com.smartgwt.client.docs.serverds

## Class OperationBinding

- java.lang.Object
- - com.smartgwt.client.docs.serverds.OperationBinding

-     public class OperationBinding
      extends java.lang.Object

  This class is not meant to be created and used, it is actually documentation of settings allowed in a DataSource descriptor (.ds.xml file). See `com.smartgwt.client.docs.serverds` for how to use this documentation.

  An operationBinding tells a DataSource how to execute one of the basic DS operations: fetch, add, update, remove. See `operationBindings`.

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `java.lang.Boolean` | `allowAdvancedCriteria` This property indicates whether this operation supports AdvancedCriteria.
    `java.lang.Boolean` | `allowMultiUpdate` Ordinarily, "update" and "remove" operations are only allowed for `DataSource`s that have a `primaryKey`, and all primary key values are present in the request.
    `java.lang.Boolean` | `autoJoinTransactions` If true, causes requests against this operation to automatically start or join a transaction.
    `java.lang.String` | `cacheSyncOperation` For an operationBinding of `operationType` "add" or "update", this property is the `operationId` of a "fetch" operationBinding to use for cache synchronization purposes (ie, to fetch the row most recently added or changed).
    `java.lang.String` | `callbackParam` Applies only to dataFormat: "json".
    `java.lang.Boolean` | `canSyncCache` For an operation of type "add" or "update", a SQLDataSource will normally obtain data to return to the client by performing the "cacheSyncOperation": a SELECT statement that retrieves the modified record by primary key.
    `java.lang.Boolean` | `creatorOverrides` Indicates that field-level declarative security rules are waived for rows that were created by the current user, as described in the discussion of `dataSource.creatorOverrides`.
    `DSRequestModifier[]` | `criteria` Elements of this feature are only available with Power or better licenses. See smartclient.com/product for details.
    `java.lang.String[]` | `customCriteriaFields` Indicates that the listed fields should be included in the default `whereClause` generated for this operationBinding, even if they are marked `customSQL="true"`.
    `java.lang.String[]` | `customFields` Indicates that the listed fields should be included in the default `selectClause` and `whereClause` generated for this operationBinding, even if they are marked `customSQL="true"`.
    `java.lang.String` | `customHQL` This feature is available with Power or better licenses only. See smartclient.com/product for details.
    `java.lang.String` | `customSQL` This feature is available with Power or better licenses only. See smartclient.com/product for details.
    `java.lang.String[]` | `customValueFields` Indicates that the listed fields should be included in the default `selectClause` generated for this operationBinding, even if they are marked `customSQL="true"`.
    `DSProtocol` | `dataProtocol` Controls the format in which inputs are sent to the dataURL.
    `java.lang.String` | `dataURL` URL to contact to fulfill DSRequests for this operationBinding.
    `java.lang.Object` | `defaultParams` HTTP parameters that should be submitted with every DSRequest.
    `java.lang.String[]` | `excludeCriteriaFields` Indicates that the listed fields should be excluded from the default `whereClause` generated for this operationBinding.
    `ExportFormat` | `exportAs` The format in which the data should be exported.
    `java.lang.String[]` | `exportFields` The list of field-names to export.
    `java.lang.String` | `exportFilename` The name of the file to save the exported data into.
    `boolean` | `exportResults` When set, causes the results of the DataSource Operation to be exported to a file, whose name and format are indicated by `exportFilename` and `exportAs` respectively.
    `java.lang.String` | `groupClause` This feature is available with Power or better licenses only. See smartclient.com/product for details.
    `java.lang.Boolean` | `invalidateCache` If set, every invocation of this operationBinding will invalidate the local cache, forcing a server visit to refresh the data.
    `java.lang.String` | `lineBreakStyle` The style of line-breaks to use in the exported output.
    `Mail` | `mail` Definition of an email message that will be sent as an after-effect of selecting or updating data.
    `java.lang.String` | `methodArguments` You can explicitly declare the arguments to be passed to `serverMethod` using this attribute.
    `java.lang.String` | `operationId` Optional operationId if this DataSource supports two or more variants of one of the basic DataSource operations, for instance, a "fetch" that uses full text search and a "fetch" that accepts per-field search criteria.
    `DSOperationType` | `operationType` Which operationType this operationBinding is for.
    `java.lang.String` | `orderClause` This feature is available with Power or better licenses only. See smartclient.com/product for details.
    `java.lang.String` | `outputs` Specifies, for this operationBinding only, the list of field names that should be returned to the client.
    `java.lang.Boolean` | `preventHTTPCaching` Configures `preventHTTPCaching` on a per-operationType basis.
    `java.lang.Boolean` | `progressiveLoading` Sets `progressive loading mode` for this particular operation, overriding the DataSource-level setting.
    `boolean` | `qualifyColumnNames` Specifies, for this specific operationBinding, whether to qualify column names with table names in any SQL we generate.
    `java.lang.String` | `recordName` For an XML DataSource, tagName of the elements to be used as records.
    `XPathExpression` | `recordXPath` For an XML or JSON DataSource, XPath expression used to retrieve the objects that will become DataSource records.
    `DSRequest` | `requestProperties` Additional properties to pass through to the `DSRequest` created for this operation.
    `VelocityExpression` | `requires` Indicates that the specified VelocityExpression must be true for a user to access this operationBinding.
    `java.lang.Boolean` | `requiresAuthentication` Whether a user must be authenticated in order to access this operation.
    `java.lang.String` | `requiresRole` Comma-separated list of user roles that are allowed to invoke the operation described by this operationBinding.
    `DataSource` | `responseDataSchema` Optional schema describing how to extract DataSource records from the XML elements selected.
    `java.lang.String` | `script` Scriptlet to be executed prior to the DataSource operation which is configured by this operationBinding.
    `java.lang.String` | `selectClause` This feature is available with Power or better licenses only. See smartclient.com/product for details.
    `java.lang.String` | `serverMethod` The name of the method to invoke on the `ServerObject` for this operationBinding.
    `ServerObject` | `serverObject` Optional ServerObject declaration that specifies the ServerObject configuration for this operationBinding.
    `java.lang.Boolean` | `skipRowCount` A SQLDataSource will normally issue two queries for a "fetch" operation when paging is enabled: one to determine the total rows available (the "row count query"), and one to fetch the specific range of rows requested.
    `boolean` | `spoofResponses` For a DataSource contacting a `WSDL web service`, setting this flag means the DataSource doesn't actually attempt to contact the server but generates a sample response instead, based on the XML Schema of the response message embedded in the WSDL.
    `SQLPagingStrategy` | `sqlPaging` The paging strategy to use for this specific OperationBinding.
    `SQLType` | `sqlType` For dataSources of `serverType` "sql" and "hibernate" only, this property determines whether "custom" operations have their custom SQL or HQL sent to the underlying database via a JDBC `executeQuery()` or a JDBC `executeUpdate()`.
    `java.lang.Boolean` | `sqlUsePagingHint` If explicitly set true or false, forces the use of a "hint" in the SQL we generate for paged queries on or off as appropriate.
    `java.lang.String` | `tableClause` This feature is available with Power or better licenses only. See smartclient.com/product for details.
    `boolean` | `useFlatFields` Setting `useFlatFields` on an operationBinding is equivalent to setting `useFlatFields` on all DataSource requests with the same `operationType` as this `operationBinding`.
    `boolean` | `useForCacheSync` For an operationBinding of `operationType` "fetch" which specifies no `operationId`, this property determines whether the operationBinding should be used for cache synchronization purposes (ie, to retrieve the record most recently added or changed).
    `java.lang.Boolean` | `useSubselectForRowCount` Whether to use the subselect technique (see `useSubselectForRowCount` for details) to derive a rowcount query for this operation.
    `DSRequestModifier[]` | `values` Elements of this feature are only available with Power or better licenses. See smartclient.com/product for details.
    `java.lang.String` | `valuesClause` This feature is available with Power or better licenses only. See smartclient.com/product for details.
    `java.lang.String` | `whereClause` This feature is available with Power or better licenses only. See smartclient.com/product for details.
    `java.lang.Object` | `xmlNamespaces` Optional object declaring namespace prefixes for use in `recordXPath` and `valueXPath` XPath expressions.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `OperationBinding()`

