Internet Engineering Task Force G. Bertrand, Ed. Internet-Draft E. Stephan Intended status: Informational France Telecom - Orange Expires: February 11, 2013 R. Peterkofsky Skytide, Inc. August 10, 2012 CDNI Logging Interface draft-bertrand-cdni-logging-01 Abstract This memo specifies the Logging interface between a downstream CDN (dCDN) and an upstream CDN (uCDN). It introduces a framework, an architecture design and a set of new requirements. Then it drafts an information model. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on February 11, 2013. Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as Bertrand, et al. Expires February 11, 2013 [Page 1] Internet-Draft CDNI Logging August 2012 described in the Simplified BSD License. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 1.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 5 2. Logging Framework and Architecture . . . . . . . . . . . . . . 6 3. Additional Requirements . . . . . . . . . . . . . . . . . . . 10 4. Rationale for Logging Interface . . . . . . . . . . . . . . . 10 4.1. Usages of CDNI Logging Information . . . . . . . . . . . . 10 4.1.1. Maintenance/Debugging . . . . . . . . . . . . . . . . 10 4.1.2. Accounting . . . . . . . . . . . . . . . . . . . . . . 11 4.1.3. End-User Experience Management . . . . . . . . . . . . 11 4.1.4. Security . . . . . . . . . . . . . . . . . . . . . . . 11 4.1.5. Legal Logging Duties . . . . . . . . . . . . . . . . . 11 4.2. Logging Information Views . . . . . . . . . . . . . . . . 11 4.3. Information Extracted From Logging Data . . . . . . . . . 12 5. Log Information Elements . . . . . . . . . . . . . . . . . . . 13 5.1. Information Elements . . . . . . . . . . . . . . . . . . . 13 5.2. Logging Record Information Elements for Content Delivery . . . . . . . . . . . . . . . . . . . . . . . . . 16 5.3. Logging Record Information Elements for . . . . . . . . . 17 5.4. Logging Record Information Elements for Other Operations . . . . . . . . . . . . . . . . . . . . . . . . 17 6. Core Logging Records . . . . . . . . . . . . . . . . . . . . . 18 6.1. Content Delivery . . . . . . . . . . . . . . . . . . . . . 18 6.2. Content Acquisition . . . . . . . . . . . . . . . . . . . 18 6.2.1. Logging Records Provided by dCDN to uCDN . . . . . . . 18 6.2.2. Logging Records Provided by uCDN to dCDN . . . . . . . 19 6.3. Content Invalidation and Purging . . . . . . . . . . . . . 19 6.4. Logging Extensibility . . . . . . . . . . . . . . . . . . 20 7. Default Logging Information Format . . . . . . . . . . . . . . 20 7.1. Logging Files . . . . . . . . . . . . . . . . . . . . . . 20 7.2. File Format . . . . . . . . . . . . . . . . . . . . . . . 20 Bertrand, et al. Expires February 11, 2013 [Page 2] Internet-Draft CDNI Logging August 2012 7.2.1. Headers . . . . . . . . . . . . . . . . . . . . . . . 21 7.2.2. Body (Logging Records) Format . . . . . . . . . . . . 21 7.2.3. Footer Format . . . . . . . . . . . . . . . . . . . . 22 8. Logging Format and Scope Negotiation . . . . . . . . . . . . . 22 9. Logging Information Transport . . . . . . . . . . . . . . . . 22 9.1. Major Requirements on Logging Protocols . . . . . . . . . 23 9.2. Recommended Logging Protocol for Non Real-Time Logging . . 23 9.3. Recommended Logging Protocol for Real-Time Logging . . . . 24 10. Logging Process . . . . . . . . . . . . . . . . . . . . . . . 24 10.1. Logging Aggregation . . . . . . . . . . . . . . . . . . . 24 10.2. Logging Filtering . . . . . . . . . . . . . . . . . . . . 25 10.3. Logging Update and Rectification . . . . . . . . . . . . . 26 11. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 26 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 13. Security Considerations . . . . . . . . . . . . . . . . . . . 27 13.1. Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 27 13.2. Non Repudiation . . . . . . . . . . . . . . . . . . . . . 27 14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 27 15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 28 15.1. Normative References . . . . . . . . . . . . . . . . . . . 28 15.2. Informative References . . . . . . . . . . . . . . . . . . 28 Appendix A. Examples Log Format . . . . . . . . . . . . . . . . . 29 A.1. W3C Common Log File (CLF) Format . . . . . . . . . . . . . 29 A.2. W3C Extended Log File (ELF) Format . . . . . . . . . . . . 30 A.3. National Center for Supercomputing Applications (NCSA) Common Log Format . . . . . . . . . . . . . . . . . . . . 32 A.4. NCSA Combined Log Format . . . . . . . . . . . . . . . . . 32 A.5. NCSA Separate Log Format . . . . . . . . . . . . . . . . . 32 A.6. Squid 2.0 Native Log Format for Access Logs . . . . . . . 32 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 33 Bertrand, et al. Expires February 11, 2013 [Page 3] Internet-Draft CDNI Logging August 2012 1. Introduction This memo specifies the Logging interface between a downstream CDN (dCDN) and an upstream CDN (uCDN). It introduces a framework, an architecture design and a set of new requirements. Then it drafts an information model. The reader should be familiar with the work of the CDNI WG: o CDNI problem statement [I-D.ietf-cdni-problem-statement] and framework [I-D.ietf-cdni-framework] identify a Logging interface, o Section 7 of [I-D.ietf-cdni-requirements] specifies a set of requirements for Logging, o [I-D.ietf-cdni-use-cases] outlines real world use-cases for interconnecting CDNs. These use cases require the exchange of Logging information between the dCDN and the uCDN. o [I-D.lefaucheur-cdni-logging-delivery] complements the present memo by proposing CDNI Logging formats for content deliveries performed using HTTP or HTTP adaptive streaming. The present document describes: o The Logging framework and architecture (Section 2), o The requirements (Section 3), o Discussion on the monitoring and the reporting use cases (Section 4) o Log information (Section 5 and Section 6), 1.1. Terminology In this document, the first letter of each CDNI-specific term is capitalized. We adopt the terminology described in [I-D.ietf-cdni-problem-statement] and [I-D.ietf-cdni-framework], and extend it with the additional terms defined below. For clarity, we use the word "Log" only for referring to internal CDN logs and we use the word "Logging" for any inter-CDN information exchange and processing operations related to CDNI Logging interface. Log and Logging formats may be different. Log: CDN internal information collection and processing operations. Bertrand, et al. Expires February 11, 2013 [Page 4] Internet-Draft CDNI Logging August 2012 Logging: Inter-CDN information exchange and processing operations. Fragmented object: [Ed. Note: Tentative of a simple definition which fits with the current CDNI charter] Fragmented objects are pieces of content provided by a CSP which are delivered individually through a CDN interconnection. They differ from a simple object because the delivery of the content to one user agent may be provided by more than one Surrogate/CDN. CDN Reporting: the process of providing the relevant information that will be used to create a formatted content delivery report provided to the CSP in differed time. Such information typically includes aggregated data that can cover a large period of time (e.g., from hours to several months). One of the usages of reporting is the collection of charging data related to CDN services and the computation of Key Performance Indicators (KPIs). CDN Monitoring: the process of providing content delivery information in real-time. The monitoring typically includes data in real time to provide a vision of the deliveries in progress, for service operation purposes. It presents a view of the global health of the services as well as information on usage and performance, for network services supervision and operation management. In particular, monitoring data can be used to generate alarms. End-User experience management: study of Logging data using statistical analysis to discover, understand, and predict user behavior patterns. Delivery Service: a specific instantiation of content delivery service configuration. For instance, a given uCDN (uCDN1) may request a given dCDN (dCDN1) to configure a Delivery Service for handling requests for HTTP Adaptive streaming videos delegated by uCDN1 and related to a specific CSP (CSP1), and another one for handling request for static pictures delegated by uCDN1 and related to CSP1. In this simple example, uCDN1 may request dCDN1 to include delivery service information in its CDNI Logging, to help uCDN provide relevant reports to CSP1. 