10.5. Using the REST Interface
The REST Interface can be used in Red Hat JBoss Data Grid's Remote Client-Server mode to perform the following operations:
- Adding data
- Retrieving data
- Removing data
10.5.1. Adding Data Using REST
In Red Hat JBoss Data Grid's REST Interface, use the following methods to add data to the cache:
- HTTP
PUTmethod - HTTP
POSTmethod
When the
PUT and POST methods are used, the body of the request contains this data, which includes any information added by the user.
Both the
PUT and POST methods require a Content-Type header.
10.5.1.1. About PUT /{cacheName}/{cacheKey}
A
PUT request from the provided URL form places the payload, from the request body in the targeted cache using the provided key. The targeted cache must exist on the server for this task to successfully complete.
As an example, in the following URL, the value
hr is the cache name and payRoll%2F3 is the key. The value %2F indicates that a / was used in the key.
http://someserver/rest/hr/payRoll%2F3
Any existing data is replaced and
Time-To-Live and Last-Modified values are updated, if an update is required.
Note
A cache key that contains the value
%2F to represent a / in the key (as in the provided example) can be successfully run if the server is started using the following argument:
-Dorg.apache.tomcat.util.buf.UDecoder.ALLOW_ENCODED_SLASH=true
10.5.1.2. About POST /{cacheName}/{cacheKey}
The
POST method from the provided URL form places the payload (from the request body) in the targeted cache using the provided key. However, in a POST method, if a value in a cache/key exists, a HTTP CONFLICT status is returned and the content is not updated.
10.5.2. Retrieving Data Using REST
In Red Hat JBoss Data Grid's REST Interface, use the following methods to retrieve data from the cache:
- HTTP
GETmethod. - HTTP
HEADmethod.
10.5.2.1. About GET /{cacheName}/{cacheKey}
The
GET method returns the data located in the supplied cacheName, matched to the relevant key, as the body of the response. The Content-Type header provides the type of the data. A browser can directly access the cache.
A unique entity tag (ETag) is returned for each entry along with a Last-Modified header which indicates the state of the data at the requested URL. ETags allow browsers (and other clients) to ask for data only in the case where it has changed (to save on bandwidth). ETag is a part of the HTTP standard and is supported by Red Hat JBoss Data Grid.
The type of content stored is the type returned. As an example, if a String was stored, a String is returned. An object which was stored in a serialized form must be manually deserialized.
10.5.2.2. About HEAD /{cacheName}/{cacheKey}
The
HEAD method operates in a manner similar to the GET method, however returns no content (header fields are returned).
10.5.3. Removing Data Using REST
To remove data from Red Hat JBoss Data Grid using the REST interface, use the HTTP
DELETE method to retrieve data from the cache. The DELETE method can:
- Remove a cache entry/value. (
DELETE /{cacheName}/{cacheKey}) - Remove all entries from a cache. (
DELETE /{cacheName})
10.5.3.1. About DELETE /{cacheName}/{cacheKey}
Used in this context (
DELETE /{cacheName}/{cacheKey}), the DELETE method removes the key/value from the cache for the provided key.
10.5.3.2. About DELETE /{cacheName}
In this context (
DELETE /{cacheName}), the DELETE method removes all entries in the named cache. After a successful DELETE operation, the HTTP status code 200 is returned.
10.5.3.3. Background Delete Operations
Set the value of the
performAsync header to true to ensure an immediate return while the removal operation continues in the background.
10.5.4. REST Interface Operation Headers
The following table displays headers that are included in the Red Hat JBoss Data Grid REST Interface:
| Headers | Mandatory/Optional | Values | Default Value | Details |
|---|---|---|---|---|
| Content-Type | Mandatory | - | - | If the Content-Type is set to application/x-java-serialized-object, it is stored as a Java object. |
| performAsync | Optional | True/False | - | If set to true, an immediate return occurs, followed by a replication of data to the cluster on its own. This feature is useful when dealing with bulk data inserts and large clusters. |
| timeToLiveSeconds | Optional | Numeric (positive and negative numbers) | -1 (This value prevents expiration as a direct result of timeToLiveSeconds. Expiration values set elsewhere override this default value.) | Reflects the number of seconds before the entry in question is automatically deleted. Setting a negative value for timeToLiveSeconds provides the same result as the default value. |
| maxIdleTimeSeconds | Optional | Numeric (positive and negative numbers) | -1 (This value prevents expiration as a direct result of maxIdleTimeSeconds. Expiration values set elsewhere override this default value.) | Contains the number of seconds after the last usage when the entry will be automatically deleted. Passing a negative value provides the same result as the default value. |
The following combinations can be set for the
timeToLiveSeconds and maxIdleTimeSeconds headers:
- If both the
timeToLiveSecondsandmaxIdleTimeSecondsheaders are assigned the value0, the cache uses the defaulttimeToLiveSecondsandmaxIdleTimeSecondsvalues configured either using XML or programatically. - If only the
maxIdleTimeSecondsheader value is set to0, thetimeToLiveSecondsvalue should be passed as the parameter (or the default-1, if the parameter is not present). Additionally, themaxIdleTimeSecondsparameter value defaults to the values configured either using XML or programatically. - If only the
timeToLiveSecondsheader value is set to0, expiration occurs immediately and themaxIdleTimeSecondsvalue is set to the value passed as a parameter (or the default-1if no parameter was supplied).
ETag Based Headers
ETags (Entity Tags) are returned for each REST Interface entry, along with a Last-Modified header that indicates the state of the data at the supplied URL. ETags are used in HTTP operations to request data exclusively in cases where the data has changed to save bandwidth. The following headers support ETags (Entity Tags) based optimistic locking:
| Header | Algorithm | Example | Details |
|---|---|---|---|
| If-Match | If-Match = "If-Match" ":" ( "*" | 1#entity-tag ) | - | Used in conjunction with a list of associated entity tags to verify that a specified entity (that was previously obtained from a resource) remains current. |
| If-None-Match | - | Used in conjunction with a list of associated entity tags to verify that none of the specified entities (that was previously obtained from a resource) are current. This feature facilitates efficient updates of cached information when required and with minimal transaction overhead. | |
| If-Modified-Since | If-Modified-Since = "If-Modified-Since" ":" HTTP-date | If-Modified-Since: Sat, 29 Oct 1994 19:43:31 GMT | Compares the requested variant's last modification time and date with a supplied time and date value. If the requested variant has not been modified since the specified time and date, a 304 (not modified) response is returned without a message-body instead of an entity. |
| If-Unmodified-Since | If-Unmodified-Since = "If-Unmodified-Since" ":" HTTP-date | If-Unmodified-Since: Sat, 29 Oct 1994 19:43:31 GMT | Compares the requested variant's last modification time and date with a supplied time and date value. If the requested resources has not been modified since the supplied date and time, the specified operation is performed. If the requested resource has been modified since the supplied date and time, the operation is not performed and a 412 (Precondition Failed) response is returned. |