  - ### Method Summary

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Field Detail

    - #### customValueFields

          public java.lang.String[] customValueFields

      Indicates that the listed fields should be included in the default `selectClause` generated for this operationBinding, even if they are marked `customSQL="true"`.

      You can specify this property as a comma-separated list (eg, "foo, bar, baz") or by just repeating the <customValueFields> tag multiple times with one field each.

      This property is only applicable to DataSources of `"sql"`.

      Default value is null

      See Also:
        `customFields`, `customCriteriaFields`, `CustomQuerying overview and related methods`

    - #### lineBreakStyle

          public java.lang.String lineBreakStyle

      The style of line-breaks to use in the exported output. See LineBreakStyle for more information.

      Default value is null

    - #### mail

          public Mail mail

      Definition of an email message that will be sent as an after-effect of selecting or updating data.

      Note that if a fixed number of different messages need to be sent, multiple `<mail>` tags may be specified. For example, one mail could be sent to an admin address, and a different message to every member of a user group.

      Default value is null

    - #### callbackParam

          public java.lang.String callbackParam

      Applies only to dataFormat: "json". Specifies the name of the query parameter that tells your JSON service what function to call as part of the response for this operation.

      Typically set once for the DataSource as a whole via `callbackParam`.

      Default value is "callback"

      See Also:
        `DataSource.callbackParam`, `ClientDataIntegration overview and related methods`

    - #### invalidateCache

          public java.lang.Boolean invalidateCache

      If set, every invocation of this operationBinding will invalidate the local cache, forcing a server visit to refresh the data.

      Default value is null

    - #### customFields

          public java.lang.String[] customFields

      Indicates that the listed fields should be included in the default `selectClause` and `whereClause` generated for this operationBinding, even if they are marked `customSQL="true"`.

      If you need to apply different sets of overrides for the `selectClause` and the `whereClause`, use `customValueFields` and/or `customCriteriaFields` instead. If you specify both `customFields` and `customCriteriaFields` or `customValueFields`, the more specific variant wins. If you specify both `customFields` and `excludeCriteriaFields`, `customFields` wins (this is another use case when you may wish to use `customValueFields` instead)

      You can specify this property as a comma-separated list (eg, "foo, bar, baz") or by just repeating the <customFields> tag multiple times with one field each.

      This property is only applicable to DataSources of `"sql"`.

      Default value is null

      See Also:
        `customValueFields`, `customCriteriaFields`, `excludeCriteriaFields`, `CustomQuerying overview and related methods`

    - #### serverMethod

          public java.lang.String serverMethod

      The name of the method to invoke on the `ServerObject` for this operationBinding.

      NOTE: If you have a `DataSource-level ServerObject` and wish to override this operation so that it simply calls a different method on the same server object, it is sufficient to specify just this property on the operationBinding: there is no need to redefine the serverObject at the operationBinding level.

      Default value is null

    - #### cacheSyncOperation

          public java.lang.String cacheSyncOperation

      For an operationBinding of `operationType` "add" or "update", this property is the `operationId` of a "fetch" operationBinding to use for cache synchronization purposes (ie, to fetch the row most recently added or changed). This property, along with `useForCacheSync` and `canSyncCache` is provided so that you can use custom database operations without sacrificing the benefits of Smart GWT's automatic cache synchronization.

      This property is only applicable to DataSources of type "sql".

      Default value is null

      See Also:
        `useForCacheSync`, `canSyncCache`, `CustomQuerying overview and related methods`

    - #### customHQL

          public java.lang.String customHQL

      This feature is available with Power or better licenses only. See smartclient.com/product for details.

