Abstract:
A method, program and system for service time analysis in a computer network are provided. The invention comprises receiving a request from a network client machine and recording the initial time value for the request. The request is forwarded to an origin server. The response stream from the origin server is instrumented with the initial time value (plus the service time taken for the origin server to respond) and sent back to the client machine. A uniform resource identifier (URI) request (e.g. images) is received from the client machine, and the service time for completing the URI is recorded. The URI request is forwarded to the origin server, and the service time value for the URI is updated to reflect the origin server response. The URI response from the origin server is then sent to the client machine.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Technical Field  
           [0002]    The present invention relates generally to computer network environments. More specifically, the invention relates to quality control and monitoring the time required to service requests.  
           [0003]    2. Description of Related Art  
           [0004]    Current quality-of-service monitors used in web server management applications collect metrics on the end user experience, the page display, and the service times. The metrics collected for the service time are focused on the service time needed to retrieve the container page only. The container page is the initially requested resource. However, this page may contain other resources that need to be retrieved in order to fulfill the request. Examples of other resources include images and embedded applications (i.e. anything embedded in the container page that needs to be retrieved with a separate request). Current quality control monitors do not track the service time taken to retrieve these other resources.  
           [0005]    In prior art QoS, there is no timing mechanism for any of the inline content that makes up a complete web page. When a page is requested using Hypertext Transport Protocol (HTTP), the container page is delivered to the web browser. At that point, the web browser parses the page and makes separate requests for each of the inline elements contained in that web page. Each of these requests is stateless, by the very nature of HTTP 1.0, and potentially stateless in HTTP 1.1. Stateless, means that the software does not keep track of configuration settings, transaction information, or any other data for the next session.  
           [0006]    In a distributed environment, it is not reasonable to assume that the web server that responded to the request for the container page is the same web server that will be asked to deliver all, or even any, of the inline elements of the page. Even if the QoS that serviced the original request (container page) received a new request for one of the inline members of the container page, it has no mechanism for recognizing the new request as a member of the original request.  
           [0007]    Therefore, it would be desirable to have a method for monitoring the service time needed to retrieve a web page, including the container page and all inline elements.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention provides a method, program and system for service time analysis in a computer network. The invention comprises receiving a request from a network client machine and recording the initial time value for the request. The request is forwarded to an origin server. The response stream from the origin server is instrumented with the initial time value (plus the service time taken for the origin server to respond) and sent back to the client machine. A uniform resource identifier (URI) request (e.g. images) is received from the client machine, and the service time for completing the URI is recorded. The URI request is forwarded to the origin server, and the service time value for the URI is updated to reflect the origin server response. The URI response from the origin server is then sent to the client machine.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:  
         [0010]    [0010]FIG. 1 depicts a pictorial representation of a network of data processing systems in which the present invention may be implemented;  
         [0011]    [0011]FIG. 2 depicts a block diagram of a data processing system that may be implemented as a server in accordance with a preferred embodiment of the present invention;  
         [0012]    [0012]FIG. 3 depicts a block diagram illustrating a data processing system in which the present invention may be implemented;  
         [0013]    [0013]FIG. 4 depicts a flowchart illustrating a general transaction association mechanism in accordance with the present invention;  
         [0014]    [0014]FIG. 5 depicts a flowchart illustrating transaction association using multiple servers in accordance with the present invention; and  
         [0015]    [0015]FIG. 6 depicts a flowchart illustrating transaction management using a hybrid of QoS reverse proxy and multiple servers, in accordance with the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]    With reference now to the figures, FIG. 1 depicts a pictorial representation of a network of data processing systems in which the present invention may be implemented. Network data processing system  100  is a network of computers in which the present invention may be implemented. Network data processing system  100  contains a network  102 , which is the medium used to provide communications links between various devices and computers connected together within network data processing system  100 . Network  102  may include connections, such as wire, wireless communication links, or fiber optic cables.  
         [0017]    In the depicted example, a server  104  is connected to network  102  along with storage unit  106 . In addition, clients  108 ,  110 , and  112  also are connected to network  102 . These clients  108 ,  110 , and  112  may be, for example, personal computers or network computers. In the depicted example, server  104  provides data, such as boot files, operating system images, and applications to clients  108 - 112 . Clients  108 ,  110 , and  112  are clients to server  104 . Network data processing system  100  may include additional servers, clients, and other devices not shown.  
         [0018]    In the depicted example, network data processing system  100  is the Internet with network  102  representing a worldwide collection of networks and gateways that use the TCP/IP suite of protocols to communicate with one another. At the heart of the Internet is a backbone of high-speed data communication lines between major nodes or host computers, consisting of thousands of commercial, government, educational and other computer systems that route data and messages. Of course, network data processing system  100  also may be implemented as a number of different types of networks, such as for example, an intranet, a local area network (LAN), or a wide area network (WAN). FIG. 1 is intended as an example, and not as an architectural limitation for the present invention.  
