Patent Publication Number: US-6985939-B2

Title: Building distributed software services as aggregations of other services

Description:
RELATED INVENTIONS 
   The present invention is related to (Ser. No. 09/956,276), which is tided “Dynamic, Real-Time Integration of Software Resources through Services of a Content Framework”, and (Ser. No. 09/956,268), which is titled “Programmatic Management of Software Resources in a Content Framework Environment”, both are which are commonly assigned to International Business Machines Corporation and which were filed concurrently herewith. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to computer software, and deals more particularly with techniques for building distributed software services as aggregations of other services. 
   2. Description of the Related Art 
   The popularity of distributed computing networks and network computing has increased tremendously in recent years, due in large part to growing business and consumer use of the public Internet and the subset thereof known as the “World Wide Web” (or simply “Web”). Other types of distributed computing networks, such as corporate intranets and extranets, are also increasingly popular. As solutions providers focus on delivering improved Web-based computing, many of the solutions which are developed are adaptable to other distributed computing environments. Thus, references herein to the Internet and Web are for purposes of illustration and not of limitation. 
   The early Internet served primarily as a distributed file system in which users could request delivery of already-generated static documents. In recent years, the trend has been to add more and more dynamic and personalized aspects into the content that is served to requesters. One area where this trend is evident is in the increasing popularity of content frameworks such as those commonly referred to as “portals” (or, equivalently, portal platforms, portal systems, or portal servers). A portal is a type of content framework which is designed to serve as a gateway, or focal point, for end users to access an aggregation or collection of information and applications from many different sources. Portals are typically visual in nature, and provide their users with a Web page known as a “portal page”. A portal page is often structured as a single overview-style page (which may provide links for the user to navigate to more detailed information). Alternatively, portal pages may be designed using a notebook paradigm whereby multiple pages are available to the user upon selecting a tab for that page. Some experts predict that portal pages will become the computing “desktop” view of the future. 
   Another area where advances are being made regarding dynamic content is in the so-called “web services” initiative. This initiative is also commonly referred to as the “service-oriented architecture” for distributed computing. Web services are a rapidly emerging technology for distributed application integration in the Internet. In general, a “web service” is an interface that describes a collection of network-accessible operations. Web services fulfill a specific task or a set of tasks. They may work with one or more other web services in an interoperable manner to carry out their part of a complex workflow or a business transaction. For example, completing a complex purchase order transaction may require automated interaction between an order placement service (i.e. order placement software) at the ordering business and an order fulfillment service at one or more of its business partners. 
   Many industry experts consider the service-oriented web services initiative to be the next evolutionary phase of the Internet. With web services, distributed network access to software will become widely available for program-to-program operation, without requiring intervention from humans. 
   Web services are generally structured using a model in which an enterprise providing network-accessible services publishes the services to a network-accessible registry, and other enterprises needing services are able to query the registry to learn of the services&#39; availability. The participants in this computing model are commonly referred to as (1) service providers, (2) service requesters, and (3) service brokers. These participants, and the fundamental operations involved with exchanging messages between them, are illustrated in  FIG. 1 . The service providers  100  are the entities having services available, and the registry to which these services are published  110  is maintained by a service broker  120 . The service requesters  150  are the entities needing services and querying  140  the service broker&#39;s registry. When a desired service is found using the registry, the service requester binds  130  to the located service provider in order to use the service. These operations are designed to occur programmatically, without human intervention, such that a service requester can search for a particular service and make use of that service dynamically, at run-time. The web services model is theoretically available for any type of computing application. However, the web services which are accessible from registries today are limited to relatively simple programs such as “Hello, World!” demo programs, programs which look up the current temperature for a particular zip code, programs which perform currency exchange calculations, and so forth. 
   The core set of standards on which web services work is being built includes HTTP (“Hypertext Transfer Protocol”), SOAP (“Simple Object Access Protocol”) and/or XML (“Extensible Markup Language”) Protocol, WSDL (“Web Services Description Language”), and UDDI (“Universal Description, Discovery, and Integration”). HTTP is commonly used to exchange messages over TCP/IP (“Transmission Control Protocol/Internet Protocol”) networks such as the Internet. SOAP is an XML-based protocol used to send messages for invoking methods in a distributed environment. XML Protocol is an evolving specification of the World Wide Web Consortium (“W3C”) for an application-layer transfer protocol that will enable application-to-application messaging, and may converge with SOAP. WSDL is an XML format for describing distributed network services. UDDI is an XML-based registry technique with which businesses may list their services and with which service requesters may find businesses providing particular services. (For more information on SOAP, refer to “Simple Object Access Protocol (SOAP) 1.1, W3C Note 08 May 2000”, which is available on the Internet at http://www.w3.org/TR/2000/NOTE-SOAP-20000508. See http://www.w3.org/2000/xp for more information on XML Protocol and the creation of an XML Protocol standard. The WSDL specification is titled “Web Services Description Language (WSDL) 1.1, W3C Note 15 Mar. 2000”, and may be found on the Internet at http://www.w3.org/TR/2001/NOTE-wsd1-20010315. For more information on UDDI, refer to the UDDI specification which is entitled “UDDI Version 2.0 API Specification, UDDI Open Draft Specification 8 Jun. 2001”, and which can be found on the Internet at http://www.uddi.org/specification.html. HTTP is described in Request For Comments (“RFC”) 2616 from the Internet Engineering Task Force, titled “Hypertext Transfer Protocol—HTTP/1.1” (June 1999).) 
   Application integration using these open standards requires several steps. The interface to a web service must be described, including the method name(s) with which the service is invoked, the input and output parameters and their data types, and so forth. WSDL documents provide this information, and are transmitted using a UDDI publish operation to a registry implemented according to the UDDI specification. Once the service is registered in the UDDI registry, service requesters can issue UDDI find requests to locate distributed services. A service requester locating a service in this manner then issues a UDDI bind request, which dynamically binds the requester to the located service using the service information from the WSDL document. (These UDDI operations have been illustrated, at a high level, in  FIG. 1 .) SOAP/XML Protocol and HTTP messages are commonly used for transmitting the WSDL documents and the UDDI requests. (Hereinafter, references to SOAP should be construed as referring equivalently to semantically similar aspects of XML Protocol. Furthermore, it should be noted that references herein to “HTTP” are intended in a generic sense to refer to HTTP-like functions. Some UDDI operations, for example, require HTTPS instead of HTTP, where HTTPS is a security-enhanced version of HTTP. These differences are not pertinent to the present invention, however, and thus no distinction is made hereinafter when discussing HTTP.) 
