Scoped referral statements

Methods, systems, and data structures for communicating object metadata are provided. A generic metadata container is presented that allows object metadata to be described in an extensible manner using protocol-neutral and platform-independent methodologies. A metadata scope refers to a dynamic universe of targets to which the included metadata statements correspond. Metadata properties provide a mechanism to describe the metadata itself, and metadata security can be used to ensure authentic metadata is sent and received. Mechanisms are also provided to allow refinement and replacement of metadata statements. The metadata container may be used to convey referral data to update routing tables in network nodes, and may also be used register referral statements and query a node for referral information.

FIELD OF THE INVENTION

The invention relates generally to computer networks and message routing over computer networks. More specifically, the invention relates to methods and systems for providing and updating routing information in an extensible manner.

BACKGROUND OF THE INVENTION

Currently, much of the utility of computer systems lies in their ability to communicate and share information with other computer systems. Information is typically passed between computer systems via computer networks. Computer networks are groups of computers interconnected by wires or wireless mechanisms such as infrared, radio, and other technologies. The Internet is a global network of many smaller computer networks connected to one another. There is no controlling central network, but rather several high level networks that are connected through network access points. A network access point is a computer hardware or software device (commonly a network router) that serves as a kind of translator between two different networks.

Web services, generally, refers to application-to-application communication over the Internet via programmatic interfaces. For example, a local application (e.g., Microsoft® Money) on a client computer may communicate with a server application on a remote computer to obtain stock ticker information. The two applications may communicate the requested ticker symbol and the corresponding results via one or more messages transmitted over the Internet, without opening or using a traditional Internet browser such as Internet Explorer®.

The advent of XML (eXtensible Markup Language) and other protocol-neutral communications mechanisms has made it easier for web services to be offered between computers residing on different networks, written in different languages, and/or using different operating systems, yet still communicate effectively in an interoperable manner. However, these protocol neutral mechanisms do not provide an extensible mechanism to describe and update local configuration determining the appropriate message path for a message intended for a specific web service.

Routing protocols such as the Routing Information Protocol (RIP) and Interior Gateway Routing Protocol (IGRP) provide router table update mechanisms. However, these protocols are not compatible for use with web services, e.g., using Simple Object Access Protocol (SOAP). In addition, RIP and IGRP are distance-based routing protocols that always route data based on a calculated shortest distance. RIP and IGRP are concerned with how to route a message at the IP layer, not how to update routing information in a router for use by an application at the application layer. Protocols such as BGP and EGP also are primarily directed to how to route messages, not how to update information in routing tables.

Another known routing protocol, Open Shortest Path First (OSPF), is a link-state routing protocol, which bases changes on the status and speeds of the physical links of the networked routers, and propagates the changes to every router on the network. When first initialized (e.g., powered on), an OSPF router uses a protocol termed a “hello protocol” to discover neighbors to which the router is connected. The router then exchanges link-state information with these routers. Using the link-state information, each router creates a database that includes of every interface, its corresponding neighbor and a metric representing the speed of that interface. Each router then passes this information along to all neighboring routers. The process is repeated in turn until every router in the network receives link state information for every other router in the network. Each router builds a tree indicating a path to every node on the network, using itself as the root. The tree is then used to create a routing table, which the router then uses to route messages in the network. OSPF, however, does not provide for updating routing tables with routing information other than that corresponding to a directly linked interface or router, nor does it provide for updating with information other than link-state information. Other limitations as with RIP and IGRP, described above, also apply to OSPF.

Thus, it would be an advancement in the art to provide a mechanism for describing exchange and deployment of message path configuration information in an extensible manner. It would be a further advancement in the art to allow message path configuration information to refer to multiple resources simultaneously. It would be a further advancement in the art to provide a message path configuration information mechanism that allows routing metadata statements to be refined by subsequent message path configuration information statements. It would be a further advancement in the art to provide a routing table update protocol that is compatible with platform-independent web services.

BRIEF SUMMARY OF THE INVENTION

The inventive method and system overcome the problems of the prior art by providing a message path configuration information container that defines a scope of resources to which the message path configuration information applies. The generic metadata container can be used to provide statements describing objects, as well as to refine previously made metadata statements, such as statement providing referral information for a message router. That is, the scope may refer to a range of message destinations, and the metadata statement may include a referral statement providing new routing information for the scoped range of original destinations. Using scoped referral metadata statements, a network node can delegate a portion of its own address space, or request that another node delegate a portion of its address space, to a different network node.

