[Frontend] Add /classify endpoint (#17032)

Signed-off-by: Frieda (Jingying) Huang <jingyingfhuang@gmail.com>

vllm/entrypoints/openai/protocol.py

@@ -1292,6 +1292,47 @@ class ScoreResponse(OpenAIBaseModel):
     usage: UsageInfo
 
 
+class ClassificationRequest(OpenAIBaseModel):
+    model: Optional[str] = None
+    input: Union[list[str], str]
+    truncate_prompt_tokens: Optional[int] = None
+    user: Optional[str] = None
+
+    # doc: begin-classification-pooling-params
+    additional_data: Optional[Any] = None
+    # doc: end-classification-pooling-params
+
+    # doc: begin-classification-extra-params
+    priority: int = Field(
+        default=0,
+        description=(
+            "The priority of the request (lower means earlier handling; "
+            "default: 0). Any priority other than 0 will raise an error "
+            "if the served model does not use priority scheduling."),
+    )
+
+    # doc: end-classification-extra-params
+
+    def to_pooling_params(self):
+        return PoolingParams(additional_data=self.additional_data)
+
+
+class ClassificationData(OpenAIBaseModel):
+    index: int
+    label: Optional[str]
+    probs: list[float]
+    num_classes: int
+
+
+class ClassificationResponse(OpenAIBaseModel):
+    id: str = Field(default_factory=lambda: f"classify-{random_uuid()}")
+    object: str = "list"
+    created: int = Field(default_factory=lambda: int(time.time()))
+    model: str
+    data: list[ClassificationData]
+    usage: UsageInfo
+
+
 class FunctionCall(OpenAIBaseModel):
     name: str
     arguments: str