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2-Tier,3-Tier datawarehouse Submitted by Manisha Dubey & Akanksha Agrawal 2 tier Architecture A two tier architecture is simply based on client-server architecture. A 2-tier architecture is one which has a client tier, and a database tier. – The database tier manages the database – The client tier is the interface between the user and the system 2 tier Architecture The Client Tier The first tier(Client tier)is the front-end clie nt layer. This layer holds the following tools query tools reporting tools analysis tools data mining tools The Database Server Tier The second tier(Database server) is the b ottom tier of the architecture datawareho use database server It is the relational database system We use the back end tools and utilities to feed data into the bottom tier These backend tools and utilities perform the extract, clean, load, and refresh functions Benefits and Limitation of 2-Tier Architecture Benefits – great for creating applications quickly using visual builder tools thanks to its simplicity – appropriate to departmental applications • e.g.) decision support, small-scale groupware, simple web-based applications Limitations – not mission-critical, not scalable Tier 2 Tier 1 SQL, File Server, HTTP protocol GUI A 2-Tier Client-Server Application Architecture Tier 1 Tier 2 Database(or Other Resource Managers) Tier 3 GUI Application RPCs, Conversations, Queues, Publish-and-Subscribe, Broadcasts, Object invocations A 3-Tier Client-Server Application Architecture Database(or Other Resource Managers) Why 3-Tier Architecture ? Needs of new world’s applications – Business will increasingly compete be being the first to market with new electronic goods and services – Companies will create virtual corporations through alliances with a shifting set of partners – Roles and relationships btw. enterprises will shift frequently as industries realign Why 3-Tier Architecture ? Reasons – Meets the requirements of large-scale internet and intranet client/server applications – Is easier to manage and deploy on the network • most of code runs on the servers, especially with zero-footprint technologies like Java applets – Minimizes network interchanges by creating abstract levels of service – Provides better security • by not exposing the database schema to the client • by enabling more fine-grained authorization on the server System administration Security Encapsulation of data Performance Scale Application reuse Ease of development Table 1-2 2-Tier vs. 3-Tier Client/Server 2-Tier 3-Tier Complex Less Complex (more logic on the client to (the application can be centrally manage) managed on the server – application programs are made visible to standard system management tools) Low High (data-level security) (fine-tuned at the service or method level) Low High (data tables are exposed) (the client invokes services or methods) Poor Good (many SQL statements are sent (only service requests and over the network; selected data responses are sent between client must be downloaded for analysis and server) on the client) Poor Excellent (limited management of client (concentrates incoming sessions; communications links) can distribute loads across multiple servers) Poor Excellent (monolithic application on client) (can reuse services and objects) High Getting Better (standard tools can be used to create the clients and tools are emerging that you can use to develop both the client and server sides of the application) Table 1-2 2-Tier vs. 3-Tier Client/Server 2-Tier 3-Tier Server-to-server infrastructure No Yes (via server-side middleware) Internet support Poor Excellent (Internet bandwidth limitations (thin clients are easier to make it harder to download fat download as applets or beans; clients and exacerbate the already remote service invocations noted limitations) distribute the application load to the server) Legacy application integration No Yes (via gateways encapsulated by services or objects) Heterogeneous database support No Yes (3-tier applications can use multiple databases within the same business transaction) Rich communication choices No Yes (only synchronous, connection- (supports RPC-like calls, but can oriented RPC-like calls) also support connectionless messaging, queued delivery, publish-and-subscribe, and broadcast) Hardware architecture flexibility Limited Excellent (you have a client and a server) (all three tiers may reside on different computers, or the second and third tiers may both reside on the same computer; with component-based environments, you can distribute the second tier across multiple servers as well) Availability Poor Excellent (can’t fail over to a backup (can restart the middle tier server) components on other servers) 3-Tier Architecture It was developed by John J. Donovan in Open Environment Corporation (OEC), a tools company he founded in Cambridge, Massachusetts A three tier architecture typically consist of – Presentation tier Domain logic tier Data storage tier Presentation tier Logic tier Get sales total Total sales Get list of all sales made last year Add all sales togeather Query Data tier Sales 1 … storage database 3-Tier Architecture Three-tier architecture is a client–server architecture in which the user interface(presentation), functional process logic ("business rules"), computer data storage and data access are developed and maintained as independent modules, most often on separate platforms. This is the topmost level of the application. The presentation tier displays information related to such services as browsing merchandise, purchasing and shopping cart contents. It communicates with other tiers by which it puts out the results to the browser/client tier and all other tiers in the network. (In simple terms it is a layer which users can access directly such as a web page, or an operating systems GUI) The logical tier is pulled out from the presentation tier and, as its own layer, it controls an application’s functionality by performing detailed processing. The data tier includes the data persistence mechanisms (database servers, file shares, etc.) The data access layer that encapsulates the persistence mechanisms and exposes the data. The data access layer should provide an Application Programming Interface (API) to the application tier that exposes methods of managing the stored data without exposing or creating dependencies on the data storage mechanisms.