In this section:
Overview
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.
Installation
The tool can be installed from the UI or command line.
UI Installation
- Choose Parasoft > Preferences and click System Properties.
- Click Add JARs and choose the com.parasoft.virtualize.listener.asynchronous.socket-1.1.0.jar file. Once this jar file is added to the Virtualize classpath, all of the required dependencies will be loaded.
- Click Apply.
- Restart Virtualize.
Command Line Installation
Add the com.parasoft.virtualize.listener.asynchronous.socket-1.1.0.jar file to the system.properties.classpath property in your settings properties file. For example:
system.properties.classpath=<path to jar>/com.parasoft.virtualize.listener.asynchronous.socket-1.1.0.jar
Once the classpath is modified, all of the required dependencies will be loaded.
Usage
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 menu.
Configuration
You can configure the following settings.
Settings
| Protocol | Specifies the protocol used to transmit messages. Options are Default: |
|---|---|
| Port | Specifies the port that the socket listener will listen on for incoming connections. Specify |
| Acceptor Threads | Specifies the number of acceptor threads used to receive messages. Not applicable if Protocol is set to
Default: |
| Worker Threads | Specifies the number of worker threads used to process messages.
Default: |
| Character Set | Specifies the character set used to decode and encode bytes. Default: |
| Connection Backlog | Specifies the number of connections allowed in the backlog before new connections will be rejected. This configuration is optional. Leaving the field empty is recommended. |
| Read Mode | Specifies the listener mode for reading messages.
Default: |
Fixed Length
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 4-byte message from the client would be considered a message.
Token Delimited
| Token Delimiter | Specifies the token that delimits messages. Default: |
|---|---|
| Token Type | Specifies the type of conversion used to get bytes from the token.
Default: |
Token Delimited Example
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.
Prefixed Variable-Length (Number)
The settings in this section only apply if the read mode is set to prefixed.
| Length of the Length Field | Determines the length of the length field. The desired number of bytes will be read and converted to a number to determine the length of the message. You can specify the following values: The default is to read 4 bytes and convert it to an integer. |
|---|---|
| Include Length Field Size in Length | Indicates if the length read should also include the length field size. For example, if the option is enabled, a 4-byte message would send a length value of 8. This is because the default length of the length field is 4 bytes and will be added to the message body length. Default: |
| Format of Static Prefix/Suffix | Specifies the type of conversion used to convert the static prefix/suffix into bytes.
Default: |
| Static Prefix | 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 | 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>. |
Prefixed Variable-Length (Number) Configuration Example
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.
Prefixed Variable-Length (String)
The settings in this section only apply if the read mode is set to prefixed-string.
| String Prefix Length | 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 Default: |
|---|---|
| Include Prefix in Length | Setting to Default: |
Prefixed Variable-Length (String) Configuration Example
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.
SSL
Set SSL Enabled [ default:false ] to true to listen over SSL.
Logging
Specify the Log Level field. This setting is optional.
- Enter
1to only log errors - Enter
2to log errors and warnings. - Enter
3to log errors, warnings, and info. - Enter
4to log errors, warnings, info, and debug.
Default is 3
Change Log
1.1
- Added support for UDP.
1.0
- Initial release.