      For a dataSource of `serverType` "hibernate", this property can be specified on an operationBinding to indicate that the server should run user-specified HQL (Hibernate Query Language), rather than the Hibernate criteria query or `saveOrUpdate` call it would normally generate to satisfy a dataSource operation via Hibernate.

      Note that inserting new records via HQL is often impractical, due to intentional restrictions in the language (it is only possible to perform an insert expressed in terms of a SELECT; the "VALUES" construct commonly used when inserting new rows singly is not supported). If you are intending to use customHQL, we recommend that you avoid doing so for `OperationBinding`s with `operationType` "add", unless you have a special requirement such as a bulk insert; if you need custom queries to perform inserts on "hibernate" dataSources, we recommend you use `customSQL`, which is valid for "hibernate" DataSources as well as "sql" dataSources.

      For other operations on "hibernate" dataSources, however, HQL has the advantage of being more portable across different database engines than is plain SQL.

      Note that using customHQL affects paging implementation. If you use it, full data set is fetched from Hibernate and records that aren't in the requested range are dropped at the server side.

      Default value is null

      See Also:
        `customSQL`, `DataSourceField.customSQL`, `CustomQuerying overview and related methods`

    - #### serverObject

          public ServerObject serverObject

      Optional ServerObject declaration that specifies the ServerObject configuration for this operationBinding. In the absence of a serverObject specification here, the one specified on the DataSource itself is used by default, if present (`serverObject`). If neither is present, then Direct Method Invocation will not be enabled for this operationBinding.

      Default value is null

      See Also:
        `DataSource.serverObject`

    - #### useForCacheSync

          public boolean useForCacheSync

      For an operationBinding of `operationType` "fetch" which specifies no `operationId`, this property determines whether the operationBinding should be used for cache synchronization purposes (ie, to retrieve the record most recently added or changed). This property has no effect on an operationBinding that specifies an operationId - see `cacheSyncOperation`.

      In order to work correctly with Smart GWT's cache synchronization system, an operationBinding marked useForCacheSync should have the following properties:

      - Able to complete its retrieval using no context other than the values of the primary key fields declared in the dataSource (these will be provided in the $criteria object passed to the operation)
      - Returns the entire record, including any values that may require joins to other tables or other complexities
      This property is only applicable to DataSources of type "sql".

      Default value is true

      See Also:
        `cacheSyncOperation`, `CustomQuerying overview and related methods`

    - #### valuesClause

          public java.lang.String valuesClause

      This feature is available with Power or better licenses only. See smartclient.com/product for details.

      For a dataSource of `serverType` "sql", this property can be specified on an operationBinding to provide the server with a bespoke set of values to add or update, for use when constructing the SQL query to perform this operation. The property should be one of the following, depending on the `operationType`:

      For "add" operations, the syntax that would be valid for an INSERT INTO query: a comma-separated list of column names enclosed in parentheses, followed by a comma-separated list of new values, enclosed in parentheses and preceded by the token "VALUES". For example:

      `<valuesClause>(name, age) VALUES("Jane Doe", 48)</valuesClause>`

      For "update" operations, the syntax that would be valid for an UPDATE query: a comma-separated list of expressions equating a column name to its new value. For example:

      `<valuesClause>name="Jane Doe", age=48</valuesClause>`

      You may find the Smart GWT-provided $values variable of particular use with this property.

      See the documentation for `customSQL` for usage examples

      Default value is null

      See Also:
        `customSQL`, `CustomQuerying overview and related methods`

    - #### criteria

          public DSRequestModifier[] criteria

      Elements of this feature are only available with Power or better licenses. See smartclient.com/product for details.

      A list of `DSRequestModifier`s that will be used to modify the criteria of each `DSRequest` that uses this operationBinding. Note that the criteria elements are applied to DSRequest criteria as follows:

      - Simple criteria: The field and value are just applied as an extra key/value pair in the criteria map, as long as the `operator` attribute is left unset, or is set to "equals". For any other setting of `operator`, the criteria is first converted to the equivalent AdvancedCriteria and then processed as described below
      - AdvancedCriteria: If the topmost operator is "and", we add the new criterion as an additional criterion directly in the existing list. Otherwise, we create a new top-level AdvancedCriteria with an operator of "and". This is then set to have two elements in its criteria: the previous top-level criteria and the new criterion.
      The effect of this is to apply any criteria specifed here as additional constraints on top of what the user has specified, and of course, the user is unable to affect this. Thus, this is a suitable and convenient place to enforce rules such as "Users can only ever see their own records".

      Default value is null

      See Also:
        `values`

    - #### requires

          public VelocityExpression requires

      Indicates that the specified VelocityExpression must be true for a user to access this operationBinding.

      As with `requiresRole`, if there an operationBinding that is the default operationBinding for the operationType, its `requires` expression is assumed to apply to all other operationBindings of the same type unless they explicitly set `requires=""`

      `requires`, if specified, applies before `operationBinding.requires` is evaluated. In this case, both `requires` expressions must be true for the request to be accepted.

      Default value is null

    - #### script

          public java.lang.String script

      Scriptlet to be executed prior to the DataSource operation which is configured by this operationBinding.

      Scriptlets are used similarly to DMIs configured via `serverObject` - they can add business logic by modifying the DSRequest before it's executed, modifying the default DSResponse, or taking other, unrelated actions.

      For example:

               <operationBindings>
                  <operationBinding operationType="add">
                      <script language="groovy">
                         ... Groovy code ...
                      </script>
                  </operationBinding>
               </operationBindings>

      Scriptlets can be written in any language supported by the "JSR 223" standard, including Java itself. See the `DMI Script Overview` for rules on how to return data, add additional imports, and other settings.

