Schema checking for TCP operators using the confirmWireFormat parameter
SPL standard and specialized toolkits > spl 1.2.1 > spl.adapter > Schema checking for TCP operators using the confirmWireFormat parameter
Use the confirmWireFormat parameter on TCPSource and TCPSink operators to confirm that the transmitted data is compatible. When the parameter value is true, information about the expected data is sent by the operator with the role parameter set to server. The operator with the role parameter set to client compares the information to what it expects, and returns a yes or no answer. The transmitted data is defined in the etc/xsd/SPL/wireFormatMode.xsd and etc/xsd/SPL/tupleTypeModel.xsd files and describes the format, encoding, compression, and tuple schema for the data.
Wire format description
The following table defines the data that is sent when the confirmWireFormat parameter value is true and the role parameter value is server.
Location and type |
Description |
|---|---|
8 byte (network byte order) |
Magic number 0x6D6B6F72616E6461ULL |
4 byte (network byte order) |
Length of a string to follow that contains the wire format description. |
UTF-8 encoded bytes |
A string that describes the wire format description in XML using the wireFormatModel.xsd. |
Response
The following table defines the data that is expected when the confirmWireFormat parameter value is true and the role parameter value is server, or the data that is sent when the confirmWireFormat parameter value is true and the role parameter value is client.
Location and type |
Description |
|---|---|
8 byte (network byte order) |
Magic number 0x6D6B6F72616E6461ULL |
1 byte |
The response: 0x00 (compatible), 0x01 (incompatible) or 0x02 (compatible and drop connection). |
4 byte (network byte order) |
Length of the following UTF-8 response message (or 0 if there is no message). |
UTF-8 encoded bytes |
A string that contains the message that is logged on the server side when a response is received. |
If the answer is 0x00, the response message is logged as L_INFO. If the answer is 0x01 or 0x02, the response message is logged as L_ERROR.
Interaction with the reconnectionPolicy parameter
If an operator with a role parameter value of server and a confirmWireFormat parameter value of true receives a 0x01 (incompatible) or 0x02 (compatible and drop connection) answer in the response or there was an error in the protocol, the entire connection attempt is ignored and it is not considered a connection. The reconnectionPolicy parameter does not apply.
If an operator with a role parameter value of client and a confirmWireFormat parameter value of true receives a 0x01 (incompatible) or 0x02 (compatible and drop connection) answer in the response or there was an error in the protocol, the connection attempt fails and the reconnectionPolicy parameter is used to control the ensuing behavior. Each failed attempt is one connection and counts towards the reconnectionBound parameter.
If an operator with a role parameter value of client has a reconnectionPolicy parameter value of InfiniteRetry and the schemas are incompatible, it continues to try to re-establish the connection.