         [0019]    Referring to FIG. 2, a block diagram of a data processing system that may be implemented as a server, such as server  104  in FIG. 1, is depicted in accordance with a preferred embodiment of the present invention. Data processing system  200  may be a symmetric multiprocessor (SMP) system including a plurality of processors  202  and  204  connected to system bus  206 . Alternatively, a single processor system may be employed. Also connected to system bus  206  is memory controller/cache  208 , which provides an interface to local memory  209 . I/O bus bridge  210  is connected to system bus  206  and provides an interface to I/O bus  212 . Memory controller/cache  208  and I/O bus bridge  210  may be integrated as depicted.  
         [0020]    Peripheral component interconnect (PCI) bus bridge  214  connected to I/O bus  212  provides an interface to PCI local bus  216 . A number of modems may be connected to PCI bus  216 . Typical PCI bus implementations will support four PCI expansion slots or add-in connectors. Communications links to network computers  108 - 112  in FIG. 1 may be provided through modem  218  and network adapter  220  connected to PCI local bus  216  through add-in boards.  
         [0021]    Additional PCI bus bridges  222  and  224  provide interfaces for additional PCI buses  226  and  228 , from which additional modems or network adapters may be supported. In this manner, data processing system  200  allows connections to multiple network computers. A memory-mapped graphics adapter  230  and hard disk  232  may also be connected to I/O bus  212  as depicted, either directly or indirectly.  
         [0022]    Those of ordinary skill in the art will appreciate that the hardware depicted in FIG. 2 may vary. For example, other peripheral devices, such as optical disk drives and the like, also may be used in addition to or in place of the hardware depicted. The depicted example is not meant to imply architectural limitations with respect to the present invention.  
         [0023]    The data processing system depicted in FIG. 2 may be, for example, an eServer pSeries system, a product of International Business Machines Corporation in Armonk, N.Y., running the Advanced Interactive Executive (AIX) or Linux operating systems.  
         [0024]    With reference now to FIG. 3, a block diagram illustrating a data processing system is depicted in which the present invention may be implemented. Data processing system  300  is an example of a client computer. Data processing system  300  employs a peripheral component interconnect (PCI) local bus architecture. Although the depicted example employs a PCI bus, other bus architectures such as Accelerated Graphics Port (AGP) and Industry Standard Architecture (ISA) may be used. Processor  302  and main memory  304  are connected to PCI local bus  306  through PCI bridge  308 . PCI bridge  308  also may include an integrated memory controller and cache memory for processor  302 . Additional connections to PCI local bus  306  may be made through direct component interconnection or through add-in boards. In the depicted example, local area network (LAN) adapter  310 , SCSI host bus adapter  312 , and expansion bus interface  314  are connected to PCI local bus  306  by direct component connection. In contrast, audio adapter  316 , graphics adapter  318 , and audio/video adapter  319  are connected to PCI local bus  306  by add-in boards inserted into expansion slots. Expansion bus interface  314  provides a connection for a keyboard and mouse adapter  320 , modem  322 , and additional memory  324 . Small computer system interface (SCSI) host bus adapter  312  provides a connection for hard disk drive  326 , tape drive  328 , CD-ROM drive  330 , and DVD drive  332 . Typical PCI local bus implementations will support three or four PCI expansion slots or add-in connectors.  
         [0025]    An operating system runs on processor  302  and is used to coordinate and provide control of various components within data processing system  300  in FIG. 3. The operating system may be a commercially available operating system, such as Windows 2000, which is available from Microsoft Corporation. An object oriented programming system such as Java may run in conjunction with the operating system and provide calls to the operating system from Java programs or applications executing on data processing system  300 . “Java” is a trademark of Sun Microsystems, Inc. Instructions for the operating system, the object-oriented operating system, and applications or programs are located on storage devices, such as hard disk drive  326 , and may be loaded into main memory  304  for execution by processor  302 .  
         [0026]    Those of ordinary skill in the art will appreciate that the hardware in FIG. 3 may vary depending on the implementation. Other internal hardware or peripheral devices, such as flash ROM (or equivalent nonvolatile memory) or optical disk drives and the like, may be used in addition to or in place of the hardware depicted in FIG. 3. Also, the processes of the present invention may be applied to a multiprocessor data processing system.  
         [0027]    As another example, data processing system  300  may be a stand-alone system configured to be bootable without relying on some type of network communication interface, whether or not data processing system  300  comprises some type of network communication interface. As a further example, data processing system  300  may be a Personal Digital Assistant (PDA) device, which is configured with ROM and/or flash ROM in order to provide non-volatile memory for storing operating system files and/or user-generated data.  
