Liferay Interview Questions
1) What are the
various ways in which you can customize the default behavior of Liferay that
ships to you?
Ans) One can customize Liferay by writing:
Portlets
Themes
Layout Templates
Hooks
Ans) One can customize Liferay by writing:
Portlets
Themes
Layout Templates
Hooks
EXT
2) What is the difference between a Liferay Hook and Liferay EXT?
Ans:Hook:
Hooks is a feature to catch hold of the properties and JSP files into an instance of the portal as if catching them with a hook. Hook plugins are more powerful plugins that come to complement portlets, themes, layout templates, and web modules. A hook plugin is always combined with a portlet plugin. For instance, the portlet social-portlet is a portlet plugin for Social Office with hooks. In general, hooks would be very helpful tools to customize the portal without touching the code part of the portal. In addition, you would use hooks to provide patches for the portal systems or social office products.
source:Liferay Portal 6 Enterprise Intranets
2) What is the difference between a Liferay Hook and Liferay EXT?
Ans:Hook:
Hooks is a feature to catch hold of the properties and JSP files into an instance of the portal as if catching them with a hook. Hook plugins are more powerful plugins that come to complement portlets, themes, layout templates, and web modules. A hook plugin is always combined with a portlet plugin. For instance, the portlet social-portlet is a portlet plugin for Social Office with hooks. In general, hooks would be very helpful tools to customize the portal without touching the code part of the portal. In addition, you would use hooks to provide patches for the portal systems or social office products.
source:Liferay Portal 6 Enterprise Intranets
EXT:
EXT is used to customize and extend the Liferay portal. EXT builds a new ROOT webapp and replaces by a huge build mechanism your existing Liferay portal.
The Liferay EXT Environment is where you would ideally make changes to the portal itself. In other words, this is where you customize or “extend” the portal. You may ask, “Why can’t we just make the changes to the portal source directly?” The answer is that you technically CAN, but if and when you have to upgrade, you will have a tough time sorting out what is out-of-the-box and what is customized. EXT Environment keeps things separate.
EXT is used to customize and extend the Liferay portal. EXT builds a new ROOT webapp and replaces by a huge build mechanism your existing Liferay portal.
The Liferay EXT Environment is where you would ideally make changes to the portal itself. In other words, this is where you customize or “extend” the portal. You may ask, “Why can’t we just make the changes to the portal source directly?” The answer is that you technically CAN, but if and when you have to upgrade, you will have a tough time sorting out what is out-of-the-box and what is customized. EXT Environment keeps things separate.
3) Suppose I want to
customize the behavior of Calendar portlet that comes out of the box with
Liferay, how can I do that?
Ans: The behavior of Calendar portlet can be modified using EXT or write a separate Calendar portlet meeting the user requirements.
Ans: The behavior of Calendar portlet can be modified using EXT or write a separate Calendar portlet meeting the user requirements.
4) How will you
configure Liferay to authenticate users from LDAP?
Ans: Go to configuring liferay with LDAP
Ans: Go to configuring liferay with LDAP
5) What is inter portlet
communication and how can that be achieved?
Ans: Inter portlet communication (IPC) was introduced in JSR 286
More reading:
http://www.liferay.com/web/james.min/blog/-/blogs/241107
http://www.liferay.com/community/wiki/-/wiki/Main/Inter-portlet+communication
Ans: Inter portlet communication (IPC) was introduced in JSR 286
More reading:
http://www.liferay.com/web/james.min/blog/-/blogs/241107
http://www.liferay.com/community/wiki/-/wiki/Main/Inter-portlet+communication
6) What is the
difference between view and edit modes of a portlet?
Ans: view mode is what is displayed a user logs in to the liferay portal and various portlets are displayed to him.
edit mode is the configuration options that are displayed when the edit button is clicked on the portlet.
Ans: view mode is what is displayed a user logs in to the liferay portal and various portlets are displayed to him.
edit mode is the configuration options that are displayed when the edit button is clicked on the portlet.
7) What is service.xml
and how will you use Liferay service builder?
