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API proxy configuration reference

As a developer working with the Apigee Edge, your primary development activities involve configuring API proxies that function as proxies for APIs or backend services. This document is a reference of all configuration elements available to you when building API proxies. 

If you are learning how to build API proxies, it is recommended that you begin with the topic  Build a simple API proxy.

API proxy structure

An API proxy consists of the following configuration:

Base Configuration Primary configuration settings for an API proxy. See Base Configuration.
ProxyEndpoint Configuration Settings for the inbound HTTP connection (from requesting apps to Apigee Edge), request and response flows, and policy attachments. See ProxyEndpoint.
TargetEndpoint Configuration Settings for the outbound HTTP connection (from Apigee Edge to the backend service), request and response flows, and policy attachments. See TargetEndpoint.
Flows ProxyEndpoint and TargetEndpoint request and response pipelines to which polices can be attached. See Flows.
Policies XML-formatted configuration files that conform to the Apigee Edge policy schemas. See Policies.
Resources Scripts, JAR files, and XSLT files referenced by policies to execute custom logic. See Resources.

API proxy directory structure and contents

The components in the table above are defined by configuration files in the following directory structure:

Configuration files and directory structure of an API proxy

This section explain the configuration files and directory structure of an API proxy.

Base Configuration

/apiproxy/weatherapi.xml

The base configuration for an API proxy, which defines the name of the API proxy. The name must be unique within an organization.

Sample configuration:

<APIProxy name="weatherapi">
</APIProxy>

Base Configuration Elements

Name Description Default Required?
APIProxy  
name The name of the API proxy, which must be unique within an organization. The characters you are allowed to use in the name are restricted to the following: A-Z0-9._\-$ % N/A Yes
revision The revision number of the API proxy configuration. You do not need to explicitly set the revision number, since Apigee Edge automatically tracks the current revision of the API proxy. N/A No
ConfigurationVersion The version of the API proxy configuration schema to which this API proxy conforms. The only supported value currently is majorVersion 4 and minorVersion 0. This setting may be used in the future to enable evolution of the API proxy format. 4.0 No
Description A textual description of the API proxy. If provided, the description will display in the Edge management UI. N/A No
DisplayName A user-friendly name that may be different from the name attribute of the API proxy configuration. N/A No
Policies A list of policies in the /policies directory of this API proxy. You will normally only see this element when the API proxy was created using the Edge management UI. This is simply a 'manifest' setting, designed to provide visibility into the contents of the API proxy. N/A No
ProxyEndpoints A list of ProxyEndpoints in the /proxies directory of this API proxy. You will normally only see this element when the API proxy was created using the Edge management UI. This is simply a 'manifest' setting, designed to provide visibility into the contents of the API proxy. N/A No
Resources A list of resources (JavaScript, Python, Java, XSLT) in the /resources directory of this API proxy. You will normally only see this element when the API proxy was created using the Edge management UI. This is simply a 'manifest' setting, designed to provide visibility into the contents of the API proxy. N/A No
TargetServers A list of TargetServers referenced in any TargetEndpoints of this API proxy. You will normally only see this element when the API proxy was created using the Edge management UI. This is simply a 'manifest' setting, designed to provide visibility into the contents of the API proxy. N/A No
TargetEndpoints A list of TargetEndpoints in the /targets directory of this API proxy. You will normally only see this element when the API proxy was created using the Edge management UI. This is simply a 'manifest' setting, designed to provide visibility into the contents of the API proxy. N/A No

ProxyEndpoint

/apiproxy/proxies/default.xml

The ProxyEndpoint configuration defines the inbound (client-facing) interface for an API proxy. When you configure a ProxyEndpoint, you are setting up a network configuration that defines how client applications ('apps') should invoke the proxied API.

