Endpoint properties reference

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This topic describes transport properties that can be set in TargetEndpoint and ProxyEndpoint configurations to control messaging and connection behavior. For full coverage of the TargetEndpoint and ProxyEndpoint configuration options, see API proxy configuration reference.

TargetEndpoint Transport Properties

The HTTPTargetConnection element in TargetEndpoint configurations defines a set of HTTP transport properties. You can use these properties to set transport-level configurations.

Properties are set on TargetEndpoint HTTPTargetConnection elements as shown in this example configuration:

<TargetEndpoint name="default">
  <HTTPTargetConnection>
    <URL>http://mocktarget.apigee.net</URL>
    <Properties>
      <Property name="request.retain.headers">User-Agent,Referer,Accept-Language</Property>
      <Property name="retain.queryparams">apikey</Property>
    </Properties>
  </HTTPTargetConnection>
</TargetEndpoint>

TargetEndpoint Transport Property Specification

Property Name Default Value Description
allow.tls.session.resumption true If true (the default) clients reuse TLS sessions when making new connections to the target. Set to false if you do not want TLS session reuse. Session reuse generally means shorter connection times, but some targets may not support session reuse or have difficulty with it.
keepalive.timeout.millis 60000 Connection idle timeout for the target connection in the connection pool. If the connection in the pool is idle beyond the specified limit, then the connection is closed.
connect.timeout.millis

3000

Target connection timeout. Apigee returns an HTTP 503 status code if a connection timeout occurs.

io.timeout.millis 55000

If there is no data to read for the specified number of milliseconds, or if the socket is not ready to write data for a specified number of milliseconds, then the transaction is treated as a timeout.

  • If a timeout happens while writing the HTTP request, 408 Request Timeout is returned.
  • If a timeout happens while reading the HTTP response, 504 Gateway Timeout is returned.

See Setting io.timeout.millis and api.timeout.

supports.http11 true If this is true and the client sends a 1.1 request, the target is also sent a 1.1 request, otherwise 1.0 request is sent to the target.
use.proxy true

This property applies to Apigee hybrid only.

If the Apigee hybrid overrides file contains the HTTP_PROXY configuration, as described in Configure forward proxying for API proxies, then use this property to manage/control which proxies should not use the proxy configuration.

If set to false, the API Proxy will skip the HTTP proxy configurations specified in the Apigee hybrid overrides file for target connections set in the proxy.

use.proxy.tunneling true

This property applies to Apigee hybrid only.

If this is set to true, and proxy configurations are specified Apigee hybrid overrides file as described in Configure forward proxying for API proxies, then target connections are set to use the specified tunnel. If the target uses TLS/SSL, then this property is ignored, and the message is always sent using a tunnel.

request.streaming.enabled false

By default (false), HTTP request payloads are read into a buffer, and policies that can operate on the payload work as expected. In cases where the payloads are larger than the buffer size (10 MB in Apigee), you can set this attribute to true. When true, HTTP request payloads are not read into a buffer; they are streamed as-is to the target endpoint. In this case, any policies that operate on the payload in the TargetEndpoint request flow are bypassed. See also Streaming requests and responses.

response.streaming.enabled false

By default (false), HTTP response payloads are read into a buffer, and policies that can operate on the payload work as expected. In cases where the payloads are larger than the buffer size (10 MB in Apigee), you can set this attribute to true. When true, HTTP response payloads are not read into a buffer; they are streamed as-is to the ProxyEndpoint response flow. In this case, any policies that operate on the payload in the TargetEndpoint response flow are bypassed. See also Streaming requests and responses.

success.codes N/A

By default, Apigee treats HTTP code 4XX or 5XX as errors, and it treats HTTP code 1XX, 2XX, 3XX as success. This property enables explicit definition of success codes, for example, 2XX, 1XX, 505 treats any 100, 200 and 505 HTTP response codes as success.

Setting this property overwrites the default values. Therefore, if you want to add HTTP code 400 to the list of default success codes, set this property as:

<Property name="success.codes">1xx,2xx,3xx,400</Property>

If you want only HTTP code 400 to be treated as a success code, set the property as:

<Property name="success.codes">400</Property>

By setting HTTP code 400 as the only success code, the codes 1xx, 2xx, and 3xx are treated as failures.

compression.algorithm N/A By default, Apigee honors the compression type set (gzip, deflate or none) for messages received. If the request is received from the client using, for example, gzip compression, then Apigee forwards the request to the target using gzip compression. If the response received from target uses deflate, then Apigee forwards the response to the client using deflate. Supported values are:
  • gzip: always send message using gzip compression
  • deflate: always send message using deflate compression
  • none: always send message without any compression

See also: Does Apigee support compression/de-compression with GZIP/deflate compression?

