How to validate fields of a bidirectional grpc streaming api on every new part, just not on the stream.
You are building a bidirectional gRPC streaming API and need to ensure that each part of the stream (every individual message) is validated before it’s processed. This validation needs to occur continuously throughout the stream, not just when the stream is first initiated.
Please fine the proto message below validating content value
Creating a Protobuf Message below
syntax = "proto3";
message ChatMessage {
string user_id = 1; // User ID for identifying the sender
string content = 2[
(google.api.field_behavior) = REQUIRED,
(buf.validate.field).int32.gte = 1,
(buf.validate.field).int32.lte = 10000
]; // Content of the message
int64 timestamp = 3; // Timestamp of the message
}
service ChatService {
rpc ChatStream(stream ChatMessage) returns (stream ChatMessage);
}
But the buf.validate.field will only validate content value in the stream request (part I)
For any further parts ( I, II, III) the validation will not work since its applied on stream request and not on each part.
s each message in the stream arrives, you want to make sure that it adheres to certain rules or constraints. This means that instead of validating all messages at once (at the beginning of the stream), each message needs to be validated as it arrives. This ensures that only valid data is processed, while invalid messages can be rejected or flagged immediately.
DATA约束：例如，在聊天应用程序的情况下，您可能需要验证：
用户ID不为空，并且匹配特定格式（例如，字母数字，3-20个字符）。 消息的内容不是空的，也不会超过最大长度（例如500个字符）。 时间戳是有效的Unix时间戳（将来不是或太老）。
Enters : javax.validation
javax.validation in Java is the standard validation framework used for validating Java beans (POJOs), and you can integrate it into your gRPC service logic to perform field-level validation during the streaming process.
**step 1:** Setting Up javax.validation
<dependency>
<groupId>javax.validation</groupId>
<artifactId>javax.validation-api</artifactId>
<version>2.0.1.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<version>6.0.13.Final</version> <!-- Choose the version that suits you -->
</dependency>
**step 2:**
Since you’ll use javax.validation, the gRPC generated POJOs will work, but you may want to create a Java class that corresponds to the ChatMessage to apply validation annotations. This is usually a wrapper class.
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import javax.validation.constraints.Pattern;
import java.io.Serializable;
public class ChatMessageWrapper implements Serializable {
@NotNull(message = "User ID cannot be null")
@Pattern(regexp = "[A-Za-z0-9_-]{3,20}", message = "User ID must be alphanumeric and between 3-20 characters")
private String userId;
@NotNull(message = "Content cannot be null")
@Size(min = 1, max = 500, message = "Content must be between 1 and 500 characters")
private String content;
@NotNull(message = "Timestamp cannot be null")
private Long timestamp;
// Getters and setters
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public Long getTimestamp() {
return timestamp;
}
public void setTimestamp(Long timestamp) {
this.timestamp = timestamp;
}
}
**step 3:**
Server-side Validation Logic (Bidirectional Streaming)
import io.grpc.stub.StreamObserver;
import javax.validation.ConstraintViolation;
import javax.validation.Validation;
import javax.validation.Validator;
import java.util.Set;
public class ChatServiceImpl extends ChatServiceGrpc.ChatServiceImplBase {
private final Validator validator = Validation.buildDefaultValidatorFactory().getValidator();
@Override
public StreamObserver<ChatMessage> chatStream(StreamObserver<ChatMessage> responseObserver) {
return new StreamObserver<ChatMessage>() {
@Override
public void onNext(ChatMessage chatMessage) {
// Validate each incoming ChatMessage
ChatMessageWrapper wrapper = new ChatMessageWrapper();
wrapper.setUserId(chatMessage.getUserId());
wrapper.setContent(chatMessage.getContent());
wrapper.setTimestamp(chatMessage.getTimestamp());
Set<ConstraintViolation<ChatMessageWrapper>> violations = validator.validate(wrapper);
// If there are validation errors, we can send an error response
if (!violations.isEmpty()) {
for (ConstraintViolation<ChatMessageWrapper> violation : violations) {
System.out.println("Validation error: " + violation.getMessage());
}
// Optionally, respond with an error message
responseObserver.onNext(ChatMessage.newBuilder()
.setUserId("Server")
.setContent("Validation failed.")
.setTimestamp(System.currentTimeMillis())
.build());
responseObserver.onCompleted();
return;
}
// If the message is valid, process the message
// For now, just echo the message back to the client
responseObserver.onNext(chatMessage);
}
@Override
public void onError(Throwable t) {
// Handle stream error (e.g., client disconnects)
t.printStackTrace();
}
@Override
public void onCompleted() {
// Handle stream completion
responseObserver.onCompleted();
}
};
}
}
bidirectional streaming in gRPC, you want to validate each part of the stream individually. Since each message that flows in the stream needs to be validated before it’s processed, you can do this in the server’s ChatStream method on onNext()
Performance consideration: Keep in mind that validating every part of the stream can introduce overhead. You might want to optimize this by performing validation checks on fields that are critical or applying them conditionally based on business logic.