DETAILED DESCRIPTION OF THE INVENTION

According to one or more aspects of the invention, metadata is described using any protocol neutral communications mechanism, e.g., extensible Markup Language (XML), as further described below.FIG. 2illustrates an example of a suitable computing system environment100on which the invention may be implemented in whole or in part. The computing system environment100is only one example of a suitable computing environment and is not intended to suggest any limitation as to the scope of use or functionality of the invention. Neither should the computing environment100be interpreted as having any dependency or requirement relating to any one or combination of components illustrated in the exemplary operating environment100.

FIG. 3illustrates a block relational diagram of an object and corresponding metadata. Broadly, an object301is described by various metadata elements303,305,307,309,311. Each metadata element describes some aspect of object301. Object301may be any computer or network object, such as a file, URL, URI, address, directory, web service, router, server, etc. Metadata elements303,305,307,309,311are used to describe features corresponding to object301. Object301may alternatively be a conventional, non-computer object, such as a computer user (i.e., a person). Object301may alternatively be referred to herein as a resource or network resource.

For example, a web service301may be described by various metadata elements303,305,307,309,311. Each metadata element may be communicated by the web service object301(or by a web service description service) to a requestor (not shown) to indicate how the requestor can communicate with the web service to receive information provided by the web service. Alternatively, object metadata might not be used by a requester, but instead may be used by the web service itself upon receipt from an authorized provider (e.g., providing updated policy metadata, access control metadata, etc.).

Suppose web service object301is a mailbox web service. Metadata element303may describe communication policies of web service301, such as by indicating that web service301requires a Microsoft Passport ID, messages must be encrypted using triple-DES encryption, messages cannot exceed 1 MB in size, etc. Metadata element305may describe message routing information specific to the web service, e.g., indicating that messages intended for web service object301should be sent to a specified address or through a specified router or routers, as further described below.

Metadata element307may describe access information. That is, metadata may be used to describe who is authorized to access web service301, such as only those users whose account is paid up to date. Access metadata may also include an access control list (ACL) defining who can access the mailbox web service. Metadata element309may describe transaction coordination information for communicating with web service301, such as by indicating a transaction coordinator for web service301, and/or other transaction information as described in copending application Ser. No. 10/211,299, filed Aug. 5, 2002, entitled “Coordinating Transactional Web Services.”

Metadata element311may describe custom features specific to web service object301, such as mailbox services provided (supported addresses, mail formats, mail protocols, confirmation of delivery, etc.), requirements for various services, and the like.

FIG. 4illustrates a block diagram of a generic metadata element according to an illustrative aspect of the invention. Metedata element401may include a scope403, one or more properties405, one or more statements407, and security information409.

Scope403indicates an arbitrary universe of targets (i.e., the object or objects) to which metadata element401corresponds. For example, scope403may include a URI (http://www.Microsoft.com/), indicating that metadata element401describes any web page or web service located under that URI. Scope403may include a portion of a directory hierarchy (e.g., c:\root\users\jdoe\), indicating that metadata element401describes all files located at or below the specified subdirectory. Scope403can also refer to users or user identities, e.g., *@xyz.com, jdoe@xyz.com, “John Doe”, etc. Scope403may also refer to a user based on biometric information, e.g., by including a digital representation of biometric information specific to the user, such as a fingerprint, thus indicating that the metadata element401describes the user with the fingerprint to which the digital biometric information corresponds.

Scope403may describe multiple objects using lists, ranges, or any known object description technique, and may describe the universe of targets in an additive (John Doe, but no one else) or subtractive (everyone but John Doe) manner, using declarative (scope =“John Doe”), programmatic (scope=run this Java applet), extensional (scope=John, Bill, Mary) and/or intesional (e.g., scope=The Jones Family, scope=John's mother's dog) descriptors. Scope403may describe the scope using arbitrarily complex relationships. Using the generic scope container, metadata element401can refer to virtually any object. For example, scope can refer to messages of a specified form, and further based on whether the current location is an intermediary node in a network or a terminal node of a data message. Scope403can also depend on whether messages are being sent from a location or to a location, and messages that contain specific information (e.g., the word “banana” in the message body). Scope can refer to messages that have been authenticated, and even to messages that have been authenticated using a specified technology (e.g., X509) or service (e.g., VeriSign), security token of a specific format as well as authority, strength of authentication, biometric data, smart card, or the like. Scope can also refer to the message in which the scope is being communicated (e.g., by message ID). One of skill in the art will appreciate that scope403can refer to any universe of targets that can be positively identified based on the data stored in scope403.