1.2. Abbreviations o API: Application Programming Interface o CCID: Content Collection Identifier o CDN: Content Delivery Network Bertrand, et al. Expires February 11, 2013 [Page 5] Internet-Draft CDNI Logging August 2012 o CDNP: Content Delivery Network Provider o CoDR: Content Delivery Record o CSP: Content Service Provider o DASH: Dynamic Adaptive Streaming over HTTP o dCDN: downstream CDN o FTP: File Transfer Protocol o HAS: HTTP Adaptive Streaming o KPI: Key Performance Indicator o PVR: Personal Video Recorder o SID: Session Identifier o SFTP: SSH File Transfer Protocol o SNMP: Simple Network Management Protocol o uCDN: upstream CDN 2. Logging Framework and Architecture The framework of the Logging interface is straightforward: dCDN logs any information related to the completion of any task performed by a dCDN on behalf of an uCDN and any exchange related to the management of the contents that the said dCDN delivers on behalf of an uCDN, as discussed in Section 6.1. Logging is a mandatory feature for a CDN, especially if the CDN is interconnected to other CDNs. Logging provides the raw material for some essential operations of a delivery service, such as monitoring, reporting, billing, etc. As stated in [I-D.ietf-cdni-problem-statement], "the CDNI Logging interface enables details of logs or events to be exchanged between interconnected CDNs". Figure 1 provides an example of Logging information exchanges. uCDN is connected to dCDN-1 and dCDN-2. Both dCDN-1, dCDN-2, and uCDN deliver content for CSP. The Logging interface enables the uCDN to obtain Logging data from dCDN-1 and dCDN-2. In the example, uCDN Bertrand, et al. Expires February 11, 2013 [Page 6] Internet-Draft CDNI Logging August 2012 uses the Logging data: o to analyze the performance of the delivery operated by the dCDNs and to adjust its operations (e.g., request routing) as appropriate, o to provide reporting (non real-time) and monitoring (real-time) information to CSP. For instance, uCDN merges Logging data, extracts relevant KPIs, and presents a formatted report to CSP, in addition to a bill for the content delivered. uCDN may also provide Logging data as raw log files to CSP, so that CSP uses its own Logging analysis tools. +-----+ | CSP | +-----+ ^ Reporting and monitoring data | Billing ,--,--. Logging ,-' `-. Logging Data ( uCDN ) Data ....> `-. _,-'<.... | `-'-'-' | ,--v--. ^ ^ ,--v--. ,-' `-. | | ,-' `-. ( dCDN-1 )<--+ +-->( dCDN-2 ) Logging `-. ,-' Logging `-. _,-'<...Data `--'--' Tuning `--'-' | ^ ,--|--. Logging | ,' `-. Tuning + -->( dCDN-3 ) `. ,-' `--'--' Figure 1: Exchange of Logging Information A dCDN integrates the logging of its downstream CDNs in the Logging that it provides to the uCDN, as required by [I-D.ietf-cdni-requirements] (LOG-3). Figure 1 represents bi-directional arrows between dCDN and uCDN for the exchange of Logging data, because even if the common case involves the uCDN retrieving Logging data on the dCDN, the reverse case where the dCDN retrieves Logging data (e.g., related to dCDN's content acquisition requests to the uCDN) on the uCDN is also Bertrand, et al. Expires February 11, 2013 [Page 7] Internet-Draft CDNI Logging August 2012 possible. Note that the format of Logging data that the dCDN provides might be different from the one that the dCDN uses internally. In this case, the dCDN needs to reformat the Logging data before it provides this data to the uCDN. Similarly, an uCDN might reformat the Logging data that it receives before providing it to the CSP or to its uCDN. Such reformatting operations are time consuming (delays in the Logging chain) and introduce a processing burden. Therefore, it is recommended that the CDNI Logging format be as close as possible from the most common CDN Log formats. Figure 2 presents the Logging Architecture. More details on the Logging operations are provided in Section 10. A dCDN prepares the Logging data requested by the uCDN. This preparation involves operations such as filtering, aggregating, anonymizing, and summarizing the logs. The uCDN downloads the corresponding Logging Records and performs its own reporting for the CSP. Bertrand, et al. Expires February 11, 2013 [Page 8] Internet-Draft CDNI Logging August 2012 +------+ | CSP | +------+ ^ ^ Reporting, Monitoring, Billing ^ ---^--------------------- Logging Record ------------------------- / ^ Upstream CDN \ selection / Downstream CDN \ |+-----+ +-------------+ | and format nego. | +-------------+ +-----+| || |**| Control | |<---------------->| | Control |**| || || | +-------------+ | | +-------------+ | I || || I | | | | n || || n | +-------------+ | | +-------------+ | t || || t |<<| Logging | | | | Logging |<<| e || || e | +-------------+ |<---------------->| +-------------+ | r || || r | | Logging Records | | c L || || c L | | | | o o || || o o | +-------------+ | | +-------------+ | n g || || n g |<<|Req-Routing | | | |Req-Routing |>>| n i || || n i | +-------------+ | | +-------------+ | e c || || e c | | | | c || || c | +-------------+ | | +-------------+ | t || || t |<<| Metadata | | | | Metadata |>>| i || || i | +-------------+ | | +-------------+ | o || || o | | | | n || || n | +-------------+ | | +-------------+ | || || |<<| Distribution| |******************| | Distribution|>>| || |+-----+ +-------------+ | Acquisition | +-------------+ +-----+| \ / \ . * / ------------------------- ---------.-*------------- . . * . Request . * Delivery . +--.-*--+ ..................Request............| User | | Agent | +-------+ Figure 2: Logging Architecture In Figure 2, the Logging Record selection and format negotiation occurs at Control Interface level, as these operations provide static information for initializing the Logging interface. Logging data captures information elements that may be available at various stages during the life-cycle of content distribution. The arrows (">>") in Figure 2 represent the direction of information elements in the Logging process. Bertrand, et al. Expires February 11, 2013 [Page 9] Internet-Draft CDNI Logging August 2012 3. Additional Requirements Section 7 of [I-D.ietf-cdni-requirements], already specifies a set of requirements for Logging (LOG-1 to LOG-16). Some security requirements also affect Logging (e.g., SEC-4). 4. Rationale for Logging Interface [I-D.ietf-cdni-framework] and [I-D.ietf-cdni-problem-statement] introduce the rationale for the Logging interface as a means for an uCDN to acquire some visibility on the contents the dCDN delivers on behalf of the uCDN. dCDN provides the uCDN with elements of information and Logging Records for operating the CDN interconnection and reporting to the CSP. This section develops use cases that require exchange of Logging information. 