      The following variables are available for DMI scriptlets:

      - dataSource: the current DataSource
      - dsRequest: the current DSRequest
      - criteria: shortcut to DSRequest.getCriteria() (a Map)
      - values: shortcut to DSRequest.getValues() (a Map)
      - oldValues: shortcut to DSRequest.getOldValues() (a Map)
      - sqlConnection: SQLDataSource only: the current SQLConnection object. If using `automatic transactions` are enabled, this SQLConnection is in the context of the current transaction.
      - beanFactory: the spring BeanFactory (when applicable)

      Scriptlets also have access to a set of contextual variables related to the Servlets API, as follows:

      - servletRequest: the current ServletRequest
      - session: the current HttpSession
      - rpcManager: the current RPCManager
      - servletResponse: the current ServletResponse (advanced use only)
      - servletContext: the current ServletContext(advanced use only)
      As with DMI in general, be aware that if you write scriptlets that depend upon these variables, you preclude your DataSource from being used in the widest possible variety of circumstances. For example, adding a scriptlet that relies on the `HttpSession` prevents your DataSource from being used in a command-line process.

      Default value is null

    - #### sqlPaging

          public SQLPagingStrategy sqlPaging

      The paging strategy to use for this specific OperationBinding. If this property is not set, we fall back to the `sqlPaging` value, and the defaults described in the documentation for that property.

      Default value is null

      See Also:
        `DataSource.sqlPaging`

    - #### groupClause

          public java.lang.String groupClause

      This feature is available with Power or better licenses only. See smartclient.com/product for details.

      For a dataSource of `serverType` "sql", this property can be specified on an operationBinding to provide the server with a bespoke GROUP BY clause to use when constructing the SQL query to perform this operation. The property should be a comma-separated list of column names and/or expressions, forming a valid GROUP BY clause in the syntax of the underlying database. The server will insert the text of this property immediately after the "GROUP BY" token.

      Note that specifying this property enables you to use aggregate functions (such as COUNT and SUM) in your `selectClause`. Also note that care is required when using groupClause to ensure that the selectClause contains the fields you are grouping by. Failure to do this correctly will result in a runtime SQL error.

      This property is only applicable to operationBindings of `operationType` "fetch".

      See the documentation for `customSQL` for usage examples

      Default value is null

      See Also:
        `customSQL`, `selectClause`, `CustomQuerying overview and related methods`

    - #### dataProtocol

          public DSProtocol dataProtocol

      Controls the format in which inputs are sent to the dataURL.

      When a DataSource operation such as fetchData() is invoked on this DataSource or a component bound to this DataSource, the data passed to the operation, if any, will be sent to the `dataURL`. The `dataProtocol` property controls the format in which the data is sent: SOAP message, HTTP GET or POST of parameters, etc.

      The `dataProtocol` property need not be set for a DataSource with a WebService ( `serviceNamespace` is set), in this case, SOAP messaging is used by default.

      Developers may completely bypass the Smart GWT comm system by setting dataProtocol to `"clientCustom"`. In this case Smart GWT will not attempt to send any data to the server after calling `DataSource.transformRequest`. Instead the developer is expected to implement `transformRequest()` such that it performs the necessary data action outside of Smart GWT, and then calls `DataSource.processResponse`, passing in the `requestId` and an appropriate set of DSResponse properties to indicate the result of the action.

      NOTE: when `dataFormat` is "iscServer", `dataProtocol` is not consulted. Instead, Smart GWT uses a proprietary wire format to communicate with the Smart GWT server, and the server-side DSRequest and DSResponse objects should be used to access request data and form responses.

      Default value is "getParams"

      See Also:
        `DSProtocol`, `ClientDataIntegration overview and related methods`

    - #### sqlUsePagingHint

          public java.lang.Boolean sqlUsePagingHint

      If explicitly set true or false, forces the use of a "hint" in the SQL we generate for paged queries on or off as appropriate. If not set, defaults to the `sqlUsePagingHints` value. Note this property is only applicable to `SQL` DataSources, only when a `paging strategy` of "sqlLimit" is in force, and it only has an effect for those specific database products where we employ a native hint in the generated SQL in an attempt to improve performance.

      Default value is null

      See Also:
        `DataSource.sqlUsePagingHint`

    - #### allowMultiUpdate

          public java.lang.Boolean allowMultiUpdate

      Ordinarily, "update" and "remove" operations are only allowed for `DataSource`s that have a `primaryKey`, and all primary key values are present in the request. This is because an update of a DataSource with no primary key, or an update request that has missing primary key values, cannot be guaranteed to affect only one record.

      Setting this property on an operationBinding circumvents this restriction for that operation only.

      Warning: Be aware that this is a potentially dangerous setting and should be used with care. With this flag set, you have no guarantee that an update will not change or remove every row in a table.

      Default value is null

    - #### recordXPath

          public XPathExpression recordXPath

      For an XML or JSON DataSource, XPath expression used to retrieve the objects that will become DataSource records.

      For example, an "ItemSearch" web service might return a "Results" structure containing metadata along with the set of Items that one might want to display in a grid. An XPath expression like "/Results/Items" could be used to retrieve just the Items, which would then become DataSource records.

      For a JSON web service, the `recordXPath` is applied to the returned JSON data via `XMLTools.selectObjects`. Only limited XPath syntax is allowed; see `selectObjects()` for details.

      For processing XML results, see `xmlNamespaces` for information on the namespaces that are available in this XPath expression. If you are contacting a WSDL web service, note that `recordName` is an alternative way to specify which records should be selected by their tagName or type, and this is usually simpler.

      To learn about XPath, try the following search: http://www.google.com/search?q=xpath+tutorial

      Default value is null

      See Also:
        `ClientDataIntegration overview and related methods`

    - #### requiresRole

          public java.lang.String requiresRole

      Comma-separated list of user roles that are allowed to invoke the operation described by this operationBinding. If the current user has any of the roles listed, they can invoke the operation. Also note that `authentication.superuserRole` can be specified in the `server.properties` file. If set this denotes a "super user" role - any user with that role will have access to all operations, regardless of the "requiresRole" settings for the operation.

      Whether the current user has a given role is determined by calling the standard Java servlets method `httpServletRequest.isUserInRole()`, hence works with both simple J2EE security (realms and form-based authentication) and JAAS (Java Authentication & Authorization Service).

