zzPortal: Select Application pattern
http://www.ibm.com/developerworks/patterns/portal/select-application-topology.htmlPortal: Select Application pattern
Overview
After identifying the Business and Integration patterns thatcomprise the Portal composite pattern, the next step in planning ane-business application is to choose the Application pattern(s) thatapply to the business drivers and objectives. An Application patternshows the principal layout of the application, focusing on the shape ofthe application, the application logic, and the associated data.
The selection of an Application pattern is based on the selectedBusiness patterns, Integration patterns, and Composite patterns. TheApplication patterns use logical tiers to illustrate various ways toconfigure the interaction between users, applications and data.
The building of each solution requires that specific businessdrivers be satisfied. There is a high probability that each solutionwill share characteristics with many of the Application patternsmentioned; however, the Application patterns available range fromsimple to more complex. Therefore, chose the simplest Applicationpattern that satisfies the requirements of your business objectives.
Each Application pattern has associated Business and IT drivers. Thearchitect should review each of the Business and IT drivers with theassociated Application pattern to determine the best fit for therequirements.
Recall the Business and Integration patterns identified earlier asthe mandatory building blocks of the Portal composite pattern were:
[*]Access Integration
[*]Self-Service
[*]Collaboration
[*]Information Aggregation
[*]Application Integration
The figure below shows the specific Application patterns that can beused to enable various types of functionality found in each Businessand Integration pattern. Note that some of these Applications aremandatory (blue type) to a properly-functioning Portal, and some areoptional (red type).
Portal application patterns
This figure differs slightly from the original redbook (SG24-6087)because the Dec 2004 re-engineering of the Information Aggregation andData Integration patterns changed some of the Application pattern names.
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Application patterns
Though a complete Portal solution requires multiple Applicationpatterns, each Application pattern can be analyzed individually interms of the functionality it brings to the overall solution, and thebusiness and IT drivers it satisfies. Review the following Applicationpatterns and select those for which you would like to see additionalRuntime information.
Access Integration::Web Single Sign-On application pattern
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The Web Single Sign-On application pattern (as part of the Access Integration pattern) provides a framework for seamless application access through unified authentication services.
Business and IT Drivers
[*]Provide single sign on across multiple applications
[*]Reduce Total Cost of Ownership (TCO)
[*]Reduce user administration cost
The primary business driver for choosing this Application pattern isto provide seamless access to multiple applications with a singlesign-on while continuing to protect the security of enterpriseinformation and applications.
Simplification and increased efficiency of user profile management is the main IT driver for Single Sign-On.
Benefits
[*]Users can access their application portfolio easily and securely
[*]User profile information is centralized in a common directory, simplifying profile management and reducing costs
[*]Application development cost is reduced by providing a standard security solution
Limitations
Many existing applications are not capable of accepting a standardset of user credentials as a substitute for local authentication.Integration with such systems can be difficult or even impossible.
The Portal composite pattern
A fundamental characteristic of a portal implementation is that ofinformation aggregation. In order to enhance this experience for theuser, a Single Sign-On (SSO) solution makes sense. This allows the userto more quickly access the information and avoid worrying about whichapplication they are accessing. It also allows for easiermaintainability by the organization sponsoring the portal.
Single Sign-On functionality requires more than just making surethat the applications that already exist in an enterprise support acentral authentication capability. The existing processes must bechanged to accommodate this new method of validating a user’s accesscapability. An analysis of the existing profiling mechanisms andoverall security policies in a organization is the starting point forthis type of effort.
For more information, please see the IBM Redpaper A Secure Portal Extended With Single Sign-On, REDP-3743.
Access Integration::Pervasive Device Access application pattern
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The Access Integration patternis used to provide consistent access to various applications usingmultiple device types. In order to provide pervasive device access toan existing Business pattern, the Pervasive Device Access applicationpattern adds a new tier to the architecture. This tier is responsiblefor the pervasive extensions to the original application. The functionof this tier is to convert the HTML issued by the applicationpresentation logic into a format appropriate for the pervasive device.In this way, the Pervasive Device Access application pattern provides astructure for extending the reach of individual applications frombrowsers and fat clients to pervasive devices such as PDAs and mobilephones.