4.1. Usages of CDNI Logging Information This section presents the usage of the Logging Records by an uCDN. It does not make any assumption on where the Logging Records are produced. Logging Records may be produced either by the uCDN or a dCDN. 4.1.1. Maintenance/Debugging Logging is useful to permit the detection (and limit the risk) of content delivery failures. In particular, Logging facilitates the resolution of false configuration issues. To detect faults, Logging must enable the reporting of any CDN operation success and failure, such as request redirection, content acquisition, etc. The uCDN can summarize such information into KPIs. For instance, Logging format should allow the computation of the number of times during a given epoch, a content delivery related to a specific service succeeds/fails. Logging is useful to analyze the performance of content delivery services. This implies computing KPIs from the Logging data for service quality analysis and monitoring (see Section 4.3). Logging enables the CDN providers to evaluate the QoS level related to a specific delivery service. For instance, one aspect of this QoS level could be measured through the average delivery throughput experienced by End-Users in a given region for this specific service over a period of time. Logging enables the CDN providers to identify and troubleshoot Bertrand, et al. Expires February 11, 2013 [Page 10] Internet-Draft CDNI Logging August 2012 performance degradations. In particular, Logging enables the communication of traffic data (e.g., the amount of traffic that has been forwarded by a dCDN on behalf of an uCDN over a given period of time), which is particularly useful for CDN and network planning operations. 4.1.2. Accounting Logging is essential for accounting, to permit inter-CDN billing, and CSP billing by uCDN. For instance, Logging enables the uCDN to check the total amount of traffic delivered by every dCDN and for every delivery service, as well as, the associated bandwidth usage (e.g., peak, 95th percentile), and the maximum number of simultaneous sessions over a given period of time. 4.1.3. End-User Experience Management The goal of End-User experience management is to gather any relevant information to meter audience, analyze user behavior, etc. For instance, Logging enables the CDN providers to report on content consumption (e.g., delivered sessions per content) in a specific geographic area. 4.1.4. Security The goal of security is to prevent and monitor unauthorized access, misuse, modification, and denial of access of a service. A set of information is logged for security purposes. In particular, access to content is usually collected to permit the CSP to detect infringements of content delivery policies and other abnormal End- User behaviors. 4.1.5. Legal Logging Duties Depending on the country considered, the CDNs may have to retain specific Logging information during a legal retention period, to comply with judicial requisitions. 4.2. Logging Information Views Logging information is useful to the uCDN and potentially to the CSP. Different views of the Logging information may be provided depending on privacy, business, and scalability constraints. Some kind of information format adaptation capability may be supported by an uCDN to present some (e.g., filtered, aggregated) data in the appropriate format (raw log files, reports) to the CSP. More details on these operations are provided in Section 10. Bertrand, et al. Expires February 11, 2013 [Page 11] Internet-Draft CDNI Logging August 2012 We provide a non-exhaustive list and description of tools that can be fed with Logging information. o Tools used by the uCDN's operator: billing tools (information system), customer experience intelligence, reporting tools, security auditing tools, dimensioning tools, strategic planning and investment... o Tools used by CSPs: customer experience management tools, reporting tools, security auditing tools... 4.3. Information Extracted From Logging Data This section presents, for explanatory purposes, a non-exhaustive list of information that can be extracted/produced from logs. Depending on the inter-CDN agreement, this information may be computed by the uCDN or by the dCDN. Nevertheless, it is usually the uCDN that computes KPIs, because uCDN and dCDN may have different definitions of the KPIs and the computation of some KPIs requires a vision of all the deliveries performed by the uCDN and all its dCDNs. CSPs require specific information, such as KPIs, about the delivery of their content. The Logging data must contain appropriate information to enable CSPs or the uCDN to extract the required KPIs. In the present section, we list important examples of KPIs: o Number of delivery requests received from End-Users in a given region for each piece of content, during a given period of time (e.g., hour/day/week/month), o Percentage of delivery successes / failures among the aforementioned requests o Number of failures listed by failure type (e.g., HTTP error code) for requests received from End-Users in a given region and for each piece of content, during a given period of time (e.g., hour/ day/week/month), o Number and cause of delivery premature termination for End-Users in a given region and for each piece of content, during a given period of time (e.g., hour/day/week/month), o Maximum and mean number of simultaneous sessions established by End-Users in a given region, for a given delivery service, and during a given period of time (e.g., hour/day/week/month), o Volume of traffic delivered for sessions established by End-Users in a given region, for a given delivery service, and during a Bertrand, et al. Expires February 11, 2013 [Page 12] Internet-Draft CDNI Logging August 2012 given period of time (e.g., hour/day/week/month), o Maximum, mean, and minimum delivery throughput for sessions established by End-Users in a given region, for a given delivery service, and during a given period of time (e.g., hour/day/week/ month) o Cache-hit and byte-hit ratios for requests received from End-Users in a given region for each piece of content, during a given period of time (e.g., hour/day/week/month) o Top 10 of the most popular requested content (with time repartition into day/week/month), o Terminal type (mobile, PC, STB, if this information can be acquired from the browser type header, for example). Additional KPIs can be computed from other sources of information than the Logging, for instance, data collected by a content portal or by specific client-side APIs. Such KPIs are out of scope for the present memo. 5. Log Information Elements CDNI must specify a set of Logging information elements to avoid log format regeneration, which would affect the performance of the log handling chain. A common set of Logging information element eases the sharing of logs among the CDNs and the use of log processing tools, for instance, to prepare reporting. Existing CDNs Logging functions collect and consolidate logs performed by their Surrogates. Surrogates usually store the logs using a format derived from Web servers' and caching proxies' log standards such as W3C, NCSA [ELF] [CLF], or Squid format [squid]. In practice, these formats are adapted to cope with CDN specifics. Appendix A presents examples of commonly used log formats. 