Coherence 5 2 3 – Turn Websites Into Apps Together

Designing a website is no longer a simple task.

Coherence allows you to turn any website into a full-blown Windows appplication in seconds. Simply type in a name, url, and grab a favicon, and your good to go. Step 2/3 Smart Devices. Next, add some smart devices and put your home to work. SmartThings works with a wide range of connected devices, including lights, cameras, locks, thermostats, sensors, and more.

It has evolved from having available just a bunch of elements and experience to have a large set of tools, frameworks, libraries and other components at our disposal.

Nevertheless, there is a notion that hasn't change:

A website must be visually consistent.

All sites have – or at least should have – a unified structure and a visual guide, even those that are apparently simple.

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In the end, a website is an important part of the company branding.

It should be consistent.

Therefore, implementing a guide becomes crucial when it comes to having an aesthetically visual appearance, organized and compatible.

Enter… STYLE GUIDES!

A Style Guide is a series of standards that allow unifying all the visual components of a page, site or web application.

Style guides and visual coherence importance in web design

Take this as an example:

You are the new member of our Front End Development team.

And you are asked to integrate a new section within the web application that is already live.

• Where should you start?
• What elements should be recycled?
• Which sources, effects and other interactions would you have to apply?

A Style Guide helps to solve these types of questions, without having to guess which components to use and waste time in the process.

The components are the key

When creating a Style Guide, it is necessary to take into account the elements and visual behaviors that are constantly repeated in the website/application.

These elements are called components and are crucial when designing and implementing a style guide.

Elements such as:

• text -in block or simple paragraphs-,
• the behavior of links in all their states,
• buttons,
• images,
• navigation menu,
• color palette,
• basic grid, etc.

Are part, or should be part of, that universe of elements or components. Giving us a defined visual block whose elements can be easily reused.

Creating your own style guide for web design

Creating a style guide does not have to be an impossible or hard task.

Following these few steps, you can have a visual guide tailored to your requirements.

Collect basic information:

Start by gathering the basics of your site or web application: the main color palette, the size of the texts, or even the grid you use is a good start.

Select more elements until you have something solid and strong.

Add 'use patterns':

There are elements that have their own behavior. For example, the animation speed of a pop-up, the way in which the navigation menu disappears when sliding down, etc. ( We've got a great article about the imortance of use patterns and usability)

It is important to note all these behaviors since they are part of the dynamics of the website and its visual identity.

Update it regularly:

Wwebsites change constantly due and these changes should be reflected in your style guide.

There can be no place for ambiguity, so it is important to track any changes, however minimal, and update the visual information.

Voilá. Now you can start using your visual guide

Some would say that previously described steps are simple and easy to apply – in theory.

But these steps, alongside with hundreds of projects running at the same time, can be overwhelming, at least at the beginning.

But, if you already decided to try, and managed to do it, congratulations! You already have your first Visual Style Guide…

Now, use it!

The most important thing here is sharing what you have accomplished with the whole team. It is a guide, and therefore it must be recognized as such.

As a first step, everyone involved in the creation and visual implementation must be aware of it. Obviously, this will have many changes, even from the beginning due to the feedback process.

Perhaps an element that has apparently been overlooked is how the presentation of this guide should be. You can choose, if you are a designer, to create a template in your favorite editing program; Photoshop is usually the preferred choice by many.

On the contrary, if you have the ability to write HTML and CSS code, why do not experiment creating a style sheet with all the elements, labels, behaviors and color guides?

This usually becomes really important because, when creating modules with predefined styles, the implementation is usually simple and hassle-free, eliminating unnecessary trauma. The type of trauma that usually arises during the creation of new templates, sections or pages in your websites/applications.

There you have it: a general overview of the creation of a Style Guide.

Remember that this document is a visual guide, an element that can add not only structure to your site/application, but that will give more fluidity in your daily routine as a designer or as a developer; and, in general, to the entire work team.

Translated by Christian Zapata

Note:

This chapter contains the following sections:

Coherence*Web provides session state persistence and management. It is a session management module that uses Coherence caches for storing and managing session data. This chapter describes how to set up and deploy Coherence*Web so that it can be used by applications running on WebLogic Server.

