Virgo Snaps with Apache Tiles integration

byArek Burdach
May 9, 2011
3 minute read

After smoke tests become time to try using Virgo Snaps in more practical way. In modular application it will be useful to run it with templating framework. According to animal-menu-bar sample it will be better if developer of snap will not know anything about layout of host application and snippets like:

<jsp:include page="/../top.jsp"/>
(...)
<jsp:include page="/../bottom.jsp"/>

will be not necessary to put in snap pages. So lets modify a bit hosts jsps. Template page could look similar to old index.jsp:

<%@ taglib prefix="tiles" uri="http://tiles.apache.org/tags-tiles" %>
<jsp:include page="top.jsp"/>

<tiles:insertAttribute name="body" />

<jsp:include page="bottom.jsp"/>

Now index.jsp should not have includes:

 <p>
 The Snap Menu Bar sample is intended to showcase the ability to dynamically change the content of a menu bar using snaps. Each
 of the snaps that might be displayed in the menu bar includes a top and bottom JSP page and inherits it's styling from the host
 bundle.  Therefore, the snap bundle is only responsible for showing a small subset of content.
 </p>

Template definition should have one template without any attributes (it will be added dynamicly):

<tiles-definitions>
    <definition name="defaultTemplate" template="/template.jsp">
    </definition>
</tiles-definitions>

To dynamic adding this definitions we must implement our TilesView. I’ve used one which is a part of parancoe – Open Source Java Web Framework available on Google Code: http://code.google.com/p/parancoe/source/browse/plugins/parancoe-plugin-tiles/src/main/java/org/parancoe/plugin/tiles/CheapTilesView.java?r=f42be9c3c8e2df436d4970cfdaea1aff73d9cfdb and modify it a bit for our purposes. Most interesting part is:

    protected void renderMergedOutputModel(Map model, HttpServletRequest request,
            HttpServletResponse response)
            throws Exception {

        try {
            super.renderMergedOutputModel(model, request, response);
        } catch (TilesException te) {
            lazyRegisterThanRender(request, response);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    private void lazyRegisterThanRender(HttpServletRequest request, HttpServletResponse response) throws IllegalStateException {
        ServletContext servletContext = getServletContext();
        MutableTilesContainer container = (MutableTilesContainer)
                ServletUtil.getContainer(servletContext);;
        Definition definition = new Definition();

        String[] arr = parsePath(getUrl());
        String subContextPart = arr[0];
        String mainUrlPart    = arr[1];

        definition.setName(getUrl());
        definition.setExtends((String) getAttribute(KEY_DEFAULT_TEMPLATE,
                DEFAULT_DEFAULT_TEMPLATE));
        String attributeList = (String) getAttribute(KEY_DEFAULT_ATTRIBUTES,
                DEFAULT_DEFAULT_ATTRIBUTES);

        String[] attributes = attributeList.split(",");
        if (attributes.length == 1) {
            addAttributeWithPathValueToDefinition(attributes[0], subContextPart, mainUrlPart, definition);
        } else {
            for (String attribute : attributes) {
                addAttributeWithPathValueToDefinition(attributes[0], subContextPart, mainUrlPart + "_" + attribute, definition);
            }
        }

        container.register(definition, request, response);
        container.render(getUrl(), new Object[]{request, response});
    }

How can we see here, lazyRegisterThanRender will be invoked if Tiles will have problems in our case in resolving view name. This method registering new template which extends default one. It also adds attributes taking its values from view name. parsePath parsing path in form: view@snap or only: view:

private String[] parsePath(String path) {
        String[] arr = new String[] {"", ""};
        int indexOfAt = path.indexOf('@');
        if (indexOfAt > 0) {
            arr[0] = '/' + path.substring(indexOfAt+1, path.length());
            arr[1] = path.substring(0, indexOfAt);
        } else {
            arr[1] = path;
        }
        return arr;
    }

In our case will be only body attribute.

To use Tiles we should define tilesConfigurer in spring context. But before this we must declare DispatcherServlet in web.xml which will past requests to our controllers in web.xml:

<servlet>
    <servlet-name>snap</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <load-on-startup>2</load-on-startup>
</servlet>

<servlet-mapping>
    <servlet-name>snap</servlet-name>
    <url-pattern>/*</url-pattern>
</servlet-mapping>

After this simply adding WEB-INF/snap-servlet.xml context of application will be read:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
      http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
      http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
          http://www.springframework.org/schema/osgi http://www.springframework.org/schema/osgi/spring-osgi.xsd"
        default-autowire="byName">