5.1. Information Elements This section describes a set of information elements that structure Logging information generated by the dCDN. The section does not prescribe a particular encoding (such as SNMP SMI or alternatives). All fields in the Logging information are optional unless stated otherwise. However, if a given CDN decides to support some of the Logging information fields, it must conform to the definition and format of this field specified in the present memo, to guarantee that interconnected CDNs share a common understanding of the Logging Bertrand, et al. Expires February 11, 2013 [Page 13] Internet-Draft CDNI Logging August 2012 semantic and syntax. +-------------+-----------------------------------------------------+ | Name | Description | +-------------+-----------------------------------------------------+ | Start-time | A start date and time associated with a logged | | | event; for instance, the time at which a Surrogate | | | received a content delivery request or the time at | | | which an origin server received a content | | | acquisition request. | | End-time | An end date and time associated with a logged | | | event. For instance, the time at which a Surrogate | | | completed the handling of a content delivery | | | request (e.g., end of delivery or error). | | Duration | The duration of an operation in milliseconds. For | | | instance, this field could be used to provide the | | | time it took to the Surrogate to send the requested | | | file to the End-User, or the time it took the | | | Surrogate to acquire the file on a cache-miss | | | event. | | Client-IP | The IP address of the User Agent that issued the | | | logged request (or of a proxy). | | Operation | The kind of operation that is logged; for instance, | | | Acquisition, Delivery, or Purging. | | URI_full | The full requested URL (e.g., | | | "http://node1.peer-a.op-b.net/cdn.csp.com/movies/po | | | tter.avi?param=11&user=toto"). When HTTP request | | | redirection is used, this URI includes the | | | Surrogate FQDN. If the association of requests to | | | Surrogates is confidential, the dCDN can present | | | only URI_part to uCDN. | | URI_part | The requested URL path (e.g., | | | /cdn.csp.com/movies/potter.avi?param=11&user=toto | | | if the full request URL was | | | "http://node1.peer-a.op-b.net/cdn.csp.com/movies/po | | | tter.avi?param=11&user=toto"). The URI without | | | host-name typically includes the "CDN domain" | | | (ex.cdn.csp.com) - cf. [I-D.ietf-cdni-framework]: | | | it enables the identification of the CSP service | | | agreed between the CSP and the CDNP operating the | | | uCDN. | | Protocol | The protocol and protocol version of the message | | | that triggered the Logging entry. | | Request-met | The protocol method of the request message that | | hod | triggered the Logging entry. | | Status | The protocol method of the reply message related to | | | the Logging entry | Bertrand, et al. Expires February 11, 2013 [Page 14] Internet-Draft CDNI Logging August 2012 | Bytes-Trans | The number of bytes at application-layer | | ferred | protocol-level (e.g., HTTP) of the reply message | | | related to the Logging entry. It includes the size | | | of the response headers. | | Bytes-recei | The number of bytes (headers + body) of the message | | ved | that triggered the Logging entry. | | Referrer | The value of the Referrer header in an HTTP | | | request. | | User-Agent | The value of the User Agent header in an HTTP | | | request. | | Cookie | The value of the Cookie header in an HTTP request. | | Record-dige | A digest of the Logging Record; it enables | | st | detecting corrupted Logging Records. | | CCID | A Content Collection IDentifier (CCID) eases the | | | correlation of several Logging Records related to a | | | Content Collection (e.g., a movie split in chunks). | | SID | A Session Identifier (SID) eases the correlation | | | (and aggregation) of several Logging Records | | | related to a session. The SID is especially | | | relevant for summarizing HAS Logging information | | | [I-D.brandenburg-cdni-has]. | +-------------+-----------------------------------------------------+ Table 1: Logging Record Information Elements NB: we define three fields related to the timing of logged operations: Start-time, End-time, and Duration. Only two of these three fields are required to obtain relevant timing information on the operation. Start-time is typically useful for human readers (e.g., while debugging), however, most servers log the operations End-time which correspond to the time of log record generation. Multiple header fields, in addition to User Agent and Referrer, could be reproduced in the Logging entries. Note that uCDN may want to filter Logging data by user (and not by IP address) to provide more relevant information to the CSP. In such case, a user may be identified as a combination of several pieces of information such as the client IP and User Agent or through the SID. The URI_full provides information on the Surrogate that provided the content. This information can be relevant, for instance, for Inter- Affiliates scenarios [I-D.ietf-cdni-use-cases]. However, in some cases it may be considered as confidential and the dCDN may provide URI_part instead. Table 2 illustrates the definition of the information elements. It provides examples using Apache log format strings [apache] when they Bertrand, et al. Expires February 11, 2013 [Page 15] Internet-Draft CDNI Logging August 2012 exist. The table is here for illustration and does not prescribe a specific encoding. +------------+------------------+-----------------------------------+ | Name | String | Example | +------------+------------------+-----------------------------------+ | Time | %t | [10/Oct/2000:13:55:36-0700] | | Duration | - | - | | Client-IP | - | - | | Operation | - | - | | URI_log | - | - | | Protocol | %H | HTTP/1.0 | | Request | %m | GET | | method | | | | Status | %>s | 200 | | Bytes | %O | 2326 | | transferre | | | | d | | | | Bytes | - | - | | received | | | | Header | \"%{Referrer}i\" | "http://www.example.com/start.htm | | | \"%{User-agent}i | l" "Mozilla/4.08 [en] (Win98; I | | | \" | ;Nav)" | +------------+------------------+-----------------------------------+ Table 2: Examples using Apache format 5.2. Logging Record Information Elements for Content Delivery Table 3 details specific Logging fields that dCDN may provide to uCDN and that are related to content delivery operations. +-------------------+-----------------------------------------------+ | Name | Definition | +-------------------+-----------------------------------------------+ | uCDN-ID | An element authenticating the operator of the | | | uCDN as the authority having delegated the | | | request to the dCDN. | | Delivering-CDN-ID | An identifier (e.g., an aggregation of an IP | | | address and a FQDN) of the Delivering CDN. | | | The Delivering-CDN-ID might be considered as | | | confidential by the dCDN. In such case, the | | | dCDN could either not provide this field to | | | the uCDN or overwrite the Delivering-CDN-ID | | | with its on identifier. | | End-User-IP | The IP address of the client making a content | | | delivery request (or of its proxy). | Bertrand, et al. Expires February 11, 2013 [Page 16] Internet-Draft CDNI Logging August 2012 | Cache-bytes | The number of body bytes served from caches. | | | This quantity permits the computation of the | | | byte hit ratio. | | Action | The Action describes how a given request was | | | treated locally: through which transport | | | protocol, with or without content | | | revalidation, with a cache hit or cache miss, | | | with fresh or stale content, and if relevant | | | with which error. Example with Squid format | | | [squid]: "TCP_REFRESH_FAIL_HIT" means that an | | | expired copy of an