com.nike.wingtips.servlet

Class HttpSpanFactory

java.lang.Object

com.nike.wingtips.servlet.HttpSpanFactory

public class HttpSpanFactory
extends java.lang.Object

Creates Span objects extracted from a HttpServletRequest. NOTE: If a span exists in the request but is not explicitly defined with TraceHeaders.TRACE_SAMPLED set to false, then fromHttpServletRequest(HttpServletRequest, List) will default it to be sampleable.

Method Summary

Methods

Modifier and Type	Method and Description
static com.nike.wingtips.Span	fromHttpServletRequest(javax.servlet.http.HttpServletRequest servletRequest, java.util.List<java.lang.String> userIdHeaderKeys)
static com.nike.wingtips.Span	fromHttpServletRequestOrCreateRootSpan(javax.servlet.http.HttpServletRequest servletRequest, java.util.List<java.lang.String> userIdHeaderKeys)
static java.lang.String	getSpanName(javax.servlet.http.HttpServletRequest request)
static java.lang.String	getUserIdFromHttpServletRequest(javax.servlet.http.HttpServletRequest servletRequest, java.util.List<java.lang.String> userIdHeaderKeys) Attempts to pull a valid ID for the user making the request.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

fromHttpServletRequest

public static com.nike.wingtips.Span fromHttpServletRequest(javax.servlet.http.HttpServletRequest servletRequest,
                                            java.util.List<java.lang.String> userIdHeaderKeys)

Parameters:

servletRequest - The incoming request that may have Span information embedded in the headers. If this argument is null then this method will return null.

userIdHeaderKeys - This list of header keys will be used to search the request headers for a user ID to set on the returned span. The user ID header keys will be searched in list order, and the first non-empty user ID header value found will be used as the Span.getUserId(). You can safely pass in null or an empty list for this argument if there is no user ID to extract; if you pass in null then the returned span's Span.getUserId() will be null.

Returns:

The Span stored in the given request's trace headers (e.g. TraceHeaders.TRACE_ID, TraceHeaders.TRACE_SAMPLED, TraceHeaders.PARENT_SPAN_ID, etc), or null if the request is null or doesn't contain the necessary headers.
NOTE: TraceHeaders.TRACE_ID is the minimum header needed to return a non-null Span. If TraceHeaders.SPAN_ID is missing then a new span ID will be generated using TraceAndSpanIdGenerator.generateId(). If TraceHeaders.TRACE_SAMPLED is missing then the returned span will be sampleable. If TraceHeaders.SPAN_NAME is missing then HttpRequestTracingUtils.UNSPECIFIED_SPAN_NAME will be used as the span name.

fromHttpServletRequestOrCreateRootSpan

public static com.nike.wingtips.Span fromHttpServletRequestOrCreateRootSpan(javax.servlet.http.HttpServletRequest servletRequest,
                                                            java.util.List<java.lang.String> userIdHeaderKeys)

Returns:

A Span object created from the headers if they exist (see fromHttpServletRequest(HttpServletRequest, List) for details), or if the headers don't have enough information then this will return a new root span with a span name based on the results of getSpanName(HttpServletRequest) and user ID based on the result of getUserIdFromHttpServletRequest(HttpServletRequest, List). Since this method is for a server receiving a request the returned span's Span.getSpanPurpose() will be Span.SpanPurpose.SERVER.

getUserIdFromHttpServletRequest

public static java.lang.String getUserIdFromHttpServletRequest(javax.servlet.http.HttpServletRequest servletRequest,
                                               java.util.List<java.lang.String> userIdHeaderKeys)

Attempts to pull a valid ID for the user making the request.

Returns:

The HTTP Header value of the user ID if it exists, null otherwise. The request's headers will be inspected for the user ID using the given list of userIdHeaderKeys in list order - the first one found that is not null/empty will be returned.

getSpanName

public static java.lang.String getSpanName(javax.servlet.http.HttpServletRequest request)

Returns:

Span name appropriate for a new root span for this request