{"id":2425,"date":"2011-05-25T12:46:12","date_gmt":"2011-05-25T17:46:12","guid":{"rendered":"http:\/\/jianmingli.com\/wp\/?p=2425"},"modified":"2011-05-25T12:46:12","modified_gmt":"2011-05-25T17:46:12","slug":"jsr-227-a-standard-data-binding-data-access-facility-for-j2ee","status":"publish","type":"post","link":"https:\/\/jianmingli.com\/wp\/?p=2425","title":{"rendered":"JSR 227: A Standard Data Binding & Data Access Facility for J2EE"},"content":{"rendered":"

Overview<\/h2><\/span>\n

* Based on Oracle ADF Model framework
\n* Provides an generic API between UI layer and data services layer.
\n* Provides a standard abstraction for any Java view and controller to bind to any data services.
\n* Decouples UI layer from data model layer.
\n* Examples of view and controller:
\n– JSP
\n– JSTL
\n– JSF
\n– Struts
\n– Swing
\n* Examples of service technologies:
\n– SOAP web services
\n– EJB session beans
\n– POJOs that provide access to a model layer<\/p>\n

Runtime Architecture<\/h2><\/span>\n

Data Binding Facility (DBF)<\/h3><\/span>\n

* UI <- binding interfaces -> DBF<\/strong> <- data control interfaces -> Data Controls <-> Services <-> Model Object<\/p>\n

Roles<\/h3><\/span>\n

* Data Control Provider: creates data controls for a particular service technology (e.g. SOAP WS, EJB SB)
\n* DBF Provider: provides data binding facility
\n* Application Developer: uses DBF to access data services<\/p>\n