      If you wish to use a role-based security scheme that does not make use of the servlet API's standards, Smart GWT Server also implements the `setAuthenticated` and `setUserRoles` methods on `RPCManager`. You can use this API to tell Smart GWT that all the requests in the queue currently being processed are associated with a user who has the roles you supply; in this case, Smart GWT will not attempt to resolve the user's roles via `httpServletRequest.isUserInRole()`. When taking this approach, the `rpcManager.setUserRoles()` method should be called on the server for each transaction received from the client. We recommend doing this by overriding the special IDACall servlet and checking server side state to determine the current user's roles, calling the API, and then calling `handleDSRequest()` or `handleRPCRequest()` directly to handle the request(s) passed in.
      Here's an example of this approach which assumes the current user's roles has been set directly on the HttpSession object as a comma-separated-string attribute "roles":

             public class SecureIDACall extends IDACall {

                 public void processRequest(HttpServletRequest request,
                         HttpServletResponse response)
                  throws ServletException, IOException
                 {
                     HttpSession session = request.getSession();
                     Object roles = session == null ? null : session.getAttribute("roles");

                     if (roles != null) {
                         try {
                             RequestContext context = RequestContext.instance(this, request, response);
                             RPCManager rpc = new RPCManager(request, response);
                             rpc.setAuthenticated(true);
                             rpc.setUserRoles((String) roles);

                             // call processRPCTransaction() to iterate through all RPCRequests and
                             // DSRequests and execute them
                             processRPCTransaction(rpc, context);

                         } catch (Throwable e) {
                             handleError(response, e);
                         }
                     } else {
                         super.processRequest(request, response);
                     }
                 }
             }

      If there is an operationBinding declared for a given operationType which does not have an `operationId`, that is, it is the default operationBinding for the type, then any other operationBinding of the same type is assumed to have the same setting for `requiresRole` as the default operationBinding for the operationType. For example, given these declarations:

                <operationBinding operationType="fetch" requiresRole="manager">
                      ... settings ...
                 </operationBinding>
                <operationBinding operationType="fetch" operationId="fetchWithExtraFields">
                      ... settings ...
                 </operationBinding>

      The second operationBinding requires the "manager" role even though there is no explicit `requiresRole` declaration. To prevent the "manager" role being required by the second operationBinding, add `requireRole=""`.

      Note that if `requiresRole` is set, all operations on the DataSource require the roles set for the DataSource as a whole, even if they declare individual `requiresRole` attributes.

      This property is valid only for a server-side DataSource when using the Smart GWT Server.

      Default value is null

    - #### customCriteriaFields

          public java.lang.String[] customCriteriaFields

      Indicates that the listed fields should be included in the default `whereClause` generated for this operationBinding, even if they are marked `customSQL="true"`.

      You can specify this property as a comma-separated list (eg, "foo, bar, baz") or by just repeating the <customCriteriaFields> tag multiple times with one field each.

      This property is only applicable to DataSources of `"sql"`.

      Default value is null

      See Also:
        `customFields`, `customValueFields`, `excludeCriteriaFields`, `CustomQuerying overview and related methods`

    - #### exportResults

          public boolean exportResults

      When set, causes the results of the DataSource Operation to be exported to a file, whose name and format are indicated by `exportFilename` and `exportAs` respectively. When no exportFilename is provided, the default is Results and the default value of exportAs is csv. Once the Operation completes, `exportDisplay` specifies whether the exported data will be downloaded to the file-system or displayed in a new window. The default value of exportDisplay is "download" which displays the Save As dialog. See `ExportDisplay` for more information.

      The export field-list can also be configured, see `exportFields`.

      You can also configure the style of line-breaks to use when generating the output. See LineBreakStyle for more information.

      As well as setting this and other properties on the `OperationBinding`, Exports can be initiated in two other ways. You can set properties on the dsRequest by passing requestProperties into `DataSource.exportData`. Note that this method does not support exporting to JSON format (see this post for more detail). Additionally, custom server code may set export-related properties on the `DSResponse`.

      Format Examples

      XML format

                <List>
                    <Object>
                        <id>10101</id>
                        <displayName>Record 10101</displayName>
                    </Object>
               </List>

      JSON Format

                [
                    { id: 10101, displayName: "Record 10101" }
                ]

      CSV Format

                id,displayName
                10101,"Record 10101"

      Default value is false

    - #### recordName

          public java.lang.String recordName

      For an XML DataSource, tagName of the elements to be used as records.

      This is a simple alternative to `recordXPath` when the elements to be used as records all share a tagName.

      When a DataSource has a WebService, `recordName` can also be set to the name of any `complexType` declared within the WebService's WSDL file.

      Default value is null

      See Also:
        `ClientDataIntegration overview and related methods`

    - #### defaultParams

          public java.lang.Object defaultParams

      HTTP parameters that should be submitted with every DSRequest.

      Useful for authenticated services that require a sessionId with every request.

      Can be set for all operations of a given DataSource as DataSource.defaultParams.

      Default value is null

      See Also:
        `ClientDataIntegration overview and related methods`

    - #### requestProperties

          public DSRequest requestProperties

      Additional properties to pass through to the `DSRequest` created for this operation. Note that these will be cumulative with and will override on a per-property basis any properties set via `requestProperties`.

      These properties are applied before `DataSource.transformRequest` is called.

      Default value is null

      See Also:
        `DSRequest`, `DataSource.requestProperties`, `ClientDataIntegration overview and related methods`

    - #### tableClause

          public java.lang.String tableClause

      This feature is available with Power or better licenses only. See smartclient.com/product for details.

      For a dataSource of `serverType` "sql", this property can be specified on an operationBinding to provide the server with a bespoke table clause to use when constructing the SQL query to perform this operation. The property should be a comma-separated list of tables and views, and you can use any special language constructs supported by the underlying database. The server will insert the text of this property immediately after the "FROM" token.