Business and IT Drivers
[*]Provide universal access to information and services
[*]Time to Market
[*]Reduce Total Cost of Ownership (TCO)
Striving to provide universal access to information and applicationsis often the primary business driver for choosing this Applicationpattern. The primary IT driver for choosing this Application pattern isto quickly extend the reach of applications to new device types withouthaving to modify every individual application to enable its use byadditional device types.
The Portal composite pattern
The Portal composite pattern supports the use of pervasive deviceaccess. In fact, "any type of device" access is supported through theuse of templates in the pervasive access device tier. At this tier, thesession data containing the type of device is known and the properlyformatted content can be delivered. This formatted content can betranscoded in content management or datasource nodes, or it can betranscoded "dynamically" when requested by a specific type of client.This will depend on the frequency of updates to the data.
It is architecturally sound to separate the storage, management, andtranscoding of content from the presentation of that content. Thismeans that it is best to allow the content management system to reducethe requirements of the Web server tier to the output of this alreadyformatted content.
Access Integration::Personalized Delivery application pattern
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The Access Integration::PersonalizedDelivery application pattern provides a framework for giving access toapplications and information tailored to the interests and roles of aspecific user or group. This Application pattern extends basic usermanagement by collecting rich profile data that can be kept current upto the user’s current session. Data collected can be related toapplication, business, personal, interaction, or access device-specificpreferences.
Business and IT Drivers
The primary business driver for choosing this Application patternis to increase usability and improve the efficiency of Web applicationsby tailoring their presentation to the user’s role, interests, habitsand/or preferences.
Benefits
[*]Users’ interaction with the site is benefited because of increased perception of control and efficiency
[*]Fine-grained control of users’ access to applications is enabled according to role and preferences by the enterprise
[*]Improved user effectiveness is enabled by adapting the complexity and detail of content to a user’s skill level
Limitations
Personalized Delivery can be very complex and expensive to fully implement.
The Portal composite pattern
This Application pattern supports the separation of the businesslogic, business rules, and presentation. Each one of these has part ofthe responsibility for providing the personalized experience to theuser of the portal. The application server handles business logic thatimplements the business rules meta-data contained in thepersonalization server node. Once presentation of the personalized datais required, the presentation server node will access the correctlyformatted and/or aggregated data for display to the portal user.
Self-Service::Directly Integrated Single Channel application pattern
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The Directly Integrated Single Channel application pattern (from the Self-Service business pattern)provides a structure for applications that need one or morepoint-to-point connections with back-end applications but only need tofocus on one delivery channel. This Application pattern can also beused to implement any one of the delivery channels.
Business and IT Drivers
[*]Improve the organizational efficiency
[*]Reduce the latency of business events
[*]Leverage existing skills
[*]Leverage legacy investment
[*]Back end application integration
The primary business driver for choosing this Application pattern isto reduce the latency of business events by providing real-time accessto back-end applications and data from Web applications.
The IT Driver for choosing this Application pattern is to leverage legacy investments and existing skills.
The Portal composite pattern
The Portal composite pattern is involved in the direct connectionbetween the portal user and a back-end application (e.g. Lotus Sametimeor CICS based application). Once the portal user is authenticated viathe directory and security services node and the session level securityin the application server node, the WPS Portlet API will passauthentication credential information to the back-end application ordatasource. Once complete, the user will now have a direct connectionto that application and the portal system will not generally broker thecommunication. This works in most implementations.
As shown in the figure below, the Directly Integrated Single Channelapplication pattern can be used in a variety of ways. For example, theportal application can be more than just green screen scraping withHost on Demand/Host Publisher portlet. The portal application can alsobe a collaboration portlet using collaboration services as well as aroll your own portlet for using Web services.
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Collaboration::Store and Retrieve application pattern
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The Store and Retrieve application pattern (as part of the Collaboration business pattern)allows users to collaborate with others on the network interactively.Unlike the Point-to-Point application pattern, this pattern does notrequire both partners to be online at the same time. It also does notrequire the client to know the physical or direct address of otherusers of the solution.
A common implementation of this pattern is content management.Content Management allows two or more users to interact on a singlepiece "content" (e.g. images, text, other data, etc.) via the contentmanagement mechanism.