Coherence*Web is an alternative to the WebLogic Server in-memory HTTP state replication services. Consider using Coherence*Web if you are encountering any of these situations:

• Your application works with large HTTP session state objects

• You run into memory constraints, due to storing HTTP session object data

• You want to offload HTTP session storage to an existing Coherence cluster

• You want to share session state across enterprise applications and Web modules

2.1 Overview of the Coherence*Web SPI

Collect basic information:

Start by gathering the basics of your site or web application: the main color palette, the size of the texts, or even the grid you use is a good start.

Select more elements until you have something solid and strong.

Add 'use patterns':

There are elements that have their own behavior. For example, the animation speed of a pop-up, the way in which the navigation menu disappears when sliding down, etc. ( We've got a great article about the imortance of use patterns and usability)

It is important to note all these behaviors since they are part of the dynamics of the website and its visual identity.

Update it regularly:

Wwebsites change constantly due and these changes should be reflected in your style guide.

There can be no place for ambiguity, so it is important to track any changes, however minimal, and update the visual information.

Voilá. Now you can start using your visual guide

Some would say that previously described steps are simple and easy to apply – in theory.

But these steps, alongside with hundreds of projects running at the same time, can be overwhelming, at least at the beginning.

But, if you already decided to try, and managed to do it, congratulations! You already have your first Visual Style Guide…

Now, use it!

The most important thing here is sharing what you have accomplished with the whole team. It is a guide, and therefore it must be recognized as such.

As a first step, everyone involved in the creation and visual implementation must be aware of it. Obviously, this will have many changes, even from the beginning due to the feedback process.

Perhaps an element that has apparently been overlooked is how the presentation of this guide should be. You can choose, if you are a designer, to create a template in your favorite editing program; Photoshop is usually the preferred choice by many.

On the contrary, if you have the ability to write HTML and CSS code, why do not experiment creating a style sheet with all the elements, labels, behaviors and color guides?

This usually becomes really important because, when creating modules with predefined styles, the implementation is usually simple and hassle-free, eliminating unnecessary trauma. The type of trauma that usually arises during the creation of new templates, sections or pages in your websites/applications.

There you have it: a general overview of the creation of a Style Guide.

Remember that this document is a visual guide, an element that can add not only structure to your site/application, but that will give more fluidity in your daily routine as a designer or as a developer; and, in general, to the entire work team.

Translated by Christian Zapata

Note:

This chapter contains the following sections:

Coherence*Web provides session state persistence and management. It is a session management module that uses Coherence caches for storing and managing session data. This chapter describes how to set up and deploy Coherence*Web so that it can be used by applications running on WebLogic Server.

Coherence*Web is an alternative to the WebLogic Server in-memory HTTP state replication services. Consider using Coherence*Web if you are encountering any of these situations:

• Your application works with large HTTP session state objects

• You run into memory constraints, due to storing HTTP session object data

• You want to offload HTTP session storage to an existing Coherence cluster

• You want to share session state across enterprise applications and Web modules

2.1 Overview of the Coherence*Web SPI

The Coherence*Web Service Provider Interface (SPI) consists of the coherence-web-spi.war file. This file must be deployed with the coherence.jar file to enable Coherence*Web functionality in your applications.

In Coherence*Web, the following default cache configurations are defined:

• The Coherence*Web SPI for WebLogic Server is configured with local-storage disabled. The server will serve requests and will not be used to host data. This means a Coherence cache server must be running in its own JVM, separate from the JVM running WebLogic Server.

• The timeout for requests to the cache server to respond is 30 seconds. If a request to the cache server has not responded in 30 seconds, a com.tangosol.net.RequestTimeoutException exception is thrown.

The Coherence caches used by the Coherence*Web SPI are configured by the session-cache-config.xml file. This file is located inside the coherence-web-spi.war file under the WEB-INFclasses directory. Make any cache configuration changes in the session-cache-config.xml file.