Ans: service.xml is a configuration file which consists the details for database entities that are used in a portlet. The service builder uses the service.xml to generate the DAO/DTO classes for a portlet.
service.xml is also used by the Liferay server to create the database tables and columns for entities mentioned in service.xml.
Ans: service.xml is a configuration file which consists the details for database entities that are used in a portlet. The service builder uses the service.xml to generate the DAO/DTO classes for a portlet.
service.xml is also used by the Liferay server to create the database tables and columns for entities mentioned in service.xml.
8 ) Suppose I have a
portlet written for Liferay 5.2.3 and I want to run it on Liferay 6, how can I
do that? What if I get some spring and hibernate related exceptions with
Liferay 6?
Ans: It is very difficult to find the technology updates done in Liferay versions. The plugins SDK was modified in Liferay 6 so if your Liferay 5.3 portlet doesn’t run properly on Liferay 6 then it is better to write a new portlet for Liferay 6 rather than trying to modify the portlet or source code for Liferay 6.
Ans: It is very difficult to find the technology updates done in Liferay versions. The plugins SDK was modified in Liferay 6 so if your Liferay 5.3 portlet doesn’t run properly on Liferay 6 then it is better to write a new portlet for Liferay 6 rather than trying to modify the portlet or source code for Liferay 6.
9) There is a
requirement from the client that out of 4 portlets that you have written only 2
should be visible to a particular category of users. How will you achieve that?
What if some fields in the remaining 2 portlets have also to be controlled
based on user role?
Ans:
Ans:
10) What is the purpose
of portal-ext.properties?
Ans: portal-ext.properties contains various configuration parameters. These settings can be modified or further settings can be added. For example, there is no existing section for database pool in portal-ext.properties but one can add the same as described in question 25.
Ans: portal-ext.properties contains various configuration parameters. These settings can be modified or further settings can be added. For example, there is no existing section for database pool in portal-ext.properties but one can add the same as described in question 25.
11) What steps will you
follow to change the layout and theme of the portal pages?
Ans: Follow this excellent guide for Liferay theme and layout customization
Ans: Follow this excellent guide for Liferay theme and layout customization
12) Suppose I want to
change the background color of the footer in Liferay, what steps should I
follow?
13) Which JSR is being
implemented by Liferay?
Ans: JSR 286 which is the reference for Portals from Oracle.
Ans: JSR 286 which is the reference for Portals from Oracle.
14) What improvements
would you like to see in Liferay 6 portal?
Ans: There is no end to what features a CMS server can provide. For good and valid points read the following which are the changes done in Liferay 6.1.
a) Documents, video, audio, images, and other media types are now stored in a single unified library.
“Speaking my language”—For each document type (i.e., financial report, surveillance video, etc.) administrators can customize metadata (i.e., author, reporting period, etc.) into terms familiar to the end user.
b) Mount multiple repositories (e.g. Liferay, Alfresco, Documentum) while maintaining a common UI.
Website planning and updating made easy—Multiple teams can work on several variations of a site simultaneously (e.g. Halloween, Thanksgiving, Christmas variations) and schedule publication dates for each.
c) Enhanced staging means automatic versioning with history, undo support at the site and page level, and preview based on scheduled publications.
d) Specific pages and page areas can be designated as user customizeable
Dynamic site templates become an option—changes to the parent template force changes on any associated children sites.
e) Users can create Sites without the need to designate ties to Organizations or Communities.
Direct links between web content enables users to specify relationships, such as linking an invitation list to a Christmas party calendar event.
f) Data lists can be published as workflow-enabled forms that capture information such as an RSVP, tasks tracking and managing issues.
g) Open participation is encouraged in 6.1—users who have yet to create Liferay accounts can still rate content and have their say in forums, message boards, and wikis.
Ans: There is no end to what features a CMS server can provide. For good and valid points read the following which are the changes done in Liferay 6.1.
a) Documents, video, audio, images, and other media types are now stored in a single unified library.
“Speaking my language”—For each document type (i.e., financial report, surveillance video, etc.) administrators can customize metadata (i.e., author, reporting period, etc.) into terms familiar to the end user.
b) Mount multiple repositories (e.g. Liferay, Alfresco, Documentum) while maintaining a common UI.