Business and IT Drivers
[*]Time to market
[*]Improve the organizational efficiency
[*]Reduce the latency of business events
[*]Easy to adapt during mergers and acquisitions
[*]Require deferred collaboration
[*]Many users
[*]Leverage existing skills
[*]Network addressing independence
[*]Managed service
[*]Maintainability
Guidelines for use
This Application pattern should be used when:
[*]The physical or direct addresses of other clients on the network are not known
[*]The pattern can support both synchronous and asynchronouscommunication. This provides ability to support a wide range ofsolutions from bulletin boards and workrooms to interactive chat rooms
[*]A server can be set up that will allow multiple clients to log inand share information with other users by posting messages on (orsending e-mail to) the server for later retrieval
Benefits
[*]This Application pattern is simple to implement
[*]Since this Application pattern does not require that a client knowthe direct address of the destination, it is ideal for solutions wherethe network addresses are not published or where these addresses changefrequently
[*]Most of the functions of this pattern can be implemented using commercially available collaboration solutions
[*]This pattern requires very minimal custom code and is cost effective to maintain
Limitations
[*]This pattern calls for the implementation of server software andassociated hardware to support new users. This means that this will addto the overall complexity of the solution
[*]The nature and type of collaboration supported by this pattern aresimplistic. For more complex communications, later Application patternsare more appropriate
The Portal composite pattern
The Portal composite pattern supports this through the use of thecontent management and collaboration nodes. Content Management canprovide asynchronous collaboration on content assets or documents andthe collaboration can be in the form of threaded discussion forums orteamrooms where information is shared in a common space.
Collaboration::Directed Collaboration application pattern
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The Collaboration::DirectedCollaboration application pattern allows users to collaborate withothers on the network interactively. This Application pattern requiresthe two interacting users to be online simultaneously. It also requiresusers to register with a server. In this pattern all of the users arepeers and there are no client-server or master-slave relationshipsbetween the tiers in the pattern.
Business and IT Drivers
[*]Time to market
[*]Improve organizational efficiency
[*]Reduce the latency of business events
[*]Easy to adapt during mergers and acquisitions
[*]Require instantaneous collaboration
[*]Many users
[*]Leverage existing skills
[*]Network addressing independence
[*]Managed service
[*]Maintainability
[*]Complex data types
[*]Significant network bandwidth
This approach can be used to quickly establish collaboration betweenusers of a solution without having to go through the process ofdeveloping a lot of custom code. It allows users to simultaneously andinteractively modify shared applications and data.
This pattern requires all the users to register with the server. Theuser’s profile, preferences and security privileges are stored on aserver directory. This means that the client does not need to know thephysical or direct address of other clients. It also allows us toimplement different security levels, and implement more complexcollaboration styles that include sharing applications and complex datatypes.
This is the ideal Application pattern to choose if the current focusis to establish synchronous sophisticated collaboration functionswithin a solution. This solution is also applicable when the clientshave permanent and preferably high-speed network connections. Thesolution is also cost-effective to develop because many of thesefunctions are available in off-the-shelf products.
This pattern is not a good fit for solutions where there are limitations on the processing power of the clients.
The Portal composite pattern
Collaboration in the case of the Portal composite pattern isusually enabled through this type of collaboration. It is generally inthe form of instant messaging because communication is essentially abrokered real-time interaction.
Information Aggregation::User Information Access application pattern
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Business and IT Drivers
[*]Require specialized derived data (e.g. subset, point in time, correlated datat, targeted to user group etc)
[*]Distil meaningful information from a vast amount of sructured and unstructured data
[*]Require R/O access to derived or aggregated data allowing data manipulation under user control
[*]Require option to drill through source data
[*]Require reliable, extended availability of the data
[*]Optimized for future access performance
[*]Require protection of operational system performance
Benefits
The use of read-only data provides for maximum consistency in a multi-user analysis or reporting environment.
Limitations
As mentioned, the vast majority of access to data in the UIApattern is read-only. However, this is really a convention, since UIAproducts and the data access methods they use are fully open toread/write access as well. As shown in the figure above, read/writeaccess, when allowed, should be against data sources that are not ownedor managed by applications. This reduces the risk to data integritysomewhat, but does not eliminate it entirely, depending on how the datasource is maintained.
The Portal composite pattern
The Portal composite pattern supports this through the use of theSearch & Indexing node. For more information on this applicationpattern, please see the IBM Redbook Patterns: Information Aggregation and Data Integration with DB2 Information Integrator, SG24-7101.