The following sample ProxyEndpoint configuration would be stored under /apiproxy/proxies:

<ProxyEndpoint name="default">
  <PreFlow/>
  <Flows/>
  <PostFlow/>
  <HTTPProxyConnection>
    <BasePath>/weather</BasePath>
    <VirtualHost>default</VirtualHost>
  </HTTPProxyConnection>
  <FaultRules/>
  <DefaultFaultRule/>
  <RouteRule name="default">
    <TargetEndpoint>default</TargetEndpoint>
  </RouteRule>
</ProxyEndpoint>

The required configuration elements in a basic ProxyEndpoint are:

ProxyEndpoint Configuration Elements

Name Description Default Required?
ProxyEndpoint  
name The name of the ProxyEndpoint. Must be unique within the API proxy configuration, when (in rare cases) multiple ProxyEndpoints are defined. The characters you are allowed to use in the name are restricted to the following: A-Z0-9._\-$ %. N/A Yes
PreFlow Defines the policies in the PreFlow flow of a request or response. N/A Yes
Flows
Defines the policies in the conditional flows of a request or response.
N/A Yes
PostFlow
Defines the policies in the PostFlow flow of a request or response.
N/A Yes
HTTPProxyConnection Defines the network address and URI path associated with the API proxy
BasePath

A required string that uniquely identifies the URI path used by Apigee Edge to route incoming messages to the proper API proxy.

The BasePath is a URI fragment (for example /weather) appended to the base URL of an API proxy (for example, http://apifactory-test.apigee.net). BasePath must be unique within an environment. Uniqueness is validated when an API proxy is generated or imported.

Using a wildcard in base paths

You can use one or more /*/ wildcards in API proxy base paths to future-proof your proxies. For example, a base path of /team/*/members allows clients to call https://[host]/team/blue/members and https://[host]/team/green/members without you needing to create new API proxies to support new teams. Note that /**/ is not supported.

/ Yes
VirtualHost

Associates an API proxy with specific base URLs for an environment. A VirtualHost is a named configuration that defines one or more URLs for an environment.

The named VirtualHosts defined for a ProxyEndpoint determine the domains and ports on which an API proxy is exposed, and, by extension, the URL that apps use to invoke an API proxy.

By default, two named VirtualHosts are defined for an environment: default and secure. An organization may also define custom domains. To ensure that an API proxy is available only over HTTPs, for example, set the VirtualHost in the HTTPProxyConnection to secure.

default Yes
Properties A set of optional HTTP configuration settings can be defined as properties of a ProxyEndpoint. See Endpoint properties reference. N/A No
FaultRules
Defines how the ProxyEndpoint reacts to an error. A fault rule specifies two items:
  • A Condition that specifies the fault to be handled based on the pre-defined category, subcategory, or name of the fault
  • One or more policies that define the behavior of the fault rule for the corresponding Condition

See Fault handling.

N/A No
DefaultFaultRule

Handles any errors (system, transport, messaging or policy) that are not explicitly handled by another fault rule.

See Fault handling.

N/A No
RouteRule Defines the destination of inbound request messages after processing by the ProxyEndpoint request pipeline. Usually, the RouteRule points to a named TargetEndpoint configuration, but it can also point directly to a URL.
Name Required attribute, which provides a name for the RouteRule. The characters you are allowed to use in the name are restricted to the following: A-Z0-9._\-$ %. For example, Cat2 %_ is a legal name. N/A Yes
Condition An optional conditional statement used for dynamic routing at runtime. Conditional RouteRules are useful, for example, to enable content-based routing to support backend versioning. N/A No
TargetEndpoint

An optional string that identifies a named TargetEndpoint configuration. A named TargetEndpoint is any TargetEndpoint defined in the same API proxy under the/targets directory).

By naming a TargetEndpoint, you indicate where request messages should be forwarded after processing by the ProxyEndpoint request pipeline. Note that this is an optional setting.

A ProxyEndpoint may call a URL directly. For example, a JavaScript or Java resource, functioning in the role of an HTTP client, may perform the basic duty of a TargetEndpoint, which is to forward requests to a backend service.

N/A No
URL An optional string that defines an outbound network address called by the ProxyEndpoint, bypassing any TargetEndpoint configurations that might be stored under /targets N/A No

How to configure RouteRules

A named TargetEndpoint refers to a configuration file under /apiproxy/targets to which the RouteRule forwards a request after processing by the ProxyEndpoint.

