com.sap.conn.jco

## Class JCo

- java.lang.Object
- - com.sap.conn.jco.JCo

-     public abstract class JCo
      extends Object

  The main factory class of JCo. With the methods in this class it is possible to create the instances of JCo classes, e.g. the data containers such as implementations of JCoStructure, JCoTable or JCoParameterList. Further you can create instances of metadata for implementing your own repository if you need to do so.

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `JCo()`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `static void` | `addTraceListener(JCoTraceListener listener)` Adds a trace listener, that receives all trace events of JCo.
    `static JCoAbapObject` | `createAbapObject(JCoClassMetaData classMetaData, Map<String,Object> initialValues)` This is a constructor for an instance of an ABAP class.
    `static JCoBackgroundUnitAttributes` | `createBackgroundUnitAttributes()` Creates an empty instance of function/request unit attributes.
    `static JCoClassMetaData` | `createClassMetaData(JCoClassMetaData metaData)` Returns a newly created instance of JCoClassMetaData, which is initially a copy of the passed JCoClassMetaData.
    `static JCoClassMetaData` | `createClassMetaData(String name)` Returns a newly created and empty instance of JCoClassMetaData with the passed initial capacity for new field information.
    `static JCoClassMetaData` | `createClassMetaData(String name, String[] parentClasses, String[] implementedInterfaces, int capacity)` Returns a newly created and empty instance of JCoClassMetaData with the passed initial capacity for new field information.
    `static JCoCustomRepository` | `createCustomRepository(String name)` Returns a custom repository, which allows to add custom defined function templates and record metadata definitions.
    `static JCoFunctionTemplate` | `createFunctionTemplate(String name, JCoListMetaData imports, JCoListMetaData exports, JCoListMetaData changing, JCoListMetaData tables, AbapException[] exceptions)` This factory method allows to create a JCoFunctionTemplate that can be used in later function module executions.
    `static JCoFunctionTemplate` | `createFunctionTemplate(String name, JCoListMetaData imports, JCoListMetaData exports, JCoListMetaData changing, JCoListMetaData tables, AbapException[] exceptions, boolean supportsASXML)` This factory method allows to create a JCoFunctionTemplate that can be used in later function module executions.
    `static JCoFunctionUnit` | `createFunctionUnit(JCoBackgroundUnitAttributes unitAttributes)` Creates a new (empty) unit of functions, which is used for bgRFC commuication in the function model.
    `static JCoFunctionUnit` | `createFunctionUnit(String unitID, JCoBackgroundUnitAttributes unitAttributes)` Creates a new (empty) unit of functions, which is used for bgRFC commuication in the function model.
    `static JCoListMetaData` | `createListMetaData(JCoListMetaData metaData)` Returns a newly created instance of JCoListMetaData, which is initially a copy of the passed JCoListMetaData.
    `static JCoListMetaData` | `createListMetaData(String name)` Returns a newly created and empty instance of JCoListMetaData.
    `static JCoListMetaData` | `createListMetaData(String name, int capacity)` Returns a newly created and empty instance of JCoListMetaData with the passed initial capacity for new field information.
    `static JCoRecordMetaData` | `createRecordMetaData(JCoRecordMetaData metaData)` Returns a newly created instance of JCoRecordMetaData, which is initially a copy of the passed JCoRecordMetaData.
    `static JCoRecordMetaData` | `createRecordMetaData(String name)` Returns a newly created and empty instance of JCoRecordMetaData.
