In this section:
The asynchronous socket listener supports high levels of concurrency from socket-based clients using asynchronous reads and writes. It can be configured to read fixed length, prefixed variable length, or token delimited messages from the socket. Connections from the client are kept open until the client closes the connection or an error occurs in the listener. The listener logs an error and closes the client connection if a matching response is not heard. This is to prevent clients from waiting for responses to requests that the listener will not send.
The tool can be installed from the UI or command line.
Add the com.parasoft.virtualize.listener.asynchronous.socket-1.0.jar file to the system.properties.classpath property in your localsettings properties file. For example:
system.properties.classpath=<path to jar>/com.parasoft.virtualize.listener.asynchronous.socket-1.0.jar
Once the classpath is modified, all of the required dependencies will be loaded.
Once the asynchronous socket listener is installed, Asynchronous Socket Listener will be available in the Transports> Custom tab of the Virtual Asset configuration panel. Open this panel by double-clicking a virtual asset’s Virtualize Server node.
If multiple custom listeners are available, you can select the one you want to use from the Select Implementation box.
You can configure the following settings.
| Port [0 - 65535] | Specifies the port that the socket listener will listen on for incoming connections. Specify 0 to automatically select an open port. After the asset is deployed, the selected port will be printed in the console. |
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| Worker Threads [minimum: 1, default: 50] | Specifies the number of worker threads used to process messages. |
| Character Set [default: UTF-8] | Specifies the character set used to decode and encode bytes. |
| Connection Backlog [optional] | Specifies the number of connections allowed in the backlog before new connections will be rejected. Recommended to leave at the default. |
| Read Mode [fixed, prefixed, prefixed-string, token][default: prefixed] | Specifies the listener mode for reading messages.
Default is |
Specify the size of the fixed message in the Fixed Length [default: 1024] field.
For example, if the size of messages is always four bytes, a client might send the following request
[0, 0, 0, 0]
The listener would send back a response of the same size, for example:
[1, 1, 1, 1]
Each four-byte message from the client would be considered a message.
| Token Delimiter [default: byte 23, End-Of-Transmission-Block] | Specifies the token that delimits messages. Default is |
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| Token Type [string, hex, byte] [default: hex] | Specifies the type of conversion used to get bytes from the token.
Default is |
If a new line (\n) delimiter is specified, then if a client sends multiple requests, the listener would process each message individually and send back a response for each message.
hello world\n foo bar\n |
good night world\n bar foo\n |
The listener processes each request and then sends back the response before handling the next message, even if all the messages are received as one read.
The settings in this section only apply if the read mode is set to prefixed.
| Length of the Length Field (1, 2, 3, 4, or 8) [default: 4, int] | Determines the length of the length field. The desired number of bytes will be read and converted to a number to determine how long the message is. The default is to read 4 bytes and convert it to an integer. |
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| Include Prefix in Length [true, false] [default: true] | Indicates if the length read from the prefix should also include the length of the prefix. For example, if the option is enabled, a 4-byte message would send a prefix that had a value of 8. This is because the Default is |
| Static Prefix [optional] | Specifies a prefix segment to be added to the message that may be required. If specified, the message format will be <PREFIX_BYTES><LENGTH_FIELD_BYTES><MESSAGE_DATA_BYTES>. |
| Static Suffix [optional] | Specifies a suffix segment of the message that may be required by the socket. If specified, the message format will be <LENGTH_FIELD_BYTES><MESSAGE_DATA_BYTES><SUFFIX_BYTES>. |
If the client sends a request containing request1 that was prefixed with an int using the character set CP037 and the length includes the prefix length, then the request would be represented by the following bytes:
[0, 0, 0, 12, 114, 101, 113, 117, 101, 115, 116, 49]
The first four bytes ([0, 0, 0, 12]) are the integer 12, which is the length of the entire message including the first 4 bytes of the prefix. The remaining bytes are the string request1 as encoded by the configured character set.
The settings in this section only apply if the read mode is set to prefixed-string.
| String Prefix Length [the number of string digits to read in] [default: 4] | Specifies the size of the message length prefix. The number of bytes to read is calculated based on the number of digits converted into bytes. The listener encodes 0 into bytes and multiplies the number by the number provided in this field. |
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| Include Prefix in Length [true, false] [default: true] | Setting to true indicates that the length reads from the prefix should also include the length of the prefix. |
If the client sends a request prefixed by a string with 6 characters that has the total length of the message in bytes, then using the character set CP037 would result in the following string message:
000014request1
The 000014 part of the string is the length prefix and 14 is the total length in bytes of the entire message as encoded by the character set including the prefix. If the prefix is not included in the length, then the request from the client would be the following string:
000008request1
The 000008 part of the string is the length of request1 as encoded by the character set.
Set the SSL Enabled [ default:false ] to true to listen over SSL.
Specify the Log Level field. This setting is optional.
1 to only log errors2 to log errors and warnings.3 to log errors, warnings, and info.4 to log errors, warnings, info, and debug.Default is 3