For example, the following RouteRule refers to the configuration /apiproxy/targets/myTarget.xml:

<RouteRule name="default">
  <TargetEndpoint>myTarget</TargetEndpoint>
</RouteRule>

Direct URL Invocation

A ProxyEndpoint can also directly invoke a backend service. Direct URL invocation bypasses any named TargetEndpoints configuration under /apiproxy/targets). For this reason, TargetEndpoint is an optional API proxy configuration, although, in practice, direct invocation from the ProxyEndpoint is not recommended.

For example, the following RouteRule makes an HTTP call to http://api.mycompany.com/v2.

<RouteRule name="default">
  <URL>http://api.mycompany.com/v2</URL> 
</RouteRule>

Conditional Routes

RouteRules can be chained to support dynamic routing at runtime. Inbound requests can be routed to named TargetEndpoint configurations, directly to URLs, or to a combination of the two, based on HTTP headers, message content, query parameters, or contextual information such time of day, locale, etc.

Conditional RouteRules work like other conditional statements on Apigee Edge. See Conditions reference and Variables reference.

For example, the following RouteRule combination first evaluates the inbound request to verify the value of an HTTP header. If the HTTP header routeTo has the value TargetEndpoint1, then the request is forwarded to the TargetEndpoint named TargetEndpoint1. If not, then the inbound request is forwarded to http://api.mycompany.com/v2.

<RouteRule name="MyRoute">
  <Condition>request.header.routeTo = "TargetEndpoint1"</Condition>
  <TargetEndpoint>TargetEndpoint1</TargetEndpoint>
</RouteRule>
<RouteRule name="default">
  <URL>http://api.mycompany.com/v2</URL>
</RouteRule>

More dynamic routing

http://community.apigee.com/questions/1326/specifying-proxy-endpoint.html
shows dynamic routing to different world regions based on variables extracted from the request URI.

Null Routes

A null RouteRule can be defined to support scenarios in which the request message does not need to be forwarded to the TargetEndpoint. This is useful when the ProxyEndpoint performs all of the necessary processing, for example by using JavaScript to call an external service or retrieving data from a lookup to the API Services' key/value store.

For example, the following defines a null Route:

<RouteRule name="GoNowhere"/>

Conditional null Routes can be useful. In the following example, a null Route is configured to execute when an HTTP header request.header.X-DoNothing have a value other than null.

<RouteRule name="DoNothingOnDemand">
  <Condition>request.header.X-DoNothing != null</Condition>
</RouteRule>

Remember, RouteRules can be chained, so a conditional null Route would typically be one component of a set of RouteRules designed to support conditional routing.

A practical use of a conditional null Route would be in support of caching. By using the value of the variable that is set by the Cache policy, you can configure an API proxy to execute the null Route when an entry is served from the cache.

<RouteRule name="DoNothingUnlessTheCacheIsStale">
  <Condition>lookupcache.LookupCache-1.cachehit is true</Condition>
</RouteRule>

TargetEndpoint

A TargetEndpoint is the outbound equivalent of a ProxyEndpoint. A TargetEndpoint functions as client to a backend service or API -- it sends requests and receives responses.

An API proxy needn't have any TargetEndpoints. ProxyEndpoints can be configured to call URLs directly. An API proxy with no TargetEndpoints usually contains a ProxyEndpoint that either directly calls a backend service, or that is configured to call a service using Java or JavaScript.

TargetEndpoint Configuration

/targets/default.xml

The TargetEndpoint defines the outbound connection from Apigee Edge to another service or resource.

