Arcitura Education SOA Design & Architecture Lab S90.09 Exam Questions

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Total 40 questions

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Question 1

Service Consumer A sends Service A a message containing a business document (1). The business document is received by Component A, which keeps the business document in memory and forwards a copy to Component B (3). Component B first writes portions of the business document to Database A (4). Component B writes the entire business document to Database B and then uses some of the data values from the business document as query parameters to retrieve new data from Database B (5). Next, Component B returns the new data back to Component A (6), which merges it together with the original business document it has been keeping in memory and then writes the combined data to Database C (7). The Service A service capability invoked by Service Consumer A requires a synchronous request-response data exchange. Therefore, based on the outcome of the last database update, Service A returns a message with a success or failure code back to Service Consumer A (8). Databases A and B are shared and Database C is dedicated to the Service A service architecture.

There are several problems with this architecture: First, the response time of Database A is often poor, resulting in Component B taking too much time to provide a response to Component A . This results in Component A consuming too many runtime resources while it holds the business document in memory and it also causes unreasonable delays in responding to Service Consumer A . Additionally, Database B is being replaced with a different database product that supports a proprietary file format. This will disable the current interaction between Component B and the new Database B . What steps can be taken to solve these problems?

AThe State Repository pattern is applied so that Component A can defer the business document data to a state database while it waits for a response from Component B . The Service Data Replication pattern is applied so that Component B can interact with a database that is replicated from the shared Database A . This will improve performance and reliability that will affect both Component A and Service Consumer A . Finally, the Legacy Wrapper pattern is applied so that Database B is wrapped in a standardized contract. This will establish a new wrapper utility service that will allow Database B to be replaced with a different database product without affecting Service A . Furthermore, the Data Format Transformation pattern can be applied within the new wrapper utility service to enable it to convert to and from the new proprietary file format.

BThe State Repository pattern is applied so that Component A can defer the business document data to a state database while it waits for a response from Component B . The Asynchronous Queuing pattern can be applied so that a messaging queue is established between Service Consumer A and Service A, thereby guaranteeing delivery and avoiding Service Consumer A from being tied up too long waiting for Service A to respond. Finally, the Data Format Transformation pattern can be applied to enable Component B to convert to and from the new proprietary file format introduced by the database product that is replacing Database B .

CThe Legacy Wrapper pattern is applied so that Database B is wrapped in a standardized contract. This will establish a new wrapper utility service that will allow Database B to be replaced with a different database product without affecting Service A . The Data Format Transformation pattern can be applied within the new wrapper utility service to enable it to convert to and from the new proprietary file format. The Service Data Replication pattern is applied so that Component B can interact with a database that is replicated from the shared Database B, regardless of what database product is used to replace Database B . The Service Abstraction principle can be further applied to hide the implementation details, including the changes mentioned in this solution, from Service Consumer A .

DNone of the above.

Answer : A

Question 2

Service Consumer A sends a message with a business document to Service A (1), which writes the business document to Database A (2). Service A then forwards the business document to Service B (3), which writes the business document to Database B (4). Service B then responds to Service A with a message containing a failure or success code (5) after which Service A responds to Service Consumer A with a message containing a failure or success code (6). Upon receiving the message, Service Consumer A updates a log table in Database B (7). The log entry is comprised of the entire business document. Database A is dedicated to the Service A service architecture and Database B is a shared database.

You are told that the database updates performed by Service A and Service B must be either both successful or they cannot happen at all. The database update performed by Service Consumer A must happen after it is given the outcome of the database updates performed by Service A and Service B . Given that Service Consumer A must also update Database B as part of this service composition architecture, how is it possible to fulfill these requirements?

AThe State Repository pattern can be applied so that Service A writes the business document data to a separate state database until it receives a response message from Service B . If the response message contains a success code, Service A writes the business document to Database A . If the response contains a failure code, Service A discards the data that was written to the state database.

BThe Service Data Replication pattern can be applied to Service Consumer A and Service B so that separate dedicated databases can be established allowing Service Consumer A to make updates independently of Service B . Service A is simply redesigned to not write the business document to Database A until after it receives a message containing a success code from Service B .

CThe Atomic Service Transaction pattern can be applied to encompass Service A, Service B and Service Consumer A . This will guarantee that all of the actions performed by the service composition participants will either be successful or will be rolled back if anyone is not successful.

DNone of the above.

