On Fri, Jun 28, 2019 at 7:09 PM [email protected] < [email protected]> wrote:
> Hi community. > > I'm reproducing an exception using Complex Features and WFS GeoJSONBuilder > on Geoserver 2.16 (master) with this stack trace: > > net.sf.json.JSONException: Nesting too deep. > at net.sf.json.util.JSONBuilder.push(JSONBuilder.java:270) > at net.sf.json.util.JSONBuilder.object(JSONBuilder.java:240) > at > org.geoserver.wfs.json.ComplexGeoJsonWriter.encodeFeature(ComplexGeoJsonWriter.java:105) > at > org.geoserver.wfs.json.ComplexGeoJsonWriter.encodeComplexAttribute(ComplexGeoJsonWriter.java:563) > at > org.geoserver.wfs.json.ComplexGeoJsonWriter.encodeProperty(ComplexGeoJsonWriter.java:409) > at > org.geoserver.wfs.json.ComplexGeoJsonWriter.encodeProperty(ComplexGeoJsonWriter.java:383) > at java.util.ArrayList.forEach(ArrayList.java:1257) > > This exception is not present on previous versions (2.14 for example) and > looks like we are facing it since now some extra "properties" attributes > were added to GeoJSON encoding recently. > Bit of context, in 2.16.x full features are always encoded as GeoJSON features, no matter where in the containment hierachy, that preserves their identity and makes them recognizeable as features. Before they were plain json object without type or identity. However, if one has a model in which everything is an identifiable feature, it's adding an extra level of "properties" per object. We could also discuss having a flag in the WFS configuration on whether to preserve nature and identity of nested features (and/or a request parameter, I believe there is already a map of "format options" in WFS, but not 100% sure). > > Checking for the root problem seems like json-lib JSONBuilder class has a > hard-coded limit of 20 nested levels as we can see on: > > > https://github.com/aalmiray/Json-lib/blob/master/src/main/java/net/sf/json/util/JSONBuilder.java#L61 > > Since we added new levels to GeoJSON encoding it is a good idea to relax a > bit this limit, but as you can see the problem is this limit is not > configurable since the static variable is final. So I see two solutions to > this: > > - Fork json-lib and relax limit or make it configurable. > - Use reflection for modify the value at runtime. > > Third option we cannot afford in the short term: rewrite the json encoder using another library (jackson?). And yep, it's a lot of work, hence the "cannot afford". Running inside a security manager is uncommon, but not unheard of... the intersection of complex json users with deeply nested models and users running inside a security manager might as well be empty, but I'd be more comfortable having our own fork of jettison, considering tha the library is basically dead anyways (there is a semi-dormant version at https://github.com/jettison-json/jettison still limiting encoding to 20, but I believe there were backwards compat issues, Torben, is it jettison or am I confusing it with another library?) we have forked other libraries for similar reasons. We should probably schedule a sprint in the future to cleanup our json/geojson management situation, since now both OGC batch of services and practical usage are agreeing on favoring JSON over XML. > Of course the first solution sounds better since reflection can be > problematic for some environments (for example blocked by a security > manager). > > I currently did a fork relaxing the limit to 5000 in: > https://github.com/fernandor777/Json-lib/tree/limit-fix-2.4 > A fixed limit is still fixed... I'd recommend making it at least tunable with a system variable, e.g. maxFeatures = Integer.parseInt(System.getProperty("json.maxFeatures", 5000) Also, 5000 seems like a large limit, I'm guessing it would allow 5000 by 5000 objects in memory before encoding, that seems a too big of a number. How about defaulting to 100? Cheers Andrea == GeoServer Professional Services from the experts! Visit http://goo.gl/it488V for more information. == Ing. Andrea Aime @geowolf Technical Lead GeoSolutions S.A.S. Via di Montramito 3/A 55054 Massarosa (LU) phone: +39 0584 962313 fax: +39 0584 1660272 mob: +39 339 8844549 http://www.geo-solutions.it http://twitter.com/geosolutions_it ------------------------------------------------------- *Con riferimento alla normativa sul trattamento dei dati personali (Reg. UE 2016/679 - Regolamento generale sulla protezione dei dati “GDPR”), si precisa che ogni circostanza inerente alla presente email (il suo contenuto, gli eventuali allegati, etc.) è un dato la cui conoscenza è riservata al/i solo/i destinatario/i indicati dallo scrivente. Se il messaggio Le è giunto per errore, è tenuta/o a cancellarlo, ogni altra operazione è illecita. Le sarei comunque grato se potesse darmene notizia. This email is intended only for the person or entity to which it is addressed and may contain information that is privileged, confidential or otherwise protected from disclosure. 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