Design Time Architecture<\/h2><\/span>\n

* Relies on metadata
\n– data control metadata
\n– binding metadata<\/p>\n

Data Controls<\/h2><\/span>\n

* Must implement interface:<\/p>\n

\r\njavax.bindings.datacontrol.DataControl\r\n<\/pre>\n
Data Control Life Cycle<\/h3><\/span>\n
Instantiating<\/h4><\/span>\n
* All implementations of DataControl interface should provide a no-argument constructor so it can be instantiated via retrospection.
\n* Metadata key string is passed into DataControl.configure()<\/em> to
\n– find metadata by metadata key
\n– use metadata to acquire an instance of the data control
\n– prepare itself to receive requests<\/p>\n
Cleaning up<\/h4><\/span>\n
* DataControl.release()<\/em> should be implemented to release all references and resources.
\n* After release()<\/em> method call, data control is ready to be garbage collected.<\/p>\n
Demarcation of Requests<\/h4><\/span>\n
* Data controls for services that require demarcated requests and sessions should implement interface:<\/p>\n
javax.bindings.datacontrol.ManagedDataControl <\/pre>\n
* Demarcation methods:<\/p>\n
\r\n# Initialize method:\r\nManagedDataControl.beginRequest(HashMap request);\r\n\r\n# Cleanup method\r\nManagedDataControl.endRequest(HashMap request);\r\n\r\n# Reset transaction state\r\nManagedDataControl.resetState();\r\n<\/pre>\n
Retrieving Data<\/h3><\/span>\n
Accessing Attributes of the Service<\/h4><\/span>\n
\r\n# Obtain data provider:\r\nDataControl.getDataProvider();\r\n\r\n# Get access attributes\r\nDataControl.getAttributeValue(AttributeContext ctx);\r\n<\/pre>\n
* AttributeContext defines two properties:
\n– dataProvider
\n– attributeName<\/p>\n
Updating Data<\/h3><\/span>\n
* Data controls that need to update data should implement interface:<\/p>\n
javax.bindings.datacontrol.UpdateableDataControl<\/pre>\n
* Chaining Data values:<\/p>\n
setAttributeValue()<\/pre>\n
* Create\/Delete Rows:<\/p>\n
\r\n# Construct an oracle.bindings.RowContext object\r\nRowContext rctx = new RowContext();\r\n\r\n# Insert row data\r\nUpdateableDataControl.createRowData(RowContext ctx);\r\n\r\n# Deleting row data\r\nUpdateableDataControl.removeRowData(RowContext ctx);\r\n<\/pre>\n
Transaction Control<\/h3><\/span>\n
* Data controls for services that provide transactions should implement interface:<\/p>\n
javax.bindings.datacontrol.TransactionalDataControl<\/pre>\n
* TransactionalDataControl interface defines:<\/p>\n
\r\nTransactionalDataControl.commitTransaction();\r\nTransactionalDataControl.rollbackTransaction();\r\nTransactionalDataControl.isTransactionDirty();\r\n<\/pre>\n
Invoking Operations<\/h2><\/span>\n
\r\nDataControl.invokeOperation(RowContext ctx, OperationBinding binding);\r\n<\/pre>\n
Notifying the DBF of Data Changes<\/h2><\/span>\n
* Data controls that need to broadcast events when data changes should implement the interface:<\/p>\n
javax.binding.events.DataChangeManager<\/pre>\n
* Register\/unregister listener:<\/p>\n
\r\n# Construct a listening class and implement:\r\njavax.binding.events.DataChangeListener lisnr = new DataChangeListener();\r\n\r\n# Add listener: \r\nDataChangeManager.addDataChangeListener(DataObject do, lsnr);\r\n\r\n# Remove listener:\r\nDataChangeManager.removeDataChangeListener(DataObject do);\r\n<\/pre>\n
Structure of Events<\/h3><\/span>\n
* Data change events are instances of the class <\/p>\n
javax.binding.events.DataChangeEvent<\/pre>\n
Metadata and Tooling<\/h2><\/span>\n
Bindings<\/h2><\/span>\n
\"JSR-227<\/a>
JSR-227 Binding Context<\/p><\/div>\n
Binding Context<\/h3><\/span>\n
* Is an instance of java.util.Map<\/em>
\n* Allows lookup of all bindings and data controls needed by a module
\n* Its life cycle is controlled by DBF
\n* Contains binding containers
\n– binding container for the current page should be accessible by the String key “bindings”<\/p>\n
Binding Container<\/h3><\/span>\n
* Implements javax.bindings.BindingContainer interface, which itself extends java.util.Map
\n* Allows lookup of binding instances used by a single region
\n* Contains instances of UI control bindings
\n* Can be nested<\/p>\n
Binding Container Life Cycle<\/h3><\/span>\n
BindingContainer.refresh()<\/em>
\nBindingContainer.release()<\/em><\/p>\n
Retrieval of Control Bindings<\/h3><\/span>\n
\r\n# Get a java.util.List of all control bindings in the container:\r\nBindingContainer.getControlBindings() ;\r\n\r\n# Get a List of AttributesBinding instances in the container:\r\nBindingContainer.getAttributeBindings(); \r\n\r\n# Get a List of only the OperationBinding instances in the container:\r\nBindingContainer.getOperationBindings();\r\n\r\n# Get a single control binding. \r\n# It takes, as a parameter, a unique string identifier called the binding\u2019s name. \r\n# It returns null if no control binding matching the name is found.\r\nBindingContainer.getControlBinding();\r\n\r\n# A typesafe version of getControlBinding() that returns an OperationBinding instance, \r\n# typed to OperationBinding. \r\n# It accepts the binding\u2019s name as a parameter, \r\n# and returns null if either no binding matching that name is found \r\n# or if the binding matching the name is not an instance of OperationBinding.\r\nBindingContainer.getOperationBinding();\r\n<\/pre>\n