If you are deploying the coherence-web-spi.war file as a shared library, copy the updated session-cache-config.xml file to the application's classpath. For example, when using WAR-scoped Coherence*Web, place the session-cache-config.xml file in the application's WEB-INF/classes directory. Similarly, for EAR-scope, place the updated file in the APP-INF/classes directory; for application server-scope, place it on the system classpath. Placing the file in these locations will override the session-cache-config.xml file in the shared library.

Coherence*Web provides several session locking modes to control concurrent access of sessions. Both Coherence*Web and the Coherence*Web SPI employ optimistic locking by default. This allows concurrent access to a session by multiple threads in a single JVM or multiple JVMs while prohibiting concurrent modification. See 'Session Locking Modes' for more information about locking modes.

By itself, the Coherence*Web SPI does not require a load balancer to run in front of the WebLogic Server tier. However, you will require a load balancer if you employ sticky session optimization with any of the non-Optimistic locking modes. The default load balancer enforces HTTP session JVM affinity, however, other load balancing alternatives are available. WebLogic Server ships with several different proxy plug-ins which enforce JVM session stickiness. Documentation for configuring the WebLogic Server proxy plug-in is available at this URL:

2.2 Configuring and Deploying Coherence*Web—Main Steps

Coherence*Web includes a deployable shared library that contains a native plug-in to the WebLogic Server HTTP Session Management interface. The following steps summarize how to prepare your deployments to use Coherence*Web with applications running on WebLogic Server:

1. Download Oracle Coherence to your file system. See 'Download Oracle Coherence'.

2. Modify the web.xml file in the WAR deployment if your application requires advanced configuration for Coherence*Web. 'Configure Coherence*Web' describes the parameters that can be configured for Web applications. The entire set of Coherence*Web parameters are described in Appendix A, 'Coherence*Web Context Parameters.'

3. (Optional) Configure the WebLogic-generated HTTP session cookie parameters in the weblogic.xml or weblogic-application.xml file. See 'Configure the Session Cookies'.

4. (Optional for testing; strongly suggested for production) Start a Cache Server Tier in a separate JVM from the one running WebLogic Server. See 'Start a Cache Server'.

5. Determine the appropriate packaging based on your deployment requirements and follow the packaging instructions. Depending on your version of WebLogic Server, see 'Configure Cluster Nodes'.

2.2.1 Download Oracle Coherence

All of the files needed by Coherence*Web, including the coherence-web-spi.war file, are included in the Coherence distribution.

By default, Coherence 3.6 is installed with WebLogic Server 10.3.4. The default location of the Coherence directory is C:OracleMiddlewarecoherence_3.6. If you are using WebLogic Server 10.3.4, you can download Coherence 3.7 and save it to your file system. Ensure that your applications reference coherence-web-spi.war, coherence.jar, and other library files that are in the Coherence 3.7 distribution.

Similarly, if you are working with WebLogic Server 10.3.3, you might already have Coherence installed in a coherence_3.5 directory. Again, you can download Coherence 3.7 and save it to your file system. Ensure that your applications reference coherence-web-spi.war, coherence.jar, and other library files that are in the Coherence 3.7 distribution.

If you are using WebLogic Server 10.3.2 or earlier, simply download the Coherence distribution to your file system.

Applying Required Software Patches

Some older versions of WebLogic Server require you to apply software patches before you can work with Coherence and Coherence*Web. Table 2-1 identifies the versions of WebLogic Server and their associated patches.

Table 2-1 Required Software Patches for WebLogic Server

You can obtain the patches either through the SmartUpdate utility in the WebLogic Server Administration Console or by going to My Oracle Support.

To use SmartUpdate, see the instructions in the WebLogic Server Administration Console. For production environments, you should review the Smart Update production installation notes.

To use My Oracle Support, go to the My Oracle Support web site.

Select the Patches tab, click on the SimpleSearch link, and on the subsequent screen submit a search for a Patch Number/Name with the appropriate value (for example, 11399293). Download the patch zip file from the displayed results. Instructions for applying the Coherence patch are located in the README.txt included in the patch zip file.