object requested through | | | TCP was in the cache. Squid attempted to | | | make an If-Modified-Since request, but it | | | failed. The old (stale) object was delivered | | | to the client. | +-------------------+-----------------------------------------------+ Table 3: Delivery Information Elements 5.3. Logging Record Information Elements for Table 4 details specific Logging fields that are related to content acquisition operations. [Ed. Note: split this section in two parts: logs provided by uCDN / logs provided by dCDN?] +------------+------------------------------------------------------+ | Name | Definition | +------------+------------------------------------------------------+ | dCDN | An element authenticating the operator of the dCDN | | identifier | as the authority requesting the content to the uCDN | +------------+------------------------------------------------------+ Table 4: Acquisition Information Elements These information elements may be used in Content Acquisition Logging provided by dCDN to uCDN and potentially in Content Acquisition Logging provided by uCDN to dCDN. 5.4. Logging Record Information Elements for Other Operations Logging can be used for debugging. Therefore, all kind of CDN operations might be logged, depending on the agreement between the dCDN and the uCDN. In particular, operations related to Request Routing, Metadata and Control interfaces can be logged. Bertrand, et al. Expires February 11, 2013 [Page 17] Internet-Draft CDNI Logging August 2012 6. Core Logging Records This section defines a set of central events that a dCDN should register and publish through the Logging interface. We classify the logged events depending on the CDN operation to which they relate: Content Delivery, Content Acquisition, Content Invalidation/Purging, etc. 6.1. Content Delivery Some CSPs pay a lot of attention to the protection of their content (e.g., premium video CSPs). To fulfill the needs of these CSPs, a CDN shall log all the details of the content delivery authorizations. This means that a dCDN must be able to provide Logging detailing the content delivery/content acquisition authorizations and denials as well as information on why the request is authorized/denied. CSPs and CDSP pay a lot of attention to errors related to content delivery. It is therefore of upmost importance that the dCDN provides detailed error information in the Logging data. This information should typically be available even when Logging is aggregated (cf. Section 10.1). The content delivery events triggering the generation of a Logging Record include: o Reception of a content request, The generated Logging Record typically embeds information about: o Denial of delivery (error or unauthorized request) for a request, o Beginning of delivery (authorization) of a requested content, o End of an authorized delivery (success), o End of an authorized delivery (failure). 6.2. Content Acquisition 6.2.1. Logging Records Provided by dCDN to uCDN When the uCDN requires the dCDN to provide Logging for acquisition related events, the events triggering the generation of a Logging Record include: Bertrand, et al. Expires February 11, 2013 [Page 18] Internet-Draft CDNI Logging August 2012 o Emission of a content acquisition request (first try or retry) for a cache hit or a cache miss with content revalidation The generated Logging Record typically embeds information about: o Reception of a reply indicating denial of delivery (error or unauthorized request) for a content acquisition request, o End of an authorized acquisition (success), o End of an authorized acquisition (failure) Note that a dCDN may acquire content only from the uCDN. It this case, the uCDN can log the dCDN's content acquisition operations itself, and thus, the uCDN may not require the dCDN to log acquisition related events (except for security or debugging reasons). 6.2.2. Logging Records Provided by uCDN to dCDN When the dCDN requires the uCDN to provide Logging for acquisition related events, the events triggering the generation of a Logging Record include: o Reception of a content acquisition request for the considered delivery service for a cache hit or a cache miss with content revalidation The generated Logging Record typically embeds information about: o Emission of a reply indicating denial of delivery (error or unauthorized request) for a content acquisition request, o End of an authorized acquisition (success), o End of an authorized acquisition (failure). 6.3. Content Invalidation and Purging When the uCDN requests a dCDN to log invalidation/purging events (e.g., for security), the events triggering the generation of a Logging Record include: o Reception of a content invalidation/purging request The generated Logging Record typically embeds information about: Bertrand, et al. Expires February 11, 2013 [Page 19] Internet-Draft CDNI Logging August 2012 o Denial of the invalidation/purging request (error or unauthorized request), o Beginning of invalidation/purging (authorization) for a given content purging request, o End of an authorized invalidation/purging (success), o End of an authorized invalidation/purging (failure). 6.4. Logging Extensibility Future usages might introduce the need for additional Logging fields. In addition, some use-cases such as an Inter-Affiliate Interconnection [I-D.ietf-cdni-use-cases], might take advantage of extended Logging exchanges. Therefore, it is important to permit CDNs to use additional Logging fields besides the standard ones, if they want. For instance, an "Account-name" identifying the contract enforced by the dCDN for a given request could be provided in extended fields. The required Logging Records may depend on the considered services. For instance, static file delivery (e.g., pictures) typically does not include any delivery restrictions. By contrast, video delivery typically implies strong content delivery restrictions, as explained in [I-D.ietf-cdni-use-cases], and Logging could include information about the enforcement of these restrictions. Therefore, to ease the support of varied services as well as of future services, the Logging interface should support optional Logging Records. 7. Default Logging Information Format Interconnected CDNs may support various Logging formats. However, they must support at least the default Logging format described here. 7.1. Logging Files [Ed. Note: How many files (one per type of Delivery Service (e.g., HTTP, WMP) and per type of Event (e.g., Errors, Delivery, Acquisition,...?)and what would be inside... These aspects will be detailed in future versions.] 7.2. File Format [Ed. note: The Logging file format is not necessarily independant of the selected transport protocol. The definition of the Logging file format should be carried out consistently with the candidate protocol Bertrand, et al. Expires February 11, 2013 [Page 20] Internet-Draft CDNI Logging August 2012 analysis for Logging transport. The present content of this section is therefore non definitive.] 