    `static JCoRecordMetaData` | `createRecordMetaData(String name, int capacity)` Returns a newly created and empty instance of JCoRecordMetaData with the passed initial capacity for new field information.
    `static JCoRequestUnit` | `createRequestUnit(JCoBackgroundUnitAttributes unitAttributes)` Creates a new (empty) unit of requests, which is used for bgRFC communication in the request/response model.
    `static JCoRequestUnit` | `createRequestUnit(String unitID, JCoBackgroundUnitAttributes unitAttributes)` Creates a new (empty) unit of requests, which is used for bgRFC commuication in the request/response model.
    `static JCoStructure` | `createStructure(JCoRecordMetaData metaData)` Returns a newly created instance of JCoStructure with the passed metadata information.
    `static JCoStructure` | `createStructure(JCoTable table, int row)` Returns a newly created instance of JCoStructure with the metadata used for the given table instance.
    `static JCoTable` | `createTable(JCoRecordMetaData metaData)` Returns a newly created instance of JCoTable with the passed metadata information.
    `static JCoThroughput` | `createThroughput()` Returns a newly created instance of JCoThroughput.
    `static JCoUnitIdentifier` | `createUnitIdentifier(String unitID, JCoUnitIdentifier.Type unitType)` Creates a new unit identifier.
    `static JCoConnectionMonitor` | `getConnectionMonitor()` Returns the connection monitor for all currently available connections.
    `static List<String>` | `getCustomDestinationIDs(String destinationID)` Creates and returns a list with IDs of all custom destinations created by the destination with the given destinationID.
    `static List<String>` | `getDestinationIDs()` Creates and returns a list containing IDs of all available cached destinations.
    `static JCoDestinationMonitor` | `getDestinationMonitor(String destinationID)` Retrieves a monitoring object for a specific destination identified by the given ID.
    `static String` | `getMiddlewareProperty(String key)` Returns the current value for the given middleware property or null, if there is no value set.
    `static String` | `getProperty(String key)` Returns the current value for the given JCo property or null, if there is no value set.
    `static JCoRepository` | `getRepository(String repositoryID)` Returns the repository instance corresponding to the given repository ID or null if the repository isn't available.
    `static String` | `getRepositoryDestinationID(String destinationID)` Returns the destination ID used by repository instances internally.
    `static JCoDestinationMonitor` | `getRepositoryDestinationMonitor(String destinationID)` Retrieves a monitoring object for a specific repository destination of the destination identified by the given ID.
    `static List<String>` | `getRepositoryIDs()` Returns a list containing IDs of all repository instances that are kept internally.
    `static int` | `getTraceLevel()` Returns the current trace level.
    `static String` | `getTracePath()` Returns the current trace path.
    `static String` | `getVersion()` Returns the version of the JCo implementation.
    `static JCoRepositoryQueryResult` | `queryMetaDataSet(JCoRepository repository, List<String> functions, List<String> types, List<String> classes)` Queries the meta data for function, type and class lists.
    `static void` | `removeTraceListener(JCoTraceListener listener)` Removes the given trace listener from the list of JCoTraceListeners.
    `static void` | `setMiddlewareProperty(String key, String value)` Sets a value for the given middleware property.
    `static void` | `setProperty(String key, String value)` Sets a value for the given JCo property.
    `static void` | `setTrace(int level, String path)` Turns on the JCo trace.