      See the documentation for `customSQL` for usage examples

      Default value is null

      See Also:
        `customSQL`, `CustomQuerying overview and related methods`

    - #### sqlType

          public SQLType sqlType

      For dataSources of `serverType` "sql" and "hibernate" only, this property determines whether "custom" operations have their custom SQL or HQL sent to the underlying database via a JDBC `executeQuery()` or a JDBC `executeUpdate()`. The default value of null means the same as "query", so you only need to use this property when your custom SQL or HQL updates data.

      Default value is null

      See Also:
        `CustomQuerying overview and related methods`

    - #### operationType

          public DSOperationType operationType

      Which operationType this operationBinding is for. This property is only settable on an operationBinding, not a DataSource as a whole.

      Default value is null

      See Also:
        `ClientDataIntegration overview and related methods`

    - #### allowAdvancedCriteria

          public java.lang.Boolean allowAdvancedCriteria

      This property indicates whether this operation supports AdvancedCriteria. This setting overrides `allowAdvancedCriteria` for this operation only. See `DataSource.supportsAdvancedCriteria` for further information.

      NOTE: If you specify this property in a DataSource descriptor (`.ds.xml` file), it is enforced on the server. This means that if you run a request containing AdvancedCriteria against an OperationBinding that advertises itself as `allowAdvancedCriteria:false`, it will be rejected.

      Default value is null

      See Also:
        `DataSource.allowAdvancedCriteria`

    - #### exportAs

          public ExportFormat exportAs

      The format in which the data should be exported. Default is "csv". See `ExportFormat` for more information.

      Default value is "csv"

    - #### spoofResponses

          public boolean spoofResponses

      For a DataSource contacting a `WSDL web service`, setting this flag means the DataSource doesn't actually attempt to contact the server but generates a sample response instead, based on the XML Schema of the response message embedded in the WSDL.

      The spoofed response will include all complexType elements and will fill in appropriate values by type for all simpleType elements, although the spoofed data will not conform to all xs:restriction declarations (eg xs:pattern).

      Note that if your WSDL does not fully describe the response format (some WSDL services just have a placeholder <xs:any> element), Smart GWT can only produce a partial response. To use a hand-generated sample response, just save an XML file to disk and use the `dataURL` setting to point to it.

      Default value is false

      See Also:
        `ClientDataIntegration overview and related methods`

    - #### preventHTTPCaching

          public java.lang.Boolean preventHTTPCaching

      Configures `preventHTTPCaching` on a per-operationType basis.

      Default value is null

    - #### creatorOverrides

          public java.lang.Boolean creatorOverrides

      Indicates that field-level declarative security rules are waived for rows that were created by the current user, as described in the discussion of `dataSource.creatorOverrides`. This setting overrides `dataSource.creatorOverrides`, for this operation only.

      Default value is null

      See Also:
        `DataSourceField.editRequires`, `DataSourceField.viewRequires`, `DataSource.creatorOverrides`, `FieldLevelAuth overview and related methods`

    - #### qualifyColumnNames

          public boolean qualifyColumnNames

      Specifies, for this specific operationBinding, whether to qualify column names with table names in any SQL we generate. Overrides the `qualifyColumnNames` property. Only applicable to dataSources of `serverType` "sql".

      Default value is true

    - #### outputs

          public java.lang.String outputs

      Specifies, for this operationBinding only, the list of field names that should be returned to the client. Typically this will be a subset of the `fields`, but note that this is not a requirement; `outputs` can include fields that are not defined in the DataSource's field list. In this case, the server will return extra fields even if `dropExtraFields` is true.

      You specify this property as a string containing a comma-separated list of field names (eg, "foo, bar, baz")

      Default value is null

    - #### autoJoinTransactions

          public java.lang.Boolean autoJoinTransactions

      If true, causes requests against this operation to automatically start or join a transaction. if false, causes requests against this operation to be committed individually. If null, falls back to `autoJoinTransactions`.

      See `autoJoinTransactions` for further details of Smart GWT's automatic transaction control.

      Default value is null

    - #### whereClause

          public java.lang.String whereClause

      This feature is available with Power or better licenses only. See smartclient.com/product for details.

      For a dataSource of `serverType` "sql", this property can be specified on an operationBinding to provide the server with a bespoke WHERE clause to use when constructing the SQL query to perform this operation. The property should be a valid expression in the syntax of the underlying database. The server will insert the text of this property immediately after the "WHERE" token.

      You may find the Smart GWT-provided $criteria variable of particular use with this property.

      See the documentation for `customSQL` for usage examples

      Default value is null

      See Also:
        `customSQL`, `CustomQuerying overview and related methods`

    - #### excludeCriteriaFields

          public java.lang.String[] excludeCriteriaFields

      Indicates that the listed fields should be excluded from the default `whereClause` generated for this operationBinding.

      This enables you to use these fields in a `custom query` while still allowing the $defaultWhereClause to be generated for all other fields. For example, you might take a particular field and apply it in the WHERE clause of a subquery.

      You can specify this property as a comma-separated list (eg, "foo, bar, baz") or by just repeating the <customCriteriaFields> tag multiple times with one field each. Note that if a field is included in both excludeCriteriaFields and `customCriteriaFields`, customCriteriaFields wins.

      This property is only applicable to DataSources of `"sql"`.

      Default value is null

      See Also:
        `customCriteriaFields`, `CustomQuerying overview and related methods`

    - #### useFlatFields

          public boolean useFlatFields

      Setting `useFlatFields` on an operationBinding is equivalent to setting `useFlatFields` on all DataSource requests with the same `operationType` as this `operationBinding`.

      Typical usage is to combine operationBinding.useFlatFields with `searchForm.useFlatFields`, with the `SearchForm` bound to the `input message` of the web service operation set as `wsOperation`. This allows gratuitous nesting to be consistently bypassed in both the user presentation and in the actual XML messaging.