         [0028]    The depicted example in FIG. 3 and above-described examples are not meant to imply architectural limitations. For example, data processing system  300  also may be a notebook computer or hand held computer in addition to taking the form of a PDA. Data processing system  300  also may be a kiosk or a Web appliance.  
         [0029]    The present invention involves Quality of Service (QoS), which is the ability to define and measure a level of performance in a data communication system; in the present context, the time taken to fulfill requests for data. The present invention can be implemented using three separate methods for solving the service time problem. However, these methods have significant overlap in how they work, and more than one method might be needed to accommodate various customer scenarios. The three methods have the following configurations:  
         [0030]    1. QoS monitoring is handled by a single QoS reverse proxy.  
         [0031]    2. QoS monitoring is handled by several “transaction agents” and redirected through the QoS reverse proxy.  
         [0032]    3. QoS monitoring is handled by several “transaction agents” and collected by the QoS controller.  
         [0033]    All three of these methods take advantage of the cookie present in each request originating from an instrumented container page; that is, a page containing the QoS JavaScript agent. The cookie is data stored on a client computer and used by web sites to keep track of a user&#39;s patterns and preferences. The cookie is a key that can be used to impose the notion of a session on a series of otherwise disparate requests. Each method creates a table of key/value pairs, where the key is the cookie inserted into the Hypertext Transport Protocol (HTTP) request header and the value is the time stamp signifying when the service time for a given Uniform Resource Identifier (URI) is complete.  
         [0034]    The prior art QoS technology can provide individual times on each element as long as all of the requests are obtained from the same web server. However, this is not the typical case for retrieving a web page. In a distributed environment, it is not reasonable to assume that the web server that responded to the request for the container page is the same web server that will be asked to deliver all, or even any, of the inline elements of the page. Even if the QoS that serviced the original request (container page) received a new request for one of the inline members of the container page, it has no mechanism for recognizing the new request as a member of the original request.  
         [0035]    The present invention produces a relationship between the original page and its inline elements through session IDs, sampling periods, and/or deployment strategies. The mathematical algorithm for the present invention is as follows:  
         [0036]    For each request with ID &lt;id num&gt; 
         [0037]    start time=min(all request times)  
         [0038]    stop time=max(all response times)  
         [0039]    (Note: the start time will be the container page.)  
         [0040]    The goal is for QoS to be able to recognize all of the members of the request and produce a metric that states “the total time for the parent request and all of its inline content to be save was ‘x’”.  
         [0041]    Referring to FIG. 4, a flowchart illustrating a general transaction association mechanism is depicted in accordance with the present invention. When the request for the container page is received, the QoS reverse proxy will mark the T1 value for the request (step  401 ) and forward the request to the origin server for processing (step  402 ). The T1 value is inserted as part of the Javascript agent that gets sent in the container page stream. This keeps the system stateless. The present invention does not depend on the same QoS that instrumented the response page being the QoS that receives the Javascript agent request from the client. Upon receiving the response stream from the origin server (step  403 ), the reverse proxy will instrument a valid response stream with the JavaScript agent and respond to the original client request with this instrumented response stream (step  404 ). The instrumentation contains the original T1 value as well as the service time taken for the container page. As the page is received at the client, the browser parses the page and issues a request for each of the URIs that make up the presentation of the page, which are generally the images contained on the page (step  405 ). As each request is received by the QoS agent, i.e. either the reverse proxy or some other agent (such as a web server plug-in), the agent searches for the JavaScript-inserted cookie in the request headers and creates a new table entry using the value of this cookie as the key in the table, if the key does not already exist (step  406 ). The QoS agent then forwards the request to the origin server (step  407 ). When the origin server responds with the resource (step  408 ), the QoS agent marks the time of the response T2, updates the table entry value with this time stamp, and responds to the requesting client (step  409 ). This is possible because the child process, or thread, that received the client request will also receive the origin server response. The web browser on the client will run the Javascript agent which will make the request. When the QoS agent receives the JavaScript-generated request that contains the transaction record, the agent retrieves the cookie from the request headers, searches the table for this key, and retrieves the time value from the entry. The difference between this value and the T1 value of the transaction record is the service time for the transaction.  
         [0042]    None of the methods of the present invention require the current data upload or event semantics to change. The records produced by the QoS monitor are uploaded after processing, and any events that occur are forwarded using the event notification system.  
         [0043]    Collecting service times on all transactions may incur an unacceptable overhead. Therefore, all of the methods in the present invention will support the notion of service time sampling. In order to support sampling, two new commands will need to be added to the QoS controller. These are the “sample_on” and “sample_off” commands. When the sample_on command is issued, the QoS monitor will begin to collect service time metrics on all of the URIs that pass through the QoS agent. When the controller issues the sample_off command, the QoS agent will cease collecting service time metrics and make the collected data available for processing. Like other QoS commands, these commands will be issued using HyperText Transport Protocol Secure (HTTPS). However, HTTP may be used as well.  
