided and/or other additional functionality may be available. 
     In at least some embodiments, a server that implements a portion or all of one or more of the technologies described herein may include a general-purpose computer system that includes or is configured to access one or more computer-accessible media.  FIG. 11  depicts a general-purpose computer system that includes or is configured to access one or more computer-accessible media. In the illustrated embodiment, computing device  1100  includes one or more processors  1110   a ,  1110   b  and/or  1110   n  (which may be referred herein singularly as “a processor  1110 ” or in the plural as “the processors  1110 ”) coupled to a system memory  1120  via an input/output (I/O) interface  1130 . Computing device  1100  further includes a network interface  1140  coupled to I/O interface  1130 . 
     In various embodiments, computing device  1100  may be a uniprocessor system including one processor  1110  or a multiprocessor system including several processors  1110  (e.g., two, four, eight or another suitable number). Processors  1110  may be any suitable processors capable of executing instructions. For example, in various embodiments, processors  1110  may be general-purpose or embedded processors implementing any of a variety of instruction set architectures (ISAs), such as the x86, PowerPC, SPARC or MIPS ISAs or any other suitable ISA. In multiprocessor systems, each of processors  1110  may commonly, but not necessarily, implement the same ISA. 
     System memory  1120  may be configured to store instructions and data accessible by processor(s)  1110 . In various embodiments, system memory  1120  may be implemented using any suitable memory technology, such as static random access memory (SRAM), synchronous dynamic RAM (SDRAM), nonvolatile/Flash®-type memory or any other type of memory. In the illustrated embodiment, program instructions and data implementing one or more desired functions, such as those methods, techniques and data described above, are shown stored within system memory  1120  as code  1125  and data  1126 . 
     In one embodiment, I/O interface  1130  may be configured to coordinate I/O traffic between processor  1110 , system memory  1120  and any peripherals in the device, including network interface  1140  or other peripheral interfaces. In some embodiments, I/O interface  1130  may perform any necessary protocol, timing or other data transformations to convert data signals from one component (e.g., system memory  1120 ) into a format suitable for use by another component (e.g., processor  1110 ). In some embodiments, I/O interface  1130  may include support for devices attached through various types of peripheral buses, such as a variant of the Peripheral Component Interconnect (PCI) bus standard or the Universal Serial Bus (USB) standard, for example. In some embodiments, the function of I/O interface  1130  may be split into two or more separate components, such as a north bridge and a south bridge, for example. Also, in some embodiments some or all of the functionality of I/O interface  1130 , such as an interface to system memory  1120 , may be incorporated directly into processor  1110 . 
     Network interface  1140  may be configured to allow data to be exchanged between computing device  1100  and other device or devices  1160  attached to a network or networks  1150 , such as other computer systems or devices, for example. In various embodiments, network interface  1140  may support communication via any suitable wired or wireless general data networks, such as types of Ethernet networks, for example. Additionally, network interface  1140  may support communication via telecommunications/telephony networks, such as analog voice networks or digital fiber communications networks, via storage area networks, such as Fibre Channel SANs (storage area networks), or via any other suitable type of network and/or protocol. 
     In some embodiments, system memory  1120  may be one embodiment of a computer-accessible medium configured to store program instructions and data as described above for implementing embodiments of the corresponding methods and apparatus. However, in other embodiments, program instructions and/or data may be received, sent or stored upon different types of computer-accessible media. Generally speaking, a computer-accessible medium may include non-transitory storage media or memory media such as magnetic or optical media, e.g., disk or DVD/CD coupled to computing device  1100  via I/O interface  1130 . A non-transitory computer-accessible storage medium may also include any volatile or non-volatile media such as RAM (e.g. SDRAM, DDR SDRAM, RDRAM, SRAM, etc.), ROM etc., that may be included in some embodiments of computing device  1100  as system memory  1120  or another type of memory. Further, a computer-accessible medium may include transmission media or signals such as electrical, electromagnetic or digital signals conveyed via a communication medium such as a network and/or a wireless link, such as those that may be implemented via network interface  1140 . Portions or all of multiple computing devices such as those illustrated in  FIG. 11  may be used to implement the described functionality in various embodiments; for example, software components running on a variety of different devices and servers may collaborate to provide the functionality. In some embodiments, portions of the described functionality may be implemented using storage devices, network devices or special-purpose computer systems, in addition to or instead of being implemented using general-purpose computer systems. The term “computing device,” as used herein, refers to at least all these types of devices and is not limited to these types of devices. 