7.2.1. Headers As initially proposed in [I-D.lefaucheur-cdni-logging-delivery], Logging files must include a header with the information described in Figure 3. +----------------+-------------------+------------------------------+ | Field | Description | Examples | +----------------+-------------------+------------------------------+ | Format | Identification of | standard_cdni_errors_http_v1 | | | CDNI Log format. | | | Fields | A description of | | | | the records format| | | | (list of fields). | | | Log-ID | Identifier | abcdef1234 | | | for the CDNI Log | | | | file (facilitates | | | | detection of | | | | duplicate Logs | | | | and tracking in | | | | case of | | | | aggregation). | | | Log-Timestamp | Time, in | [20/Feb/2012:00:29.510+0200] | | | milliseconds, the | | | | CDNI Log was | | | | generated. | | | Log-Origin | Identifier of the | cdn1.cdni.example.com | | | authority (e.g., | | | | dCDN or uCDN) | | | | providing the Log-| | | | -ging | | +----------------+-------------------+------------------------------+ Figure 3: Logging Headers 7.2.2. Body (Logging Records) Format [Ed. note: the W3C extended log format is a good base candidate to look at.] [Ed. Note: The format for Time is still to be agreed on. RFC 5322 (Section 3.3) format could be used or ISO 8601 formatted date and time in UTC (same format as proposed in Bertrand, et al. Expires February 11, 2013 [Page 21] Internet-Draft CDNI Logging August 2012 [draft-caulfield-cdni-metadata-core-00]). Also see RFC5424 Section 6.2.3.] [Ed. Note: Records used for real time information and non-real time information could use different formats.] 7.2.3. Footer Format As initially proposed in [I-D.lefaucheur-cdni-logging-delivery], Logging files must include a footer with the information described in Figure 4. +---------+----------------------------------------------+----------+ | Field | Description | Examples | +---------+----------------------------------------------+----------+ | Log | Digest of the complete Log (facilitates | | | Digest | detection of Log corruption) | | +---------+----------------------------------------------+----------+ Figure 4: Logging footers 8. Logging Format and Scope Negotiation [Ed. Note: Format should be negotiated per delivery service] [Ed. Note: uCDN shall be able to select the type of events that a dCDN should include in the Logging that the latter provides to the uCDN.] 9. Logging Information Transport As presented in [I-D.ietf-cdni-problem-statement], several protocols already exist that could potentially be used to exchange CDNI Logging between interconnected CDNs. The dCDN could publish non real-time Logging on a server where the uCDN would retrieve it using for example SSH File Transfer Protocol (SFTP). If the CDNs need to exchange real-time information through the Logging interface, they could potentially rely on Web APIs, Syslog, SNMP... The main criterion for selecting a Logging transport protocol is the time constraint for delivering the Logging. Therefore, the present section highlights the candidate protocols for real-time and non real-time Logging exchanges. Bertrand, et al. Expires February 11, 2013 [Page 22] Internet-Draft CDNI Logging August 2012 9.1. Major Requirements on Logging Protocols Logging data is sensitive as it provides the raw material for producing bills etc. Therefore, the protocol delivering the Logging data must be reliable to avoid information loss. In addition, the protocol must scale to support the transport of large amounts of Logging data. Finally, this protocol must comply with the requirements identified in [I-D.ietf-cdni-requirements]. CDNs need to trust Logging information, thus, they want to know: o who issued the Logging (authentication), and o if the Logging has been modified by a third party (integrity). This is extremely important, as the logs can provide a basis for accounting/billing. Logging also contains confidential data, and therefore, it should not be protected from eavesdropping. All these needs translate into security requirements on both the Logging data format and on the Logging protocol. [Ed. note: cf. requirements draft: "SEC-4 [MED] The CDNI solution should be able to ensure that the Downstream CDN cannot spoof a transaction log attempting to appear as if it corresponds to a request redirected by a given Upstream CDN when that request has not been redirected by this Upstream CDN. This ensures non-repudiation by the Upstream CDN of transaction logs generated by the Downstream CDN for deliveries performed by the Downstream CDN on behalf of the Upstream CDN."] 9.2. Recommended Logging Protocol for Non Real-Time Logging as explained in [I-D.ietf-cdni-problem-statement], "SNMP traps pose scalability concerns and SNMP does not support guaranteed delivery of Traps and therefore could result in log records being lost and the consequent CoDRs and billing records for that content delivery not being produced as well as that content delivery being invisible to any analytics platforms." [Ed. Note: timing constraints... cf LOG-6 offline vs. constrained time / on demand access to real-time logging information] [Ed. Note: in a later version, this memo will include an analysis of candidate protocols, based upon a set of (basic) requirements, such as reliable transport mode, preservation of the integrity of the Bertrand, et al. Expires February 11, 2013 [Page 23] Internet-Draft CDNI Logging August 2012 information conveyed by the protocol, etc.] The offline exchange of non real-time Logging could rely on several protocols. In particular, the dCDN could publish the Logging on a server where the uCDN would retrieve them using a secure protocol (yet to be identified). [Ed. note: event-triggered or periodic, why?] [Ed. note: Propose protocol and add call flow] 9.3. Recommended Logging Protocol for Real-Time Logging The uCDN must be able to retrieve real-time information via near real-time methods such as: Syslog, SNMP, or through APIs, for example. [Ed. note: dCDN does not just forward requests for real time logging. It should probably provide other (more complex?) information in real time about the ongoing sessions (e.g., for every active session : IP of the client, service, CDN name, content consumed (full URL), average bit rate, downloaded size, date of session start?) 10. Logging Process We walk through a "day in the life" of a CDN interconnection to present functions the two CDNs may require to exchange Logging information. This will serve to illustrate many of the functions that could be supported through CDNI Logging interface. We describe capabilities, such as log aggregation, anonymizing, and filtering, that might be added to CDNI in a later stage, to optimize Logging operations. 10.1. Logging Aggregation CDNs typically handle millions of records per day. The processing of these records to extract relevant monitoring and reporting information is expensive in terms of CPU and time. Therefore, as stated in [I-D.ietf-cdni-framework], "a design tradeoff in the Logging interface is the degree of aggregation or summarization of data." In particular, dCDNs must aggregate the logs of their elements (e.g., the Surrogates) to avoid both the complexity of distributing multiple log files to the uCDN and to avoid disclosing information about dCDN's internal topology. This aggregation alleviates the Logging processing burden for the uCDN. Bertrand, et al. Expires February 11, 2013 [Page 24] Internet-Draft CDNI Logging August 2012 Many situations also lead to the delivery of fragments of content (DASH, failure of delivery, partial delivery, PVR actions, etc.). A dCDN may not publish a Logging Record for each piece of content it delivers, because this can lead to unacceptably large logs. In particular, a Logging Record could provide aggregated information about the delivery of several content pieces. uCDN and dCDN must be able to agree on a level of granularity for the Logging Records. This problem is well described for the case of HTTP adaptive streaming in [I-D.ietf-cdni-framework] and [I-D.brandenburg-cdni-has]. In the current version of the draft, we identify the following options that may be considered for reducing the amount of Logging data. o