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

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

- - ### Constructor Detail

    - #### JCo

          public JCo()

  - ### Method Detail

    - #### getVersion

          public static String getVersion()

      Returns the version of the JCo implementation.
      Returns:
        the version of the JCo implementation

    - #### createCustomRepository

          public static JCoCustomRepository createCustomRepository(String name)

      Returns a custom repository, which allows to add custom defined function templates and record metadata definitions.
      Parameters:
        `name` - The name of the repository to create.
      Returns:
        a newly created custom repository

    - #### createRecordMetaData

          public static JCoRecordMetaData createRecordMetaData(String name)

      Returns a newly created and empty instance of JCoRecordMetaData.
      Parameters:
        `name` - The name of the record metadata.
      Returns:
        a newly created JCoRecordMetaData

    - #### createRecordMetaData

          public static JCoRecordMetaData createRecordMetaData(String name,
                                               int capacity)

      Returns a newly created and empty instance of JCoRecordMetaData with the passed initial capacity for new field information. This factory method should be used, if you know how many fields the record metadata will have to avoid incremental adjustments of the internal data containers.
      Parameters:
        `name` - The name of the record metadata.
        `capacity` - The initial capacity for this metadata object.
      Returns:
        a newly created JCoRecordMetaData

    - #### createRecordMetaData

          public static JCoRecordMetaData createRecordMetaData(JCoRecordMetaData metaData)

      Returns a newly created instance of JCoRecordMetaData, which is initially a copy of the passed JCoRecordMetaData. Use this factory method in order to create similar metadata objects to minimize the code.
      Parameters:
        `metaData` - the JCoRecordMetaData object to copy from
      Returns:
        a newly created JCoRecordMetaData
      See Also:
        `JCoMetaData.setName(String)`

    - #### createListMetaData

          public static JCoListMetaData createListMetaData(String name)

      Returns a newly created and empty instance of JCoListMetaData.
      Parameters:
        `name` - The name of the list metadata.
      Returns:
        a newly created JCoListMetaData

    - #### createListMetaData

          public static JCoListMetaData createListMetaData(String name,
                                           int capacity)

      Returns a newly created and empty instance of JCoListMetaData with the passed initial capacity for new field information. This factory method should be used, if you know how many fields the record metadata will have to avoid incremental adjustments of the internal data containers.
      Parameters:
        `name` - The name of the list metadata.
        `capacity` - The initial capacity for this metadata object.
      Returns:
        a newly created JCoListMetaData

    - #### createListMetaData

          public static JCoListMetaData createListMetaData(JCoListMetaData metaData)

      Returns a newly created instance of JCoListMetaData, which is initially a copy of the passed JCoListMetaData. Use this factory method in order to create similar metadata objects to minimize the code.
      Parameters:
        `metaData` - the JCoListMetaData object to copy from
      Returns:
        a newly created JCoListMetaData

    - #### createClassMetaData

          public static JCoClassMetaData createClassMetaData(String name,
                                             String[] parentClasses,
                                             String[] implementedInterfaces,
                                             int capacity)

      Returns a newly created and empty instance of JCoClassMetaData with the passed initial capacity for new field information. If you know how many fields the class metadata will have, you may set capacity accordingly to avoid incremental adjustments of the internal data containers. Otherwise set capacity to '0'.
      Parameters:
        `name` - class type name
        `parentClasses` - parent classes of the class type being created
        `implementedInterfaces` - interfaces implemented by the class type being created
        `capacity` - the number of preallocated field expected for that class metadata object
      Returns:
        a new instance of JCoClassMetaData fitting to the parameters

    - #### createClassMetaData

          public static JCoClassMetaData createClassMetaData(String name)

      Returns a newly created and empty instance of JCoClassMetaData with the passed initial capacity for new field information. If you know how many fields the class metadata will have, you may set capacity accordingly to avoid incremental adjustments of the internal data containers. Otherwise set capacity to '0'.
      Parameters:
        `name` - class type name
      Returns:
        a new instance of JCoClassMetaData fitting to the parameter

    - #### createClassMetaData

          public static JCoClassMetaData createClassMetaData(JCoClassMetaData metaData)

      Returns a newly created instance of JCoClassMetaData, which is initially a copy of the passed JCoClassMetaData. Use this factory method in order to create similar metadata objects to minimize the code.
      Parameters:
        `metaData` - the JCoClassMetaData object to copy from
      Returns:
        a newly created JCoClassMetaData

    - #### createFunctionTemplate

          public static JCoFunctionTemplate createFunctionTemplate(String name,
                                                   JCoListMetaData imports,
                                                   JCoListMetaData exports,
                                                   JCoListMetaData changing,
                                                   JCoListMetaData tables,
                                                   AbapException[] exceptions)