Answer : D

Question 3

Service A is a task service that sends Service B a message (2) requesting that Service B return data back to Service A in a response message (3). Depending on the response received. Service A may be required to send a message to Service C (4) for which it requires no response. Before it contacts Service B, Service A must first retrieve a list of code values from its own database (1) and then place this data into its own memory. If it turns out that it must send a message to Service C, then Service A must combine the data it receives from Service B with the data from the code value list in order to create the message it sends to Service C . If Service A is not required to invoke Service C, it can complete its task by discarding the code values. Service A and Service C reside in Service Inventory A . Service B resides in Service Inventory B . You are told that the services in Service Inventory A were designed with service contracts based on different design standards than the services in Service Inventory B . As a result, Service A and Service B use different data models to represent the data they need to exchange. Therefore, Service A and Service B cannot currently communicate. Furthermore, Service C is an agnostic service that is heavily accessed by many concurrent service consumers. Service C frequently reaches its usage thresholds during which it is not available and messages sent to it are not received. How can this service composition architecture be changed to avoid these problems?

AThe Data Model Transformation pattern can be applied by establishing an intermediate processing layer between Service A and Service B that can transform a message from one data model to another at runtime. The Intermediate Routing and Service Agent patterns can be applied so that when Service B sends a response message, a service agent can intercept the message and, based on its contents, either forward the message to Service A or route the message to Service C . The Service Autonomy principle can be further applied to Service C together with the Redundant Implementation pattern to help establish a more reliable and scalable service architecture.

BThe Data Model Transformation pattern can be applied by establishing an intermediate processing layer between Service A and Service B that can transform a message from one data model to another at runtime. The Asynchronous Queuing pattern can be applied to establish an intermediate queue between Service A and Service C so that when Service A needs to send a message to Service C, the queue will store the message and retransmit it to Service C until it is successfully delivered. The Service Autonomy principle can be further applied to Service C together with the Redundant Implementation pattern to help establish a more reliable and scalable service architecture.

CThe Data Model Transformation pattern can be applied by establishing an intermediate processing layer between Service A and Service B that can transform a message from one data model to another at runtime. The Intermediate Routing and Service Agent patterns can be applied so that when Service B sends a response message, a service agent can intercept the message and, based on its contents, either forward the message to Service A or route the message to Service C . The Service Statelessness principle can be applied with the help of the State Repository pattern so that Service A can write the code value data to a state database while it is waiting for Service B to respond.

DNone of the above.

Answer : B

Question 4

Service Consumer A sends a message to Service A (1), which then forwards the message to Service B (2). Service B forwards the message to Service C (3), which finally forwards the message to Service D (4). Services A, B, and C each contain logic that reads the content of the message and, based on this content, determines which service to forward the message to. As a result, what is shown in the Figure is one of several possible runtime scenarios.

You are told that the current service composition architecture is having performance problems because of two specific reasons. First, too many services need to be explicitly invoked in order for the message to arrive at its destination. Secondly, because each of the intermediary services is required to read the entire message contents in order to determine where to forward the message to, it is taking too long for the overall task to complete. What steps can be taken to solve these problems without sacrificing any of the functionality that currently exists?

AThe Intermediate Routing pattern can be applied together with the Service Agent pattern in order to establish a set of service agents capable of intercepting and forwarding the message based on pre-defined routing logic. To avoid the need for service agents to read the entire message contents, the Messaging Metadata pattern can be applied so that content relevant to the routing logic is placed in the header of a message. This way, only the message header content needs to be read by the service agents.

BThe Intermediate Routing pattern can be applied together with the Service Agent pattern in order to establish a set of service agents capable of intercepting and forwarding the message based on pre-defined routing logic. To avoid the need for service agents to read the entire message contents, the Rules Centralization pattern can be applied so that content relevant to the routing logic is isolated into a separate Rules service. This way, service agents are only required to access the Rules service in order to determine where to forward messages to. The Standardized Service Contract principle will need to be applied to ensure that the new Rules service and the new service agents provide service contracts that are compliant to existing design standards.

CThe Intermediate Routing pattern can be applied together with the Service Agent pattern in order to establish a set of service agents capable of intercepting and forwarding the message based on pre-defined routing logic. The Service Discoverability principle can be applied to improve the communications quality of message contents, which will reduce the time required by service agents to read the message contents at runtime.

DNone of the above.

