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2 // // - ' = ;2 + & $ + 2 $8 ; $ & #2 $2 8; &8 ; #24$ -24 readfile { abrir el archivo; determinar su tamaño; reservar esa cantidad de memoria; leer el archivo a memoria; cerrar el archivo; B B B B B $ errorodetype readfile { initializar errorode = 0; abrir el archivo; if (archivobierto { determinar el tamaño del archivo; if (obtuvemedida { reservar esa cantidad de memoria; if (tengomemoria { leer el archivo a memoria; if (fallalectura { errorode = -1; else { errorode = -2; else { errorode = -3; cerrar el archivo; if (archivonoierra && errorode == 0 { errorode = -4; else { errorode = errorode and -4; else { errorode = -; return errorode; D EFGH B$ - I+ $ readfile { try { abrir el archivo; determinar su tamaño; reservar esa cantidad de memoria; leer el archivo a memoria; cerrar el archivo; catch (fallapertura { catch (falladeterminandomedida { catch (fallareservamemoria { catch (fallalectura { catch (filelosefailed { #24 $ readfile method1 { call method2; method2 { call method3; method3 { call readfile; Imethod1 J

3 1$ method1 { errorodetype error; error = call method2; if (error procesarerror; else seguir; errorodetype method2 { errorodetype error; error = call method3; if (error return error; else seguir; errorodetype method3 { errorodetype error; error = call readfile; if (error return error; else seguir; $ 8 ; 2 4 method1 { try { call method2; catch (exception { doerrorprocessing; method2 throws exception { call method3; method3 throws exception { call readfile; 2 2 J ' 8 ; #2K4-24 L > M 2-2 N 4 catch (InvalidIndexException e { 1 4 catch (rrayexception e { 1 4 catch (Exception e { - + +e + -M 8; 4 8- ; - // // ' 3 // $ $// - $J / INIT INIT EXE / NOK Go / EXE NOK, timeout / EXE / OK BORT BORT / OK / OMMIT OMMIT / TM RM K

4 9 $ J $ +? $ + 1O $ P 0/ INIT INIT EXE / NOK Go / EXE EXE / OK NOK / BORT BORT / OK / PREPRE PREPRE / K P P K / OMMIT OMMIT / TM RM $ $J + $J + $ $ + I 1O? K$ +1>Q 913Q $ 3-3-?$ 913Q $ - & =+ N & N&+& + > ' ' - & 3 2 & ' R(1' 1@ - + '9$ - R4 R43 = SQ 3 = SQ TX X

5 > R > R ' R(1' tx_open 1 tx_close tx_begin 9 0 tx_rollback 3 & tx_commit tx_set_commit_return $0 0> tx_set_transaction_contr 0& & 0 1 ol 0& & tx_set_transaction_timeo $ ut 3 4 tx_info R> R(1' xa_start xa_end xa_prepare xa_commit xa_recover xa_forget ' - 0 > 0/ > 0/ 3 & = 0 ax_reg ' 0 ax_unreg ' > R R$ (->9(? 9-$ U@>$ 1 R R > R 1$ > $$P$ P$ $P 1@12 $ J $ R(1' 1$RR >' >1 R(1' > $> 11>1$322 9&"$ 0 M $M > = M$M M$ 1@1$M RRR(1' 1@1$ >1 $ = $ $ $ 2 ' $ -3 ' / 3 1-1R >$/R(1 R ' $' 1- $? T

6 1- ' $?O - 0&$ P$' Transaction Disabled NotSupported Supported$ Required$ X RequiresNew - + #- utoomplete $ $ 0 2 ontextutilsetomplete ontextutilsetbort - M9 = -M9 $ 2 M'>M'> -M9 + -M9 $ NotSupported RequiredN Supports$ X RequiresNew Mandatory$ $& javaxejbejbontextsetrollbackonly( M9/0 // // Y Design Patterns: Elements of Reusable Object- Oriented Software "#$"$"&"&" '#(#( +, - /0 ' 1 2,/ 3, V