Website planning and updating made easy—Multiple teams can work on several variations of a site simultaneously (e.g. Halloween, Thanksgiving, Christmas variations) and schedule publication dates for each.
c) Enhanced staging means automatic versioning with history, undo support at the site and page level, and preview based on scheduled publications.
d) Specific pages and page areas can be designated as user customizeable
Dynamic site templates become an option—changes to the parent template force changes on any associated children sites.
e) Users can create Sites without the need to designate ties to Organizations or Communities.
Direct links between web content enables users to specify relationships, such as linking an invitation list to a Christmas party calendar event.
f) Data lists can be published as workflow-enabled forms that capture information such as an RSVP, tasks tracking and managing issues.
g) Open participation is encouraged in 6.1—users who have yet to create Liferay accounts can still rate content and have their say in forums, message boards, and wikis.
15) There are 1000 users
using the portlet developed by you, how will you take care of transaction
management.
Ans: There is no need to worry about transaction management when using the Liferay server. The server itself takes care of transactions. The code generated using Service Builder can also be used with the need to think about transaction management.
Ans: There is no need to worry about transaction management when using the Liferay server. The server itself takes care of transactions. The code generated using Service Builder can also be used with the need to think about transaction management.
16) A client has two
different portal applications for Sales and HR department. The client wants to
run these portal applications on same server but with separate URL’s like
http://: /sales and http://: /hr. How will you achieve that?
Ans: Two instances of the server can be made to run on single machine which will make the two instances to run on different ports but with same IP address. The configuration for running multiple Liferay servers on single machine is dependent upon the server being used like Tomcat, JBoss and GlassFish etc.
The steps to run multiple Tomcat instances on Linux are given here.
Ans: Two instances of the server can be made to run on single machine which will make the two instances to run on different ports but with same IP address. The configuration for running multiple Liferay servers on single machine is dependent upon the server being used like Tomcat, JBoss and GlassFish etc.
The steps to run multiple Tomcat instances on Linux are given here.
17) What are the minimum
Java methods one needs to override in order to write a portlet?
Ans: One needs to override the doView(RenderRequest renderRequest, RenderResponse renderResponse) method after overriding the MVCPortlet class.
Ans: One needs to override the doView(RenderRequest renderRequest, RenderResponse renderResponse) method after overriding the MVCPortlet class.
18) How will you make the
user to go from one JSP to another JSP page in a portlet?
Ans: The hyper links to other JSP pages should be encoded using renderURL tags as shown below:
Ans: The hyper links to other JSP pages should be encoded using renderURL tags as shown below:
The use of these render
tags causes the next JSP page to open within the portlet window. If the links
don’t use render tags then the next JSP will open in a new window/tab in the
web browser.
19) While building a
service using service builder, what is the purpose of specifying
remoteservice=true in service.xml?
20) How to control the
category in which the liferay portlet created by me will be displayed?
Ans: The category of liferay portlet can be controlled by using liferay-display.xml. The category is configured by adding the following:
Ans: The category of liferay portlet can be controlled by using liferay-display.xml. The category is configured by adding the following:
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<display>
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<category name="category.admin">
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<portlet id="9" ></portlet>
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<portlet id="40" ></portlet>
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<portlet id="79" ></portlet>
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<portlet id="80" ></portlet>
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</category>
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<category name="category.cms">
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<category name="category.alfresco">
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<portlet id="91" ></portlet>
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</category>
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</category>
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...
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<display>
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21) What is hot
deployment feature of Liferay? Where will you place your portlets for them to
be deployed without server restart?
Ans: Hot deployment of Liferay portlets allows one to deploy/re-deploy portlets without the need to restart the Liferay server. For hot deployment one can use the deploy target of ANT build script that ships with Liferay or use Eclipse plugin which also internally uses this ANT script.
Ans: Hot deployment of Liferay portlets allows one to deploy/re-deploy portlets without the need to restart the Liferay server. For hot deployment one can use the deploy target of ANT build script that ships with Liferay or use Eclipse plugin which also internally uses this ANT script.