      Note that `useFlatFields` is not generally recommended for use with input messages where multiple simple type fields exist with the same name, however if used in this way, the first field to use a given name wins. "first" means the first field encountered in a depth first search. "wins" means only the first field will be available in data binding, and only the first field will be populated in the generated XML message.

      Default value is false

      See Also:
        `ClientDataIntegration overview and related methods`

    - #### responseDataSchema

          public DataSource responseDataSchema

      Optional schema describing how to extract DataSource records from the XML elements selected.

      Once a set of XML elements have been selected via `recordXPath` or `recordName`, those elements are normally transformed to JavaScript objects using the `fields` of the DataSource that owns the operationBinding. A `responseDataSchema` can be specified instead if the XML differs in some way between different DataSource operations, such that different values for `field.valueXPath` may be necessary to extract the same DataSource record from slightly different XML structures.

      Default value is null

      See Also:
        `ClientDataIntegration overview and related methods`

    - #### exportFields

          public java.lang.String[] exportFields

      The list of field-names to export. If provided, the field-list in the exported output is limited and sorted as per the list.

      If exportFields is not provided, the exported output includes all visible fields from the DataSource (field.hidden=false), sorted in the order they're defined.

      Default value is null

    - #### exportFilename

          public java.lang.String exportFilename

      The name of the file to save the exported data into.

      Default value is null

    - #### values

          public DSRequestModifier[] values

      Elements of this feature are only available with Power or better licenses. See smartclient.com/product for details.

      A list of `DSRequestModifier`s that will be used to modify the values object of each `DSRequest` that uses this operationBinding.

      Default value is null

      See Also:
        `criteria`

    - #### selectClause

          public java.lang.String selectClause

      This feature is available with Power or better licenses only. See smartclient.com/product for details.

      For a dataSource of `serverType` "sql", this property can be specified on an operationBinding to provide the server with a bespoke SELECT clause to use when constructing the SQL query to perform this operation. The property should be a comma-separated list of column names and/or expressions, and you can refer to any scalar function supported by the underlying database. The server will insert the text of this property immediately after the "SELECT" token.

      Note that if you also specify a `groupClause`, you can use aggregate functions such as SUM and COUNT in the selectClause.

      This property is only applicable to operationBindings of `operationType` "fetch".

      See the documentation for `customSQL` for usage examples

      Default value is null

      See Also:
        `customSQL`, `CustomQuerying overview and related methods`

    - #### customSQL

          public java.lang.String customSQL

      This feature is available with Power or better licenses only. See smartclient.com/product for details.

      For a dataSource of `serverType` "sql" or "hibernate", this property can be specified on an operationBinding to indicate that the server should run user-specified SQL, rather than the query it would normally generate to satisfy a dataSource operation. This property allows you to provide a fully-customized query; an alternative is to provide custom "pieces" to the query generator, via properties such as `whereClause` and `valuesClause`. See the `CustomQuerying` for more details.

      For a dataSource of type "sql", the Smart GWT server generates a number of useful query "pieces", and makes them available to your custom SQL code via the Velocity templating language (note that this is not available for "hibernate" dataSources).

      We also make the template variables $criteria and $values available, to give you direct access to the supplied criteria, and to the new field values for update and add operations. These variables are available to both "sql" and "hibernate" dataSources.

      Note that you should use this feature with care. In particular, writing customSQL code that makes use of a particular database engine's features or syntax will make your application less portable.

      See `CustomQuerying` for an overview of writing custom queries and clauses.

      ### Examples

      An example using the Smart GWT-supplied query pieces. This custom query will give exactly the same result as the Smart GWT-generated query:

      `<operationBinding operationId="customFetch" operationType="fetch">
      <customSQL>
      SELECT $defaultSelectClause FROM $defaultTableClause WHERE $defaultWhereClause ORDER BY $defaultOrderClause
      </customSQL>
      </operationBinding>
      `

      An example using the Smart GWT-supplied $criteria template variable:

      `<operationBinding operationId="customFetch" operationType="fetch">
      <customSQL>
      SELECT foo, bar, baz FROM MyTable WHERE bar > $criteria.someValue
      </customSQL>
      </operationBinding>
      `

      An update example:

      `<operationBinding operationId="myUpdateOp" operationType="update">
      <customSQL>
      UPDATE $defaultTableClause SET $defaultValuesClause WHERE bar <= $criteria.someValue
      </customSQL>
      </operationBinding>
      `

      Default value is null

      See Also:
        `customHQL`, `DataSourceField.customSQL`, `CustomQuerying overview and related methods`

    - #### skipRowCount

          public java.lang.Boolean skipRowCount

      A SQLDataSource will normally issue two queries for a "fetch" operation when paging is enabled: one to determine the total rows available (the "row count query"), and one to fetch the specific range of rows requested.

      For very large datasets the row count query can be expensive, and it can make more sense to use the "progressive loading" strategy discussed in the `ResultSet` docs.

      Setting skipRowCount="true" will avoid the "row count query", but as a consequence `totalRows` will be set to match the requested `endRow` since the totalRows is unknown. To implement the progressive loading pattern, use a DMI to to set totalRows to be larger than the requested endRow by the number of rows you would like the user to be able to scroll ahead in one jump.

      Default value is null

    - #### methodArguments

          public java.lang.String methodArguments

      You can explicitly declare the arguments to be passed to `serverMethod` using this attribute. This isn't required - in the absence of `methodArguments`, the DMI implementation will still automatically pass a stock set of arguments to your method (see the overview in `ServerObject`), but specifying arguments gives you the ability to call pre-existing methods without adding Smart GWT-specific code.

      The format for specifying `methodArguments` is as a comma separated list of VTL (Velocity Template Language) expressions. See the VTL Reference and Velocity User Guide for an overview of how to use VTL.