   The goal of web services is to provide service requesters with transparent access to program components which may reside in one or more remote locations, even though those components might run on different operating systems and be written in different programming languages than those of the requester. While a significant amount of work has been done to define the goals, architecture, and standards on which web services will be based, much work remains to be done to make web services operate effectively and efficiently. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide a technique for dynamically integrating software resources (including, but not limited to, web services) in a distributed network. 
   Another object of the present invention is to provide a technique for leveraging a portal model and framework for real-time integration of software resources as web services. 
   A further object of the present invention is to define techniques for making software resources available for web services using a portlet model. 
   Yet another object of the present invention is to define techniques for using portlets as web service intermediaries. 
   Another object of the present invention is to provide a technique for enabling programmatic management of software resources used in web services. 
   A further object of the present invention is to provide a composition model for building web services as aggregations of other services and/or software resources. 
   Still another object of the present invention is to provide a composition utility which enables fast and efficient construction of web services from other services and/or software resources. 
   A further object of the present invention is to leverage a dual aggregation model for web services. 
   Other objects and advantages of the present invention will be set forth in part in the description and in the drawings which follow and, in part, will be obvious from the description or may be learned by practice of the invention. 
   To achieve the foregoing objects, and in accordance with the purpose of the invention as broadly described herein, the present invention provides methods, systems, and computer program products for building distributed software services as aggregations of other services. In preferred embodiments, this technique comprises: determining a taxonomy of interest for a new distributed software service; programmatically scanning a network-accessible registry to locate registered services having the taxonomy of interest; determining if each located service has a predetermined deployment interface; and providing the located services to a service composition tool if the determining step has a positive result. 
   The technique may further comprise adding the predetermined deployment interface to the located service when the located service does not have the deployment interface, and may also or alternatively further comprise determining if each located service has a predetermined system interface for managing that located service. The technique may further comprise building the new service using selected ones of the provided services. 
   A directed graph representation of the new service may be created, wherein nodes of the directed graph represent operations of the new service and edges of the directed graph represent transition conditions of the new service, and wherein data mapping operations are associated with selected ones of the edges. A markup language document may be created to represent the directed graph representation and to register the markup language document in a network-accessible registry. 
   The new service is preferably modeled as a portlet, as has at least one of (1) a deployment interface and (2) a system interface. 
   The present invention will now be described with reference to the following drawings, in which like reference numbers denote the same element throughout. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  provides a diagram illustrating the participants and fundamental operations of a service-oriented architecture, according to the prior art; 
       FIG. 2  illustrates a sample portal page in which content from visually-oriented portlets is rendered, according to the prior art; 
       FIG. 3  is a block diagram illustrating a portlet structured as a web service proxy, according to preferred embodiments of the present invention; 
       FIGS. 4A and 4B  illustrate the content of sample WSDL documents specifying a deployment interface and a system interface, respectively, according to preferred embodiments of the present invention; 
       FIG. 5  illustrates a graphical web service composition tool of the type which may be created according to the teachings of the present invention; 
       FIGS. 6 ,  7 ,  9 ,  12 ,  13 , and  17  provide flowcharts depicting logic which may be used to implement preferred embodiments of the present invention; 
       FIG. 8  illustrates a web services stack which may be used in a networking environment in which the present invention operates; 
       FIG. 10  provides a sample “tModel” which may be used to publish information to a registry; 
       FIGS. 11A–11C  are used to illustrate signatures of methods, and the need to provide a signature superset when dynamic run-time binding is to be used; 
       FIG. 14  illustrates a sample “plug link” specification which is representative of those used according to the present invention; 
       FIGS. 15A–15C  provide syntax used to describe mapping of data between operations; 
       FIG. 16  is a simple example of information that may be contained in a transformation registry; and 
       FIG. 18  provides an overview of components used in describing the present invention. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   The promise of web services is that disparate applications will be able to interoperate like never before, offering a new breed of seamless hyper-integrated applications through openness and urbanization of enterprise systems. Web services will make distributed software resources more widely available, and will allow software to be marketed as a service. As web services become widespread, there will be a need for managing the services and for an aggregation point where these services can be aggregated to form new services which can then be deployed. A content framework such as a portal platform provides many built-in services for content management and service hosting, such as persistence, personalization, and transcoding. The present invention defines novel techniques for leveraging portal platforms, extending the platforms to provide for aggregation, deployment, and management of web services. Providing access to software services through portal aggregation will lower integration costs and help speed time-to-market. This type of portal usage for application-to-application communication may be referred to as an “application portal”, in contrast to the “visual portals” which are designed to display information to human users. Companies providing application portals today promote low-cost Enterprise Application Integration (“EAI”) and provide application access and management through a standard portal platform. However, existing EAI products do not yet programmatically integrate web services nor do they integrate web services in real-time, and these existing products require that small “engagements” are manually provided as the “glue” necessary to define a static binding to hook web services into a portal before applications can be deployed. (For example, an engagement may be needed to surface the interface to an enterprise&#39;s customer relationship management, or “CRM”, software resources at the visual portal. The engagements often use proprietary software and/or custom-defined XML communications. This approach is therefore not suitable for dynamic, programmatic aggregation or integration on a global scale.) Current estimates are that creating such engagements requires anywhere from several days to several weeks. JamCracker, Onyx, and USInternetworking are among the companies providing EAI using application portals today. No systems are known to the inventors which enable real-time deployment of software resources by aggregating them in a modeling composition tool, and then programmatically integrating and managing them using open industry standards as disclosed herein. 
   The present invention defines techniques for integrating web services and other back-end software resources into an application portal platform using a portlet model or paradigm, thereby creating new web services. One commercially-available portal platform on which the present invention may be implemented is the WebSphere® Portal Server (“WPS”) from the International Business Machines Corporation (“IBM”). (“WebSphere” is a registered trademark of IBM.) Note, however, that while discussions herein are in terms of a portal platform, the inventive concepts are applicable to other types of content frameworks which provide analogous functionality and are also applicable to portals other than WPS, and thus references to portals and their portlet paradigm is by way of illustration and not of limitation. Using the disclosed techniques, an application portal functions not only as an access point for statically integrating services after manually providing engagements, as in the prior art, but also functions as a full web service utility. In its capacity as a web service utility, a portal platform according to the present invention provides programmatic management of web services and dynamic run-time integration of web services. 
   One aspect of the present invention also provides a tool for composition or aggregation of new web services. Using this composition tool, a systems administrator (or, equivalently, a service composer or other person) may define a new service composed of more fine-grained services. According to preferred embodiments of this aspect, the fine-grained services from which other services are built may reside locally or remotely, and the techniques disclosed herein enable referencing those services and using those services in a transparent manner without regard to whether they are local or remote. The fine-grained services may include any form of programming logic, including script programs, Java™ classes, COM classes, EJBs (“Enterprise JavaBeans”™), stored procedures, IMS or other database transactions, legacy applications, and so forth. (“Java” and “Enterprise JavaBeans” are trademarks of Sun Microsystems, Inc.) The web services created in this manner can then automatically be managed by the portal platform and can also be used in creating new web services in a recursive manner, as will be described. 