Properties405describe properties of metadata element401. That is, properties405may be thought of as metadata describing metadata element401, such as name, author, expiration date/time, etc., of metadata element401.

Each statement407provides some substantive metadata included in metadata element401. Statements may be affirmatively recited (e.g., Max_Msg_Len=1024) or included by reference (e.g., Include IDREF=“xx”), where the IDREF indicates a file or other object storing one or more metadata statements. Inclusion by reference may be used, for example, when multiple metadata elements need to ensure that identical statements are used. One of skill in the art will appreciate that any external reference may be used to include metadata statements, such as a URI, etc., and also that inclusion by reference may also be used for scope, properties, and security elements.

Security409describes security semantics and/or authentication measures to be applied to metadata element401. For example, security409may include a digital signature to ensure that the metadata comes from a source authorized to promulgate the included or referenced metadata statements. One of skill in the art will appreciate that multiple scope, properties, statement, and/or security elements may be included in metadata element401as necessary, e.g., to include a scope with two mutually exclusive ranges making up the universe of targets. In addition, scopes, properties, statements, and security information may all be described using arbitrarily complex relationships using any combination of logical operands.

The generic metadata element401may be described in any protocol-neutral or platform-independent description language, such as XML, Java (or other Java-derived language), and the like. A metadata element described using XML may take a form similar to that illustrated inFIG. 5. One of skill in the art will appreciate that alternative syntax may be used without departing from the spirit and scope of the invention. For example, when the scope refers to a single object, a metadata element may omit the scope reference and instead include an attribute such as <Metadata about=“ . . . ”> . . . </Metadata>. Metadata statements as described herein may be sent as part of data messages, e.g., simple object access protocol (SOAP) messages, or may be included in web service description documents, such as WSDL documents.

FIG. 6illustrates a flow chart for a method of creating a scoped metadata container according to an illustrative embodiment of the invention. In step601an empty container is created. In step603, the scope is defined and stored in a scope section of the container or, alternatively, as an attribute. In step605, properties are optionally set and stored in a properties section of the container. In step607, metadata statements are associated with the container and stored in a statements section of the container. In step609, security and authentication information is optionally stored in a security section of the container.

According to another illustrative aspect of the invention, with reference toFIG. 7, one metadata element703may refine, replace, restrict, or intersect with another metadata element701. For example, within a business organization, each division of the company may use standard division-wide metadata that is required to be included in all metadata elements (e.g., similar to using an “Include IDREF”-type statement) produced by that division. Likewise each department might require standard department-wide metadata included in metadata elements produced by that department, and the company as a whole may require standard company-wide metadata statements included in each metadata element produced by the company. If metadata statements conflict between two levels of the metadata hierarchy (e.g., company versus division), the invention provides a resolution mechanism to determine which statements, if any, remain in effect. For example, a division may include a metadata statement indicating that maximum message length is 1 MB. However, company-wide guidelines may require inclusion of another metadata statement that includes an indication that maximum message length can only be 512 KB. This may be resolved in various ways according to various aspects of the invention.

When two metadata elements refer to the same scope, one metadata element can merge with, replace, or intersect with another metadata element. When the statements of two metadata elements do not conflict, the two metadata elements may be merged together. When the statements do conflict, one metadata element may replace the other, or they may be intersected. During intersection, non-conflicting metadata statements are merged, while conflicting metadata statements are selected according to the most recent or superceding metadata element.

For example, as illustrated inFIG. 7, suppose metadata element701contains statements W, X, and Y, and suppose metadata element703, which intersects with element701, contains statements X′, Y, and Z. An intersection of metadata elements701and703would contain statements W, X′, Y, and Z. Other merge/intersection techniques may also be used as desired. In addition, a metadata element may also indicate that it cannot be replaced, for example, by including <Metadata Final=“T”> . . . </Metadata> to indicate that that specific metadata element cannot be replaced or intersected with another metadata element. Those of skill in the art will appreciate that various metadata tags, or attributes, may be used to indicate the nature of the relationship between two metadata elements, e.g., invalidates, replaces, intersects, refines, merges, or the like.