      This factory method allows to create a JCoFunctionTemplate that can be used in later function module executions. It is normally only used for hardcoded repositories or if you provide your own JCoRepository that uses a different location for the metadata. The metadata objects used here for the parameter lists have to be locked before to avoid inconsistencies.
      Parameters:
        `name` - the name of the function module which is represented by the function template definition
        `imports` - the metadata for all import parameters of the represented function module
        `exports` - the metadata for all export parameters of the represented function module
        `changing` - the metadata for all changing parameters of the represented function module
        `tables` - the metadata for all table parameters of the represented function module
        `exceptions` - array of AbapExceptions, that belong to the represented function module
      Returns:
        a new instance of a JCoFunctionTemplate that consists of the passed metadata
      Throws:
        `IllegalArgumentException` - in case a metadata object passed as parameter is not locked.

    - #### createFunctionTemplate

          public static JCoFunctionTemplate createFunctionTemplate(String name,
                                                   JCoListMetaData imports,
                                                   JCoListMetaData exports,
                                                   JCoListMetaData changing,
                                                   JCoListMetaData tables,
                                                   AbapException[] exceptions,
                                                   boolean supportsASXML)

      This factory method allows to create a JCoFunctionTemplate that can be used in later function module executions. It is normally only used for hardcoded repositories or if you provide your own JCoRepository that uses a different location for the metadata. The metadata objects used here for the parameter lists have to be locked before to avoid inconsistencies.
      Parameters:
        `name` - the name of the function module which is represented by the function template definition
        `imports` - the metadata for all import parameters of the represented function module
        `exports` - the metadata for all export parameters of the represented function module
        `changing` - the metadata for all changing parameters of the represented function module
        `tables` - the metadata for all table parameters of the represented function module
        `exceptions` - array of AbapExceptions, that belong to the represented function module
        `supportsASXML` - flag indicating whether this function module supports the ASXML semantics for serialization in the RFC protocol
      Returns:
        a new instance of a JCoFunctionTemplate that consists of the passed metadata
      Throws:
        `IllegalArgumentException` - in case a metadata object passed as parameter is not locked.

    - #### createStructure

          public static JCoStructure createStructure(JCoRecordMetaData metaData)

      Returns a newly created instance of JCoStructure with the passed metadata information. The metadata object has to be locked to prevent changes on it and thus inconsistencies in the structure.
      Parameters:
        `metaData` - the metadata instance.
      Returns:
        a newly created JCoStructure
      Throws:
        `IllegalArgumentException` - if metaData is null or is not locked

    - #### createStructure

          public static JCoStructure createStructure(JCoTable table,
                                     int row)

      Returns a newly created instance of JCoStructure with the metadata used for the given table instance. The structure values are copied from the table line with the given row index.
      Parameters:
        `table` - the table is being used as template for the structure.
        `row` - the table line index used to copy the values.
      Returns:
        a newly created JCoStructure
      Throws:
        `IllegalArgumentException` - row is out of bounds or table is null

    - #### createTable

          public static JCoTable createTable(JCoRecordMetaData metaData)

      Returns a newly created instance of JCoTable with the passed metadata information. The metadata object has to be locked to prevent changes on it and thus inconsistencies in the table.
      Parameters:
        `metaData` - the metadata instance.
      Returns:
        a newly created JCoTable
      Throws:
        `IllegalArgumentException` - if metaData is null or is not locked

    - #### createAbapObject

          public static JCoAbapObject createAbapObject(JCoClassMetaData classMetaData,
                                       Map<String,Object> initialValues)

      This is a constructor for an instance of an ABAP class. The passed map consists of the initial values that should be set in the instance on creation. This is especially required for read-only attributes, which can no longer be modified afterwards through the `setValue()` methods.
      Parameters:
        `classMetaData` - The metadata describing the ABAP object.
        `initialValues` - A map whose entries will be used as initial values for the instance. Unknown fields will be ignored.
      Returns:
        The new instance fitting to the passed metadata instance and the initial values
      Throws:
        `ConversionException` - if one of the values could not be converted into the corresponding attribute type
      Since:
        JCo 3.0.3