22) Does Liferay support
email notifications out of the box for portlets involving workflow?
23) What is the purpose
of mode and persistence packages which are created by the Liferay service
builder?
24) If there are 3
portlets and all of them need to talk to different database systems (say
MysSQL, Oracle and SQL Server) because of some legacy application requirements.
How will you make them connect to different databases?
Ans: Liferay server doesn’t support multiple database connectivity out of the box. One needs to use JDBC or other database interaction technologies in order to use different databases for various portlets.
Ans: Liferay server doesn’t support multiple database connectivity out of the box. One needs to use JDBC or other database interaction technologies in order to use different databases for various portlets.
25) Can you configure
the database connection pool created by Liferay?
Ans: One can configure database connection pool by editing portal-ext.properties by adding the following snipped. The portal-ext.properties file is present in /webapps/ROOT/WEB-INF/classes/
Ans: One can configure database connection pool by editing portal-ext.properties by adding the following snipped. The portal-ext.properties file is present in /webapps/ROOT/WEB-INF/classes/
XML | copy code | ?
# Liferay can use C3PO, DBCP, or Primrose
for connection pooling. See
# com.liferay.portal.dao.jdbc.util.DataSourceFactoryBean
for the actual
# implementation. It is important to
understand the strengths and weaknesses
# of each provider so that you can choose
the best one that fits your
# deployment scenario. Provider specific
properties can also be passed along
# directly to the provider. For example,
the property
# "jdbc.default.acquireIncrement"
is read by C3PO, the property
# "jdbc.default.maxActive" is
read by DBCP, and the property
# "jdbc.default.base" is read by
Primrose.
#
# The default provider is C3PO.
#
jdbc.default.liferay.pool.provider=c3po
#jdbc.default.liferay.pool.provider=dbcp
#jdbc.default.liferay.pool.provider=primrose
#
# The following properties will be read by
C3PO if Liferay is configured to
# use C3PO in the property
"jdbc.default.liferay.pool.provider". See
#
http://www.mchange.com/projects/c3p0/index.html#configuration for a list
# of additional fields used by C3PO for
configuring database connections.
#
jdbc.default.acquireIncrement=5
jdbc.default.connectionCustomizerClassName=com.liferay.portal.dao.jdbc.pool.c3p0.PortalConnectionCustomizer
jdbc.default.idleConnectionTestPeriod=60
jdbc.default.maxIdleTime=3600
jdbc.default.maxPoolSize=100
jdbc.default.minPoolSize=10
jdbc.default.numHelperThreads=3
#jdbc.default.transactionIsolation=1
#
# The following properties will be read by
DBCP if Liferay is configured to
# use DBCP in the property
"jdbc.default.liferay.pool.provider". See
#
http://commons.apache.org/dbcp/configuration.html for a list of additional
# fields used by DBCP for configuring
database connections.
#
#jdbc.default.defaultTransactionIsolation=READ_UNCOMMITTED
jdbc.default.maxActive=100
jdbc.default.minIdle=10
jdbc.default.removeAbandonedTimeout=3600
#
# The following properties will be read by
Primrose if Liferay is configured
# to use Primrose in the property
"jdbc.default.liferay.pool.provider". See
# http://www.primrose.org.uk/primrose3/primroseConfig.html
for a list of
# additional fields used
by Primrose for configuring database connections.