   The disclosed techniques build on the portal concept of a plug-in, which is referred to in the art as a “portlet”. Portlets are known in the prior art which are visual in nature. In the visual portal model, each portlet is responsible for obtaining a portion of the content that is to be rendered as part of the complete portal page for the user. By convention, the portlet&#39;s “service” method is invoked to return markup language (such as Hypertext Markup Language, or “HTML”) syntax encapsulating the result of the portlet&#39;s execution. Once the visual portlet&#39;s content has been aggregated with other markup language syntax by the portal page from which it was invoked, the result is a Web page whose content is well suited for the needs of the portal page&#39;s human user.  FIG. 2  provides an example of a prior art portal page  200  from a visual portal, where this portal page includes content from three visually-oriented portlets (see elements  210 ,  220 ,  230 ). Portlet  210  in this example displays news headlines. Portlet  220  shows a stock ticker for the user&#39;s favorite stocks, and portlet  230  displays the current weather and weather forecast for the user&#39;s selected city. 
   In many content-rich visual portals, the output of visually-oriented portlets is aggregated physically on the portal page according to the portlets&#39; content categorization or taxonomy. For example, output of news feed portlets may be provided on one tabbed page of a notebook-style visual portal, with output of weather portlets on another tabbed page and perhaps the output of portlets of interest to an enterprise&#39;s employees may be provided on another. Or, portlet output may be grouped within logical sections of a single portal page. The physical layout of the portal page may therefore enable end users to find information more quickly and efficiently. Work is ongoing to build remote interfaces to visually-oriented portlets such that visual portals can aggregate content from applications which may be located on machines other than the machine on which the portal code resides. This aggregated content will then be presented on the portal page, and whether it was obtained from a locally-available portlet or from a remote portlet will be transparent to the end user. (See, for example, “WebSphere Portal Server and Web Services Whitepaper”, T. Schaeck, published by IBM on the Internet at http://www-4.ibm.com/software/solutions/webservices/pdfwPS.pdf, which discusses remote interfaces to visually-oriented portlets.) 
   A portal platform provides a number of services for the portlets it hosts, as described above. The present invention leverages portlets as a portal interface, and also builds upon the concept of a remote portlet interface (where this concept is extended as disclosed herein to apply to programmatic portlets), to enable access to software resources. Portlets functioning according to the present invention are also referred to herein as “web service intermediaries” or “web service proxies”, or simply as “intermediaries” or “proxies”. That is, a portlet may now act as an intermediary between an application or software resource requesting a particular service and a software resource providing that service. According to the present invention, the software resource performing a particular function may be statically bound to a web service proxy (for example, at development time), or a web service proxy may be bound to a software resource which is dynamically selected (for example, based upon criteria which are evaluated at run-time). In either case, the portlet proxy receives request messages and forwards them to the software resource to which it is bound; once the software resource has completed the requested function, it returns its response to the portlet proxy which then forwards the response to the requester. 
   A block diagram illustrating a portlet structured as a web service proxy is shown in  FIG. 3 . As shown therein, portlet proxy  340  includes a deployment interface  310 , a system interface  320 , and a functional interface  330 . The portlet proxy communicates with a portal platform  300  using these interfaces, acting as an intermediary between the portal platform and the software resource  350  which carries out the function of interest. Details of each functional interface are specific to the web service provided by software resource  350 , and do not form part of the present invention. The present invention, however, makes the functional interface of the software resources available as an interface  330  of the portlet proxy. (Exposing the functional interface using WSDL definitions and SOAP services may be accomplished using a commercially-available tool such as the IBM Web Services Toolkit, or “WSTK”, during the deployment process.) The deployment interface and system interface will be described in more detail below. 
   The software resources invoked using the techniques of the present invention are typically designed for program-to-program interaction, but may alternatively be visual in nature. For example, visually-oriented resources may be invoked during execution of a web service which operates primarily in a program-to-program manner. The term “programmatic portlet” is used herein to refer generally to portlet proxies according to the present invention, whether or not the underlying software resource involves visually-oriented code. 
   A deployment interface and a system interface are defined for each portlet which serves as a web service proxy, according to preferred embodiments of the present invention. (In alternative embodiments, advantages of the present invention may be realized by implementing either the deployment interface or the system interface separately, and such implementations are within the scope of the present invention. For example, there may be cases in which it may be desirable not to implement management services for some web services. In such cases, the system interface may be omitted; alternatively, a system interface might be provided which has no operations or which has operations implemented as empty functions.) These new interfaces may also be referred to as the deployment port type and system port type, respectively. A portlet according to the present invention thus defines a service provider type that includes the port types necessary for portal integration of software resources and service interaction and management. (“Port types” is a term used in the art to signify the specification of a portlet&#39;s operations, and “service provider type” is a term used to signify a collection of port types.) 
   The deployment interface enables a portlet proxy (that is, an aggregated web service which is represented by a portlet proxy) to be used in subsequent web service composition operations, in a recursive manner. For example, the deployment interface of a portlet “A” provides information about portlet A for use as portlet A is aggregated with other portlets to form a new web service “Z”; by defining a deployment interface for web service Z, according to the present invention, information about web service Z can subsequently be provided as service Z is used for composing other new services. 
   The system interface is used for run-time management of portlets (that is, of web services represented by portlet proxies) by the portal platform. Use of the system interface allows the portal platform to perform functions such as logging of events, billing, and other types of administrative operations pertaining to execution of the web service. This requires 2-way communication between the portal platform and the portlet proxy, and uses novel techniques which are disclosed herein. 
   Referring now to the sample WSDL documents in  FIGS. 4A and 4B  (representing interface definitions), the deployment interface specification and system interface specification, respectively, are illustrated. According to preferred embodiments, the deployment and system port types are represented as WSDL documents for registration in a registry. As shown at  410  of the WSDL document  400  in  FIG. 4A , the example deployment interface is named “Deployment” and includes operations such as “getDisplayName” and “getDisplayIcon16×16” (see element  430 ). These operations may be used, for example, to retrieve a descriptive name of the web service and to retrieve a graphic image representing the web service for placement on a palette of a web service composition tool (such as that illustrated in  FIG. 5 ). According to the WSDL specification, the input and output messages used for communicating with a service are specified in “&lt;message&gt;” elements  420 , where the parameters used by those messages are defined as “&lt;part&gt;” elements. Thus, a message element is defined for each message of each operation specified for this port type. (Refer to the WSDL specification for more information about the details of a WSDL document.) 
