WebSocket Server
The WebSocket Server source is a multithreaded source that listens on a WebSocket endpoint and processes the contents of all authorized WebSocket client requests. For information about supported versions, see Supported systems and versions.
The WebSocket Server source can use multiple threads to enable parallel processing of data from multiple WebSocket clients. The source can also send responses back to the source system when used in a microservice flow.
Before you configure the source, perform additional steps to configure the WebSocket clients.
When you configure the WebSocket Server source, you specify the maximum number of concurrent requests to determine how many threads to use. You define the listening port, application ID, and the maximum message size. You can also configure SSL/TLS properties, including default transport protocols and cipher suites.
When you want the source to send responses back to the source system as part of a microservice flow, you configure the data format and other characteristics of the responses.
When a flow stops, the WebSocket Server source notes where it stops reading. When the flow starts again, the source continues processing from where it stopped by default. You can reset the offset to process all requested data.
Prerequisites
Before you run a flow with the WebSocket Server source, complete the following prerequisites to configure the WebSocket clients.
Send data to the listening port
Configure the WebSocket clients to send data to the WebSocket Server listening port.
When you configure the WebSocket Server source, you define a listening port number where the source listens for data. To pass data to the flow, configure each WebSocket client to send data to a URL that includes the listening port number.
<ws | wss>://<sdc_hostname>:<listening_port>/The URL includes the following components:
- <ws | wss> - Use wss for secure WebSocket connections over HTTPS.
- <sdc_hostname> - The Data Collector host name.
- <listening_port> - The port number where the source listens for data.
For example: wss://localhost:8080/
Include the application ID in requests
Configure the WebSocket clients to include the WebSocket Server application ID in each request.
When you configure the WebSocket Server source, you define an application ID that is used to pass requests to the source. All messages sent to the source must include the application ID.
Include the application ID for each client request in one of the following ways:
- In request headers
- Add the following information to the request header for all WebSocket requests
that you want the source to
process:
X-SDC-APPLICATION-ID: <application_ID> - In a query parameter in the URL
- If you cannot configure the client request headers - for example if the requests are generated by another system - then configure each WebSocket client to send data to a URL that includes the application ID in a query parameter.
Multithreaded processing
The WebSocket Server source performs parallel processing and enables the creation of a multithreaded flow.
The WebSocket Server source uses multiple concurrent threads based on the Max Concurrent Requests property. Each thread connects to the source system, creates a batch of data, and passes the batch to an available flow runner.
A flow runner is a sourceless flow instance - an instance of the flow that includes all of the processors, executors, and targets in the flow and handles all flow processing after the source. Each flow runner processes one batch at a time, just like a flow that runs on a single thread. When the flow of data slows, the flow runners wait idly until they are needed, generating an empty batch at regular intervals. You can configure the Runner Idle Time flow property to specify the interval or to opt out of empty batch generation.
Multithreaded flows preserve the order of records within each batch, just like a single-threaded flow. But since batches are processed by different flow runners, the order that batches are written to targets is not ensured.
For example, say you set the Max Concurrent Requests property to 5. When you start the flow, the source creates five threads, and Data Collector creates a matching number of flow runners. Upon receiving data, the source passes a batch to each of the flow runners for processing. In the batch, WebSocket Server includes only the WebSocket requests with the specified application ID.
At any given moment, the five flow runners can each process a batch, so this multithreaded flow processes up to five batches at a time. When incoming data slows, the flow runners sit idle, available for use as soon as the data flow increases.
For more information about multithreaded flows, see Multithreaded flow overview.
Generated microservice responses
In a microservice flow, the WebSocket Server source can send a response back to the originating WebSocket client.
- Records received from microservice targets
- Flow error records received when the flow is configured to use the Send Response to Source flow error handling
The source generates a single response for each batch of records received. The source can generate the response in JSON or XML format. The response can include an envelope or only raw data.
Responses with an envelope
| Response Key or Element | Value |
|---|---|
| httpStatusCode | The status code associated with the records in the
response. If the records in the generated response share the same status code, the code is written to the httpStatusCode key or element. If the records have different status codes, the httpStatusCode is set to 207 for multiple statuses. |
| data | A list of records passed to the source by the microservice targets used in the flow. |
| error | A list of flow error records passed to the source by the Send Response to Source flow error handling. |
| errorMessage | The error message associated with the first error
record in the response. Used only when the response includes error records. |
{
"httpStatusCode":<status code>,
"data":[<list of success records>],
"error":[<list of error records>],
"errorMessage": <error message, if any>
}Raw responses
When configured to send a raw response, the source generates a response that contains either the list of records passed from the microservice targets or the list of error records passed by the Send Response to Source flow error handling. If the source receives data records from targets and error records from the flow, then the source includes only the error records in the response. If the source receives no data records from targets and no error records from the flow, then the source generates an empty response.
Sample responses
- Single record
- The source receives a single record from the Send Response to Source
target. The target is configured to use the 200 status code.For a response with an envelope, the source sends the following response:
{ "httpStatusCode":200, "data":[{"ID":"103","NAME":"Jack","AGE":"37","STATE":"MD"}], "error":[], "errorMessage":null }For a raw response, the source sends the following response:{"ID":"103","NAME":"Jack","AGE":"37","STATE":"MD"} - Multiple data and error records
- The source receives several records, data and error. Because each record has
a different status code, the response uses status code 207 for multiple
statuses. The errorMessage key includes the error associated with the first
record which has a missing ID. The source is configured to present multiple
records as multiple JSON objects.For a response with an envelope, the source sends the following response:
{ "httpStatusCode":207, "data":[{"ID":"248","NAME":"Pina","AGE":"24","STATE":"RI"}], "error":[{"NAME":"Liz","AGE":"37","STATE":"DE"}, {"ID":"302","NAME":"Roco","AGE":"","STATE":"CA"}], "errorMessage":"COMMON_0001 - Stage precondition: CONTAINER_0051 - Unsatisfied precondition(s) '${record:exists('/ID')}'" }For a raw response, the source sends the following response:{"NAME":"Liz","AGE":"37","STATE":"DE"}, {"ID":"302","NAME":"Roco","AGE":"","STATE":"CA"}
Data formats
The WebSocket Server source processes data differently based on the data format that you select.
The WebSocket Server source processes data formats as follows:
- Binary
- Generates a record with a single byte array field at the root of the record.
- Datagram
- Generates a record for every message. The source can process collectd messages, NetFlow 5 and NetFlow 9 messages, and the following types of syslog messages:
- Delimited
- Generates a record for each delimited line.
- JSON
- Generates a record for each JSON object. You can process JSON files that include multiple JSON objects or a single JSON array.
- Log
- Generates a record for every log line.
- Protobuf
- Generates a record for every protobuf message. By default, the source assumes messages contain multiple protobuf messages.
- SDC Record
- Generates a record for every record. Use to process records generated by a Data Collector flow using the SDC Record data format.
- Text
- Generates a record for each line of text or for each section of text based on a custom delimiter.
- XML
- Generates records based on a user-defined delimiter element. Use an XML element directly under the root element or define a simplified XPath expression. If you do not define a delimiter element, the source treats the XML file as a single record.
Configuring a WebSocket Server source
About this task
Configure a WebSocket Server source to generate multiple threads for parallel processing of WebSocket client requests.