    - #### createFunctionUnit

          public static JCoFunctionUnit createFunctionUnit(String unitID,
                                           JCoBackgroundUnitAttributes unitAttributes)

      Creates a new (empty) unit of functions, which is used for bgRFC commuication in the function model. The given id is assigned to the unit and cannot be changed. bgRFC supports IDs with length 32 chars as hex decimal representation of 16 bytes
      Note: This API is for special cases only - especially for recovering after failure. Applications should use createFunctionUnit() to create a new unit instead of this API.
      Parameters:
        `unitID` - ID to be assigned to the function unit
      Returns:
        a newly created function unit
      Since:
        JCo 3.0.3

    - #### createFunctionUnit

          public static JCoFunctionUnit createFunctionUnit(JCoBackgroundUnitAttributes unitAttributes)

      Creates a new (empty) unit of functions, which is used for bgRFC commuication in the function model. A new unit identifier will be generated internally.
      Returns:
        a newly created function unit
      Since:
        JCo 3.0.3

    - #### createRequestUnit

          public static JCoRequestUnit createRequestUnit(String unitID,
                                         JCoBackgroundUnitAttributes unitAttributes)

      Creates a new (empty) unit of requests, which is used for bgRFC commuication in the request/response model. The given id is assigned to the unit and cannot be changed. bgRFC supports IDs with length 32 chars as hex decimal representation of 16 bytes
      Note: This API is for special cases only - especially for recovering after failure. Applications should use createRequestUnit() to create a new unit instead of this API.
      Parameters:
        `unitID` - ID to be assigned to the request unit
      Returns:
        a newly created request unit
      Since:
        JCo 3.0.3

    - #### createRequestUnit

          public static JCoRequestUnit createRequestUnit(JCoBackgroundUnitAttributes unitAttributes)

      Creates a new (empty) unit of requests, which is used for bgRFC communication in the request/response model. A new unit identifier will be generated internally.
      Returns:
        a newly created request unit
      Since:
        JCo 3.0.3

    - #### createBackgroundUnitAttributes

          public static JCoBackgroundUnitAttributes createBackgroundUnitAttributes()

      Creates an empty instance of function/request unit attributes.
      Returns:
        instance of unit attributes
      Since:
        JCo 3.0.3

    - #### createUnitIdentifier

          public static JCoUnitIdentifier createUnitIdentifier(String unitID,
                                               JCoUnitIdentifier.Type unitType)

      Creates a new unit identifier. The unit identifier is created by a function/request unit instance automatically. This API can be used to create a unit identifier instance, if the unit ID and the unit type were saved to a database separately.
      Returns:
        instance of unit identifier
      Since:
        JCo 3.0.3

    - #### getRepositoryIDs

          public static List<String> getRepositoryIDs()

      Returns a list containing IDs of all repository instances that are kept internally.
      Returns:
        list of repository IDs

    - #### getRepository

          public static JCoRepository getRepository(String repositoryID)
                                             throws JCoRuntimeException

      Returns the repository instance corresponding to the given repository ID or null if the repository isn't available.
      Parameters:
        `repositoryID` - ID of the requested repository
      Returns:
        the repository instance or null
      Throws:
        `JCoRuntimeException` - if an internal exception occurs, e.g. repositoryID is null

    - #### getDestinationIDs

          public static List<String> getDestinationIDs()

      Creates and returns a list containing IDs of all available cached destinations. The IDs returned by this API can be used to obtain a destination monitor for a destination.
      Returns:
        a new list containing IDs for all (used) destinations

    - #### getCustomDestinationIDs

          public static List<String> getCustomDestinationIDs(String destinationID)
                                                      throws JCoRuntimeException