According to another aspect of the invention, logical inferences or an inherent or natural hierarchy may be used to determine whether one metadata element supercedes another. For example, a metadata element with scope=http://www.foo.com/bar may automatically supercede another metadata element with scope=http://www.foo.com/.

Using metadata refinement and replacement, a web service can define default metadata for general services, and refine the default metadata for based on various service levels. For example, a default metadata element may indicate that Passport authentication must be used, but remain silent as to each user's maximum mailbox size. This default metadata can then be refined to indicate that the maximum mailbox size for users in the default “silver” service level is 1.5 MB. Another metadata element may refine the default metadata element and indicate, for messages authenticated as being from a “gold” service level member, the maximum mailbox size is 10 MB.

As indicated above, routing metadata may be used to convey information directed towards adding, updating, and querying routing information for an object (e.g., a web service), referred to herein as referral metadata. Referral metadata may be used to configure message path information in a network node. Prior to being able to effectively communicate with a web service, a requestor must learn where to send messages in order to contact the web service. That is, the requester must obtain the referral metadata associated with the web service in order to learn where to send messages to communicate with the web service. According to an illustrative aspect of the invention, a metadata type may optionally be included, e.g., <Metadata Type=“referral”> . . . </Metadata> to indicate a class or type of metadata. One of skill in the art will appreciate that alternative syntax, as is known in the art, may be used to indicate a metadata type. For example, metadata statements may include a “type” indicator instead of placing the “type” indicator in the metadata element's header.

FIG. 8illustrates a modified scoped metadata element801adapted for use as a referral metadata element according to an illustrative aspect of the invention. The scope803indicates the range objects to which the referral metadata element applies. That is, the message path configuration information conveyed in the referral metadata element applies for messages directed to any object encompassed by the scope. As is illustrated inFIG. 8, the scope may be defined as one or more specific objects, or any object meeting certain criteria (e.g., having a certain prefix). One of skill in the art will appreciate that the scope can be defined in any manner such that a Boolean determination can be made as whether an object falls within the scope and that metadata attributes, or tags, may be renamed as applicable to make readability easier to a human user, without departing from use and functionality described herein.

Metadata statements805indicate the message handler to which messages can be sent in order to reach the object or objects encompassed by the scope. Each message handler may be a message intermediary (such as a router or a machine that substantively processes the message prior to delivery to the recipient) or a message recipient, collectively referred to as nodes. Metadata statement805may include one or more attributes811indicating a specific message handler to which the message can be directed. The ‘exact’ attribute (or similar) may be used to indicate nodes for which an exact match is needed, and may be expressed as a uniform resource identifier (URI). The ‘prefix’ attribute (or similar) may be used to indicate nodes for which a prefix match is needed. Optionally, referral metadata element may include properties807(e.g., name author, unique message ID, etc.) and security information809, as described above.

According to an illustrative aspect of the invention, referral information may indicate a choice of acceptable referral options, e.g., by including multiple attributes811in the statements805of the metadata element801. Optionally, an order of preference for each option may be provided. For example, a web service may provide two login servers. The web service may further indicate priorities for each server, e.g., that the first server should be used as a default, that second server should be used when the first server becomes unavailable or overloaded. The web service may optionally also specify requirements for each option. For example, if the first server is to be used, the message must contain an authentication token using the X.509 standard by the Internet Engineering Task Force (IETF). Logical operands or equivalents can be used (e.g., AND, NOT, OR, XOR, OPTIONAL, REQUIRED, etc.) to describe relationships, scopes, choices, and the like, or alternatively, individual attributes may be specified for each criterion.

According to another aspect of the invention, with reference toFIG. 9, conditions may be placed on referral metadata. As illustrated inFIG. 9, the referral metadata may be associated with a time-to-live (TTL), indicating that the referral metadata is only good for the specified period of time, which, in this example, is 43,200,000 milliseconds, or 12 hours. Other conditions may also or alternatively be included in each referral metadata element.

In an illustrative embodiment of the invention, the referral metadata elements may be stored in a header of a SOAP message, along with other headers that perform other unique functions (e.g., security, authentication, message routing), thus creating a composable message protocol such as is described in co-pending application Ser. No. 09/983,555 (filed Oct. 24, 2001). As illustrated inFIG. 10, the SOAP header may refer to a SOAP schema providing additional information to the recipient or an intermediary processing the message.FIG. 10illustrates using SOAP the metadata generally illustrated inFIG. 9.