Token Validation<\/h3><\/span>\n
* Could be used to prevent multiple submit actions<\/p>\n
\r\n# Returns true if token validation is enabled, false otherwise:\r\nBindingContainer.isTokenValidationEnabled();\r\n\r\n# Obtain state token:\r\nBindingContainer.getStateToken();\r\n\r\n# Should throw an exception if token is invalid:\r\nBindingContainer.validateToken()\r\n<\/pre>\n
Data Validation<\/h3><\/span>\n
* Binding container implementations should also implement the method BindingContainer.validate().
\n* This method is a delegate method, which should call DataControl.validate() on every data control referenced by the container.<\/p>\n
Control Bindings<\/h2><\/span>\n
* All control bindings mus implement interface<\/p>\n
javax.bindings.ControlBinding<\/pre>\n
* Control bindings provide data access for individual UI controls
\n* Control bindings include bindings to
\n– individual attribute values
\n– entire model objects with multiple attributes
\n– collections that maintain entire ranges of model objects
\n– execute operation son the model layer<\/p>\n
Identify and Resolve Control Bindings<\/h3><\/span>\n
* Each control binding must have a unique string within its binding container<\/p>\n
\r\n# Obtain control binding name: \r\nControlBinding.getName();\r\n\r\n# Obtain complete dot delimited path: \r\nControlBinding.getPath();\r\n\r\n# Obtain all aspects of data controls: \r\nControlBinding.getProviderFullName()\r\n<\/pre>\n
Releasing Control Bindings<\/h3><\/span>\n
* Release a control bindings: ControlBinding.release()<\/p>\n
Attribute Bindings<\/h3><\/span>\n
* All attribute bindings should implement interface<\/p>\n
javax.bindings.AttributeBinding<\/pre>\n
* Attribute bindings provide both read and write access to a single <\/strong>attribute<\/p>\n
\r\n# read: \r\nAttributeBinding.getInputValue();\r\n\r\n# write: \r\nAttributeBinding.setInputValue();\r\n\r\n# read only access: \r\nAttributeBinding.isReadOnly();\r\n\r\n# Attribute can have labels\r\nAttributeBinding.getLabel();\r\n<\/pre>\n
Attributes Bindings<\/h3><\/span>\n
* Must implement<\/p>\n
javax.bindings.AttributesBinding<\/pre>\n
* Provide index-based<\/strong> access (both read and write ) to multiple <\/strong>attribute values<\/p>\n
\r\n# read: \r\nAttributesBinding.getInputValue();\r\n\r\n# write: \r\nAttributesBinding.setInputValue(int idx, myVal);\r\n\r\n# is updateable: \r\nAttributesBinding.isUpdateable();\r\n\r\n# Get an array of labels: \r\nAttributesBinding.getLabelSet();\r\n<\/pre>\n
Range Bindings<\/h3><\/span>\n
* Must implement<\/p>\n
javax.bindings.RangeBinding<\/pre>\n
* Provide read only<\/strong> access to attribute values over a collection<\/strong><\/p>\n
\r\nRangeBinding.getRangeSet();\r\n<\/pre>\n
Operation Bindings<\/h3><\/span>\n
* Must implement<\/p>\n
javax.bindings.OperationBinding<\/pre>\n
* Methods defined in OperationBinding interface:<\/p>\n
\r\nOperationBinding.isOperationEnabled();\r\nOperationBinding.getParamsMap();\r\nOperationBinding.execute(); # Should delegate to  DataControl.invokeOperation()\r\nOperationBinding.getResult();\r\nOperationBinding.getErrors();\r\n<\/pre>\n
* Provide access to operations supported by the data control<\/p>\n
\r\n# Get OperationInfo object from binding\r\nOperationInfo opinfo = OperationBinding.getOperationInfo();\r\n\r\n# Use OperationInfo object to obtain various operation info:\r\nopinfo.getInstanceName(); \r\nopinfo.getOperationName();\r\nopinfo.getReturnName();\r\n<\/pre>\n
References<\/h2><\/span>\n
* JSR-227 Early Access<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
Overview * Based on Oracle ADF Model framework * Provides an generic API between UI layer and data services layer. * Provides a standard abstraction for any Java view and controller to bind to any data services. * Decouples UI … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[97],"tags":[],"class_list":["post-2425","post","type-post","status-publish","format-standard","hentry","category-jsr"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p8cRUO-D7","_links":{"self":[{"href":"https:\/\/jianmingli.com\/wp\/index.php?rest_route=\/wp\/v2\/posts\/2425","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jianmingli.com\/wp\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jianmingli.com\/wp\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jianmingli.com\/wp\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/jianmingli.com\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2425"}],"version-history":[{"count":29,"href":"https:\/\/jianmingli.com\/wp\/index.php?rest_route=\/wp\/v2\/posts\/2425\/revisions"}],"predecessor-version":[{"id":2456,"href":"https:\/\/jianmingli.com\/wp\/index.php?rest_route=\/wp\/v2\/posts\/2425\/revisions\/2456"}],"wp:attachment":[{"href":"https:\/\/jianmingli.com\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2425"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jianmingli.com\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2425"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jianmingli.com\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2425"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}