Package thredds.server.opendap.servers

Interface ServerMethods

All Known Subinterfaces:

ServerArrayMethods

All Known Implementing Classes:

NcSDArray, NcSDByte, NcSDCharArray, NcSDFloat32, NcSDFloat64, NcSDGrid, NcSDInt16, NcSDInt32, NcSDString, NcSDStructure, NcSDUInt16, NcSDUInt32, SDArray, SDByte, SDFloat32, SDFloat64, SDGrid, SDInt16, SDInt32, SDList, SDSequence, SDString, SDStructure, SDUInt16, SDUInt32, SDURL

public interface ServerMethods

This interface defines the additional behaviors that Server side types need to support. These include:

The file I/O operations of which each variable must be capable.

The projection information. A projection defines the variables specified by a constraint to be returned by the server. These methods store projection information for a non-vector variable. Each variable type used on the server-side of OPeNDAP must implement this interface or one of its descendents.

The methods that define how each type responds to relational operators. Most (all?) types will not have sensible responses to all of the relational operators (e.g. SDByte won't know how to match a regular expression but SDString will). For those operators that are nonsensical a class should throw InvalidOperator.

See Also:

ServerArrayMethods, Operator

Method Summary

Modifier and Type	Method	Description
boolean	equal(opendap.dap.BaseType bt)	The Operator class contains a generalized implementation of this method.
boolean	greater(opendap.dap.BaseType bt)	The Operator class contains a generalized implementation of this method.
boolean	greater_eql(opendap.dap.BaseType bt)	The Operator class contains a generalized implementation of this method.
boolean	isProject()	Check the projection state of this variable.
boolean	isRead()	Get the value of the Read property.
boolean	isSynthesized()	Get the value of the Synthesized property.
boolean	less(opendap.dap.BaseType bt)	The Operator class contains a generalized implementation of this method.
boolean	less_eql(opendap.dap.BaseType bt)	The Operator class contains a generalized implementation of this method.
boolean	not_equal(opendap.dap.BaseType bt)	The Operator class contains a generalized implementation of this method.
boolean	read(String datasetName, Object specialO)	Read a value from the named dataset for this variable.
boolean	regexp(opendap.dap.BaseType bt)	The Operator class contains a generalized implementation of this method.
void	serialize(String dataset, DataOutputStream sink, CEEvaluator ce, Object specialO)	Server-side serialization for OPeNDAP variables (sub-classes of BaseType).
void	setProject(boolean state)	Set the Project property of this variable.
void	setProject(boolean state, boolean all)	Set the state of this variable's projection.
void	setRead(boolean state)	Set the Read property.
void	setSynthesized(boolean state)	Set the Synthesized property.

Method Detail

setSynthesized

void setSynthesized(boolean state)

Set the Synthesized property.

Parameters:

state - If true then the variable is considered a synthetic variable and no part of OPeNDAP will ever try to read it from a file, otherwise if false the variable is considered a normal variable whose value should be read using the read() method. By default this property is false.

See Also:

isSynthesized(), read(String, Object)

isSynthesized

boolean isSynthesized()

Get the value of the Synthesized property.

Returns:

true if this is a synthetic variable, false otherwise.

setRead

void setRead(boolean state)

Set the Read property. A normal variable is read using the read() method. Once read the Read property is true. Use this function to manually set the property value. By default this property is false.

Parameters:

state - true if the variable has been read, false otherwise.

See Also:

isRead(), read(String, Object)

isRead

boolean isRead()

Get the value of the Read property.

Returns:

true if the variable has been read, false otherwise.

See Also:

read(String, Object), setRead(boolean)

read

boolean read(String datasetName,
             Object specialO)
      throws opendap.dap.NoSuchVariableException,
             IOException

Read a value from the named dataset for this variable.

Parameters:

datasetName - String identifying the file or other data store from which to read a vaue for this variable.

specialO - This Object is a goody that is used by a Server implementations to deliver important, and as yet unknown, stuff to the read method. If you don't need it, make it a null.

Returns:

true if more data remains to be read, otehrwise false.

Throws:

opendap.dap.NoSuchVariableException - When a variable can't be found.

IOException - When there is a problem reading data.

setProject

void setProject(boolean state,
                boolean all)

Set the state of this variable's projection. true means that this variable is part of the current projection as defined by the current constraint expression, otherwise the current projection for this variable should be false.

For simple variables and for children of DVector, the variable either is or is not projected. For children of DConstructor, it may be that the request is for only part of the constructor type (e.g., only oe field of a structure). However, the structure variable itself must be marked as projected given the implementation of serialize. The serialize() method does not search the entire tree of variables; it relies on the fact that for a particular variable to be sent, the path from the top of the DDS to that variable must be marked as `projected', not just the variable itself. This keeps the CEEvaluator.send() method from having to search the entire tree for the variables to be sent.

Parameters:

state - true if the variable is part of the current projection, false otherwise.

all - set (or clear) the Project property of any children.

See Also:

CEEvaluator

setProject

void setProject(boolean state)

Set the Project property of this variable. This is equivalent to calling setProject(, true).

Parameters:

state - true if the variable is part of the current projection, false otherwise.

See Also:

setProject(boolean), CEEvaluator

isProject

boolean isProject()

Check the projection state of this variable. Is the this variable marked as projected? If the variable is listed in the projection part of a constraint expression, then the CE parser should mark it as projected. When this method is called on such a variable it should return true, otherwise it should return false.

