| Chapter 5. The Peer-to-Peer Client/Server (PPCS) Component | ||
|---|---|---|
 | Part II. C-Language Components |  |
Chapter 5. The Peer-to-Peer Client/Server (PPCS) Component
Provides access to database files via the Superbase Peer-to-Peer Client/Server protocol. This access is read/write/delete but does not provide the ability to modify the database definition or create or modify database tables.
ppcstype1
Description
Objects of type ppcstype1 are a base from which data available from some PPCS server can be accessed. Each object of type ppcstype1 uses one communication medium such as UDP or a serial port.
Type Tags
db1base
Object Value
Objects of type ppcstype1 have no value, and it is an error to try to get or set this value.
ppcstype1.new()
Description
Creates a new ppcstype1 object and specifies the nature of the comunication method it will use. Parameters must be specified for exactly one of the possible media.
Prototype
ppcstype1.new (
integer udpporttxfactorserialportbaudrateparitystopbitserrorusername
Parameters
| Parameter | Default value | Type name | Description |
|---|---|---|---|
| udpport | None | integer |
The UDP port number to use for the new ppcstype1 object. If
this is specified then no parameters for other communication media
should be given. If udpport
is assigned the value .nul then a random port
will be assigned.
|
| txfactor | 0 | integer | The transmission delay to use when communicating. Generally this does not need to be specified. |
| serialport | None | integer | The serial port to use for the new ppcstype1 object. If this is specified then no parameters for other communication media should be given. |
| baudrate | 19200 | integer | The baud rate to use if the new ppcstype1 object is to use serial communications. |
| parity | 0 | integer | The parity to use for serial communications. Permitted values are: 0 (no parity), 1 (odd parity) and 2 (even parity). |
| stopbits | 1 | integer | The number of stop bits to use in serial communications. Permitted values are 1 and 2. |
| error | .nul | integer |
Specifies an object that is used to output any error code generated during the
execution of the method. This parameter must be an object, not an
integer value. If error is
not specified or is .nul then any error that
occurs during object creation will halt the program. If an error
object is specified and an error occurs during execution then the
error code is output into that object and the method returns
.nul.
|
| username | platform dependent | string | The username must be at least one character in length and cannot be greater than eighteen characters in length. The username for a ppcstype1 object is the username used for all operations performed on files opened using the ppcstype1 object. |
Properties
| Property | Type | Description |
|---|---|---|
| _ | type(*) | This property is provided for use by the user to attach any object of any type to the type in which this property is provided. |
| __ | type(*) | This property is provided for use by the user to attach any object of any type to the type in which this property is provided. It has the additional feature of being marked with the resolve keyword, so that object resolution can continue down this property. |
| parity | integer |
Contains the parity setting being used, if the object uses serial
communications, or .nul if not.
|
| serialport | integer |
Contains the number of the serial port in use, if the object uses
communications, or .nul if not.
|
| stopbits | integer |
Contains the number of stop bits being used, if the object uses serial
communications, or .nul if not.
|
| txfactor | integer | Contains a transmission factor value that can be used to slow down the communication with the other end of the PPCS connection. |
| type | type | Specifies the ppcstype1 type object. |
| udpport | integer |
Contains the UDP port number if the object uses UDP, or
.nul if not.
|
| username | string |
Contains the username for all PPCS operations performed using the
ppcstype1 object.
|
Methods
gettablenames()
Description
Gets the names of the PPCS files which are available on a specified PPCS
server. If the attempt to get the table names is successful then
.nul is returned. If the attempt is not successful
and neither the error nor
errortext parameters are
provided then an error is raised. If the attempt is not successful
and at least one of the error
or errortext parameters are
provided then .nul is returned and error
information is output in the error or
errortext objects provided.