# jdbc.default.base=100
#jdbc.default.connectionTransactionIsolation=TRANSACTION_READ_UNCOMMITTED
jdbc.default.idleTime=1800000
jdbc.default.numberOfConnectionsToInitializeWith=10
26) Can you list down
various tools and frameworks used by Liferay? e.g. It uses Lucene for search
Ans: One can go through the source code of Liferay and list the toll and technologies being used. I am listing my list here:
Struts, Vaadin, Lucene, Solr, Log4j, ANT, Axis, Apache Commons, Freemarker, EHCache, Hibernate, jFreeChart, JSPWiki, Xerces, Velocity, Spring, SLF4j, Quartz, POI, HyperSonic, Xalan, Ajax, HTML, JavaScript, Java, CSS,
Ans: One can go through the source code of Liferay and list the toll and technologies being used. I am listing my list here:
Struts, Vaadin, Lucene, Solr, Log4j, ANT, Axis, Apache Commons, Freemarker, EHCache, Hibernate, jFreeChart, JSPWiki, Xerces, Velocity, Spring, SLF4j, Quartz, POI, HyperSonic, Xalan, Ajax, HTML, JavaScript, Java, CSS,
27) Suppose a client is
pursuing a Liferay based solution to their requirements, what non-functional
clarifications will you ask from the customer?
Ans: The non-functional requirements to look out for are:
a) Automated Startup on booting server
b) Automated database backup
c) Concurrent access to users
d) Ability to add more user roles
Ans: The non-functional requirements to look out for are:
a) Automated Startup on booting server
b) Automated database backup
c) Concurrent access to users
d) Ability to add more user roles
28) Is there a build
number associated to a portlet assigned by the service builder? Where can we
find the current build number?
29) Have you tried the
Liferay 6 Eclipse plugin? What all limitations have you found?
30) How do you log
events in a portlet? Do I need to configure Log4J for every portlet or is there
a common place where one can configure Log4J so that all Liferay portlets can
use logging API?
31) Do you know how to
update your setup of Liferay 5.2.3 to Liferay 6?
Ans: Liferay website itself lists the steps for upgrading from 5.2.3 to Liferay 6. One should be though aware of how to take database backup and how to patch Liferay in general.
Ans: Liferay website itself lists the steps for upgrading from 5.2.3 to Liferay 6. One should be though aware of how to take database backup and how to patch Liferay in general.
32) Can I run my Struts
1.3 based legacy application as a portlet application? How?
Ans: Yes it is possible to convert legacy application into a portlet by making the legacy application to follow the requirements of a Liferay plugin and then deploying the same on Liferay server.
Ans: Yes it is possible to convert legacy application into a portlet by making the legacy application to follow the requirements of a Liferay plugin and then deploying the same on Liferay server.
33) Is it a good design
to meet the customer requirements by creating a single portlet or splitting
them into multiple portlets? What criteria will you use to split the
functionality into multiple portlets?
Ans: It is better to split multiple requirements into individual portlets and the use inter-portlet communication for meeting the business requirements. The advantage of splitting functionality is enhanced usability, reduced coupling, better maintainability. Using the typical requirements, one can create separate portlets for Create, Modify, View, Delete and Search of each entity but you should have the user in confidence before making any UI decisions.
Ans: It is better to split multiple requirements into individual portlets and the use inter-portlet communication for meeting the business requirements. The advantage of splitting functionality is enhanced usability, reduced coupling, better maintainability. Using the typical requirements, one can create separate portlets for Create, Modify, View, Delete and Search of each entity but you should have the user in confidence before making any UI decisions.
34) What advantages do
you see in running the Liferay portal application on a application server like
JBoss than running it on a web server like Tomcat?
Ans: The decision about using application or web server is totally dependent on the fact that some portlets may be using EJB/JMS and hence would require application server instead of web server. As far as Liferay is concerned, there is no difference in features provided by Liferay depending upon server.
Ans: The decision about using application or web server is totally dependent on the fact that some portlets may be using EJB/JMS and hence would require application server instead of web server. As far as Liferay is concerned, there is no difference in features provided by Liferay depending upon server.
35) What all other
portals have you heard of? How do you compare them to Liferay?
Ans: Other vendors have also rolled out portals which are reference implementation of JSR 286. The list includes:
Apache JetSpeed
JBoss GateIn
Oracle WebLogic Portal
IBM Websphere Portal
SAP NetWeaver
Ans: Other vendors have also rolled out portals which are reference implementation of JSR 286. The list includes:
Apache JetSpeed
JBoss GateIn
Oracle WebLogic Portal
IBM Websphere Portal
SAP NetWeaver
36) How will you
implement i18n in a portal application? What if you want the user to choose his
language preference?
