PHP处理HAPI-FHIR客户端POST请求的HTTP响应写法是否正确？

问题场景 #

PHP服务端返回的HTTP响应触发HAPI-FHIR客户端抛出异常，报错信息如下：

Failed delivery for (MessageId: ID: on ExchangeId: <..>). caught: ca.uhn.fhir.rest.client.exceptions.FhirClientConnectionException: HAPI-1359: Failed to parse response from server when performing POST to URL
伴随DataFormatException：HAPI-1861: Failed to parse JSON encoded FHIR content: HAPI-1857: Did not find any content to parse

客户端因此每隔一小时重复发送相同Bundle消息重试。

问题代码 #

用户编写的PHP响应代码：

$_http_status_line = "HTTP/1.1 201 Created "; 
$_date_string = make_date_string_reponse($_debug_level); 
$_general_header = $_date_string . "; ";  
$_etag_header = "ETag: W/\"1\"; "; 
$_location_header = "Location: https://<some.url>/; "; 
$_response_header = $_etag_header . " " . $_location_header . " "; 
$_last_modified_date_string = make_date_string_reponse($_debug_level); 
$_content_type_header = "Content-Type: application/fhir+json;charset=utf-8; "; 
$_last_modified_header = "Last-Modified: {$_last_modified_date_string}; "; 
$_entity_header = $_content_type_header . $_last_modified_header . " "; 
$_http_header = $_general_header . $_response_header . $_entity_header . "\n" ; 
$_http_response = $_http_status_line . $_http_header;   
header($_http_response); 

生成的错误响应：

HTTP/1.1 201 Created Tue, 12 Dec 2023 04:54:37 GMT; ETag: W/"1";  Location: https://<some.url>/;  Content-Type: application/fhir+json;charset=utf-8; Last-Modified: Tue, 12 Dec 2023 04:54:37 GMT;

错误分析 #

1. HTTP头设置方式完全错误：PHP的header()函数要求每个HTTP头单独调用设置，状态行与响应头需分离。用户将状态行、所有响应头拼接成一个字符串传入header()，导致客户端无法识别正确的头结构——所有头被错误附加在状态行后，不符合HTTP协议"状态行→换行→每个头单独一行→双换行→响应体"的格式规范。
2. 缺少FHIR格式的响应体：HAPI-FHIR客户端收到201响应时，期望获取创建后的FHIR资源JSON内容。当前响应无任何响应体，触发"Did not find any content to parse"错误。

修复方案 #

1. 正确设置HTTP响应头 #

使用header()函数单独设置每个响应头，状态行单独处理：

// 设置状态码
header("HTTP/1.1 201 Created");

// 生成日期字符串
$_date_string = make_date_string_reponse($_debug_level);
$_last_modified_date_string = make_date_string_reponse($_debug_level);

// 逐个设置响应头
header("Date: {$_date_string}");
header("ETag: W/\"1\"");
header("Location: https://<some.url>/");
header("Content-Type: application/fhir+json;charset=utf-8");
header("Last-Modified: {$_last_modified_date_string}");

2. 返回FHIR格式的响应体 #

设置完所有头后，输出创建成功的FHIR资源JSON（至少是符合FHIR规范的操作响应），示例：

// 返回FHIR标准操作响应
echo json_encode([
    "resourceType" => "OperationOutcome",
    "issue" => [
        [
            "severity" => "information",
            "code" => "informational",
            "details" => ["text" => "Resource created successfully"]
        ]
    ]
]);

验证说明 #

修复后，HTTP响应将符合标准格式：

HTTP/1.1 201 Created
Date: Tue, 12 Dec 2023 04:54:37 GMT
ETag: W/"1"
Location: https://<some.url>/
Content-Type: application/fhir+json;charset=utf-8
Last-Modified: Tue, 12 Dec 2023 04:54:37 GMT

{"resourceType":"OperationOutcome","issue":[{"severity":"information","code":"informational","details":{"text":"Resource created successfully"}}]}

客户端将能正确解析响应头与响应体，停止重试行为。

内容的提问来源于stack exchange，提问作者evert