Here's a sample TargetEndpoint configuration:

<TargetEndpoint name="default">
  <PreFlow/>
  <Flows/>
  <PostFlow/>
  <HTTPTargetConnection>
    <URL>http://weather.yahooapis.com</URL>
  </HTTPTargetConnection>
  <FaultRules/>
  <DefaultFaultRule/>
  <ScriptTarget/>
  <LocalTargetConnection/>
</TargetEndpoint>

TargetEndpoint Configuration Elements

Name Description Default Required?
TargetEndpoint  
name The name of the TargetEndpoint, which must be unique within the API proxy configuration. The name of the TargetEndPoint is used in the ProxyEndpoint RouteRule to direct requests for outbound processing. The characters you are allowed to use in the name are restricted to the following: A-Z0-9._\-$ % N/A Yes
PreFlow Defines the policies in the PreFlow flow of a request or response. N/A Yes
Flows
Defines the policies in the conditional flows of a request or response.
N/A Yes
PostFlow
Defines the policies in the PostFlow flow of a request or response.
N/A Yes
HTTPTargetConnection With its child elements, specifies a backend resource reach via HTTP.
URL Defines the network address of the backend service to which the TargetEndpoint forwards request messages. N/A No
LoadBalancer

Defines one or more named TargetServer configurations. Named TargetServer configurations can be used for load balancing defining 2 or more endpoint configuration connections.

You can also use TargetServers to decouple API proxy configurations from concrete backend service endpoints URLs.

See Load balance API traffic across multiple backend servers.

N/A No
Properties A set of optional HTTP configuration settings can be defined as properties of a TargetEndpoint. See Endpoint properties reference. N/A No
LocalTargetConnection With its child elements, specifies a resource to be reached locally, bypassing network characteristics such as load balancing and message processors.

To specify the target resource, include either the APIProxy child element (with the ProxyEndpoint element) or the Path child element.

For more information, see Consuming one proxy from another proxy.

APIProxy Specifies the name of an API proxy to use as a target for requests. The target proxy must be in the same organization and environment as the proxy sending requests. This is an alternative to using the Path element. N/A No
ProxyEndpoint Used with APIProxy to specify the name of the target proxy's ProxyEndpoint. N/A No
Path Specifies the endpoint path of an API proxy to use as a target for requests. The target proxy must be in the same organization and environment as the proxy sending requests. This is an alternative to using APIProxy. N/A No
FaultRules
Defines how the TargetEndpoint reacts to an error. A fault rule specifies two items:
  • A Condition that specifies the fault to be handled based on the pre-defined category, subcategory, or name of the fault
  • One or more policies that define the behavior of the fault rule for the corresponding Condition

See Fault handling.

N/A No
DefaultFaultRule

Handles any errors (system, transport, messaging or policy) that are not explicitly handled by another FaultRule.

See Fault handling.

N/A No
ScriptTarget  
ResourceURL

Defines the resource type (node) and the name of the main Node.js script that implements TargetEndpoint functionality.

<ResourceURL>node://server.js</ResourceURL>

ScriptTarget is an alternative to HTTPTargetConnection. (A TargetEndpoint can define either an HTTPTargetConnection or a ScriptTarget, but not both.)

See Adding Node.js to an existing API proxy.

N/A Yes
EnvironmentVariable

Optionally pass environment variables to the main Node.js script. 

See Understanding Edge support for Node.js modules.

N/A No
Arguments

Optionally pass arguments to the main Node.js script.

See Understanding Edge support for Node.js modules.

N/A No

SSL TargetEndpoint Configuration

TargetEndpoints often need to manage HTTPS connections with heterogenous backend infrastructure. For this reason, a number of SSL configuration settings are supported.

SSL TargetEndpoint Configuration Elements

Name Description Default Required?
SSLInfo  
Enabled Indicates whether SSL is enabled for the Endpoint true Yes
TrustStore A keystore containing trusted server certificates. N/A No
ClientAuthEnabled A setting that turns on outbound client authentication (2-way SSL) false No
KeyStore A keystore containing private keys used for outbound client authentication N/A Yes (if ClientAuthEnabled is true)
KeyAlias The key alias of the private key used for outbound client authentication N/A Yes (if ClientAuthEnabled is true)
Ciphers

Supported ciphers for outbound SSL. If no ciphers are specified, then all ciphers available for the JVM will be permitted.

To restrict ciphers, add the following elements listing the supported ciphers:

<Ciphers>
 <Cipher>TLS_RSA_WITH_3DES_EDE_CBC_SHA</Cipher>    
 <Cipher>TLS_RSA_WITH_DES_CBC_SHA</Cipher>
</Ciphers>
N/A No
Protocols Supported protocols for outbound SSL. If no protocols are specified, then all protocols available for the JVM will be permitted.