    <bean id="tilesConfigurer" class="org.springframework.web.servlet.view.tiles2.TilesConfigurer">
        <property name="definitions">
            <list>
                <value>/WEB-INF/tiles.xml</value>
            </list>
        </property>
        <property name="useMutableTilesContainer" value="true"/>
    </bean>

    <bean id="tilesViewResolver" class="org.springframework.web.servlet.view.tiles2.TilesViewResolver">
        <property name="attributesMap">
            <map>
                <entry key="CheapTilesView.DEFAULT_TEMPLATE" value="defaultTemplate"/>
                <entry key="CheapTilesView.DEFAULT_ATTRIBUTES" value="body"/>
            </map>
        </property>
        <property name="viewClass" value="CheapTilesView"/>
    </bean>

    <bean class="MainController"/>

</beans>

After this, we must to add templates definitions: lib/tiles-jsp.tld and few entries in template.mf:

Manifest-Version: 1
Bundle-SymbolicName: animal.menu.bar
Bundle-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: Multiple Styles Host
Web-ContextPath: /animal-menu-bar
Import-Library:
 org.springframework.spring;version="[3.0,3.1)"
Import-Bundle:
 com.springsource.org.apache.taglibs.standard;version="[1.1.2,1.3)",
 com.springsource.javax.servlet.jsp.jstl;version="[1.1.2, 1.1.3)",
 org.eclipse.virgo.snaps.api;version="[1.0,2.0)",
 com.springsource.org.apache.tiles;version="2.1.3",
 org.apache.tiles.core;version="2.1.3",
 org.apache.tiles.servlet;version="2.1.3",
 org.apache.tiles.jsp;version="2.1.3"
Import-Package:
 org.eclipse.virgo.snaps.core;version="[1.0,2.0)",
 javax.servlet;version="2.5",
 javax.servlet.http;version="2.5",
 javax.servlet.jsp;version="2.1",
 org.tuckey.web.filters.urlrewrite;version="[3.1.0,3.1.0]",
 org.springframework.js.resource;version="[2.0,2.1)",
 org.springframework.stereotype;version="[3.0,3.1)",
 org.springframework.web.bind.annotation;version="[3.0,3.1)",
 org.springframework.web.servlet;version="[3.0,3.1)",
 org.springframework.web.servlet.view.tiles2;version="[3.0,3.1)",
 org.apache.tiles;version="2.1.3",
 org.apache.tiles.context;version="2.1.3",
 org.apache.tiles.impl;version="2.1.3",
 org.apache.tiles.jsp.context;version="2.1.3",
 org.apache.tiles.mgmt;version="2.1.3",
 org.apache.tiles.renderer.impl;version="2.1.3",
 org.apache.tiles.servlet.context;version="2.1.3"

Our MainController will look like:

@Controller
public class MainController {
    @RequestMapping("/")
    public String rootHandler() {
        return "index";
    }
    @RequestMapping("/index.htm")
    public String snapHandler(@RequestParam("snap") String snap) {
        return "index@" + snap;
    }
}

So we must change top.jsp in host application:

                <snaps:snaps var="snaps">
                    <c:forEach var="snap" items="${snaps}">
                        <li><a href="<c:url value="index.htm?snap=${snap.properties['link.path']}"/>">
                            ${snap.properties['link.text']}</a>
                        </li>
                    </c:forEach>
                </snaps:snaps>

And also in snap.properties of both snaps link.path so it should be equals to snap subcontext (e.g. cat, dog).

After all of this we will have some troubles with resources handling so will be necessary to add urlrewrite filters like it was writed on Rob’s blog about Spring Slices – precursor of Snaps:

Our repository/usr should have:

commons-beanutils-1.8.0.jar
commons-digester-1.8.1.jar
com.springsource.org.apache.commons.collections-3.2.1.jar
com.springsource.org.apache.tiles-2.1.3.jar
com.springsource.org.tuckey.web.filters.urlrewrite-3.1.0.jar
org.eclipse.virgo.snaps.api.jar
org.eclipse.virgo.snaps.core.jar
tiles-core-2.1.3.jar
tiles-jsp-2.1.3.jar
tiles-servlet-2.1.3.jar

which we can copy from maven repository.

Patch with these changes is available on github

Arek Burdach

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Integration testing custom validation constraints in Jersey 2

byPiotr Jagielski
October 26, 2013

I recently joined a team trying to switch a monolithic legacy system into set of RESTful services in Java. They decided to use latest 2.x version of Jersey as a REST container which was not a first choice for me, since I’m not a big fan of JSR-* specs. But now I must admit that JAX-RS 2.x is doing things right: requires almost zero boilerplate code, support auto-discovery of features and prefers convention over configuration like other modern frameworks. Since the spec is still young, it’s hard to find good tutorials and kick-off projects with some working code. I created jersey2-starter project on GitHub which can be used as starting point for your own production-ready RESTful service. In this post I’d like to cover how to implement and integration test your own validation constraints of REST resources.