Transmit only summaries, for instance, a summary may aggregate information of all deliveries that occur during a 5 minutes time slot or provide only Logging data related to content items that have been delivered at least a specific number of times. Note that such aggregation leads to an information loss. This may be problematic for some usages of Logging (e.g., debugging) and some information should always be present, for instance, information about content delivery errors (403,404,...). The use multiple levels of Logging granularity such as in Apache (debug, notice, etc.) may help in providing the most relevant amount of information depending on the intended Logging usage, without having to renegotiate the Logging format. o For HAS content, a way to compress logs with minimal information loss would be to merge all success 200 OK records Records related to the same level of video Quality into a single record with appropriate Start-time and End-time. The only information lost in this process would be the Start-time and End-time for every video chunk. o Losslessly compress the Logging data. o Agree on a Logging retention duration and optionally on a maximum size of the Logging data that the dCDN must keep. If this size is exceeded, the dCDN must alert the uCDN but may not keep more Logs for the considered time period. [Ed. Note: cite Syslog's concepts for aggregation ] 10.2. Logging Filtering The dCDN must be able to present only relevant information to the uCDN, to avoid unnecessary Logging processing load for the uCDN and Bertrand, et al. Expires February 11, 2013 [Page 25] Internet-Draft CDNI Logging August 2012 potentially to protect End-Users' privacy. Hence, the downstream CDN filters its logs, and passes the relevant records directly to each upstream CDN. This requires that the downstream CDN can recognize the set of log entries that relate to each upstream CDN, for instance thanks to the "uCDN identifier" information element Table 3. The dCDN must be able to filter some internal scope data such as information related to its internal alarms (security, failures, load, etc). In some use cases described in [I-D.ietf-cdni-use-cases], the interconnected CDNs do not want to disclose details on their internal topology. The dCDN must be able to filter confidential data on the dCDN's topology (number of servers, location, etc.). In particular, information about the requests served by every Surrogate is confidential. Therefore, the Logging information must be protected so that data such as Surrogates host-names is not disclosed to the uCDN. In the "Inter-Affiliates Interconnection" use case, this information may be disclosed to the uCDN because both the dCDN and the uCDN are operated by entities of the same group. 10.3. Logging Update and Rectification If Logging is generated periodically, it is important that the sessions that start in one Logging period and end in another are correctly reported. If they are reported in the starting period, then the Logging of this period will be available only after the end of the session, which delays the Logging generation. A Logging rectification / update mechanism could be useful to reach a good trade-off between the Logging generation delay and the Logging accuracy. Depending on the selected Logging protocol(s), such mechanism may be particularly invaluable for real time Logging, which must be provided rapidly and cannot wait for the end of operations in progress. 11. Open Issues The level of granularity of the date/time information must be specified (clock accuracy). When to log the end of a session when the End-User pauses a video display? [Ed. Note: check if all requirements are fulfilled by the proposed solution] Bertrand, et al. Expires February 11, 2013 [Page 26] Internet-Draft CDNI Logging August 2012 [Ed. note: (comment from Kevin) how are errors handled ? If the client gets handed a bunch of 403s and 404s, but still gets the content eventually, without triggering an event, are those still logged? For Bytes-Transferred, if there were aborted requests, do those get counted as well? Not all client behavior can be correlated with the simplified log.] 12. IANA Considerations This memo includes no request to IANA. 13. Security Considerations 13.1. Privacy CDNs have the opportunity to collect detailed information about the downloads performed by End-Users. The provision of this information to another CDN introduces End-Users privacy protection concerns. 13.2. Non Repudiation Logging provides the raw material for charging. It permits the dCDN to bill the uCDN for the content deliveries that the dCDN makes on behalf of the uCDN. It also permits the uCDN to bill the CSP for the content delivery service. Therefore, non-repudiation of Logging data is essential. Some of the security issues and requirements on Logging are highlighted in Section 9.1. 14. Acknowledgments The authors would like to thank Anne Marrec, Yannick Le Louedec, and Christian Jacquenet for detailed feedback on early versions of this document and for their input on existing Log formats. The authors would like also to thank Fabio Costa, Yvan Massot, Renaud Edel, and Joel Favier for their input and comments. Finally, they thank the contributors of the EU FP7 OCEAN project for valuable inputs. 15. References Bertrand, et al. Expires February 11, 2013 [Page 27] Internet-Draft CDNI Logging August 2012 15.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 15.2. Informative References [CLF] A. Luotonen, "The Common Log-file Format, W3C (work in progress)", 1995, . [ELF] Phillip M. Hallam-Baker and Brian Behlendorf, "Extended Log File Format, W3C (work in progress), WD-logfile- 960323", . [I-D.bertrand-cdni-experiments] Faucheur, F. and L. Peterson, "Content Distribution Network Interconnection (CDNI) Experiments", draft-bertrand-cdni-experiments-02 (work in progress), February 2012. [I-D.brandenburg-cdni-has] Brandenburg, R., Deventer, O., Faucheur, F., and K. Leung, "Models for adaptive-streaming-aware CDN Interconnection", draft-brandenburg-cdni-has-03 (work in progress), July 2012. [I-D.ietf-cdni-framework] Peterson, L. and B. Davie, "Framework for CDN Interconnection", draft-ietf-cdni-framework-01 (work in progress), July 2012. [I-D.ietf-cdni-problem-statement] Niven-Jenkins, B., Faucheur, F., and N. Bitar, "Content Distribution Network Interconnection (CDNI) Problem Statement", draft-ietf-cdni-problem-statement-08 (work in progress), June 2012. [I-D.ietf-cdni-requirements] Leung, K. and Y. Lee, "Content Distribution Network Interconnection (CDNI) Requirements", draft-ietf-cdni-requirements-03 (work in progress), June 2012. [I-D.ietf-cdni-use-cases] Bertrand, G., Emile, S., Burbridge, T., Eardley, P., Ma, K., and G. Watson, "Use Cases for Content Delivery Network Interconnection", draft-ietf-cdni-use-cases-10 (work in Bertrand, et al. Expires February 11, 2013 [Page 28] Internet-Draft CDNI Logging August 2012 progress), August 2012. [I-D.lefaucheur-cdni-logging-delivery] Faucheur, F., Viveganandhan, M., and K. Leung, "CDNI Logging Formats for HTTP and HTTP Adaptive Streaming Deliveries", draft-lefaucheur-cdni-logging-delivery-01 (work in progress), July 2012. [RFC3444] Pras, A. and J. Schoenwaelder, "On the Difference between Information Models and Data Models", RFC 3444, January 2003. [RFC3466] Day, M., Cain, B., Tomlinson, G., and P. Rzewski, "A Model for Content Internetworking (CDI)", RFC 3466, February 2003. [RFC3568] Barbir, A., Cain, B., Nair, R., and O. Spatscheck, "Known Content Network (CN) Request-Routing Mechanisms", RFC 3568, July 2003. [apache] "Apache 2.2 log files