      Creates and returns a list with IDs of all custom destinations created by the destination with the given destinationID. The IDs returned by this API can be used to obtain a destination monitor for a custom destination.
      Parameters:
        `destinationID` - ID of the destination used for the creation of the custom destinations
      Returns:
        a list containing the IDs of existing custom destinations
      Throws:
        `JCoRuntimeException`

    - #### getRepositoryDestinationID

          public static String getRepositoryDestinationID(String destinationID)
                                                   throws JCoRuntimeException

      Returns the destination ID used by repository instances internally. In case the destination does not instantiate its own and uses the repository from another destination, null is returned.
      Parameters:
        `destinationID` - of the destination
      Returns:
        destination id or null
      Throws:
        `JCoRuntimeException` - is thrown if destination id null or the destination id does not exists

    - #### getDestinationMonitor

          public static JCoDestinationMonitor getDestinationMonitor(String destinationID)
                                                             throws JCoRuntimeException

      Retrieves a monitoring object for a specific destination identified by the given ID. Thus, you can get runtime information about that destination.
      Parameters:
        `destinationID` - the unique destination ID for which the monitor should be returned
      Returns:
        the destination monitor instance for the destination
      Throws:
        `JCoRuntimeException` - in case of issues while getting and creating the destination monitor

    - #### getRepositoryDestinationMonitor

          public static JCoDestinationMonitor getRepositoryDestinationMonitor(String destinationID)
                                                                       throws JCoRuntimeException

      Retrieves a monitoring object for a specific repository destination of the destination identified by the given ID. This could be the monitor for the destination itself or of some other destination that serves as repository destination - depending on the configuration. Thus, you can get runtime information about that destination.
      Parameters:
        `destinationID` - the unique destination ID for which the monitor for the repository destination should be returned
      Returns:
        the destination monitor instance for the repository destination
      Throws:
        `JCoRuntimeException` - in case of issues while getting and creating the destination monitor
      Since:
        JCo 3.0.7

    - #### getConnectionMonitor

          public static JCoConnectionMonitor getConnectionMonitor()

      Returns the connection monitor for all currently available connections.
      Returns:
        the connection monitor
      Throws:
        `JCoRuntimeException` - if an unexpected situation occurs while creating the monitor
        `UnsupportedOperationException` - if the monitor is not supported in the current environment

    - #### createThroughput

          public static JCoThroughput createThroughput()

      Returns a newly created instance of JCoThroughput. Throughput instances can be used to measure the performance of RFC calls. It automatically, sums up all the measured data for times and data amounts.
      Returns:
        a newly created JCoThroughput

    - #### getMiddlewareProperty

          public static String getMiddlewareProperty(String key)

      Returns the current value for the given middleware property or null, if there is no value set.
      Parameters:
        `key` - the name of the property for which you want to get the value
      Returns:
        the current value of the property

    - #### getProperty

          public static String getProperty(String key)

      Returns the current value for the given JCo property or null, if there is no value set.
      Parameters:
        `key` - the name of the property for which you want to get the value
      Returns:
        the current value of the property

    - #### setMiddlewareProperty

          public static void setMiddlewareProperty(String key,
                                   String value)

      Sets a value for the given middleware property. If the value is not applicable to the given property, a JCoRuntimeException will be thrown. The supported properties are listed in the table below:

      Property name | Description
      --- | ---
      `jco.middleware.max_startup_delay` | The maximum time in seconds between restart tries for a JCoServer. Serves as default value, if there is no server specific one. Values below 60 seconds are not allowed. (Default: 3600)
      `jco.middleware.wait_for_request_time` | Sets the trace level for JCo. Alternative to `JCo.setTrace()`. Find details there.
      `jco.middleware.snc_lib` | The location of the SNC library. Serves as default value, if there is no server or destination specific configuration. (Default: "")
      `jrfc.client_connect_timeout` | The timeout for a logon try after having established the technical client connection to an ABAP server. Provide it in seconds (Default: 60s)