   The WSDL document  450  in  FIG. 4B  defines the system interface, which in the example is named “System” (see element  460 ). A complex data type named “Event” is defined (see element  470 ), comprising 2 string parameters and a date parameter. This data type may be used, for example, when exchanging logging data to be recorded in an auditing log file. A “logEvent” operation is defined (see element  490 ), and in this example is a 1-way operation invoked using a “logEventReceive” message (see element  480 ) which has a parameter of type Event. In addition, the example defines a “reportUsage” operation which has 2 messages “reportInput” and “reportOutput”. 
   The deployment port type is used at design time, and allows a new web service to be composed with a web service composition tool such as that illustrated by  FIG. 5 . The deployment port type contains operations pertinent to the modeling composition process. Representative examples of operations which may be useful for this purpose include “getIcon16×16” and “getIcon32×32” to retrieve icons (such as  520   a ,  520   b ) of different sizes for placement on a portlet palette (illustrated by element  510 ), “getDisplayName” and “getDisplayDescription” to provide textual information for presenting to a service composer (such as that illustrated at  521   a  and  521   b ), “getAuthorName” to retrieve an identification of the software developer or the service composer, and so forth. 
   Turning now to  FIG. 6 , logic is depicted which may be used for creating a portlet proxy for use in a composition tool such as that represented by the sample user interface of  FIG. 5 . Note that while the description of  FIG. 6  is presented herein in terms of preparing a WSDL document describing the portlet&#39;s operations, this logic also outlines what is required for a developer creating source code for a software resource. For example, if the software resource will report information through its system interface for quality of service or billing purposes, the developer must provide code to gather the appropriate data and return this data when requested; the method or methods which perform this function may then be identified as part of the system port type of the portlet proxy for the software resource. (See interface  320  of  FIG. 3 , for example, illustrating that the system interface of portlet proxy  340  exposes the management operations of software resource  350 .) This process comprises first determining the operations that will be exposed as the portlet proxy&#39;s published functional interface (Block  600 ). For example, suppose a programmatic portlet such as the portlet represented by icon  520   a  in  FIG. 5  provides order fulfillment services. The public interface of this portlet might include a method named “receivePurchaseOrder” (see element  530 ), which can be used to invoke operations of the underlying software resource. Preferably, a human determines which methods of a software resource should be publicly exposed; alternatively, programmatic operations could be used to select the methods which comprise the public interface. (For example, programmatic operations might be designed to select all public methods for exposing, or perhaps to select only the “getter” public methods.) 
   Once the public interface is identified, WSDL markup language syntax is programmatically created to specify this information. This comprises generating &lt;message&gt; and &lt;operation&gt; elements, similar to those illustrated in  FIGS. 4A and 4B . The composer may be asked to supply information for use in this process, such as the port type name, the location of the name space information, and so forth. Or, this information or parts thereof may be programmatically generated and/or retrieved from a configuration file. 
   Techniques for programmatic generation of markup language syntax (using input supplied by a human, as well as programmatically-derived information) are known in the art, and a detailed description thereof is not deemed necessary for an understanding of the present invention. IBM&#39;s WSTK is an example of a commercially-available product which may be used to programmatically generate WSDL for an existing software resource. See “The Web services (r)evolution: Part 4, Web Services Description Language (WSDL)”, G. Glass (February 2001), published by IBM on the Internet at http://www-106.ibm.com/developerworks/webservices/library/ws-peer4, which presents an example of programmatically generating a WSDL document for a simple weather service which has “getTemp” and “setTemp” operations.  FIG. 4  of this document illustrates asking a composer which methods of a class should be used in creating a public interface. It should be noted that references herein to using a WSDL syntax generator are merely for purposes of illustration; alternatively, a developer might manually create WSDL documents or another type of markup language syntax tool might be used for this purpose. 
   In addition to specifying the public interface, the portlet&#39;s deployment port type information must be created (Block  610 ). An example of the deployment port type is illustrated in  FIG. 4A . If the port type information is programmatically generated, for example using WSTK, this process comprises parsing the software resource&#39;s class definition to locate its methods providing the operations of the predefined deployment port type and to identify the parameters and parameter types of each method, and then generating &lt;message&gt; and &lt;operation&gt; elements, as well as &lt;part&gt; elements and &lt;type&gt; definitions as necessary. The composer may be asked to provide input during this process, as needed, such as populating the parameters for the messages of the operations. (For example, to populate the “displayIcon16×16Output” parameter of the “getDisplayIcon16×16Output” message, the composer might specify the Uniform Resource Locator, or “URL”, of a particular image file.) The portlet&#39;s system port type information is also created (Block  620 ), in a similar manner, resulting in a WSDL document such as that shown in  FIG. 48 . (In preferred embodiments, the deployment and system interface definitions are placed in separate WSDL documents as shown in the examples of  FIGS. 4A and 4B  because they describe different behavior.) 
   Finally, the portlet proxy for the web service is published to a registry (Block  630 ), after which the portlet proxy is available for use in composing new web services and its services are available for invocation (e.g. using a conventional UDDI find and bind). In preferred embodiments, documents known in the art as “tModels” are used for publishing a portlet proxy&#39;s web services information to a registry. (A “tModel”, according to the UDDI specification, is metadata which describes the specifications and the versions of specifications that were used to design published services. “tModel” is a generic term for a service “blueprint”, defining the conventions to which the registered service conforms. For example, if a registered service includes an “HTTP 1.1 tModel”, then this service is known to adhere to certain requirements and conventions associated with that tModel—and, by implication, adheres to particular requirements in its use of HTTP.) Note that a WSDL port type definition can be a tModel; it can also be a partial tModel, which is a tModel in a tModel set. Thus, a single tModel may be used to register both the deployment and system interfaces. (Refer to the UDDI specification for more information on tModels and tModel sets.) 
   Referring now to  FIG. 7 , logic is shown which may be used to implement a service modeling and deployment process via a web service composition tool. Block  700  indicates that the new web service is modeled using portlets as proxies or templates for the service being aggregated. That is, a portlet may serve as an intermediary for a web service or for a local resource, defining an interface to the operations provided by one or more back-end software resources. However, the actual software resource(s) providing that service on the back end might not be selected and bound until run-time. The service composer is also able to reuse the composed templates and dynamically plug in different service providers for a static (development-time) binding. 
   The web service composition tool preferably provides a portlet palette for use in this modeling operation, where registered portlets for a particular taxonomy or category are presented on the palette. The service composer then creates a new web service using the composition tool, for example by right-clicking on a web service icon to display its available methods and then using drag and drop operations to position selected method invocations as operations for carrying out a service.  FIG. 9 , discussed below, illustrates logic with which information may be gathered for use by the web service composition tool, including locating the appropriate web services to use when constructing the palette. 