2.2.2 Configure Coherence*Web

The Coherence*Web SPI provides a default configuration that should satisfy most Web applications. Table 2-2 describes only those Coherence*Web context parameters where the default for the SPI version is different from the non-SPI version. Table 2-3 describes the compatibility mode context parameter which is supplied by the SPI. For complete descriptions of all Coherence*Web parameters, see Appendix A, 'Coherence*Web Context Parameters.'

You can also configure the context parameters on the command line as system properties. The system properties have the same name as the context parameters, but the dash (-) is replaced with a period (.). For example, to declare a value for the context parameter coherence-enable-sessioncontext on the command line, enter it like this:

If both a system property and the equivalent context parameter are configured, the value from the system property is used.

Table 2-2 Coherence*Web Context Parameters Configured by the SPI

Table 2-3 describes the coherence-session-weblogic-compatibility-mode context parameter which is specifically provided by the Coherence*Web SPI.

Table 2-3 Context Parameter Provided by the Coherence*Web SPI

Table 2-4 describes the coherence-factory-class context parameter. The default value, which is set by the Coherence*Web SPI, should not be changed.

Table 2-4 Context Parameter Value that Should Not be Changed

2.2.3 Configure the Session Cookies

If you are using Coherence*Web SPI, then WebLogic Server generates and parses the session cookie. In this case, any native Coherence*Web session cookie configuration parameters will be ignored. To configure the session cookies, use the WebLogic-generated HTTP session cookie parameters in the weblogic.xml or weblogic-application.xml files. Table 2-5 describes these parameters.

In this table, Updatable? indicates whether the value of the parameter can be changed while the server is running. Not applicable indicates that there is no corresponding Coherence session cookie parameter.

Table 2-5 WebLogic-Generated HTTP Session Cookie Parameters

2.2.4 Start a Cache Server

A Coherence cache server (also known as a data node) is responsible for storing and managing all cached data. It can be either a dedicated JVM or run within a WebLogic Server instance. The senior node (which is the first node) in a Coherence data cluster can take several seconds to start; the startup time required by subsequent nodes is minimal.

Whether you start the cache servers first or the WebLogic Server instances first, depends on the server topology you are employing:

• If you are using an In-Process topology (all storage-enabled WebLogic Server instances), then it does not matter if you start the cache servers first or WebLogic Server instances first.

• If you are using an Out-of-Process topology (storage-disabled WebLogic Server instances and standalone Coherence cache servers), then start the cache servers first, followed by the WebLogic Server instances. This will ensure that there is minimal (measured in milliseconds) startup time for applications using Coherence. Any additional Web applications that use Coherence are guaranteed not to be the senior data member, so they will have minimal impact on WebLogic Server startup.

  In this topology, if you do not start the cache servers first, Coherence will respond with an error message similar to the following:

2.2.4.1 To Start a Standalone Coherence Data Node

Follow these steps to start a standalone Coherence data node: Pdf to excel converter 6 2 100.

1. Create a script for starting a Coherence data node. The following is a very simple example of a script that starts a storage-enabled cache server. This example assumes that you are using a Sun JVM. See 'JVM Tuning' in Developer's Guide for Oracle Coherence for more information.

   You must include coherence-web.jar and coherence.jar on the classpath. The cache_configuration_file represents the absolute path to the cache configuration file on your file system. For Coherence*Web, this will be the session-cache-config.xml file. Note that the cache configuration defined for the cache server must match the cache configuration defined for the application servers which run on the same Coherence cluster.

   If you have additional Coherence caches running on Coherence*Web, then you must merge the cache configuration information (typically defined in the coherence-cache-config.xml file) with the session configuration contained in the session-cache-config.xml file. The cache and session configuration must be consistent across WebLogic Server and Coherence cache servers. Beatunes 5 1 0 – organize your music collection music.

2. Start one or more Coherence data nodes using the script described in the previous step.

2.2.4.2 To Start a Storage-Enabled or -Disabled WebLogic Server Instance

By default, a Coherence*Web-enabled WebLogic Server instance starts in storage-disabled mode. To start the WebLogic Server instance in storage-enabled mode, follow these steps:

1. Create a script for starting a Coherence data node. This can be similar to the script described in the previous section.