Prototype
ppcstype1var.gettablenames (
string addresstablenamespatterncodepageerrorerrortextretrytimeout
Parameters
| Parameter | Default value | Type name | Description |
|---|---|---|---|
| address | None | string | The internet address, machine name or IP address and port number of the PPCS server providing the file names to be retrieved. |
| tablenames | None | array | Specifies an object of type array which is used to output the names of the files which are available from the specified server and which match the specified pattern, if any. The first table name, if any, is placed in the array in the position '[1]', the second in position '[2]', and so on. The number of table names retrieved in placed in position '[]'. |
| pattern | "" | string |
A pattern used to restrict the table names which will be retrieved. Only names
which match the pattern will be output. The matching of a name to
a pattern follows the rules for the intrinsic function
.like1.
|
| codepage | 850 | integer | The number of the OEM codepage that will be assumed to be in use by the PPCS server providing the file. |
| error | .nul | integer |
Specifies an object that is used to output any error code generated during the
execution of the method. This parameter must be an object, not an
integer value. If error
is not specified or is .nul and errortext is not specified or is
.nul then any error that occurs during name
retrieval will halt the program. If an error object or errortext
object is specified and an error occurs during execution then the
error code or text is output into that object and the method
returns .nul.
|
| errortext | .nul | string |
Specifies an object that is used to output any error text generated during the
execution of the method. This parameter must be an object, not a
string value. If error is
not specified or is .nul and errortext is not specified or is
.nul then any error that occurs during name
retrieval will halt the program. If an error object or errortext
object is specified and an error occurs during execution then the
error code or text is output into that object and the method
returns .nul.
|
| retry | 1000000 | integer | The number of microseconds between retries, if the operation is not successful immediately. |
| timeout | 5000000 | integer | The number of microseconds allowed for the operation to complete before it is assumed that it will fail. |
openudpfile()
Description
Opens a database file on a PPCS server using UDP. The
ppcstype1 object for which the method is called must be
using UDP. If the attempt to open the file is successful then a
reference to an object of type ppcstype1file is
returned. If the attempt is not successful and neither the error nor errortext parameters are provided then
an error is raised. If the attempt is not successful and at least one
of the error or errortext parameters are provided then
.nul is returned and error information is output
in the error or errortext
objects provided.
Prototype
ppcstype1var.openudpfile (
string addressfilenamepasswordcodepageerrorerrortextretrytimeoutrecordidfieldname
Parameters
| Parameter | Default value | Type name | Description | |||
|---|---|---|---|---|---|---|
| address | None | string | The internet address, machine name or IP address and port number of the PPCS server providing the file to be opened. | |||
| filename | None | string | The name of the file to open. | |||
| password | None | string | The password to be used to access the file. | |||
| codepage | 850 | integer | The number of the OEM codepage that will be assumed to be in use by the PPCS server providing the file. | |||
| error | .nul | integer |
Specifies an object that is used to output any error code generated during the
execution of the method. This parameter must be an object, not an
integer value. If error
is not specified or is .nul and errortext is not specified or is
.nul then any error that occurs during object
creation will halt the program. If an error object or errortext
object is specified and an error occurs during execution then the
error code or text is output into that object and the method
returns .nul.
| |||
| errortext | .nul | string |
Specifies an object that is used to output any error text generated during the
execution of the method. This parameter must be an object, not a
string value. If error is
not specified or is .nul and errortext is not specified or is
.nul then any error that occurs during object
creation will halt the program. If an error object or errortext
object is specified and an error occurs during execution then the
error code or text is output into that object and the method
returns .nul.
| |||
| retry | 1000000 | integer | The number of microseconds between retries, if the operation is not successful immediately. | |||
| timeout | 5000000 | integer | The number of microseconds allowed for the operation to complete before it is assumed that it will fail. | |||
| recordidfieldname | .nul | string |
The name to use for the exposed internal unique record ID. If this is supplied then the internal record ID will be shown as an indexed unique field. The internal record id is read-only and guaranteed for the life of the record in the table. If the table is reorganized, the record ID is likely to change.
|
![[Warning]](images/warning.png)
settxfactor()
Description
Sets the transmission factor. This is used to moderate the speed at which the packets are transmitted. A factor of 0 means that the packets will be sent at the maximum speed (this may be too fast for Internet connectivity and result in difficulty reading data and excessive retries and timeouts).
Prototype
ppcstype1var.settxfactor (
integer txfactor
Parameters
| Parameter | Default value | Type name | Description |
|---|---|---|---|
| txfactor | None | integer | The factor to use to delay the server. The value 0 means no delay and the higher the number the longer the delay will become. Also each increment is a greater delay than the one before, so a setting of 3 is slower by a greater amount than just the total of the delay at 1 plus 2. |