      The Velocity context is pre-populated with the following variables - you can pass these verbatim as arguments, or call methods on these objects and pass the resulting values:

      - dsRequest: instance of the current DSRequest
      - request: the current HttpServletRequest
      - response: the current HttpServletResponse
      - rpcManager: the instance of RPCManager for this request
      - dataSource: a DataSource instance for this request
      So, for example, if you had a method signature like the following:

      `public DSResponse fetch(SupplyItem criteria, long startRow, long endRow)`

      You can invoke it by specifying `methodArguments` as follows:

      `methodArguments="$dsRequest.criteria, $dsRequest.startRow, $dsRequest.endRow"`

      Without `methodArguments`, there would be no way for you to specify `startRow/endRow` as arguments. You could, of course, simply declare the method to take a `DSRequest` object and call `getStartRow()/getEndRow()` in the body of the method.

      Default value is null

      See Also:
        `ServerObject`

    - #### canSyncCache

          public java.lang.Boolean canSyncCache

      For an operation of type "add" or "update", a SQLDataSource will normally obtain data to return to the client by performing the "cacheSyncOperation": a SELECT statement that retrieves the modified record by primary key. This accommodates sequence columns, columns with default values, database triggers and other database features that may modify data after insertion or update.

      Certain major SQL customizations can prevent the SQLDataSource from authoritatively determining the primary key used in the SQL statement, such that re-selecting the saved record may fail. By default, when `canSyncCache` has not been explicitly set, in the following cases it is assumed that the normal cacheSyncOperation cannot be used:

      - <customSQL> has been used to define an entirely custom query
      - a custom <whereClause> has been defined for an "update" or "remove" operation
      - a custom <valuesClause> has been defined for an "add" operation
      If any of these cases apply or if `canSyncCache` has been set false, the server will skip the cacheSyncOperation and return a DSResponse where `invalidateCache` has been set to true to notify client-side components that they may need to refresh their entire cache.

      Alternatively, if the default re-selection behavior will not work but a customized SQL query would work, you can define that SQL operation as another operationBinding and use `cacheSyncOperation` to declare that it should be used. Setting `cacheSyncOperation` implicitly sets `canCacheSync` to true.

      This property is only applicable to DataSources of type "sql".

      Default value is null

      See Also:
        `useForCacheSync`, `cacheSyncOperation`, `CustomQuerying overview and related methods`

    - #### xmlNamespaces

          public java.lang.Object xmlNamespaces

      Optional object declaring namespace prefixes for use in `recordXPath` and `valueXPath` XPath expressions.

      `xmlNamespaces` should be specified as a mapping from namespace prefix to namespace URI, for example:

               xmlNamespaces : {
                   az : "http://webservices.amazon.com/AWSECommerceService/2005-03-23"
               }

      By default, all namespaces declared on the document element (outermost element of the response) are made available with the prefix used in the document itself.

      Then, for non-WSDL-described XML results, if there is a default namespace on the document element, it is made available with the special prefix "default".

      For results of WSDL-described operations, the prefix "service" means the service namespace, that is, the "targetNamespace" on the <definitions> element from the WSDL file. The prefix "schema" means the namespace of the outermost element in the output message for the current operation. "default" will be the schema namespace if there is one, otherwise the service namespace.

      For basic information on XML Namespaces and their use in XPath, try the following search: http://www.google.com/search?q=XPath+xml+namespaces

      Default value is null

      See Also:
        `ClientDataIntegration overview and related methods`

    - #### dataURL

          public java.lang.String dataURL

      URL to contact to fulfill DSRequests for this operationBinding.

      `dataURL` is typically set as DataSource.dataURL rather than on each individual operationBinding.

      `dataURL` can be omitted for a DataSource using a Web Service (`serviceNamespace` is set).

      Default value is null

      See Also:
        `ClientDataIntegration overview and related methods`

    - #### requiresAuthentication

          public java.lang.Boolean requiresAuthentication

      Whether a user must be authenticated in order to access this operation. For details of what is meant by "authenticated", see `requiresAuthentication`.

      To protect access to an entire operationType (eg, all "fetch" operations), declare an operationBinding with `requiresAuthentication="true"`, `operationType` set to the operationType to be protected, but no `operationId`. This will then prevent access to the "fetch" operationType unless another `OperationBinding` declares requiresAuthentication="false" with a specific `operationId`.

      Default value is null

    - #### operationId

          public java.lang.String operationId

      Optional operationId if this DataSource supports two or more variants of one of the basic DataSource operations, for instance, a "fetch" that uses full text search and a "fetch" that accepts per-field search criteria. See `operationId` for usage.

      Default value is null

      See Also:
        `ClientDataIntegration overview and related methods`

    - #### useSubselectForRowCount

          public java.lang.Boolean useSubselectForRowCount

      Whether to use the subselect technique (see `useSubselectForRowCount` for details) to derive a rowcount query for this operation. If this property is not set, we fall back to the `useSubselectForRowCount` setting on the DataSource, and the defaults described in the documentation for that property.

      Default value is null

      See Also:
        `DataSource.useSubselectForRowCount`, `customSQL`

    - #### progressiveLoading

          public java.lang.Boolean progressiveLoading

      Sets `progressive loading mode` for this particular operation, overriding the DataSource-level setting. Note that this setting applies only to fetch operations - it has no effect if specified on any other kind of operation.

      Default value is null

      See Also:
        `DataSource.progressiveLoading`, `ProgressiveLoading overview and related methods`

    - #### orderClause

          public java.lang.String orderClause

      This feature is available with Power or better licenses only. See smartclient.com/product for details.

      For a dataSource of `serverType` "sql", this property can be specified on an operationBinding to provide the server with a bespoke ORDER BY clause to use when constructing the SQL query to perform this operation. The property should be a comma-separated list of column names and/or expressions, forming a valid ORDER BY clause in the syntax of the underlying database. The server will insert the text of this property immediately after the "ORDER BY" token.

      This property is only applicable to operationBindings of `operationType` "fetch".

      See the documentation for `customSQL` for usage examples

      Default value is null

      See Also:
        `customSQL`, `CustomQuerying overview and related methods`

  - ### Constructor Detail

    - #### OperationBinding

          public OperationBinding()