   In preferred embodiments, a directed graph is used to model the operations involved in executing the new web service. Selected portlet operations represent the nodes of the graph, and the graph edges which link the nodes represent potential transitions from one service operation or process to another. These service links can be qualified with one or more transition conditions, and also with data mapping information if applicable. The conditions specify under what conditions the next linked service should be invoked. Often, these conditions will be determined using the results of a previous service invocation. Data mapping refers to the ability to link operations between portlet port types and transfer data from one operation to another. For example, the data mapping information may indicate that the output parameters of one service are mapped to the input parameters of another service. 
   Preferred embodiments of the present invention leverage the Web Services Flow Language (“WSFL”) for directed graphs. In particular, WSFL&#39;s persistent storage techniques and run-time evaluation techniques using directed graphs are added to a web services stack to operate upon the graphs created by a service composer. For a detailed discussion of WSFL, refer to the WSFL specification, which is entitled “Web Services Flow Language (WSFL 1.0)”, Prof. Dr. F. Leymann (May 2001), available on the Internet from IBM at http://-www4.ibm.com/software/solutions/webservices/pdf/WSFL.pdf, which is hereby incorporated herein by reference as if set forth fully. (Note that the WSFL specification discusses use of directed graphs for modeling web services, but does not teach directed graphs in combination with services which are provided by programmatic portlet proxies. The WSFL specification defines a “plug link” mechanism, discussed in more detail below with reference to Block  1380  of  FIG. 13 , which can be used in a proxy model to map interfaces in a simple manner as described herein. This plug link mechanism is used by preferred embodiments of the present invention as the persistent definition of integrating portlet proxies to implement web services.) 
   A web services stack  800  used in preferred embodiments is illustrated in  FIG. 8 . Service flow support  810  is preferably provided by WSFL, as stated earlier. Service discovery  820  and service publication  830  are preferably provided using UDDI. A WSDL layer  840  supports service description documents. SOAP may be used to provide XML-based messaging  850 . Protocols such as HTTP, File Transfer Protocol (“FTP”), e-mail, message queuing (“MQ”), and so forth may be used for network support  860 . As discussed herein, WSDL is used to define web service port types and to define how to invoke operations of these port types, and WSFL is used to aggregate the web services (and therefore to aggregate their interfaces). At run-time, services are found within a registry using the UDDI service discovery process, and bound to using information from their WSDL definitions. The WSFL run-time then uses these (port type) definitions to aggregate the services. (Because the signatures of the operations will typically not match one-to-one, the WSFL plug link mechanism may be used to map between the operation interfaces.) 
   Referring again to the example composition tool user interface in  FIG. 5 , the composer has selected to begin the new service with a “receive purchase order” operation  530 . For purposes of illustration, suppose this operation evaluates the items on an incoming purchase order to determine whether they are in stock or not. Thus, a transition condition  535  indicates that if an item is out of stock, the next service to be executed is “place order with supplier”  540 , whereas if an item is in stock, transition condition  545  applies and the next service to be executed for this item is “add item to invoice”  550 . Upon occurrence of some event, such as receiving a shipment of new items or perhaps receiving a notification that the item had to be ordered from the supplier&#39;s supplier, transition condition  555  applies and a service “response from supplier”  560  is to be executed. Presumably, this service evaluates the supplier&#39;s response, and if a requested item was determined to be available, transition condition  565  applies and the item will be added to an invoice by service  550 , whereas if a requested item is not available then transition condition  575  applies and the next service to be executed is “add item to backorder”  580 . As will be obvious, the nodes and conditions illustrated in  FIG. 5  are merely for purposes of illustration. (Data mapping information has been omitted from the example.) 
   Turning now to  FIG. 9 , the process of obtaining information to present to the service composer on the user interface of a composition tool during execution of Block  700  of  FIG. 7  preferably begins at Block  900  by determining the taxonomy of interest. One way in which this may be performed is to query the composer. As shown by the example in  FIG. 5 , the composer may have requested portlet proxies pertaining to item ordering services, and therefore palette  510  includes icons  520   a ,  520   b  representing an order fulfillment service and an order payment service. Once the taxonomy is known, the registry is programmatically scanned (Block  910 ) for portlets whose tModels indicate support for that taxonomy. The scan also checks for tModels representing support for the deployment interface disclosed herein, and optionally the system interface disclosed herein. See  FIG. 10  for an example of a tModel that may be used to indicate support for the system service provider type of the present invention. (Optionally, a single tModel may be used to represent both the deployment and system service provider types. Or, a tModel similar to the one shown in  FIG. 10  may be separately created for the deployment service provider type.) Note that the WSDL document in  FIG. 4B  defines an interface template for portlet proxies conforming to the sample tModel in  FIG. 10 . This correspondence is shown, for example, in the service provider type named in the descriptive information at  1010 , and in the file name wherein the service provider type forms part of the URL at  1020 . The &lt;overviewURL&gt; element of a tModel functions as a type of import statement to reference a WSDL service specification, as is known in the art. This tModel, along with its associated key, is published as a technical blueprint for a portlet proxy registered in a UDDI registry. 
   Block  920  performs a test to see if any more portlets meeting the current criteria are available in the registry. If not, then processing continues at Block  930  where the dynamically-gathered information is used in the modeling operation to assemble aggregated services as portlet proxies. Discussion of the modeling operation continues below with reference to Block  710  of  FIG. 7 . 
   When the test in Block  920  has a positive result, then the processing of Blocks  940  through  980  is performed to obtain information about the registered portlet proxy which has been located. Block  940  obtains the portlet proxy&#39;s deployment description, which is preferably implemented to provide a description of the web service, and Block  950  obtains its deployment author information. Use of this information was previously discussed with reference to  FIG. 5 . For example, it may be used if the composer requests to see the properties of a web service presented on the user interface of the composition tool. 
   Block  960  obtains information about the icon to be displayed for this service on the user interface of the composition tool. Preferably, this information comprises an address such as a URL specifying where an icon image is stored. Block  970  obtains the deployment operations for this portlet, in effect determining what the portlet can do. 
   Preferably, obtaining the deployment information for the portlet proxy in Blocks  940  through  970  comprises executing well-known methods of the deployment interface by issuing the corresponding message from the service&#39;s deployment port type. For example, using the deployment port type defined in  FIG. 4A , the message “getDisplayIcon16×16Input” may be invoked to obtain the portlet&#39;s 16 by 16 icon, and if the portlet has a “getDisplayIcon32×32Input” message, this message can be invoked to obtain the portlet&#39;s 32 by 32 icon. (Blocks  940  through  970  should be considered as representative of the information that may be beneficially retrieved for a portlet proxy; additional or different information may be deemed useful in a particular implementation of the present invention.) 