Thus, using the above described referral metadata, with reference toFIGS. 11-13, a node1103in a network can indicate to another node1101to insert a third node1301between the two nodes1101,1103when communicating with each other.FIG. 11illustrates an original message path between node1101and node1103.FIG. 12illustrates a SOAP embodiment of a referral metadata element indicating to node1101that messages intended for node1103should be sent via node1301.FIG. 13illustrates the resultant message path after node1101receives and processes the referral metadata element illustrated inFIG. 12. Such a referral metadata element can be used in cases where an intermediary is needed in order to facilitate communications between two other nodes.

In another example, with reference toFIGS. 11,14and15, a referral metadata element can be used to insert a node1501after another node1103.FIG. 15illustrates a resultant message path after node1101(FIG. 11) receives and processes the referral metadata element illustrated inFIG. 14. The referral metadata element1401delegates a portion of the URI space of node1103so that messages intended for node1103are forwarded to node1501when the destination falls within the scope1403. This type of delegation may be used to facilitate progressive discovery when node1101may not know that node1103has delegated part of its URI space to node1501. This type of delegation may also be used when node1101has the authority to delegate a portion of the URI space of node1103to node1501. After node1103accepts referral metadata element1401, node1103will forward subsequent messages intended for any recipient with the appropriate prefix (i.e., “soap://b.org/some/part”) to node1501. Other SOAP headers, as part of a composable protocol, may provide necessary authentication and security measures to inform node1103to accept referral metadata element1401(discussed above, briefly).

In another example, with reference toFIG. 16, a referral metadata element may be used to invalidate a previous referral metadata element (or a portion thereof, e.g., a single statement). Metadata element1601invalidates metadata element1401(FIG. 14), as indicated by the relationship attribute ‘invalidates’ and the message ID corresponding to the metadata element to be invalidated (in this example, metadata element1401). After processing metadata element1601, node1501(FIG. 15) is no longer delegated a portion of the URI space of node1103.

With reference toFIGS. 17-18, another aspect of the invention provides a query mechanism so that a node can obtain/update its own routing information based on another node's routing information.FIG. 17illustrates a portion of a message including a referral metadata query1701requesting referral information with respect to a range as defined in a ‘for’ scope.FIG. 18illustrates a portion of a message including a referral metadata query response1801providing the information requested by query1701.

According to another aspect of the invention, a node can explicitly request that another node accept or reject a referral metadata element. This can be used, for example, to explicitly request that a node delegate a piece of its URI space to another node. The request may be sent in the form of a registration message, with the response returned in a registration response message.FIG. 19illustrates a registration request message1901, requesting that the node located at soap://b.org delegate a portion of its URI space to the node located at soap://c.org, and more specifically to an application program residing at soap://c.org/my/application. The node located at soap://b.org may accept or reject the request by sending an appropriate registration response message.

According to one illustrative embodiment, a node accepts a registration request by simply returning an acknowledgement message2001, as illustrated inFIG. 20, and rejects the request by returning a fault message2101, illustrated inFIG. 21, including a fault code2103. The fault code provides a reason that the request was rejected, for example, the node to which the registration was requested only accepts a specific max time-to-live (TTL) value for referral metadata statement. The fault code ‘duplicate’ or similar may be used when a node already has accepted and processed a valid referral metadata with the same message ID value. The fault code ‘notInvalidated’ or similar may be used when a node refuses to invalidate an accepted valid referral metadata statement. The refusing node may also indicate offending message ID values as part of the ‘notInvalidated’ code. Other fault codes and reasons may also or alternatively be used.

While some of the examples included herein, such as those illustrated inFIGS. 19-21, include referral metadata in a body portion of a message, in an alternative illustrative embodiment the referral metadata information may be communicated in a header portion2203of a message2201, as illustrated inFIG. 22, so that the referral information can be piggybacked in a message with other information, as appropriate. In some embodiments, all identifiers are expressed in the form of a URI without exception. In other embodiments, alternative forms of identifiers may be used.

While the invention has been described with respect to specific examples including presently preferred modes of carrying out the invention, such as using SOAP XML, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and techniques, such as using other platform-independent mechanisms such as Java or a Java-based language. Thus, the spirit and scope of the invention should be construed in view of the appended claims.