     A compute node, which may be referred to also as a computing node, may be implemented on a wide variety of computing environments, such as commodity-hardware computers, virtual machines, web services, computing clusters and computing appliances. Any of these computing devices or environments may, for convenience, be described as compute nodes. 
     A network set up by an entity such as a company or a public sector organization to provide one or more web services (such as various types of cloud-based computing or storage) accessible via the Internet and/or other networks to a distributed set of clients may be termed a provider network. Such a provider network may include numerous data centers hosting various resource pools, such as collections of physical and/or virtualized computer servers, storage devices, networking equipment, and the like, needed to implement and distribute the infrastructure and web services offered by the provider network. The resources may in some embodiments be offered to clients in various units related to the web service, such as an amount of storage for storage, processing capability for processing, as instances, as sets of related services and the like. A virtual computing instance may, for example, comprise one or more servers with a specified computational capacity (which may be specified by indicating the type and number of CPUs, the main memory size and so on) and a specified software stack (e.g., a particular version of an operating system, which may in turn run on top of a hypervisor). 
     A number of different types of computing devices may be used singly or in combination to implement the resources of the provider network in different embodiments, including general purpose or special purpose computer servers, storage devices, network devices and the like. In some embodiments a client or user may be provided direct access to a resource instance, e.g., by giving a user an administrator login and password. In other embodiments the provider network operator may allow clients to specify execution requirements for specified client applications and schedule execution of the applications on behalf of the client on execution platforms (such as application server instances, Java™ virtual machines (JVMs), general purpose or special-purpose operating systems, platforms that support various interpreted or compiled programming languages such as Ruby, Perl, Python, C, C++ and the like or high-performance computing platforms) suitable for the applications, without, for example, requiring the client to access an instance or an execution platform directly. A given execution platform may utilize one or more resource instances in some implementations; in other implementations multiple execution platforms may be mapped to a single resource instance. 
     In many environments, operators of provider networks that implement different types of virtualized computing, storage and/or other network-accessible functionality may allow customers to reserve or purchase access to resources in various resource acquisition modes. The computing resource provider may provide facilities for customers to select and launch the desired computing resources, deploy application components to the computing resources and maintain an application executing in the environment. In addition, the computing resource provider may provide further facilities for the customer to quickly and easily scale up or scale down the numbers and types of resources allocated to the application, either manually or through automatic scaling, as demand for or capacity requirements of the application change. The computing resources provided by the computing resource provider may be made available in discrete units, which may be referred to as instances. An instance may represent a physical server hardware platform, a virtual machine instance executing on a server or some combination of the two. Various types and configurations of instances may be made available, including different sizes of resources executing different operating systems (OS) and/or hypervisors, and with various installed software applications, runtimes and the like. Instances may further be available in specific availability zones, representing a logical region, a fault tolerant region, a data center or other geographic location of the underlying computing hardware, for example. Instances may be copied within an availability zone or across availability zones to improve the redundancy of the instance, and instances may be migrated within a particular availability zone or across availability zones. As one example, the latency for client communications with a particular server in an availability zone may be less than the latency for client communications with a different server. As such, an instance may be migrated from the higher latency server to the lower latency server to improve the overall client experience. 
     In some embodiments the provider network may be organized into a plurality of geographical regions, and each region may include one or more availability zones. An availability zone (which may also be referred to as an availability container) in turn may comprise one or more distinct locations or data centers, configured in such a way that the resources in a given availability zone may be isolated or insulated from failures in other availability zones. That is, a failure in one availability zone may not be expected to result in a failure in any other availability zone. Thus, the availability profile of a resource instance is intended to be independent of the availability profile of a resource instance in a different availability zone. Clients may be able to protect their applications from failures at a single location by launching multiple application instances in respective availability zones. At the same time, in some implementations inexpensive and low latency network connectivity may be provided between resource instances that reside within the same geographical region (and network transmissions between resources of the same availability zone may be even faster). 