   After obtaining the pertinent deployment information about the portlet, a representation of the portlet is added to the modeling palette (Block  980 ), and control returns to Block  920  to determine if there are more portlets of interest in the registry. The processing of Block  920  has been described above. 
   Returning now to the discussion of  FIG. 7 , once the composer completes the model of service interaction as a directed graph, at Block  710  the composer declares a service provider port type for the newly-aggregated service. In order to define this public interface, the composer may select operations to be exposed, or exported, within port types of the service of the composition, thereby identifying the public port type. The composer may select as many operations for exporting as necessary, and may also define new operations if desired. (For example, the composer might decide to define a new name for an operation, and provide a one-to-one mapping for that new name to the old name.) These exposed operations specify the means for invoking the new service. For example, with reference to the sample directed graph in  FIG. 5 , the composer would specify (at least) the operation “receivePurchaseOrder” corresponding to node  530  as a public interface. The composer may also provide a data mapping between an exposed operation and an internal service port type operation. For the sample directed graph in  FIG. 5 , having a public interface of “receivePurchaseorder”, the composer might specify (for example) a data mapping that converts data to a particular format required by this operation, such that an input parameter named “inputPurchaseOrder” adhering to a predefined type “purchaseOrder” would be available to the service upon invocation. Providing the data mapping may comprise identifying a canned transformation component such as an integer-to-float transform; identifying a stylesheet which contains an appropriate transformation, such as an XSLT (Extensible Stylesheet Language Transformations) stylesheet; identifying customized transformation logic, which may for example convert one complex data type to another; and so forth. (Refer to the discussion of  FIGS. 11A–11C  below, for more information about declaring the interface to a web service intermediary and potential web service software resources, and about providing transformation information.) The process of declaring the exposed port types (i.e. operations) results in the new service provider type for the aggregated composition. Thus, this new composition is itself a portlet proxy, or web service intermediary, that can be used as a building block in further compositions. 
   The composer also provides a mapping for the deployment port type and for the system port type, if applicable, such that the resulting web service will be able to be used within a web service composition tool and will be able to be programmatically managed by the portal platform as disclosed herein. This is preferably accomplished by prompting the composer (using a menu-driven approach, for example) to identify operations and data mappings that will then be represented in WSFL markup language &lt;export&gt; and &lt;dataLink&gt; elements, which enable providing a new interface and doing internal mapping for that interface. (Refer to section 4.5.3, “Data Links and Data Mapping”, and section 4.6.4, “Exporting Operations”, of the WSFL specification for more information on the syntax and semantics of the &lt;export&gt; and &lt;dataLink&gt; elements.) 
   In some cases, it may be desirable to generate the deployment and/or system port types (and similarly, the public interface of the portlet proxy) without reference to a particular target software resource. For example, suppose that nm-time quality of service is an important factor in choosing a service provider for some service such as credit card processing. To provide a more generic interface which will programmatically adapt to one of several target service providers after a run-time service selection, according to the present invention, the composer may be asked to provide input for use in creating the WSDL document (see the description of Blocks  600  through  620 ); this process may be assisted by parsing class definitions and having the composer point to the right operations. The examples in  FIGS. 11A and 11B  show signatures that might exist for two candidate software resources for a credit card processing operation. The example in  FIG. 11C  shows a sample signature that might be designed as a superset which includes all parameters for both possible candidates. The manner in which a nm-time mapping of input parameter values to the parameters required by the selected resource occurs is described below. 
   In preferred embodiments, a WSFL “flow model” is used to persistently store the new service composition. Thus, the flow model of the newly-composed web service is created (Block  720 ). This flow model is transmitted as a document accompanying the UDDI publish message for the new web service (Block  730 ), after which the new web service becomes automatically available to service requesters (such as other business units of an organization or its business partners). A WSFL flow model is a markup language specification of the execution sequence of the functionality provided by the web service which has been composed as a directed graph (where the directed graph was constructed during execution of Block  700 ). See section 8.4, “The Flow Models for Airline and Agent”, in the WSFL specification for examples of flow models and their syntax. The WSFL specification provides a thorough description of the syntax requirements for flow models, and that discussion is not repeated herein. 
   The flow model used with the present invention may be programmatically constructed using the logic shown in  FIG. 12 , as will now be described. 
   The flow model construction process, wherein the directed graph created by the composer is converted to a WSFL flow model, is shown in  FIG. 12  and begins at Block  1200  by locating the starting node of the graph. A WSFL activity element will be defined for each graph node, or operation, within the composition, as indicated by Block  1210 , beginning from the located starting node. (Refer to the WSFL specification for a detailed description of the syntax of the elements created during the processing of  FIG. 12 .) Block  1220  then checks to see if this graph node has any edges which have not yet been processed. If this test has a positive result, then processing continues at Block  1240  which defines a control link for that edge. Control links will provide the flow between operations, using the WSFL run-time, and thus represent the edges of the composition graph. These links are then weighted with the transition conditions that specify the conditions under which that service interaction will execute (Block  1250 ). Data links are added (Block  1260 ) to the control links, as appropriate, to define the mapping of data between activity operations. Control then returns to Block  1220  to see if this node has any more edges to be processed. 
   When the node&#39;s edges have all been processed, the test in Block  1220  has a negative result and control transfers to Block  1230 , which checks to see if any more nodes exist in the graph which have not yet been processed. If this test has a positive result, control returns to Block  1210  to begin processing the next graph node. Otherwise, the public interface to this service is defined (Block  1270 ) as a collection of the declared operations and port types specified as part of the service provider type. Creation of the flow model document for this service is then complete. 
   Note that while the WSFL run-time provides the means for programmatically constructing a flow model diagram from a directed graph which represents a web service, the present invention extends the existing support by coupling this model with traditional portlet aggregation (that is, aggregating predefined port types, as extended herein to programmatic portlets) and injecting intelligent interface aggregation through external services. (This latter topic is described in more detail below with reference to “convert-lets”.) 
   Returning to the discussion of  FIG. 7 , after publishing the flow model to the registry, at Block  740  the service selection process is performed for a newly-aggregated service. Service selection is the act of binding a portlet (that is, the service provider type defined in the portlet proxy&#39;s service definition) to an actual service provider (or providers) which provides software resources to fulfill that service process. The service selection operation may be performed according to the logic shown in  FIG. 13 , as will now be described. 
   Preferably, the composer uses a toolkit such as WSTK to access a UDDI registry containing information about services that are available for aggregation. In Block  1300 , an identification of the public or private registry to be queried is obtained. The composer may be prompted to enter this information; alternatively, it may be retrieved from a stored location such as a configuration file. The identification of one or more service taxonomies of interest is obtained (Block  1310 ), using similar techniques. The identified registry is then queried (Block  1320 ) for entries matching the selected taxonomy information. In Block  1330 , the tModels of the located entries are checked to select only the registered services which are enabled for and which conform to the deployment (and, optionally, the system) port type(s) of the present invention. 