request.retain.headers.
enabled
true By default, Apigee always retains all HTTP headers on outbound messages. When set to true, all HTTP headers present on the inbound request are set on the outbound request.
request.retain.headers N/A Defines specific HTTP headers from the request that should be set on the outbound request to the target service. For example, to passthrough the User-Agent header, set the value of request.retain.headers to User-Agent. Multiple HTTP headers are specified as a comma-separated list, for example, User-Agent,Referer,Accept-Language. This property overrides request.retain.headers.enabled. If request.retain.headers.enabled is set to false, any headers specified in the request.retain.headers property are still set on the outbound message.
response.retain.headers.
enabled
true By default, Apigee always retains all HTTP headers on outbound messages. When set to true, all HTTP headers present on the inbound response from the target service are set on the outbound response before it is passed to the ProxyEndpoint.
response.retain.headers N/A Defines specific HTTP headers from the response that should be set on the outbound response before it is passed to the ProxyEndpoint. For example, to passthrough the Expires header, set the value of response.retain.headers to Expires. Multiple HTTP headers are specified as a comma-separated list, for example, Expires,Set-Cookie. This property overrides response.retain.headers.enabled. If response.retain.headers.enabled is set to false, any headers specified in the response.retain.headers property are still set on the outbound message.
retain.queryparams.
enabled
true By default, Apigee always retains all query parameters on outbound requests. When set to true, all query parameters present on the inbound request are set on the outbound request to the target service.
retain.queryparams N/A Defines specific query parameters to set on the outbound request. For example, to include the query parameter apikey from the request message, set retain.queryparams to apikey. Multiple query parameters are specified as a comma-separated list, for example, apikey,environment. This property overrides retain.queryparams.enabled.

ProxyEndpoint Transport Properties

ProxyEndpoint HTTPTargetConnection elements define a set of HTTP transport properties. These properties can be used to set transport-level configurations.

Properties are set on ProxyEndpoint HTTPProxyConnection elements as shown in this example configuration:

<ProxyEndpoint name="default">
  <HTTPProxyConnection>
    <BasePath>/v1/weather</BasePath>
    <Properties>
      <Property name="request.streaming.enabled">true</Property>
    </Properties>
  </HTTPProxyConnection>
</ProxyEndpoint>

ProxyEndpoint Transport Property Specification

Property Name Default Value Description
X-Forwarded-For false When set to true, the virtual host's IP address is added to the outbound request as the value of the HTTP X-Forwarded-For header.
request.streaming.
enabled
false By default (false), HTTP request payloads are read into a buffer, and policies that can operate on the payload work as expected. In cases where the payloads are larger than the buffer size (10 MB in Apigee), you can set this attribute to true. When true, HTTP request payloads are not read into a buffer; they are streamed as-is to the TargetEndpoint request flow. In this case, any policies that operate on the payload in the ProxyEndpoint request flow are bypassed. See also Streaming requests and responses.
response.streaming.
enabled
false By default (false), HTTP response payloads are read into a buffer, and policies that can operate on the payload work as expected. In cases where the payloads are larger than the buffer size (10 MB in Apigee), you can set this attribute to true. When true, HTTP response payloads are not read into a buffer; they are streamed as-is to the client. In this case, any policies that operate on the payload in the ProxyEndpoint response flow are bypassed. See also Streaming requests and responses.
compression.algorithm N/A

By default, Apigee honors the compression type set (gzip, deflate or none) for messages received. For example, where a client submits a request that uses gzip compression, Apigee forwards the request to the target using gzip compression. You can configure compression algorithms to be explicitly applied by setting this property on the TargetEndpoint or ProxyEndpoint. Supported values are:

  • gzip: always send message using gzip compression
  • deflate: always send message using deflate compression
  • none: always send message without any compression

See also: Does Apigee support compression/de-compression with GZIP/deflate compression?

api.timeout N/A

Configure the timeout for individual API proxies (in milliseconds)

You can configure API proxies, even those with streaming enabled, to time out after a specified time with a 504 Gateway Timeout status.

For example, to configure a proxy to time out after 180000 milliseconds (three minutes), add the following property to HTTPTargetConnection:

<Property name="api.timeout">180000</Property>

You cannot set this property with a variable.

See Setting io.timeout.millis and api.timeout.

HTTPHeader.allowDuplicates N/A

Use this setting to allow duplicate headers (for specific headers).

<HTTPProxyConnection>
  <Properties>
     <property name = "HTTPHeader.allowDuplicates" value = "Content-Type,Authorization"/>
  </Properties>
</HTTPProxyConnection>
HTTPHeader.multiValued N/A

Use this setting to allow duplicate headers (for specific headers).

<HTTPProxyConnection>
  <Properties>
    <property name = "HTTPHeader.multiValued" value = "Content-Type,Authorization"/>
  </Properties>
</HTTPProxyConnection>

Setting io.timeout.millis and api.timeout

The operation of io.timeout.millis and api.timeout are related. On every request to an API proxy:

  1. The Ingress (aka Internal Load Balancer) sends its timeout value to the Message Processor. This timeout value defaults to 300 seconds and is not configurable.
  2. The Message Processor then sets api.timeout:
    1. If api.timeout is not set at the proxy level, use the timeout set by the Ingress.
    2. If api.timeout is set at the proxy level, set it on the Message Processor to the lesser of the Ingress timeout or the value of api.timeout.
  3. The value of api.timeout specifies the maximum amount of time an API proxy has to execute from the API request to the response.

    After each policy in the API proxy executes, or before the Message Processor sends the request to the target endpoint, the Message Processor calculates (api.timeout - elapsed time from the start of the request).

    If the value is less than zero, then the maximum amount of time to handle the request has expired and the Message Processor returns a 504 Gateway Timeout.

  4. The value of io.timeout.millis specifies the maximum amount of time that the target endpoint has to respond.

    Before connecting to a target endpoint, the Message Processor determines the lesser of (api.timeout - elapsed time from the start of the request) and io.timeout.millis. It then sets io.timeout.millis to that value.

    • If a timeout happens while writing the HTTP request, 408 Request Timeout is returned.
    • If a timeout happens while reading the HTTP response, 504 Gateway Timeout is returned.