Application Integration::Population application pattern
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The Application Integration::Population application pattern structuresthe population of a data-store with data that requires minimaltransformation and restructuring. The Population application pattern isa preparatory step and is not documented to the Runtime pattern levelfor the Portal composite pattern.
Business and IT Drivers
[*]Improve organizational efficiency
[*]Reduce the latency of business events
[*]Distill meaningful information from a vast amount of structure data
[*]Minimize total cost of ownership (TCO)
[*]Promote consistency of Operational Data
[*]Maintainability
The primary business driver for choosing Population is to copy datafrom the source data store to a target data store with minimaltransformation. The main reason for creating a copy of the data is toavoid manipulating the primary source of a company’s operational dataoften maintained by Operational Systems.
The Portal composite pattern
The Portal composite pattern supports this no-transformationpopulation through a centralized database server. However, in manyinstallations, data will be transformed before reaching its finaldestination (e.g. database or file system for serving to the web).
For more information on this application pattern, please see the IBM Redbook Patterns: Information Aggregation and Data Integration with DB2 Information Integrator, SG24-7101.
Application Integration::Population=Multi Step application pattern
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The Information Aggregation::Population=MultiStep application pattern structures the population of a data-store withstructured data that requires extensive reconciliation, transformation,and restructuring.
Business and IT Drivers
[*]Improve organizational efficiency
[*]Reduce the latency of business events
[*]Distill meaningful information from vast amounts of structured data
[*]Extensive reconciliation, transformation, and restructuring of structured data
[*]Minimize total cost of ownership (TCO)
[*]Promote consistency of Operational Data
[*]Maintainability
The primary business driver for choosing Population=Multi Step is toreconcile data from multiple data sources and to transform andrestructure it extensively to enable efficient access to information.
This Application pattern is best suited for the aggregation and distillation of meaningful information from structured data.
Benefits
This is the ideal architecture when the complex transformation ofstructured data between the source and target data store is required.
Limitations
Reconciling data from multiple sources is often a complexundertaking and requires a considerable amount of effort, time, andresources. This is especially true when different systems use differentsemantics.
The Portal composite pattern
The Portal composite pattern supports the iterative transformationof data. This data transformation can take place in the datasourcetier, in the content management node, in the presentation server node,or at the application server node (although this is not a suggestedroute). This pattern supports all of these options.
Application Integration::Population=Multi Step Gather application pattern
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The Data Integration::Population=Multi Step Gather applicationpattern provides a structure for applications that retrieve and parsedocuments and create an index of relevant documents that match aspecified selection criteria. This design is actually a specificinstance of the Population application pattern described above. Inpractice, this design may also extend the Population=Multi Stepapplication pattern, when transformation of data is required. In eithercase, the crawling and discovery mechanisms of this design aggregate aset of unstructured data. This pattern is also useful for solutionswhere there is a need to discovery content expertise within theorganization.
The Population=Multi Step Gather application pattern is apreparatory step and is not documented to the Runtime pattern level forthe Portal composite pattern.
Business and IT Drivers
[*]Improve organizational efficiency
[*]Reduce the latency of business events
[*]Provide easier access to vast amounts of unstructured data through indexing and categorization
[*]Reduce information overload
[*]Identify the experts for collaboration to improve decision cycle times
[*]Reduce knowledge loss from personnel turnover
[*]Help new employees to reduce the learning curve
[*]Minimize total cost of ownership
[*]Promote consistency of Operational Data
[*]Maintainability
The primary business driver for choosing Population=Multi StepGather is to select relevant documents from a vast set of documentsbased on specified selection criteria. The objective is to providequick access to useful information instead of bombarding the user withtoo much information.
Search engines that crawl the World Wide Web implement thisApplication pattern. It is best suited for selecting useful informationfrom a huge collection of unstructured text data. A variation of thisApplication pattern can be used for working with other forms ofunstructured data such as images, audio, and video files.
The Portal composite pattern
In any portal implementation, the ability to locate data andinformation as it is updated in the system is vital. The whole valueproposition depends, in part, on a portal user’s ability to locate theinformation they need. The Portal composite pattern supports thisthrough the Search and Indexing node. This represents both the abilityto "free-text" search or navigate the content (but only that contentthat should be available to the user) and to index the content as it isupdated.
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