      Parameters:
        `key` - the name of the property for which you want to set the value
        `value` - the new value, that the property should get
      Throws:
        `JCoRuntimeException` - if the value is not fitting to the property

    - #### setProperty

          public static void setProperty(String key,
                         String value)

      Sets a value for the given JCo property. If the value is not applicable to the given property, a JCoRuntimeException will be thrown. The supported properties are listed in the table below:

      Property name | Description
      --- | ---
      `jco.trace_path` | Sets the location of the path for JCo trace files. Alternative to `JCo.setTrace()`. Find details there.
      `jco.trace_level` | Sets the trace level for JCo. Alternative to `JCo.setTrace()`. Find details there.
      `jco.trace.format` | Allows defining the trace format. Allowed values are jco and log4j. (Default: jco)
      `jco.jarm` | If set to 1, turns on jarm performance monitoring. In that case the jarm libraries need to be in the classpath. (Default: 0)
      `jco.jdsr` | If set to 1, turns on DSR. In that case the jdsr libraries need to be in the classpath. (Default: 0)
      `jco.jdsr.comp_name` | The component name to use when creating DSR records. (Default: SAP Java Connector)
      `jco.session_timeout` | The idle timeout for JCo session contexts in minutes. (Default: 10)
      `jco.session_timeout.check_interval` | The time interval for checking whether JCo session contexts have been expired in minutes. (Default: 5)
      `jco.cpic_maxconv` | The maximum number of connections allowed by the CPIC layer. (Default: runtime environment dependent, min. 202)
      `jco.cpic_keep_alive_period` | The time a server connection has been idle, after which a keep alive ping event is sent, in seconds (Default: 300)
      `jco.cpic_keep_alive_timeout` | Timeout for a ping in ms. After that time a connection is considered as broken. (Default: 10)
      `jco.ni.dnscache.ttl` | >Caching time (time to live) in seconds of host names for successful DNS lookups (Default: value of Java security property `networkaddress.cache.ttl`, valid range is 0 [off] to 86400 [one day])
      `jco.ni.dnscache.negative.ttl` | Caching time (time to live) in seconds of host names for failed DNS lookups (Default: value of Java security property `networkaddress.cache.negative.ttl`, valid range is 0 [off] to 86400 [one day])
      `cpic.trace` | The trace level for the CPIC layer. The valid value range is from 0 (trace is off) to 3 (most verbose trace) (Default: 0)
      `jrfc.trace` | If set to 1, RFC trace is turned on for all connections within JCo. (Default: 0)
      `jco.delta_management` | If set to 0, delta management in RFC protocol is turned off in general. (Default: 1)
      `jco.use_repository_roundtrip_optimization` | If set to 1, the JCo repository tries to use the function module for roundtrip optimization for metadata lookups. (Default: 0) See SAP note 1456826 regarding back-end prerequisites.

      Note: The property `jco.session_timeout` specifies the timeout period since the last access to a session context after which the registered `SessionReferenceProvider` instance will be regularly called for checking, if the associated JCo session is still alive or not. Only if the method `SessionReferenceProvider.isSessionAlive(sessionID)` returns `false` for the specified sessionID, the associated JCo session context will be released, which means that also all still running RFC requests belonging to this context will be immediately canceled.

      Most of the above properties can also be passed as a Java system property with the -D argument when starting the JVM. These are: `jco.trace_path`, `jco.trace_level`, `jco.trace.format`, `jco.jarm`, `jco.jdsr`, `jco.session_timeout`, `jco.session_timeout.check_interval`, `jco.cpic_maxconv`, `jco.cpic_keep_alive_period`, `jco.cpic_keep_alive_timeout`, `jco.ni.dnscache.ttl`, `jco.ni.dnscache.negative.ttl`, `cpic.trace`, `jrfc.trace`, `jco.delta_management` and `jco.use_repository_roundtrip_optimization`.