2. Include the command-line property to enable local storage, -Dtangosol.coherence.session.localstorage=true, in the server startup command.

For more information about working with WebLogic Server through the command line, see 'weblogic.Server Command-Line Reference' in Oracle Fusion Middleware Command Reference for Oracle WebLogic Server.

2.2.5 Configure Cluster Nodes

The session management provided by Coherence*Web can have application server-scope, EAR-scope, or WAR-scope. Like Coherence clusters, scoping of Coherence*Web depends on the placement of the coherence.jar file in the classloader's hierarchy. You can find detailed information about each of the scopes in 'Cluster Node Isolation'.

WebLogic Server, versions 10.3.3 and later, provides several features, collectively known as ActiveCache, that allow your applications to more easily interact with the Coherence cache. For a complete discussion of these features see the Using ActiveCache guide.

Some earlier versions of WebLogic Server (such as version 10.3.1 and earlier) might need a software patch to use Coherence and Coherence*Web. To find out if your version of WebLogic Server requires a patch, see 'Applying Required Software Patches'.

The following sections describe how you can configure the different cluster node configurations to run Coherence*Web:

Note:

Coherence 5 2 3 – Turn Websites Into Apps Together App

An example of such an environment might be a deployment where multiple application teams are deploying applications written independently, without carefully coordinating and enforcing their conventions and naming standards. With this configuration, all applications are part of the same cluster—the likelihood of collisions between namespaces for caches, services, and other configuration settings is quite high and could lead to unexpected results.

For these reasons, Oracle Coherence strongly recommends that you use EAR-scoped and WAR-scoped cluster node configurations. If you are in doubt regarding which deployment topology to choose, or if this warning applies to your deployment, then donot choose the application server-scoped cluster node configuration.

2.2.5.1 Configuring Application Server-Scoped Cluster Nodes

If you are adding Coherence*Web for session management to a Coherence cluster, follow these steps:

1. Edit your WebLogic Server system classpath to include the coherence.jar file or copy the JAR file to your $DOMAIN_HOME/lib directory.

2. Use the WebLogic Server Administration Console or the command line to deploy coherence-web-spi.war file as a shared library.

3. Enable Coherence*Web in your Web application.

   Add the library reference code illustrated in Example 2-1 to the weblogic.xml file in each WAR file deployed in the WebLogic Server that intends to use Coherence*Web.

2.2.5.2 Configuring EAR-Scoped Cluster Nodes

If you are using Coherence*Web for session management in EAR-scoped cluster nodes, and your applications are running on WebLogic Server 10.3.2 or earlier, follow these steps:

1. Use the WebLogic Server Administration Console to deploy the coherence.jar and coherence-web-spi.war files as shared libraries to all of the target servers where the application will be deployed. See 'Install a Java EE Library' in Oracle Fusion Middleware Oracle WebLogic Server Administration Console Help for more information.

   If you receive an error when you attempt to deploy coherence.jar through the WebLogic Server Administration Console, you can use WLST commands. See Oracle Fusion Middleware Oracle WebLogic Server Administration Console Help for more information.

2. Reference the coherence.jar file in the weblogic-application.xml file. Store the file in the EAR's META-INF directory.

   Example 2-2 illustrates a weblogic-application.xml file.

   Example 2-2 Coherence JAR Referenced in weblogic-application.xml

3. Reference the coherence-web-spi.war file in the weblogic.xml file.

   Example 2-3 illustrates a weblogic.xml file.

   Example 2-3 Coherence Web SPI WAR Referenced in weblogic.xml

2.2.5.3 Configuring WAR-Scoped Cluster Nodes

If you are using Coherence*Web for session management in WAR-scoped cluster nodes, follow these steps:

1. Use the WebLogic Server Administration Console or the command line to deploy the coherence-web-spi.war file as a shared library to all of the target servers where the application will be deployed. See 'Install a Java EE Library' in the Oracle Fusion Middleware Oracle WebLogic Server Administration Console Help.