Custom constraints

One of the issues which bothers me when coding REST in Java is littering your class model with annotations. Suppose you want to build a simple Todo list REST service, when using Jackson, validation and Spring Data, you can easily end up with this as your entity class:

@Document
public class Todo {
    private Long id;
    @NotNull
    private String description;
    @NotNull
    private Boolean completed;
    @NotNull
    private DateTime dueDate;

    @JsonCreator
    public Todo(@JsonProperty("description") String description, @JsonProperty("dueDate") DateTime dueDate) {
        this.description = description;
        this.dueDate = dueDate;
        this.completed = false;
    }
    // getters and setters
}

Your domain model is now effectively blured by messy annotations almost everywhere. Let’s see what we can do with validation constraints (@NotNulls). Some may say that you could introduce some DTO layer with own validation rules, but it conflicts for me with pure REST API design, which stands that you operate on resources which should map to your domain classes. On the other hand - what does it mean that Todo object is valid? When you create a Todo you should provide a description and due date, but what when you’re updating? You should be able to change any of description, due date (postponing) and completion flag (marking as done) - but you should provide at least one of these as valid modification. So my idea is to introduce custom validation constraints, different ones for creation and modification:

@Target({TYPE, PARAMETER})
@Retention(RUNTIME)
@Constraint(validatedBy = ValidForCreation.Validator.class)
public @interface ValidForCreation {
    //...
    class Validator implements ConstraintValidator<ValidForCreation, Todo> {
    /...
        @Override
        public boolean isValid(Todo todo, ConstraintValidatorContext constraintValidatorContext) {
            return todo != null
                && todo.getId() == null
                && todo.getDescription() != null
                && todo.getDueDate() != null;
        }
    }
}

@Target({TYPE, PARAMETER})
@Retention(RUNTIME)
@Constraint(validatedBy = ValidForModification.Validator.class)
public @interface ValidForModification {
    //...
    class Validator implements ConstraintValidator<ValidForModification, Todo> {
    /...
        @Override
        public boolean isValid(Todo todo, ConstraintValidatorContext constraintValidatorContext) {
            return todo != null
                && todo.getId() == null
                && (todo.getDescription() != null || todo.getDueDate() != null || todo.isCompleted() != null);
        }
    }
}

And now you can move validation annotations to the definition of a REST endpoint:

@POST
@Consumes(APPLICATION_JSON)
public Response create(@ValidForCreation Todo todo) {...}

@PUT
@Consumes(APPLICATION_JSON)
public Response update(@ValidForModification Todo todo) {...}

And now you can remove those NotNulls from your model.

Integration testing

There are in general two approaches to integration testing:

test is being run on separate JVM than the app, which is deployed on some other integration environment
test deploys the application programmatically in the setup block.

Both of these have their pros and cons, but for small enough servoces, I personally prefer the second approach. It’s much easier to setup and you have only one JVM started, which makes debugging really easy. You can use a generic framework like Arquillian for starting your application in a container environment, but I prefer simple solutions and just use emdedded Jetty. To make test setup 100% production equivalent, I’m creating full Jetty’s WebAppContext and have to resolve all runtime dependencies for Jersey auto-discovery to work. This can be simply achieved with Maven resolved from Shrinkwrap - an Arquillian subproject:

    WebAppContext webAppContext = new WebAppContext();
    webAppContext.setResourceBase("src/main/webapp");
    webAppContext.setContextPath("/");
    File[] mavenLibs = Maven.resolver().loadPomFromFile("pom.xml")
                .importCompileAndRuntimeDependencies()
                .resolve().withTransitivity().asFile();
    for (File file: mavenLibs) {
        webAppContext.getMetaData().addWebInfJar(new FileResource(file.toURI()));
    }
    webAppContext.getMetaData().addContainerResource(new FileResource(new File("./target/classes").toURI()));

    webAppContext.setConfigurations(new Configuration[] {
        new AnnotationConfiguration(),
        new WebXmlConfiguration(),
        new WebInfConfiguration()
    });
    server.setHandler(webAppContext);

(this Stackoverflow thread inspired me a lot here)

