SMILA/Documentation/Processing/JSON REST API for BPEL pipelines

Processing JSON REST API

SMILA now has a HTTP REST API that allows to invoke BPEL processing workflows.

Reference

• URL:

  http://<hostname>:8080/smila/pipeline/<workflow-name>/process

• Allowed methods: GET and POST
• Response Status Codes:
  • 400 BAD REQUST: Empty input record or invalid JSON.
  • 405 METHOD NOT ALLOWED
  • 500 INTERNAL SERVER ERROR: Other errors, e.g. error during processing.

Current Limitations

• Exactly one non-empty input record must be sent, attachments cannot be added.
• Only the first result record is returned, attachments are ignored.

Example Session

You can use tools like CURL or Resty to invoke HTTP APIs from the command line. More convenient are browser extensions like RESTClient or Posterfor Firefox, cREST for Chrome or Simple REST Client for Opera. For sake of simplicity, the following examples were produced with Resty.

In these examples we'll try to invoke the standard SearchPipeline using the JSON HTTP requests. First without any query:

> resty http://localhost:8080
http://localhost:8080*
> GET /smila/pipeline/SearchPipeline/process
{
  "message" : "Cannot process an empty record."
}
> POST /smila/pipeline/SearchPipeline/process
{
  "message" : "Cannot process an empty record."
}

So this did not work, as expected. In the response headers you can see the error code returned:

> POST /smila/pipeline/SearchPipeline/process/ -v
...
< HTTP/1.1 400 Bad Request
...
{
  "message" : "Cannot process an empty record."
}

So we add a query attribute:

> POST /smila/pipeline/SearchPipeline/process/ '{ "query": "SMILA" }'
...
< HTTP/1.1 500 Server Error
...
{
  "message" : "Error processing BPEL workflow SearchPipeline: Invocation of pipeline element SearchPipeline/search failed: Error processing message SearchPipeline-7afe423a-749c-4492-aa66-38ce37dba672\ncaused by: Invocation of pipeline element SearchPipeline/search failed: Error processing message SearchPipeline-7afe423a-749c-4492-aa66-38ce37dba672\ncaused by: no single value for required parameter QueryAttribute"
}

This time the LuceneSearchPipelet complains about a missing parameter. So let's add it:

> POST /smila/pipeline/SearchPipeline/process/ '{ 
    "query": "SMILA", 
    "QueryAttribute": "Content" }' 
{
  "query" : "SMILA",
  "QueryAttribute" : "Content",
  "_recordid" : "SearchPipeline-5c2d3f3f-1e56-4362-aa4c-74aa5fa9d6e8",
  "count" : 58,
  "indexSize" : 115,
  "records" : [ {
    "_recordid" : "feeds:<Uri=tag:search.twitter.com,2005:69739397733560320>",
    "_source" : "feeds",
    "_weight" : 0.84
  }, {
    "_recordid" : "feeds:<Uri=tag:search.twitter.com,2005:69960011966713856>",
    "_source" : "feeds",
    "_weight" : 0.73
  }, 
  ...
  ] }
}

A successful search ... but we probably want to see a bit more information. So we add values for parameter "resultAttributes":

> POST /smila/pipeline/SearchPipeline/process/ '{ 
  "query": "SMILA", 
  "QueryAttribute": "Content", 
  "resultAttributes": [ "Title", "Author", "LastModifiedDate" ] }' 
{
  "query" : "SMILA",
  "QueryAttribute" : "Content",
  "resultAttributes" : [ "Title", "Author", "LastModifiedDate" ],
  "_recordid" : "SearchPipeline-2201c83a-a9b6-4cfe-a62e-6ec8ffe113ca",
  "count" : 58,
  "indexSize" : 115,
  "records" : [ {
    "_recordid" : "feeds:<Uri=tag:search.twitter.com,2005:69739397733560320>",
    "_source" : "feeds",
    "_weight" : 0.84,
    "Title" : "@AbrarAlAdwani smila 3alech. Latwaswiseen",
    "Author" : "dee_the_bee (Dalalee Boland)",
    "LastModifiedDate" : "2011-05-15T14:22:22.000+0200"
  }, {
    "_recordid" : "feeds:<Uri=tag:search.twitter.com,2005:69960011966713856>",
    "_source" : "feeds",
    "_weight" : 0.73,
    "Title" : "Finally found something to smila bout :)",
    "Author" : "MIGUELALMENDRAL (Miguel FG Almendral)",
    "LastModifiedDate" : "2011-05-16T04:59:01.000+0200"
  },
  ...
  ] }
}

Great! In the same way you can add more parameters as you need:

> POST /smila/pipeline/SearchPipeline/process/ '{ 
    "query": "SMILA", 
    "QueryAttribute": "Content", 
    "resultAttributes": [ "Title", "Author", "LastModifiedDate" ], 
    "maxcount": 1, "offset": 42, "highlight": "Content" }' 
{
  "query" : "SMILA",
  "QueryAttribute" : "Content",
  "resultAttributes" : [ "Title", "Author", "LastModifiedDate" ],
  "maxcount" : 1,
  "offset" : 42,
  "highlight" : "Content",
  "_recordid" : "SearchPipeline-f2a53434-36b1-4e25-a716-f8c02fba5ecd",
  "count" : 58,
  "indexSize" : 115,
  "records" : [ {
    "_recordid" : "feeds:<Uri=http://www.eclipse.org/forums/index.php/mv/msg/206311/660699/#msg_660699>",
    "_source" : "feeds",
    "_weight" : 0.19,
    "Title" : "Re: New SMILA tryout",
    "Author" : "Andreas Weber",
    "_highlight" : {
      "Content" : {
        "text" : "<br />\n&#62;<br />\n&#62; I've done all standard steps as we do when creating a new<br />\n&#62; <b>SMILA</b>-workspace (and as described...-workspace (and as described on the <b>SMILA</b> website - dont know the<br... website - dont know the<br />\n&#62; exact name right now):<br />\n&#62;<br />\n&#62;<br />\n&#62; check out from eclipse SVN<br />\n&#62; add a new Target Platform with path to the <b>SMILA</b> bundles and to eclipse<br..."
      }
    }
  } ]
}

You can also use GET and URL parameters to invoke the pipeline, just enter something like this in the address line of your favorite browser:

http://localhost:8080/smila/pipeline/SearchPipeline/process?query=SMILA&QueryAttribute=Content

However, this gets inconvenient if you want to add lots of parameters and attributes.