Ans: Follow the excellent guide on Liferay Internationalization
Ans: Follow the excellent guide on Liferay Internationalization
37) There is a portlet
application for managing images similar to Flickr. The user wants to see the
images in full screen. Will Liferay allow you to do that?
Ans: The full screen option can be displayed for any portlet by adding true to the corresponding liferay-portlet.xml of the particular portlet.
Ans: The full screen option can be displayed for any portlet by adding true to the corresponding liferay-portlet.xml of the particular portlet.
38) I have a war file of
the portlet which is created using service builder, what is the difference
between pasting this war file in the deploy folder of Liferay and application
folder of server (like webapps in case of Tomcat)?
Ans: Pasting the portlet in the deploy folder of liferay will cause it to be deployed into the application folder of the server automatically when the server is started.
Copying the portlet war file to application folder of server will also cause the war file to deployed as portlet.
Ans: Pasting the portlet in the deploy folder of liferay will cause it to be deployed into the application folder of the server automatically when the server is started.
Copying the portlet war file to application folder of server will also cause the war file to deployed as portlet.
The only difference is
that the ant script has deploy target which causes the portlet war to be copied
to the deploy folder of liferay server.
39) How will you setup a
clustered Liferay portal on 5 servers available to you?
Ans: Clustering involves not only clustering server but also configuring various services within Liferay. A complete guide for Liferay clustering is available here.
Ans: Clustering involves not only clustering server but also configuring various services within Liferay. A complete guide for Liferay clustering is available here.
40) How much user base
can Liferay support without affecting performance?
Ans: There are official numbers released by Liferay as shown below:
Ans: There are official numbers released by Liferay as shown below:
41) There is a JRE
shipped with Liferay package, do we not need a JDK and what is the purpose of
bundled JRE?
Ans: The JDK is required to create liferay portlets but the JRE is required for running the portlets
Ans: The JDK is required to create liferay portlets but the JRE is required for running the portlets
42) Suppose there is a
requirement from client to implement search functionality in Liferay portlet,
does Liferay provides any API out of the box to support search?
Ans: I have already written a blog post for how to write search functionality in Liferay
Ans: I have already written a blog post for how to write search functionality in Liferay
43) What are the various
ways in which one can override the default behavior of Liferay?
44) The service builder
can also build WSDL for you. What is the benefit of this feature provided by
Liferay?
Ans: Using the build WSDL target of ANT, one can deploy the portlet as a web service. JSR 286 uses the term Web Services for Remote Portals. The steps to create a web service portlet can be found here.
Ans: Using the build WSDL target of ANT, one can deploy the portlet as a web service. JSR 286 uses the term Web Services for Remote Portals. The steps to create a web service portlet can be found here.
45) How will you build a
portlet that can be added only single or multiple times in to the portal
application?
Ans: The instanceable flag should be set to true in liferay-portlet.xml present in the WEB-INF directory of every portlet application.
If the value for this flag is false then a portlet can be added only once in the portal page
Ans: The instanceable flag should be set to true in liferay-portlet.xml present in the WEB-INF directory of every portlet application.
If the value for this flag is false then a portlet can be added only once in the portal page
46) Is it possible to
set a session time out for a portlet which is different from other portlets and
the Liferay portal?
Ans: No every portlet can not be configured to have a different session timeout interval than the portal itself. If a portlet should not work after some amount of inactive time period then it can be managed using Ajax calls and keeping track of inactive time in portlet code.
Ans: No every portlet can not be configured to have a different session timeout interval than the portal itself. If a portlet should not work after some amount of inactive time period then it can be managed using Ajax calls and keeping track of inactive time in portlet code.
47) What is the flow of
HTTP request in Liferay?
48) The JSPPortlet.java
extends the MVCPortlet.java class. What purpose does MVCPortlet.java fulfill?
49) How do you perform
Junit tests on your portlet? How do tackle the dependency on the
MVCPortlet.java?
50) Is it mandatory to
have the view logic in view.jsp? Can one configure some other JSP (say
MyJSP.jsp) to be default view page than view.jsp?
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