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Ressourcespartly described in Tutorial Extending Functionalities by using System Hooks Remarksconcept article linking to the respective tutorials |
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With an AMQP Hook, messages are sent to a configured messaging system using Advanced Message Queuing Protocol 1.0 (AMPQ). Where and when these messages are sent is defined in the System Hook configuration. Any changes to the System Hook configuration will not apply until the affected services have been restarted.
The AMQP Hooks allow for asynchronous reactions to events like object creation, update or deletion. There are different types of AMQP Hooks available, each of them specialized for selected function calls. The messages contain the properties of the object which is the target of the function call triggering the AMQP Hook. The action code is included in there 
in the message as well as the history code that is added to the audit trail. The AMQP Hook can be triggered by any endpoint that induced the characteristic history codes of the AMQP Hook.
AMQP Hook Configuration
Parameters
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Parameter | Type | Description |
|---|---|---|
enable | boolean | Is this configuration active/enabled? |
predicate | string | Condition that specifies when the system hook is used. Supported scripting languages: Spring Expression Language (SpEL) und Javascript. |
type | string | Defines the processing step for which the system hook is to be used. |
url | string | AMQP server endpoint, e.g. 127.0.0.1:5672. |
user | string | Username for the AMQP server. |
password | string | Password for the AMQP server. |
queue | string | Name of the queue to which the messages are written. |
bulkSize | integer | Maximum bulk size for a message. |
Example Configuration
The configuration parameters of an the AMQP Hook is shown together with an examplary document import. The AMQP hook should send messages to a messaging system when importing compound documents, to perform an asynchronous full-text indexing (more about asynchronous full-text indexing can be found here). For this purpose, the following configuration is usedare specified in JSON format. In the configuration file, multiple AMQP Hooks can be defined in a list called amqp. It must however be observed that only one messaging queue can be used. The messaging queue specified for the first defined AMQP Hook will apply to all following AMQP Hook definitions as well. Of course, the messaging system needs to support AMQP 1.0. Any Any changes to the AMQP Hook configuration require a restart of the API Gateway.
The example code below configures an AMQP Hook triggered by a document import. This configuration has exactly one System Hook, which is an AMQP Hook of the type object.insert.document. If the evaluation of the predicate for a document on import results is true (in our example only for compound documents), the API-Gateway sends a message with the metadata of the document to the defined messaging system. In addition, the configuration specifies a bulkSize of 10, i.e. for a batch import of 100 documents matching the predicate, 10 messages with 10 metadata entries per message are written to the queue named lc.textextraction.
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{
"systemhooks": {
"amqp": [
{
"enable": true,
"predicate": "spel:(contentStreams != null && contentStreams.size() > 0 && contentStreams[0]['range'] != null && contentStreams[0]['range'].length() > 0) ? true : false",
"type": "object.insert.document",
"url": "127.0.0.1:5672",
"user": "admin",
"password": "admin_pwd",
"queue": "lc.textextraction",
"bulkSize": 10
}
]
}
} |
This configuration has exactly one System Hook, which is an AMQP Hook of the type object.insert.document. It is relevant to the API-Gateway. If the evaluation of the predicate for a document on import results is true (in our example only for compound documents), the API-Gateway sends a message with the metadata of the document to the defined messaging system. In addition, the configuration specifies a bulkSize of 10, i.e. for a batch import of 100 documents matching the predicate, 10 messages with 10 metadata entries per message are written to the queue named lc.textextraction.
Activating the AMQP
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Hook
In our example of asynchronous full-text indexing, the API-Gateway is responsible for evaluating the system hook. To apply the configuration, the API-Gateway must be restarted after saving the configuration file. Messages will then be send to the messaging system for the import of compound documents.
AMQP Hook Types
dms.response.insert
| Response Format | JSON | |||||
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| Description | ||||||
| Example Predicate | 1) reaction to every object creation: 2) reaction to every object creation having a content 3) reaction to every object creation without content: | |||||
| Action Codes - History Codes | 101 - OBJECT_CREATED_WITH_CONTENT 100 - OBJECT_CREATED | |||||
| Example Response |
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dms.response.update
| Response Format | JSON | |||||
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| Description | ||||||
| Example Predicate | 1) reaction to every object update: 2) reaction to every tag creation: 3) reaction to every tag deletion: 4) reaction to every metadata update: 5) reaction to every content update: | |||||
| Action Codes - History Codes | 300 - OBJECT_METADATA_CHANGED 301 - OBJECT_DOCUMENT_CHANGED 303 - OBJECT_UPDATE_CONTENT_MOVED 110 - OBJECT_TAG_CREATED 310 - OBJECT_TAG_UPDATED 210 - OBJECT_TAG_DELETED | |||||
| Example Response |
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dms.response.insert
| Response Format | JSON | |||||
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| Description | ||||||
| Example Predicate | 1) reaction to every object deletion: 2) reaction to every object 3) reaction to every object | |||||
| Action Codes - History Codes | 200 - OBJECT_DELETED 202 - OBJECT_FLAGGED_FOR_DELETE | |||||
| Example Response |
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Summary
In this article, we covered the AMQP Hook configuration using the example of asynchronous full text indexing. The second type of System Hooks in yuuvis® Momentum is the Webhook.
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