Answer : A

Question 5

Service A is a task service that is required to carry out a series of updates to a set of databases in order to complete a task. To perform the database updates Service A must interact with three other services, each of which provides standardized data access capabilities. Service A sends its first update request message to Service B (1), which then responds with a message containing a success or failure code (2). Service A then sends its second update request message to Service C (3), which also responds with a message containing a success or failure code (4). Finally, Service A sends a request message to Service D (5), which responds with its own message containing a success or failure code (6).

You've been asked to change this service composition architecture in order to fulfill a set of new requirements: First, if the database update performed by Service B fails, then it must be logged by Service A . Secondly, if the database update performed by Service C fails, then a notification email must be sent out to a human administrator. Third, if the database update performed by either Service C or Service D fails, then both of these updates must be reversed so that the respective databases are restored back to their original states. What steps can be taken to fulfill these requirements?

AService A is updated to perform a logging routine when Service A receives a response message from Service B containing a failure code. Service A is further updated to send an e-mail notification to a human administrator if Service A receives a response message from Service C containing a failure code. The Atomic Service Transaction pattern is applied so that Services A, C, and D are encompassed in the scope of a transaction that will guarantee that if the database updates performed by either Service C or Service D fails, then both updates will be rolled back.

BThe Compensating Service Transaction pattern is applied to Service B so that it invokes exception handling logic that logs failed database updates before responding with a failure code back to Service A . Similarly, the Compensating Service Transaction pattern is applied to Service C so that it issues an e-mail notification to a human administrator when a database update fails. The Atomic Service Transaction pattern is applied so that Services A, C, and D are encompassed in the scope of a transaction that will guarantee that if the database updates performed by either Service C or Service D fails, then both updates will be rolled back. The Service Autonomy principle is further applied to Service A to ensure that it remains consistently available to carry out this sequence of actions.

CThe Atomic Service Transaction pattern is applied so that Services A, C, and D are encompassed in the scope of a transaction that will guarantee that if the database updates performed by either Service C or Service D fails, then both updates will be rolled back. The Compensating Service Transaction pattern is then applied to all services so that the scope of the compensating transaction includes the scope of the atomic transaction. The compensating exception logic that is added to Service D automatically invokes Service B to log the failure condition and Service C to issue the e-mail notification to the human administrator. This way, it is guaranteed that the compensating logic is always executed together with the atomic transaction logic.

DNone of the above.

Answer : A

Question 6

Answer : H, L, M

Question 7

There are two problems with this service composition architecture that you are asked to address: First, both Service Consumer A and Service B need to transform the business document data from an XML format to a proprietary Comma Separated Value (CSV) in order to write the data to Database B . This has led to redundant data format transformation logic that has been difficult to keep in synch when Database B changes. Secondly, Service A is an entity service that is being reused by several other service compositions. It has lately developed reliability problems that have caused the service to become unavailable for extended periods. What steps can be taken to solve these problems?

AThe Legacy Wrapper pattern can be applied so that data access to Database B is separated into a new wrapper utility service. This way, the Data Format Transformation pattern only needs to be applied within the logic of this new service which will expose a standardized contract that both Service Consumer A and Service B can access. The Asynchronous Queuing pattern can be applied so that messaging queues are established between Service Consumer A and Service A and between Service A and Service B . The Service Autonomy principle can be further applied to Service A in order to establish a more isolated and reliable surrounding infrastructure.

BThe Legacy Wrapper pattern can be applied so that data access to Database B is separated into a new wrapper utility service. This way, the Data Format Transformation pattern only needs to be applied within the logic of this new service which will expose a standardized contract that both Service Consumer A and Service B can access. The Reliable Messaging pattern can be applied so that acknowledgements are passed between Service Consumer A and Service A and between Service A and Service B . The Service Compos ability principle can be further applied to Service A in order to optimize its service architecture for improved participation in multiple service compositions.

CThe service composition can be redesigned with the application of the Contract Centralization pattern so that instead of writing the business document to Database B, Service Consumer A sends the business document to Service B instead. This way, Service B would provide the only location where data format transformation logic for Database B needs to be carried out, which further supports the application of the Service Reusability principle. The Reliable Messaging pattern can be applied so that acknowledgements are passed between Service Consumer A and Service A and between Service A and Service B . The Service Compos ability principle can be further applied to Service A in order to optimize its service architecture for improved participation in multiple service compositions.

DNone of the above.

Answer : A