Now it’s time for the last part of the post: parametrizing our integration tests. Since we want to test validation constraints, there are many edge paths to check (and make your code coverage close to 100%). Writing one test per each case could be a bad idea. Among the many solutions for JUnit I’m most convinced to the Junit Params by Pragmatists team. It’s really simple and have nice concept of JQuery-like helper for creating providers. Here is my tests code (I’m also using builder pattern here to create various kinds of Todos):

@Test
@Parameters(method = "provideInvalidTodosForCreation")
public void shouldRejectInvalidTodoWhenCreate(Todo todo) {
    Response response = createTarget().request().post(Entity.json(todo));

    assertThat(response.getStatus()).isEqualTo(BAD_REQUEST.getStatusCode());
}

private static Object[] provideInvalidTodosForCreation() {
    return $(
        new TodoBuilder().withDescription("test").build(),
        new TodoBuilder().withDueDate(DateTime.now()).build(),
        new TodoBuilder().withId(123L).build(),
        new TodoBuilder().build()
    );
}

OK, enough of reading, feel free to clone the project and start writing your REST services!

Custom constraints

@Document
public class Todo {
    private Long id;
    @NotNull
    private String description;
    @NotNull
    private Boolean completed;
    @NotNull
    private DateTime dueDate;

    @JsonCreator
    public Todo(@JsonProperty("description") String description, @JsonProperty("dueDate") DateTime dueDate) {
        this.description = description;
        this.dueDate = dueDate;
        this.completed = false;
    }
    // getters and setters
}

@Target({TYPE, PARAMETER})
@Retention(RUNTIME)
@Constraint(validatedBy = ValidForCreation.Validator.class)
public @interface ValidForCreation {
    //...
    class Validator implements ConstraintValidator<ValidForCreation, Todo> {
    /...
        @Override
        public boolean isValid(Todo todo, ConstraintValidatorContext constraintValidatorContext) {
            return todo != null
                && todo.getId() == null
                && todo.getDescription() != null
                && todo.getDueDate() != null;
        }
    }
}

@Target({TYPE, PARAMETER})
@Retention(RUNTIME)
@Constraint(validatedBy = ValidForModification.Validator.class)
public @interface ValidForModification {
    //...
    class Validator implements ConstraintValidator<ValidForModification, Todo> {
    /...
        @Override
        public boolean isValid(Todo todo, ConstraintValidatorContext constraintValidatorContext) {
            return todo != null
                && todo.getId() == null
                && (todo.getDescription() != null || todo.getDueDate() != null || todo.isCompleted() != null);
        }
    }
}

And now you can move validation annotations to the definition of a REST endpoint:

@POST
@Consumes(APPLICATION_JSON)
public Response create(@ValidForCreation Todo todo) {...}

@PUT
@Consumes(APPLICATION_JSON)
public Response update(@ValidForModification Todo todo) {...}

And now you can remove those NotNulls from your model.

Integration testing

There are in general two approaches to integration testing:

test is being run on separate JVM than the app, which is deployed on some other integration environment
test deploys the application programmatically in the setup block.

    WebAppContext webAppContext = new WebAppContext();
    webAppContext.setResourceBase("src/main/webapp");
    webAppContext.setContextPath("/");
    File[] mavenLibs = Maven.resolver().loadPomFromFile("pom.xml")
                .importCompileAndRuntimeDependencies()
                .resolve().withTransitivity().asFile();
    for (File file: mavenLibs) {
        webAppContext.getMetaData().addWebInfJar(new FileResource(file.toURI()));
    }
    webAppContext.getMetaData().addContainerResource(new FileResource(new File("./target/classes").toURI()));

    webAppContext.setConfigurations(new Configuration[] {
        new AnnotationConfiguration(),
        new WebXmlConfiguration(),
        new WebInfConfiguration()
    });
    server.setHandler(webAppContext);

(this Stackoverflow thread inspired me a lot here)

@Test
@Parameters(method = "provideInvalidTodosForCreation")
public void shouldRejectInvalidTodoWhenCreate(Todo todo) {
    Response response = createTarget().request().post(Entity.json(todo));

    assertThat(response.getStatus()).isEqualTo(BAD_REQUEST.getStatusCode());
}

private static Object[] provideInvalidTodosForCreation() {
    return $(
        new TodoBuilder().withDescription("test").build(),
        new TodoBuilder().withDueDate(DateTime.now()).build(),
        new TodoBuilder().withId(123L).build(),
        new TodoBuilder().build()
    );
}

OK, enough of reading, feel free to clone the project and start writing your REST services!

Virgo Snaps with Apache Tiles integration

Tags:

Arek Burdach

Few thoughts on Crockford's "JavaScript: The Good Parts"

TouK on GitHub Part 1

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