2. Add the coherence.jar file to the application. You can do this in any of the following ways:

   • Import coherence.jar file as an optional package in the manifest.mf file of each module that will be using Coherence. Example 2-4 illustrates a manifest.mf file.

     Example 2-4 Manifest File that References the Coherence JAR File

   • Copy the coherence.jar file to the WAR file's WEB-INF/lib directory.

3. If you deploy the coherence-web-spi.war file as a shared library, you must also create a shared library reference by adding the stanza illustrated in Example 2-5 to theweblogic.xml file in the WAR file's WEB-INF directory.

   Example 2-5 Library Reference for a Web Application

Coherence 5 2 3 – Turn Websites Into Apps Together At Home

2.3 Scoping the Session Cookie Path

WebLogic Server and Coherence*Web handle session scoping and the session lifecycle in different ways. This can impact your decision to implement a single sign-on (SSO) strategy for your applications.

By default, WebLogic Server uses the same session ID in every Web application for a given client, and sets the session cookie path to a slash (/). This is a requirement of the WebLogic Server default thin SSO implementation, which is enabled by default. By generating a session cookie with a path of '/', clients always return the same session ID in every request to the server. In WebLogic Server, a single session ID can be mapped to multiple session objects. Each Web application will have a different session object instance even though the session ID is identical (unless session sharing is enabled).

In contrast, Coherence*Web maps a session ID to a single session instance. This means that the behavior of having multiple session instances mapped to the same ID is not replicated by default if an application uses Coherence*Web. Because the session cookie is mapped to '/' by default, a single Coherence*Web session is shared across all Web applications. The default configuration in Coherence*Web is that all session attributes are scoped to a Web application. For most purposes, this single session approach is transparent. The major difference of having a single session across all Web applications is the impact of session invalidation. If Coherence*Web is enabled and you invalidate a session in one Web application, then you invalidate that session in all Web applications that use that session instance. If your Web applications do not use thin SSO, then you can avoid this issue by scoping the session cookie to the Web application path.

Therefore, you have the following options regarding SSO:

• Enable 'WebLogic Server session compatibly mode'. This configuration is set with the coherence-session-weblogic-compatibility-mode parameter and mirrors all of the native WebLogic Server session persistence types: memory (single-server, non-replicated), file system persistence, JDBC persistence, cookie-based session persistence, and in-memory replication (across a cluster). By default, this mode is enabled. See 'Using Sessions and Session Persistence' in Developing Web Applications, Servlets, and JSPs for Oracle WebLogic Server for more information.

• Enable thin SSO functionality. Clients will use a single session across all Web applications. This means that the session life cycle will be inconsistent with all other session persistence types.

• Disable the thin SSO functionality by scoping the session cookie path to the Web application context path. This will allow the session life cycle to be consistent with all other session persistence types.

One advantage of enabling thin SSO with Coherence*Web is that it will work across all Web applications that are using the same Coherence cluster for Coherence*Web. The Coherence cluster is completely independent from the WebLogic Server cluster. The thin SSO functionality can even span multiple domains by enabling cross-domain trust in the WebLogic Server security layer.

Coherence 5 2 3 – Turn Websites Into Apps Together Multiple

2.4 Sharing Coherence*Web Sessions with Other Application Servers

Coherence 5 2 3 – Turn Websites Into Apps Together Work

If you are running Coherence*Web on WebLogic Server and on other application servers within a single cluster, then the session cookies created by WebLogic Server will not be decoded correctly by Coherence*Web on the other servers. This is because WebLogic Server adds a session affinity suffix to the cookie which is not part of the session ID stored in Coherence*Web. The other application servers must remove the WebLogic session affinity suffix from the session cookie value for Coherence*Web to be able to retrieve the session from the Coherence cache.

To strip the WebLogic session affinity suffix from the session cookie, add the coherence-session-affinity-token context parameter to the web.xml file used in the other application servers. Set the parameter value to an exclamation point (!), as illustrated in Example 2-6. The session affinity suffix will be removed from the session cookie when it is processed by the other application server.

See Appendix A, 'Coherence*Web Context Parameters' for more information on the coherence-session-affinity-token context parameter.