To restrict protocols, add the following elements listing the supported protocols:

<Protocols>
 <Protocol>TLSv1</Protocol>
 <Protocol>TLSv1.2</Protocol>
 <Protocol>SSLv2Hello</Protocol> 
</Protocols>
N/A No

Sample TargetEndpoint with outbound client authentication enabled

<TargetEndpoint name="default">
  <HttpTargetConnection>
	<URL>https://myservice.com</URL>
    <SSLInfo>
      <Enabled>true</Enabled>
      <ClientAuthEnabled>true</ClientAuthEnabled>
      <KeyStore>myKeystore</KeyStore>
      <KeyAlias>myKey</KeyAlias>
      <TrustStore>myTruststore</TrustStore>
    </SSLInfo>
  </HttpTargetConnection>
</TargetEndpoint>

For detailed instructions, see Configure client SSL from Apigee API Platform to your backend service.

Using flow variables to set SSL values dynamically

You can also dynamically set SSL/TLS details to support flexible runtime requirements. For example, if your proxy connects to two potentially different targets (a test target and a production target), you can have your API proxy programmatically detect which environment it's calling and dynamically set references to the appropriate keystore and truststore. The following Apigee Community article explains this scenario in more detail and provides deployable API proxy examples: https://community.apigee.com/articles/21424/dynamic-sslinfo-for-targetendpoint-using-variable.html.

In the following example of how SSLInfo would be set in a TargetEndpoint configuration, the values can be supplied at runtime, for example, by a Java Callout, a JavaScript policy, or an Assign Message policy. Use whichever message variables contain the values you want to set.

Variables are allowed in only the following elements.

<SSLInfo>
    <Enabled>{myvars.ssl.enabled}</Enabled>
    <ClientAuthEnabled>{myvars.ssl.client.auth.enabled}</ClientAuthEnabled>
    <KeyStore>{myvars.ssl.keystore}</KeyStore>
    <KeyAlias>{myvars.ssl.keyAlias}</KeyAlias>
    <TrustStore>{myvars.ssl.trustStore}</TrustStore>
</SSLInfo>

Variable replacement of SSL/TLS values can only be used for a TargetEndpoint. Any attempt to use SSLInfo variables in any other context, such as virtual host configuration or message logging, will cause validation failures.

Using references to set SSL values dynamically

When configuring a TargetEndpoint that uses HTTPS, you have to consider the case when the SSL cert expires, or a change to the system configuration requires you to update the cert. In an Edge for Private Cloud installation, when configuring SSL by using static values or by using flow variables, there is a chance that you will have to restart the Message Processors.  

For more, see Update an SSL certificate.

However, you can optionally configure the TargetEndpoint to use a reference to the keystore or truststore instead. The advantage to using a reference is that you can update the reference to point to a different keystore or truststore to update the SSL cert without having to restart Message Processors.    

You can only use a reference to the keystore and truststore; you cannot use a reference to the alias. When you change the reference to a keystore, ensure that the alias name of the cert is the same as in the old keystore.

For example, shown below is a TargetEndpoint that uses a reference to the keystore:

<SSLInfo> 
    <Enabled>true</Enabled> 
    <ClientAuthEnabled>false</ClientAuthEnabled> 
    <KeyStore>ref://keystoreref</KeyStore> 
    <KeyAlias>myKeyAlias</KeyAlias> 
</SSLInfo>

Use the following POST API call to create the reference named keystoreref:

curl -X POST  -H "Content-Type:application/xml" https://api.enterprise.apigee.com/v1/o/{org_name}/e/{env_name}/references \
-d '<ResourceReference name="keystoreref">
    <Refers>myTestKeystore</Refers>
    <ResourceType>KeyStore</ResourceType>
</ResourceReference>' -u email:password

The reference specifies the name of the keystore and its type.