      Some other properties can only exclusively be passed as a Java system property with the -D argument when starting the JVM. That means they cannot be modified during runtime after the JCo framework initialization anymore. This applies to the following properties listed below:

      Property name | Description
      --- | ---
      `jco.allow_non_abap_partner` | If set to 1 the RFC extern-to-extern communication is allowed. (Default: 0) For further details see SAP note 1877907 regarding the SAP JCo standalone environment and SAP note 1729203 regarding the SAP NetWeaver AS Java environment.
      `jco.program_name` | The RFC caller program name. (Default: SAPJCo<VersionNumber> [e.g. `SAPJCo30`])

      Caution: For security reasons SAP discourages to run extern-to-extern RFC communication scenarios. External or registered RFC server programs are not able to check and authenticate incoming RFC requests from external non-ABAP programs with regard to the pure RFC protocol data. Each of such external RFC requests must be regarded as insecure. It is highly recommended to secure such RFC communications with SNC (Secure Network Communication).

      Parameters:
        `key` - the name of the property for which a value should be set
        `value` - the new value for the property
      Throws:
        `JCoRuntimeException` - if the value is not fitting to the property

    - #### addTraceListener

          public static void addTraceListener(JCoTraceListener listener)

      Adds a trace listener, that receives all trace events of JCo.
      Parameters:
        `listener` - An instance of JCoTraceListener, that shall be added to the listener list

    - #### removeTraceListener

          public static void removeTraceListener(JCoTraceListener listener)

      Removes the given trace listener from the list of JCoTraceListeners.
      Parameters:
        `listener` - An instance of JCoTraceListener, that shall be removed from the listener list

    - #### setTrace

          public static void setTrace(int level,
                      String path)

      Turns on the JCo trace. Allowed levels are [0 .. 10]. The common ones used are:
      - 0 - nothing
      - 1 - errors
      - 2 - errors and warnings
      - 3 - info messages, errors and warnings
      - 4 - execution path, info messages, errors and warnings
      - 5 - verbose execution path, info messages, errors and warnings
      - 6 - verbose execution path, limited data dumps, info messages, errors and warnings
      - 7 - full execution path, data dumps with metadata, verbose info messages, errors and warnings
      - 8 - full execution path, full data dumps with metadata, verbose info messages, errors and warnings
      As path value `null`, `stdout`, `stderr` or an existing path are allowed. If path is equals `null` or `stdout` or `stderr` JCo will trace out to the standard output (error) stream. If at least one `JCoTraceListener` is registered, the trace output will be sent to the listener only. To redirect the JCo trace into a file, the path value has to be set to an existing directory.
      Parameters:
        `level` - [0 .. 10]
        `path` - `null`, `stdout`, `stderr` or an existing path

    - #### getTraceLevel

          public static int getTraceLevel()

      Returns the current trace level.
      Returns:
        trace level [0..10]
      See Also:
        `setTrace(int, String)`

    - #### getTracePath

          public static String getTracePath()

      Returns the current trace path.
      Returns:
        trace path
      See Also:
        `setTrace(int, String)`

    - #### queryMetaDataSet

          public static JCoRepositoryQueryResult queryMetaDataSet(JCoRepository repository,
                                                  List<String> functions,
                                                  List<String> types,
                                                  List<String> classes)
                                                           throws JCoException

      Queries the meta data for function, type and class lists. All meta data are fetched using one roundtrip, the result is cached in repository cache.
      Parameters:
        `repository` - repository, that will be used for the query. Only repositories connected to the ABAP system are allowed
        `functions` - list of functions to be queried or null
        `types` - list of types to be queried or null
        `classes` - list of classes to be queried or null
      Returns:
        JCoRepositoryQueryResult containing query status for requested elements
      Throws:
        `JCoException` - if a communication error will happen an JCoException with the key JCO_ERROR_COMMUNICATION will be thrown. If the specified repository instance is not connected to an ABAP system a JCoException with key JCO_ERROR_ILLEGAL_ARGUMENT will be thrown.

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