   Optionally, message mapping is performed in Block  1340  to map messages and their associated data. The mapping provides one portion of the plug link information; the other portion is the locator information discussed below (see Block  1350 ). Message mapping is typically required, and is optional when there is a dual one-to-one correspondence between operations. Mapping may be defined using several techniques, of the type which has been described earlier (such as using XSLT stylesheets, referencing program logic, and so forth). Or, “convert-lets” may be used for performing the mapping; convert-lets are described below with reference to  FIG. 15C . 
   A service locator is defined (Block  1350 ), providing a mechanism to control how the web service intermediary will bind to a web service implementation. This may comprise creating a WSFL locator binding, using a &lt;locator&gt; element to identify a WSDL or WSFL service definition; or, it may comprise creating a UDDI-type binding on a &lt;locator&gt; element. 
   A particular service provider can be selected by the composer as a static binding, for example based upon information obtained from UDDI yellow pages descriptions, for a static development-time binding of the web service intermediary to the service provider. Or, service provider selection can be specified as using a dynamic run-time binding, by using a dynamic locator. Therefore, Block  1360  checks to see if the binding will be static or dynamic. If it is to be dynamic, the selection process will be deferred until run-time, and the composer preferably indicates one or more selection criteria (Block  1370 ) as UDDI service qualifiers to be used in the dynamic binding process. Examples of the semantics of such criteria include: select a service provider using the first hit returned from searching the registry; select a provider randomly; select a service provider that matches specific service qualifiers; etc. An example was previously discussed in terms of matching quality of service criteria for selecting a credit card processing service provider. The &lt;locator&gt; element for a dynamic binding preferably contains query syntax for use with the UDDI find operation, specified as the value of the “selectionPolicy” attribute. (Refer to section 4.4.3, “Service Locators”, of the WSFL specification for more information on defining service locator elements.) 
   At Block  1380 , a plug link is generated for this web service. A WSFL “plug link” is a markup language specification of mappings between the signature of the calling and called service provider operations (that is, between the portlet proxy&#39;s standard interface and the interface of the web service implementation). Section 4.7, “Plug Links”, of the WSFL specification describes plug links in more detail.  FIG. 14  illustrates a sample plug link  1400 . In this example, the plug link specifies that if the “sendForm” message is received to invoke the “send” operation, it is to be mapped onto the “receiveForm” message to invoke the “receive” operation. 
   While plug links are known in the art, their use with portlet proxies is a novel aspect of the present invention. Note, however, that the data mapping support for plug links defined in the WSFL specification provides a relatively restricted form of data mapping. A &lt;map&gt; element is provided, as shown at  1410 , for a &lt;dataLink&gt; element of a flow model, which qualifies how to map one operation&#39;s message to another. The plug link defined by WSFL is limited to specifying a source message, a single target message, a source message attribute, and a single target message attribute. Thus, if one web service returned the markup document  1500  shown in  FIG. 15A , and needed to pass this information to an aggregated web service whose method signature was “submitName (Name: string)”, the existing WSFL syntax allows specification of a mapping that would (for example) pass the value of the &lt;firstName&gt; element from document  1500  as the input parameter to the submitName method. An example &lt;map&gt; element  1520  which may be used within a plug link document to provide this mapping is shown in  FIG. 15B . This is somewhat limiting in that operation attributes might not always map one-to-one, and transformations more complex than identifying an attribute for direct transfer might be necessary. For example, with reference to document  1500 , it might be desirable to concatenate the values of the &lt;firstName&gt; and &lt;lastName&gt; elements for transfer to the next operation. 
   The present invention, on the other hand, leverages the portal platform as an intelligent aggregator for programmatic portlets by extending the &lt;map&gt; element to include a specification of a &lt;converter&gt; attribute, as illustrated in  FIG. 15C . (The &lt;converter&gt; attribute is referenced in the WSFL specification, section 4.5.3, “Data Links and Data Mapping”. However, no information is provided therein as to how this attribute is used or implemented. Instead, the WSFL specification merely mentions that a converter attribute can specify a user-provided function for data mapping and conversion, and then goes on to state that the attribute is not yet supported.) As shown therein, the attribute value is specified as a Uniform Resource Name (“URN”) identifying the portal platform. Since the portlet proxies of the present invention represent a standard interface for a web service aggregated in the portal platform (i.e. a web service intermediary), the portal platform can be used as a repository of portlet-to-portlet operation transformations. These transformations are referred to herein as “convert-lets”, and may be referenced from the URN of a &lt;converter&gt; element. At run-time, the portal platform will automatically select the appropriate convert-let from a portal transformation registry, such as the simplified transformation registry  1600  depicted in  FIG. 16 , and apply the transformation between the web service operations. The transformations specified in this registry (see element  1610 ) may be arbitrarily complex, and may be implemented in a variety of ways. For example, an XSLT stylesheet might be specified, or a piece of code implemented as a JavaBean or perhaps even another portlet proxy (encapsulating a web service) could be specified for performing a transformation. (As will be obvious to one of skill in the art, the sample registry  1600  is merely one example of an approach that may be used for identifying the convert-lets used for converting data. For example, additional information might be contained in the registry, and formats other than the tabular format depicted in  FIG. 16  might be used. In addition, the entries in this registry are not limited to one-to-one mappings: alternatively, a collection or set of “From” portlets and/or “To” portlets might be specified. Furthermore, rules or other criteria for identifying a “From” or “To” portlet might be specified, rather than explicitly identifying the portlets by name.) 
   Optionally, if a transformation between two portlet proxy interfaces does not already exist when those portlet proxies are used in modeling a new web service, as may be determined by consulting a portal platform&#39;s transformation registry, the service composer may be prompted to provide (or identify) an appropriate convert-let. 
   Note that while the processing of  FIG. 13  has been described as an in-line part of creating a new web service (by virtue of the logic of  FIG. 7 ), this processing may also be performed for web services that have already been created and stored in the registry, to enable those services to be used according to the present invention by creating a web service intermediary for the existing web service. In this case, the tModel validation of Block  1330  may be bypassed, as the deployment and system tModels will typically have not been created for the registered web service. The deployment port type is provided by mapping the appropriate operations of the web service, as described above with reference to  FIG. 12 . (The composer may specify new operations if the existing web service does not provide the necessary operations. For example, if the web service does not include an operation to retrieve icons which will represent the service on the palette of the composition tool, the composer may add these operations.) If the underlying software resources provide auditing information, the composer may specify a mapping between these operations and the system port type. A WSFL plug link is then generated to represent this mapping and data transfer, as discussed earlier. 