Use the following GET API call to view the reference:

curl -X GET https://api.enterprise.apigee.com/v1/o/[org_name}/e/{env_name}/references/keystoreref -u uname:password

To later change the reference to point to a different keystore, ensuring that the alias has the same name, use the following PUT call:

curl -X PUT -H "Content-Type:application/xml" https://api.enterprise.apigee.com/v1/o/{org_name}/e/{env_name}/references/keystoreref \
-d '<ResourceReference name="keystoreref">
    <Refers>myNewKeystore</Refers>
    <ResourceType>KeyStore</ResourceType>
</ResourceReference>' -u email:password

TargetEndpoint with target load balancing

TargetEndpoints support load balancing across multiple named TargetServers using three load balancing algorithms.

For detailed instructions, refer to Load balance API traffic across multiple backend servers.

Policies

The /policies directory in an API proxy contains all policies available to be attached to Flows in the API proxy.

Policy Configuration Elements

Name Description Default Required?
Policy  
name

The internal name of the policy. Characters you can use in the name are restricted to: A-Z0-9._\-$ %. However, the Edge management UI enforces additional restrictions, such as automatically removing characters that are not alphanumeric.

Optionally, use the <DisplayName> element to label the policy in the management UI proxy editor with a different, natural-language name.

N/A Yes
enabled

Set to true to enforce the policy.

Set to false to "turn off" the policy. The policy will not be enforced even if it remains attached to a flow.

true No
continueOnError

Set to false to return an error when a policy fails. This is expected behavior for most policies.

Set to true to have flow execution continue even after a policy fails.

false No
async

Note: This attribute does not make the policy execute asynchronously. In most cases, leave this with the default of false.

When set to true, policy execution is offloaded to a different thread, leaving the main thread free to handle additional requests. When the offline processing is complete, the main thread comes back and finishes handling the message flow. In some cases, setting async to true improves API proxy performance. However, overusing async can hurt performance with too much thread switching.

To use asynchronous behavior in API proxies, see JavaScript callouts.

false No

Policy Attachment

As shown above, API proxy flows execute in the following sequence:

Policies are attached as processing steps to Flows. The policy's name is used to reference the policy to be enforced as a processing Step. The format of a policy attachment is the following:

<Step><Name>MyPolicy</Name></Step>

Policies are enforced in the order in which they are attached to a Flow. For example:

<Step><Name>FirstPolicy</Name></Step>
<Step><Name>SecondPolicy</Name></Step>

Policy Attachment Configuration Elements

Name Description Default Required?
Step  
Name The name of the policy to be executed by this Step definition. N/A Yes
Condition A conditional statement that determines whether the policy is enforced or not. If a policy has an associated condition, then the policy only executes if the conditional statement evaluates to true. N/A No

Flows

ProxyEndpoint and TargetEndpoint define a pipeline for request and response message processing. A processing pipeline consists of a request flow and a response flow. Each request flow and response flow is subdivided into a PreFlow, one or more optional 'conditional' or 'named' Flow, and a PostFlow.

  • PreFlow: Always executes. Executes before any conditional Flows.
  • PostFlow: Always executes. Executes after any conditional Flows.

Additionally, you can add a PostClientFlow to the ProxyEndpoint, which executes after the response is returned to the requesting client app. Only MessageLogging policies can be attached to this flow. PostClientFlow reduces API proxy latency and makes information available for logging that is not calculated until after the response is returned to the client, such as the client.send.start.time and client.send.end.time.The flow is used primarily for measuring the time interval between the start and end timestamps for the response message.

Watch a quick how-to video 

Video: Check out this short video on using a Message Logging in the PostClientFlow.

Here's an example of a PostClientFlow with a message logging policy attached.

    ...
    <PostFlow name="PostFlow">
        <Request/>
        <Response/>
    </PostFlow>
    <PostClientFlow>
        <Request/>
        <Response>
            <Step>
                <Name>Message-Logging-1</Name>
            </Step>
        </Response>
    </PostClientFlow>
    ...