         [0044]    When the data is sampled, a unique identifier will be added to the service time key/value pair in the transaction record, to differentiate it from the container-page-only service time metric. In this embodiment, the sampling rate is configured during task creation. The configuration may include a URI specification stage so that only certain URIs will be sampled.  
         [0045]    The first method addresses the customer scenario for QoS where the QoS reverse proxy handles all of the requests that make up a transaction. This includes the container page and all of the referenced resources in the container page. This is the simplest scenario. The service time metrics are collected according to the heuristic described above, and the data ends up as the Service Time (ST) value in the transaction record produced by the QoS reverse proxy. FIG. 4 has described a situation in which only one element within a container page is being retrieved. However, in actual application, the process flow in FIG. 4 can be used to retrieve multiple inline elements.  
         [0046]    Referring now to FIG. 5, a flowchart illustrating transaction association using multiple servers is depicted in accordance with the present invention. This represents the second method for implementing the present invention and involves reassembling the transaction from multiple sources. Once again, the cookies generated by the JavaScript agent are used to group the transaction components. As in the first method, a table of service times is created for each transaction component, with the cookie as the key. However, unlike the first method, a communication method is also needed between the QoS monitor and either other monitors or the web servers themselves. In addition, each web server of interest needs to have either a QoS reverse proxy working on its behalf or a plug-in that will recognize the commands, time stamp the service time requests, and make the results available to the controlling agent (a QoS monitor piece). It should be noted that creating a plug-in for the three major web servers (Apache, iplanet, and IIS) is not a significant obstacle.  
         [0047]    Whether the second method is performed using a series of QoS reverse proxies deployed in front of the machines of interest, or as a set of plug-ins integrated into the web servers, the method is similar. At “sample on” time, the QoS controller sends a command to each of the participating “listeners” (step  501 ). A listener is any QoS agent such as a reverse proxy or a web server plug-in. During the sampling period, the QoS reverse proxies create table entries for all key/value pairs and collect service time metrics (as in FIG. 4) for the transactions (step  502 ). In the preferred embodiment, the table is a shared memory table. Therefore, each child thread or process in a QoS agent can access and add new entries to the table. Those skilled in the art will appreciate that other methods of assembling the QoS data are possible. When the controller sends the sample_off command to end the sample period (step  503 ), each listener responds to the controller with the contents of the table created during this period (step  504 ). This is possible through the HTTP request/response mechanism. In this method, the controller is responsible for creating the association between the records and the service time. This requires that the records maintained by the QoS agents (for controller retrieval) contain the cookie value so that the service time analysis can take place at the controller. The records are analyzed and reformed by the controller prior to uploading the data to the management server (step  505 ). If there are no service time metrics available from the sampling period for a record, that record is unaltered and the service time it contains represents the service time of the container page only.  
         [0048]    Referring to FIG. 6, a flowchart illustrating QoS management using the third method, which is a hybrid of the first and second methods, is depicted in accordance with the present invention. At “sample on” time, the QoS controller sends a command to each of the participating listeners (step  601 ). Once the sampling has begun, all requests during the sampling period are redirected to the QoS reverse proxy (step  602 ). The redirected requests are then sent by the QoS reverse proxy to their intended destination (step  603 ). There is no time stamping of redirects because they do not explicitly return a container page. Therefore, they are left out of the timing. A header is added to this redirection to inform the recipient to process the request, thereby preventing an infinite loop. As the reverse proxy receives each response, it updates the table with the service time metrics (as in FIG. 4) (step  604 ). When the sample_off command is issued by the QoS controller (step  605 ), the QoS reverse proxy creates the transaction records with the service time data (step  606 ).  
         [0049]    The QoS reverse proxies are typically deployed on the same machine as the actual web server on which behalf they work. However, they can also sit on their own machine and work on behalf of one or more web servers. The QoS boxes are deployed inside the same firewall parameters as the web server(s) for which they act as reverse proxies. In geographical terms, they are very close to the actual web server.  
         [0050]    It is important to note that while the present invention has been described in the context of a fully functioning data processing system, those of ordinary skill in the art will appreciate that the processes of the present invention are capable of being distributed in the form of a computer readable medium of instructions and a variety of forms and that the present invention applies equally regardless of the particular type of signal bearing media actually used to carry out the distribution. Examples of computer readable media include recordable-type media, such as a floppy disk, a hard disk drive, a RAM, CD-ROMs, DVD-ROMs, and transmission-type media, such as digital and analog communications links, wired or wireless communications links using transmission forms, such as, for example, radio frequency and light wave transmissions. The computer readable media may take the form of coded formats that are decoded for actual use in a particular data processing system.  
         [0051]    The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention, the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.