     Thus, as set forth above, a content provider may provide content to a destination over a network such as the Internet using, for example, streaming content delivery techniques. A content provider may, for example, provide a content delivery service that may reside on one or more servers. The service may be scalable to meet the demands of one or more customers and may increase or decrease in capability based on the number and type of incoming client requests. The content delivery service may, in some cases, process a content item in parallel across multiple nodes of the content delivery service. This may be done, in one embodiment, to reduce the latency for rendering the content item. Portions of the content delivery service may also be migrated to be placed in a position of reduced latency with a requesting client. In some cases, the content provider may determine an “edge” of a system or network associated with the content provider that is physically and/or logically closest to a requesting client. The content provider may then, for example, “spin-up,” migrate resources, or otherwise employ components associated with the determined edge for interacting with requests from the client. Such an edge determination process may, in some cases, provide an efficient technique for identifying and employing components that are well suited to interact with a particular client, and may, in some embodiments, reduce the latency for communications between a content provider and one or more clients. 
     Each of the processes, methods and algorithms described in the preceding sections may be embodied in, and fully or partially automated by, code modules executed by one or more computers or computer processors. The code modules may be stored on any type of non-transitory computer-readable medium or computer storage device, such as hard drives, solid state memory, optical disc and/or the like. The processes and algorithms may be implemented partially or wholly in application-specific circuitry. The results of the disclosed processes and process steps may be stored, persistently or otherwise, in any type of non-transitory computer storage such as, e.g., volatile or non-volatile storage. 
     The various features and processes described above may be used independently of one another or may be combined in various ways. All possible combinations and subcombinations are intended to fall within the scope of this disclosure. In addition, certain method or process blocks may be omitted in some implementations. The methods and processes described herein are also not limited to any particular sequence, and the blocks or states relating thereto can be performed in other sequences that are appropriate. For example, described blocks or states may be performed in an order other than that specifically disclosed, or multiple blocks or states may be combined in a single block or state. The example blocks or states may be performed in serial, in parallel, or in some other manner. Blocks or states may be added to or removed from the disclosed example embodiments. The example systems and components described herein may be configured differently than described. For example, elements may be added to, removed from or rearranged compared to the disclosed example embodiments. 
     It will also be appreciated that various items are illustrated as being stored in memory or on storage while being used, and that these items or portions of thereof may be transferred between memory and other storage devices for purposes of memory management and data integrity. Alternatively, in other embodiments some or all of the software modules and/or systems may execute in memory on another device and communicate with the illustrated computing systems via inter-computer communication. Furthermore, in some embodiments, some or all of the systems and/or modules may be implemented or provided in other ways, such as at least partially in firmware and/or hardware, including, but not limited to, one or more application-specific integrated circuits (ASICs), standard integrated circuits, controllers (e.g., by executing appropriate instructions, and including microcontrollers and/or embedded controllers), field-programmable gate arrays (FPGAs), complex programmable logic devices (CPLDs), etc. Some or all of the modules, systems and data structures may also be stored (e.g., as software instructions or structured data) on a computer-readable medium, such as a hard disk, a memory, a network, or a portable media article to be read by an appropriate drive or via an appropriate connection. The systems, modules and data structures may also be transmitted as generated data signals (e.g., as part of a carrier wave or other analog or digital propagated signal) on a variety of computer-readable transmission media, including wireless-based and wired/cable-based media, and may take a variety of forms (e.g., as part of a single or multiplexed analog signal, or as multiple discrete digital packets or frames). Such computer program products may also take other forms in other embodiments. Accordingly, the present invention may be practiced with other computer system configurations. 
     Conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment. The terms “comprising,” “including,” “having” and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some or all of the elements in the list. 
     While certain example embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions disclosed herein. Thus, nothing in the foregoing description is intended to imply that any particular feature, characteristic, step, module, or block is necessary or indispensable. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions disclosed herein. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of certain of the inventions disclosed herein.