7 4 1, 4,,, 1 " ' = $ -2 # $, $, $, 4-2( 2 N> + X N> " # N> '9 & ( ( $1 N 2 # /-$" X X -" X@-1$ 3-> 3-> 2 $ &'$" #"$#$#" $'$" $' M--/' M--/' ( Intercepting Filter intercepts incoming requests and outgoing responses and applies a filter These filters may be added and removed in a eclarative manner, allowing them to be applied unobtrusively in a variety of combinations fter this preprocessing and/or post-processing is complete, the final filter in the group vectors control to the original target object For an incoming request, this is often a Front ontroller, but may be a View Front ontroller is a container to hold the common processing logic that occurs within the presentation tier and that may otherwise be erroneously placed in a View controller handles requests and manages content retrieval, security, view management, and navigation, delegating to a Dispatcher component to dispatch to a View pplication ontroller centralizes control, retrieval, and invocation of view and command processing hile a Front ontroller acts as a centralized access point and controller for incoming requests, the pplication ontroller is responsible for identifying and invoking commands, and for identifying and dispatching to views ontext Object encapsulates state in a protocol-independent way to be shared throughout your application Using ontext Object makes testing easier, facilitating a more generic test environment with reduced dependence upon a specific container View Helper encourages the separation of formatting-related code from other business logic It suggests using Helper components to encapsulate logic relating to initiating content retrieval, validation, and adapting and formatting the model The View component is then left to encapsulate the presentation formatting Helper components typically delegate to the business services via a Business Delegate or an pplication Service, while a View may be composed of multiple subcomponents to create its template omposite View suggests composing a View from numerous atomic pieces Multiple smaller views, both static and dynamic, are pieced together to create a single template The Service to orker and Dispatcher View patterns represent a common combination of other patterns from the catalog The two patterns share a common structure, consisting of a controller working with a Dispatcher, Views, and Helpers Service to orker and Dispatcher View have similar participant roles, but differ in the division of labor among those roles Unlike Service to orker, Dispatcher View defers business processing until view processing has been performed Business Delegate reduces coupling between remote tiers and provides an entry point for accessing remote services in the business tier Business Delegate might also cache data as necessary to improve performance Business Delegate encapsulates a Session Façade and maintains a oneto-one relationship with that Session Façade n pplication Service uses a Business Delegate to invoke a Session Façade Service Locator encapsulates the implementation mechanisms for looking up business service components Business Delegate uses a Service Locator to connect to a Session Façade Other clients that need to locate and connect to Session Façade, other business-tier services, and web services can use a Service Locator M--/' ( Session Façade provides coarse-grained services to the clients by hiding the complexities of the business service interactions Session Façade might invoke several pplication Service implementations or Business Objects Session Façade can also encapsulate a Value List Handler pplication Service centralizes and aggregates behavior to provide a uniform service layer to the business tier services n pplication Service might interact with other services or Business Objects n pplication Service can invoke other pplication Services and thus create a layer of services in your application Business Object implements your conceptual domain model using an object model Business Objects separate business data and logic into a separate layer in your application Business Objects typically represent persistent objects and can be transparently persisted using Domain Store omposite Entity implements a Business Object using local entity beans and POJOs hen implemented with bean-managed persistence, a omposite Entity uses Data ccess Objects to facilitate persistence The Transfer Object pattern provides the best techniques and strategies to exchange data across tiers (that is, across system boundaries to reduce the network overhead by minimizing the number of calls to get data from another tier The Transfer Object ssembler constructs a composite Transfer Object from various sources These sources could be EJB components, Data ccess Objects, or other arbitrary Java objects This pattern is most useful when the client needs to obtain data for the application model or part of the model The Value List Handler uses the GoF iterator pattern to provide query execution and processing services The Value List Handler caches the results of the query execution and return subsets of the result to the clients as requested By using this pattern, it is possible to avoid overheads associated with finding large numbers of entity beans The Value List Handler uses a Data ccess Object to execute a query and fetch the results from a persistent store Data ccess Object enables loose coupling between the business and resource tiers Data ccess Object encapsulates all the data access logic to create, retrieve, delete, and update data from a persistent store Data ccess Object uses Transfer Object to send and receive data Service ctivator enables asynchronous processing in your enterprise applications using JMS Service ctivator can invoke pplication Service, Session Façade or Business Objects You can also use several Service ctivators to provide parallel asynchronous processing for long running tasks Domain Store provides a powerful mechanism to implement transparent persistence for your object model It combines and links several other patterns including Data ccess Objects eb Service Broker exposes and brokers one or more services in your application to external clients as a web service using XML and standard web protocols eb Service Broker can interact with pplication Service and Session Façade eb Service Broker uses one or more Service ctivators to perform asynchronous processing of a request " $ # 9& $ (> ' ( begin(transaction read(pregunta if (sé (pregunta { write (respuesta commit (transaction else abort (transaction D