The API proxy processing pipeline executes Flows in the following sequence:

Request Pipeline:

  1. Proxy Request PreFlow
  2. Proxy Request Conditional Flows (Optional)
  3. Proxy Request PostFlow
  4. Target Request PreFlow
  5. Target Request Conditional Flows (Optional)
  6. Target Request PostFlow

Response Pipeline:

  1. Target Response PreFlow
  2. Target Response Conditional Flows (Optional)
  3. Target Response PostFlow
  4. Proxy Response PreFlow
  5. Proxy Response Conditional Flows (Optional)
  6. Proxy Response PostFlow
  7. PostClientFlow Response (Optional)

Only those Flows with policy attachments need to be configured in ProxyEndpoint or TargetEndpoint configurations. PreFlow and PostFlow need only be specified in a ProxyEndpoint or TargetEndpoint configuration when a policy needs to be enforced during PreFlow or PostFlow processing.

In contrast to conditional flows, the ordering of PreFlow and PostFlow elements is not important--the API proxy will always execute each at the appropriate point in the pipeline, regardless of where they appear in the Endpoint configuration.

Conditional Flows

ProxyEndpoints and TargetEndpoints support an unlimited number of conditional flows (also known as 'named flows').

The API proxy tests for the condition specified in the conditional flow and, if the condition is met, the processing steps in the conditional flow are executed by the API proxy. If the condition is not met, then the processing steps in the conditional flow are bypassed. Conditional flows are evaluated in the order defined in the API proxy and the first one whose condition is met is executed.  

By defining conditional flows, you gain the ability to apply processing steps in an API proxy based on:

  • Request URI
  • HTTP verb (GET/PUT/POST/DELETE)
  • Value of a query param, header, and form param
  • Many other types of conditions 

For example, the following conditional flow specifies that it is executed only when the request resource path is /accesstoken. Any inbound request with the path /accesstoken causes this flow to be executed, along with any policies that are attached to the flow. If the request path does not include the suffix /accesstoken, then the flow does not execute (although another conditional flow might).

<Flows>
  <Flow name="TokenEndpoint">
    <Condition>proxy.pathsuffix MatchesPath "/accesstoken"</Condition>
    <Request>
      <Step>
        <Name>GenerateAccessToken</Name>
      </Step>
    </Request> 
  </Flow>
</Flows>   

Flow Configuration Elements

Name Description Default Required?
Flow A request or response processing pipeline defined by A ProxyEndpoint or TargetEndpoint
Name The unique name of the Flow. N/A Yes
Condition A conditional statement that evaluates on or more variables to evaluate to true or false. All Flows other than the predefined PreFlow and PostFlow types must define a condition for their execution. N/A Yes
Request The pipeline associated with Request message processing N/A No
Response The pipeline associated with Response message processing N/A No

Step processing

The sequential ordering of conditional Flows is enforced by Apigee Edge. Conditional Flows execute from top to bottom. The first conditional Flow whose condition evaluates to true is executed, and only one conditional Flow is executed.

For example, in the following Flow configuration, any inbound request that does not include the path suffix /first or /second will cause the ThirdFlow to execute, enforcing the policy called Return404.

<Flows>
  <Flow name="FirstFlow">
    <Condition>proxy.pathsuffix MatchesPath "/first"</Condition>
    <Request>
      <Step><Name>FirstPolicy</Name></Step>
    </Request>
  </Flow>
  <Flow name="SecondFlow">
    <Condition>proxy.pathsuffix MatchesPath "/second"</Condition>
    <Request>
      <Step><Name>FirstPolicy</Name></Step>
      <Step><Name>SecondPolicy</Name></Step>
    </Request>
  </Flow>
  <Flow name="ThirdFlow">
    <Request>
      <Step><Name>Return404</Name></Step>
    </Request>
  </Flow>
</Flows>

Resources

"Resources" (resource files for use in API proxies) are scripts, code, and XSL transformations that can be attached to Flows using policies. These appear in the "Scripts" section of the API proxy editor in the management UI.

See Resource files for the supported resource types.

Resources can be stored in an API proxy, an environment, or an organization. In each case, a resource is referenced by name in a Policy. API Services resolves the name by moving from the API proxy, to environment, to organization level.

A resource stored at the organization level can be referenced by Policies in any environment. A resource stored at the environment level can be referenced by Policies in that environment. A resource stored at the API proxy level can be referenced only by Policies in that API proxy.

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