documentation", Feb. 2012, . [squid] "Squid Log-Format documentation", Feb. 2012, . Appendix A. Examples Log Format This section provides example of log formats implemented in existing CDNs, web servers, and caching proxies. Web servers (e.g., Apache) maintain at least one log file for logging accesses to content (the Access Log). They can typically be configured to log errors in a separate log file (the Error Log). The log formats can be specified in the server's configuration files. However, webmasters often use standard log formats to ease the log processing with available log analysis tools. A.1. W3C Common Log File (CLF) Format The Common Log File (CLF) format defined by the World Wide Web Consortium (W3C) working group is compatible with many log analysis tools and is supported by the main web servers (e.g., Apache) Access Logs. According to [CLF], the common log-file format is as follows: remotehost rfc931 authuser [date] "request" status bytes. Bertrand, et al. Expires February 11, 2013 [Page 29] Internet-Draft CDNI Logging August 2012 Example (from [apache]): 127.0.0.1 - frank [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326 The fields are defined as follows [CLF]: +------------+------------------------------------------------------+ | Element | Definition | +------------+------------------------------------------------------+ | remotehost | Remote hostname (or IP number if DNS hostname is not | | | available, or if DNSLookup is Off. | | rfc931 | The remote logname of the user. | | authuser | The username that the user employed to authenticate | | | himself. | | [date] | Date and time of the request. | | "request" | An exact copy of the request line that came from the | | | client. | | status | The status code of the HTTP reply returned to the | | | client. | | bytes | The content-length of the document transferred. | +------------+------------------------------------------------------+ Table 5: Information elements in CLF format A.2. W3C Extended Log File (ELF) Format The Extended Log File (ELF) format defined by W3C extends the CLF with new fields. This format is supported by Microsoft IIS 4.0 and 5.0. The supported fields are listed below [ELF]. Bertrand, et al. Expires February 11, 2013 [Page 30] Internet-Draft CDNI Logging August 2012 +------------+---------------------------------------------------+ | Element | Definition | +------------+---------------------------------------------------+ | date | Date at which transaction completed | | time | Time at which transaction completed | | time-taken | Time taken for transaction to complete in seconds | | bytes | bytes transferred | | cached | Records whether a cache hit occurred | | ip | IP address and port | | dns | DNS name | | status | Status code | | comment | Comment returned with status code | | method | Method | | uri | URI | | uri-stem | Stem portion alone of URI (omitting query) | | uri-query | Query portion alone of URI | +------------+---------------------------------------------------+ Table 6: Information elements in ELF format Some fields start with a prefix (e.g., "c-", "s-"), which explains which host (client/server/proxy) the field refers to. o Prefix Description o c- Client o s- Server o r- Remote o cs- Client to Server. o sc- Server to Client. o sr- Server to Remote Server (used by proxies) o rs- Remote Server to Server (used by proxies) Example: date time s-ip cs-method cs-uri-stem cs-uri-query s-port cs- username c-ip cs(User-Agent) sc-status sc-substatus sc-win32-status time-taken 2011-11-23 15:22:01 x.x.x.x GET /file 80 y.y.y.y Mozilla/ 5.0+(Windows;+U;+Windows+NT+6.1;+en-US;+rv:1.9.1.6)+Gecko/ 20091201+Firefox/3.5.6+GTB6 200 0 0 2137 Bertrand, et al. Expires February 11, 2013 [Page 31] Internet-Draft CDNI Logging August 2012 A.3. National Center for Supercomputing Applications (NCSA) Common Log Format This format for Access Logs offers the following fields: o host rfc931 date:time "request" statuscode bytes o x.x.x.x userfoo [10/Jan/2010:21:15:05 +0500] "GET /index.html HTTP/1.0" 200 1043 A.4. NCSA Combined Log Format The NCSA Combined log format is an extension of the NCSA Common log format with three (optional) additional fields: the referral field, the user_agent field, and the cookie field. o host rfc931 username date:time request statuscode bytes referrer user_agent cookie o Example: x.x.x.x - userfoo [21/Jan/2012:12:13:56 +0500] "GET /index.html HTTP/1.0" 200 1043 "http://www.example.com/" "Mozilla/ 4.05 [en] (WinNT; I)" "USERID=CustomerA;IMPID=01234" A.5. NCSA Separate Log Format The NCSA Separate log format refers to a log format in which the information gathered is separated into three separate files. This way, every entry in the Access Log (in the NCSA Common log format) is complemented with an entry in a Referral log and another one in an Agent log. These three entries can be correlated easily thanks to the date:time value. The format of the Referral log is as follows: o date:time referrer o Example: [21/Jan/2012:12:13:56 +0500] "http://www.example.com/index.html" The format of the Agent log is as follows: o date:time agent o [21/Jan/2012:12:13:56 +0500] "Microsoft Internet Explorer - 5.0" A.6. Squid 2.0 Native Log Format for Access Logs Squid [squid] is a popular piece of open-source software for transforming a Linux host into a caching proxy. Variations of Squid log format are supported by some CDNs. Bertrand, et al. Expires February 11, 2013 [Page 32] Internet-Draft CDNI Logging August 2012 Squid common access log format is as follow: time elapsed remotehost code/status bytes method URL rfc931 peerstatus/peerhost type. Squid also supports a more detailed native access log format: Timestamp Elapsed Client Action/Code Size Method URI Ident Hierarchy/ From Content According to Squid 2.0 documentation [squid], these fields are defined as follows: +-----------+-------------------------------------------------------+ | Element | Definition | +-----------+-------------------------------------------------------+ | time | Unix timestamp as UTC seconds with a millisecond | | | resolution. | | duration | The elapsed time in milliseconds the transaction | | | busied the cache. | | client | The client IP address. | | address | | | bytes | The size is the amount of data delivered to the | | | client, including headers. | | request | The request method to obtain an object. | | method | | | URL | The requested URL. | | rfc931 | may contain the ident lookups for the requesting | | | client (turned off by default) | | hierarchy | The hierarchy information provides information on how | | code | the request was handled (forwarding it to another | | | cache, or requesting the content to the Origin | | | Server). | | type | The content type of the object as seen in the HTTP | | | reply header. | +-----------+-------------------------------------------------------+ Table 7: Information elements in Squid format Squid also uses a "store log", which covers the objects currently kept on disk or removed ones, for debugging purposes typically. Bertrand, et al. Expires February 11, 2013 [Page 33] Internet-Draft CDNI Logging August 2012 Authors' Addresses Gilles Bertrand (editor) France Telecom - Orange 38-40 rue du General Leclerc Issy les Moulineaux, 92130 FR Phone: +33 1 45 29 89 46 Email: gilles.bertrand@orange.com Stephan Emile France Telecom - Orange 2 avenue Pierre Marzin Lannion F-22307 France Email: emile.stephan@orange.com Roy Peterkofsky Skytide, Inc. One Kaiser Plaza, Suite 785 Oakland CA 94612 USA Phone: +01 510 250 4284 Email: roy@skytide.com Bertrand, et al. Expires February 11, 2013 [Page 34]