   Returning again to  FIG. 7 , once the service provider selection process of Block  740  is complete, a WSFL “global model” for the service bindings is created (Block  750 ). A WSFL global model is a markup language specification of links between endpoints of web service interfaces, with each link corresponding to one web service&#39;s interaction with another web service&#39;s interface. WSFL plug links are used in the global model to describe the interaction between the portlet proxy and the selected service provider (or, alternatively, a candidate service provider). Section 4.8, “Global Model”, of the WSFL specification describes global models in more detail. 
   The global model (or models, if there is more than one candidate service provider) are published to the registry (Block  760 ), in addition to publishing the flow model at Block  720 , in order to specify binding information for use with the newly-created service composition represented by the flow model. Note that reuse of the flow model for more than one global model allows other service providers to be plug-linked into the service interaction flow through the portlet proxy by substituting a different global model. Additionally, publishing the composition&#39;s flow model in the registry allows for the flow model to be retrieved and decomposed so that elements can be added, removed, or changed (e.g. in a web service composition tool such as that illustrated by  FIG. 5 ) as necessary to create a new web service. (It may be desirable in some cases to prevent this type of decomposition and modification, for example when privacy or security is a concern. For such cases, a capability for privately publishing the flow model may be provided.) 
   Turning now to  FIG. 17 , the automated management of web services which is facilitated by the system port type of the present invention will be described in more detail. The system port type is used at run-time, and enables communication of life cycle events which are necessary for a portlet proxy to operate within a portal platform. These life cycle events include operations such as “spawn” for creating a new instance and “terminate” for terminating an instance. Additional life cycle events include “call”, for executing an instance; “enquire”, for querying the status of an instance; “suspend”, for suspending an instance; and “resume”, for resuming an instance. The WSFL specification describes these six life cycle events in more detail, and existing WSFL support is preferably used for implementing these six life cycle events. (The portal platform calls methods of visual portlets of the prior art for carrying out such events, and the portal platform preferably calls a programmatic portlet according to the present invention in the same manner.) The system port type also allows communication back to the portal platform for performing functions such as reporting of events for a log, reporting information for use in billing for services, reporting of quality of service data, reporting various types of run-time execution errors or other operational events, etc. These reporting-type functions may be referred to as an “auditing” interface of a portlet proxy. In order for this auditing information to be sent to the portal platform, the portlet proxy must have a way to initiate communications with the platform. This type of 2-way communication between a portal platform and a portlet is not available in the prior art. According to the present invention, this communication is made possible by registering the portal platform itself as a web service which is then accessible from a registry. (This registration of the portal platform may occur at any time before the platform begins interacting with programmatic portlets as disclosed herein, and thus this registration has been omitted from  FIG. 17 .) 
   When the portal platform deploys a portlet proxy which includes the system port type, the logic shown in  FIG. 17  may be used to enable communication of data using the portlet proxy&#39;s auditing interface. Beginning in Block  1700 , the portal platform searches the registry for the portlet proxy it wants to communicate with. Preferably, this search looks for a web service having a tModel which specifies the system interface (and optionally the deployment interface) disclosed herein. Upon finding an appropriate web service, the portal platform binds to the system port type of that web service (Block  1710 ). The portal platform can now initiate communications with the portlet proxy. At Block  1720 , the (previously-registered) portal platform programmatically provides its URN to the portlet proxy (for example, by invoking a “setURN” method of the portlet proxy). The portlet proxy then uses this URN to look up the portal platform&#39;s interface (from the portal platform&#39;s information in the registry), as shown in Block  1730 . The portlet proxy then uses the portal platform&#39;s registered information to bind to its system port type (Block  1740 ). At this point, the 2-way communication is established and the portlet proxy can now initiate communications with the portal platform (by programmatically invoking the appropriate operations of the platform). Block  1750  indicates that the portal platform may call life cycle operations of the portlet proxy, such as the “enquire” operation, and Block  1760  indicates that the portlet proxy may also call auditing operations of the portal platform, such as a “logEvent” or “reportUsage” operation which was previously described with reference to  FIG. 4B . 
     FIG. 18  illustrates an overview of the components which have been described herein. A portal platform  1800  includes (or accesses) a transformation registry  1805 , which stores convertlets (i.e. mappings between programmatic portlets). A first programmatic portlet  1820 , which includes a deployment interface  1822 , system interface  1824 , and web service functional interface  1826 , needs to supply information to a second programmatic portlet  1860  which includes similar interfaces  1862 ,  1864 ,  1866 . Presumably, portlet  1820  obtains this data from execution of a first web service  1840 , where plug link  1830  provides for programmatic interactions between portlet  1820  and web service  1840 , and portlet  1860  will pass this data to a second web service  1880 , using plug link  1870  to programmatically interact with web service  1880 . A transformation is required in this example before the data can be passed between the programmatic portlets. This transformation will be performed by convert-let  1850 , which has been programmatically retrieved from the transformation registry  1805 , as shown at  1852 . The WSFL run-time  1810  coordinates and manages these interactions through execution of the flow models and global models which have been created to represent the programmatic portlets  1820 ,  1860  and their interfaces to the web service implementations  1840 ,  1880 , rendering the WSFL markup by flowing the defined work flow and calling the appropriate activities through the defined mappings (or the dynamically-determined mappings specified by convert-lets). 
   As has been demonstrated, the present invention provides advantageous techniques for aggregating, deploying, and managing web services. A dual aggregation model was disclosed, whereby a WSFL run-time provided for modeling aggregation of services was combined with traditional portal aggregation services available through a portal platform (and extended as disclosed herein to address programmatic portlets), thereby providing the “glue” for using programmatic portlets in a portal platform to enable aggregating programmatic portlets in a portal in real-time. The disclosed techniques enable this to occur programmatically, without requiring manual intervention. Programmatic portlets are modeled as web service intermediaries to either local software resources or remote resources, and/or other portlets. Web service models are expressed and published as WSFL flow models, and service providers are linked using WSFL global model expressions. Open standards are leveraged for business process modeling and integration, defining significant advances in the web services field. Note that while particular standards (such as WSFL) have been referenced when describing preferred embodiments, this is for purposes of illustrating the inventive concepts of the present invention. Alternative means for providing the analogous functionality may be used without deviating from the scope of the present invention. 
   As will be appreciated by one of skill in the art, embodiments of the present invention may be provided as methods, systems, or computer program products. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product which is embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and so forth) having computer-usable program code embodied therein. 
   The present invention has been described with reference to flow diagrams and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flow diagram flow or flows and/or block diagram block or blocks. 
   These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flow diagram flow or flows and/or block diagram block or blocks. 
   The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flow diagram flow or flows and/or block diagram block or blocks. 
   While the preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims shall be construed to include the preferred embodiments and all such variations and modifications as fall within the spirit and scope of the invention.