Returns:

true if the variable is part of the current projections, false otherwise.

See Also:

setProject(boolean,boolean), setProject(boolean), CEEvaluator

equal

boolean equal(opendap.dap.BaseType bt)
       throws InvalidOperatorException,
              RegExpException,
              SBHException

The Operator class contains a generalized implementation of this method. It should be used unless a localized architecture/implementation requires otherwise.

Parameters:

bt - The variable to which to compare 'this' value.

Returns:

True when they are equal, false otherwise.

Throws:

InvalidOperatorException - When the operator cannot be applied to the two data types.

RegExpException - When the regular expression is badly formed.

SBHException - When Something Bad Happens.

See Also:

Operator

not_equal

boolean not_equal(opendap.dap.BaseType bt)
           throws InvalidOperatorException,
                  RegExpException,
                  SBHException

The Operator class contains a generalized implementation of this method. It should be used unless a localized architecture/implementation requires otherwise.

Parameters:

bt - The variable to which to compare 'this' value.

Returns:

True when they are not equal, false otherwise.

Throws:

InvalidOperatorException - When the operator cannot be applied to the two data types.

RegExpException - When the regular expression is badly formed.

SBHException - When Something Bad Happens.

See Also:

Operator

greater

boolean greater(opendap.dap.BaseType bt)
         throws InvalidOperatorException,
                RegExpException,
                SBHException

The Operator class contains a generalized implementation of this method. It should be used unless a localized architecture/implementation requires otherwise.

Parameters:

bt - The variable to which to compare 'this' value.

Returns:

True when this value is greater than the based 'bt' value, false otherwise.

Throws:

InvalidOperatorException - When the operator cannot be applied to the two data types.

RegExpException - When the regular expression is badly formed.

SBHException - When Something Bad Happens.

See Also:

Operator

greater_eql

boolean greater_eql(opendap.dap.BaseType bt)
             throws InvalidOperatorException,
                    RegExpException,
                    SBHException

The Operator class contains a generalized implementation of this method. It should be used unless a localized architecture/implementation requires otherwise.

Parameters:

bt - The variable to which to compare 'this' value.

Returns:

True when this value is greater or equal than the based 'bt' value, false otherwise.

Throws:

InvalidOperatorException - When the operator cannot be applied to the two data types.

RegExpException - When the regular expression is badly formed.

SBHException - When Something Bad Happens.

See Also:

Operator

less

boolean less(opendap.dap.BaseType bt)
      throws InvalidOperatorException,
             RegExpException,
             SBHException

The Operator class contains a generalized implementation of this method. It should be used unless a localized architecture/implementation requires otherwise.

Parameters:

bt - The variable to which to compare 'this' value.

Returns:

True when this value is less than the based 'bt' value, false otherwise.

Throws:

InvalidOperatorException - When the operator cannot be applied to the two data types.

RegExpException - When the regular expression is badly formed.

SBHException - When Something Bad Happens.

See Also:

Operator

less_eql

boolean less_eql(opendap.dap.BaseType bt)
          throws InvalidOperatorException,
                 RegExpException,
                 SBHException

The Operator class contains a generalized implementation of this method. It should be used unless a localized architecture/implementation requires otherwise.

Parameters:

bt - The variable to which to compare 'this' value.

Returns:

True when this value is less than or equal to the based 'bt' value, false otherwise.

Throws:

InvalidOperatorException - When the operator cannot be applied to the two data types.

RegExpException - When the regular expression is badly formed.

SBHException - When Something Bad Happens.

See Also:

Operator

regexp

boolean regexp(opendap.dap.BaseType bt)
        throws InvalidOperatorException,
               RegExpException,
               SBHException

The Operator class contains a generalized implementation of this method. It should be used unless a localized architecture/implementation requires otherwise.

Parameters:

bt - The variable to which to compare 'this' value.

Returns:

True when regular expression evaluates to true., false otherwise.

Throws:

InvalidOperatorException - When the operator cannot be applied to the two data types.

RegExpException - When the regular expression is badly formed.

SBHException - When Something Bad Happens.

See Also:

Operator

serialize

void serialize(String dataset,
               DataOutputStream sink,
               CEEvaluator ce,
               Object specialO)
        throws opendap.dap.NoSuchVariableException,
               DAP2ServerSideException,
               IOException

Server-side serialization for OPeNDAP variables (sub-classes of BaseType). This does not send the entire class as the Java Serializable interface does, rather it sends only the binary data values. Other software is responsible for sending variable type information (see DDS).

Writes data to a DataOutputStream. This method is used on the server side of the OPeNDAP client/server connection, and possibly by GUI clients which need to download OPeNDAP data, manipulate it, and then re-save it as a binary file.

For children of DConstructor, this method should call itself on each of the components. For other types this method should call externalize().

Parameters:

dataset - a String indicated which dataset to read from (Or something else if you so desire).

sink - a DataOutputStream to write to.

ce - the CEEvaluator to use in the parse process.

specialO - This Object is a goody that is used by a Server implementations to deliver important, and as yet unknown, stuff to the read method. If you don't need it, make it a null.

Throws:

IOException - thrown on any OutputStream exception.

opendap.dap.NoSuchVariableException - When a variable cannot be found.

DAP2ServerSideException - When there is a server error.

See Also:

BaseType, DDS, ServerDDS