Calling the elevation API with a POST request

[0nko]

Hi,
when calling the elevation API I noticed that for some of the longer path requests I started getting "Failed to parse json request" error. The json query parameter was probably too long and got cut off. So I tried sending the JSON in a POST HTTP body instead and it worked. I think mentioning this in the docs could be useful.
Ondrej

[kevinkreiser]

If the request is too large you'll get back an http 413 from this code:

https://github.com/kevinkreiser/prime_server/blob/master/src/http_protocol.cpp#L404

Most importantly though this size limit applies to both POST and GET (and any other type of request). So the limits do not differ.

"Failed to parse json request" is a message that skadi sends back when it cant make sense of the json string. So either you hit the browser limit and it cut your json off, sending only partial json to skadi or there really was a problem with the json. the only other possibility is that boost::property_tree is choaking on really large json but i've not seen problems with that yet other than it taking up lots of memory and a long time to parse

[kevinkreiser]

also, can you get us a request that produces this behavior so we can investigate what is going on?

[0nko]

You're right, the browser was cutting the json off when I was inspecting the problem. But the actual request is failing on 502: BAD GATEWAY error.

The original request:

https://elevation.mapzen.com/height?id=Cross&api_key=elevation-xxxxx&json=%7B%22encoded_polyline%22%3A%22elao%7EAcknnZe%40wMumApOvChk%40d%40nHsZjEeALuDh%40WqFM%7DAyGy_BWmFm%40iNaRifEUeEz%40gFpBoE%7ENj%40rFJh%5C%5CmBxL%7DAjGaBjFuFru%40sI%60Hu%40bxAuPU_HqB%7Df%40OwEMoEyBow%40OoG%3FiDl%40wa%40F_F%60BsBrFkFpB%60Ebk%40l%5DtOmBvIg%40%60BKbG%5DrLc%40%7CD%40m%40qIGkCcAqX%5D%7DTLsP%7C%40%7BUzEqh%40%7CEsYpGaXdP_e%40jVu%60%40wC_EaH_MjFeJz%40aEjBmCbp%40ocAeAwBqBuD%7ECuHl%40aCd%40qCFqBGkAqQ%7DZgDuH_DwHoIsRaHoZyBm%5D%5Dg%7D%40mALeJ%60%40mETkKAiHTaCqAiCaReEySiQcaA_E%7DZoDem%40s%40iWeEqa%40sAmQoD%7Dk%40yBmU_DgGsFNsVjO_DbEcQzA%7BAxBkApAoDTuDNwDkBke%40kU_De%40ia%40qB%3FvBTx_A%3FlJwDVkt%40vEsQlAmJ%60A_SlAoDVwSbBwMv%40i%5C%5ClB%7D%40FeERqGc%60Ag%40eFmEml%40e%40sEcAgMGq%40MmCm%40gGu%40qJ%7DEan%40s%40sIsFyo%40wDsa%40UoDe%40kHu%40aLeFcn%40%7B%40wLGmBuDyO%7BAmG%7D%40aDaCsFsAmCqBoFqB%7DEoIyL%7BAgEm%40kFMiVWeY%3FaHe%40u%7DA%3FoGM%7BhA%3FuGG%7DHGy_AGcc%40%3FcGGmK%3FwZ%3FidAEwFO%7DmB%3FkB%3FgFOur%40Es%5EG%7BGGg%5C%5CWco%40%3FcF%3FwkCE_Ge%40%7DaAGaG%3F_IOkX%5DsaA%5Dgp%40%3FsEWge%40Uye%40GsDe%40_Xe%40k%5BWaNMoIOwIUgNWgM%3F%5Du%40e%60%40s%40wm%40u%40yWO_IwC_fBu%40k%5EyBajAkAmr%40UaLOeNMwFaCk%7CA%7D%40sd%40MgH%7D%40iXe%40cY%5DwQsByhAsEkiCsBaaAyBu%7E%40%3FaBEeFqCuzApGutAav%40aLsZuFgIuAsAkAfDmt%40xAi%5DVeFnHkzAbGuzA%7BAyAyBwByA%7DAiM%7BMeA_Acz%40y%7E%40sPwQeZ%7B%5BsKsPyBgDeKmXwC_LkA%7BEeE%7DSeEe_%40u%40eQ%5D_JaCuj%40%7D%40sPuEmaAU%7BDOeDcKmzBoD%7Bp%40%7DEw_Ae%40_Le%40sJiGodAsAsR%5DiEwTqeDs%40%7BLyGew%40OwB%7D%40mKsA%7BNoCc%5DcAyLm%40cIgOchB%7B%40%7DKu%40gJcQwtBm%40eHuJ_nAyB_Ys%40aKwDcf%40%5DcEu%40cK%7B%40qKwIyfAm%40gIm%40qLkAcYwCqm%40sGzAsEt%40cQpCeKoB%7D%5EeQkF_CiHgDqGsDeAi%40cAi%40eJyEwDyBjLyW%60CoIz%40qGaByHeAoDaMsg%40mEiUu%40sDMgA_DgRFgFbAiDl%40kAx%60%40co%40%7C%40eFNuFDiGzAi_B%3F_Cd%40g_%40%3FkA%3Fq%40t%40ar%40l%40kTjAsJbAcFjAwGzBqGvCuHd%40mA%7E%5D%7Bw%40bA%7BB%7CDeVtFClDbA%7CEr%40p%5C%5CbGFkFbA_pAnD%7DgFLcUFsSzAimBvDokHLwo%40%5C%5C%7Bc%40l%40ev%40E%7BNj%40mz%40EuXWsEgCy%5EoDwf%40eA%7DI%3FsMqGUs_An%40%7Dc%40xCoDR%7DDr%40gXvEaShDw%5D%7CIkK%7EB_JdCia%40dOoDjB%7DT%7CKc%5BtOgNxHkAmCoDgIkAmEyBcH_DcPe%40aJO%7DG%60HqjPcBcO%7DDqJcF_E_%5EdAaMZaCLqMh%40%7DIj%40%7DTr%40_%7CAzDmEOeZZkp%40h%40cKRkKPk%5C%5Cv%40_%5DfAoI%3FeKcAgr%40mL%7DNcEqXyE%7DTaGuOuGsUcRcQ%7BQsKqUwCpBaDnBiGtAsAyRqB_Y%7BAkKwIc%5DqGuOwCeIqa%40ydAyBiFwNi%5DkBuJsF%7DNcAeAbBuBjAuA_DiH%7DEoP%7BA_F%7B%40yBmUuj%40iCeGyAmCyGuQiR%7Dg%40wT%7Be%40eOeScLqMwMyLoNwHoDmBwIsH%7BFcDsFQwSsBFqAqB%7BBiCa%60%40%7BEka%40_Iud%40iNon%40yFoYwD%7Bt%40Nwg%40dE_c%40%60Gk%5C%5CtFkQtIuKs%40aDzJkR%60C%7DDvDmG%60GsJdFiH%7EC_DrU__%40hHaOlEiLdKuXlJuc%40bFcd%40hCkf%40%5C%5C%7B%60%40m%40g%5BsAoUcF_c%40kGkc%40e%40uCyLwd%40ePml%40mYqfAgDqL%7BAgGkPyn%40O%7DDcBiLmEa%5BkFqg%40aBeXeAkN%7BEay%40_%40%7BFsAgN%5DuCoCkXgD%7BQeF%7DMcFqKwIgJ%7BJgF_Oq%40qHx%40kFrA%7DDlDeKzM_DdGoD%7EKgDfPwHvl%40%7BAdE%7DY%7Cj%40yB%7BD%7BEaIgDgH%60BcDfDiHnD%7DHjAgITyMcAaQqBg%60%40kBqWEqAkAcPwDom%40Gy%40MsAeF_y%40%5DqFO%7BB%5D%7BFiBqZg%40aJ%60DcA%7EBu%40yAsTsF_%7D%40uEsCsAeF%7BF%7Bz%40oIilAyB%7BFUeH%5C%5CiFt%40Yd%40aADsAM%7DAm%40eAcAIOySbBiVpAeI%5EqNGkJu%40uL%7B%40kSkAsC%3F%7BAGcAG_Be%40cPWwFe%40qIEy%40sAaQsBq%5Es%40kTd%40mKhBkJnDkLhCkQfCac%40sP%7DBeKwEiM%7BHkPgIcFaBiHeBaHkAmE_%40sPl%40u%40NyLvAgJ%7B%40cVyH_X_K%7BF%7DCkFqEyCcFqB_%5C%5CaCaOaBmHmA%7BDeJiJyk%40_i%40cAaB%7BFcPsFsO%7DEgFmE%7BB%7BFKg%5DzK%5DNuEtAeFwZ%5DeDsAyWe%40qU%7BAgjAkAw%5Du%40cHcA%7BK%60CwCrZ%7D%5EdAiA%60BwBsAiEaB_FkBwJMyA_Ey%5BsFob%40uEy%5C%5C%7DD%7BWcB%7DKk%40%7BEu%40ok%40%3F%7DDu%40wGuDg%5Em%40qG%7DOqfBmTi%7EBkQenByBmVsL%7BrAsPakByQqjB%7BAb%40c%60%40%7CKmErAeFdBqWlJcVkxB%7BUcwBsP%7BzAsPg%7BAaCyTyMcjAm%40cGqL_eA%7D%40kHs%40qGgNsnAcMiiAyAqLaCt%40_c%40jOqR%7EFwIl%40mJFkZ%7BEd%40qBrEmRxC_%5EnIiE%60H_C%7EC%7DHd%40wJyB_SiWivBmEk%60%40%7BK_y%40%7D%40wGiBoSkBmKaGyIm_%40ua%40kGmEag%40cQwv%40i%5Bku%40cVdEuv%40vIgaBlc%40iAiLct%40%5D%7DDeAcKaCuLiBeOiH%7Dx%40qBsTiByJcGoMaCk%40sA%7DAmE_CaCuBcKqZoSyl%40_d%40%7D%7CAkF_QiRy%60%40cKiRoIyXiCgPcA%7BKsAei%40m%40eDyHq%60%40%7DXauAmKi%60%40wMy%60%40w%7C%40e%7DB%7Di%40c%7BAaBqDs%60%40xe%40e%7E%40meC_i%40ouAiu%40ihBg%5ErXmZ%7B%7C%40e_%40kbAwb%40s%7E%40_Sy_%40aCaH%7BU%7EFsVrI%7DJvGaHtBob%40oF%7BQdAmDyC_JoHcF_PsFcTiC_Q%7BAiTMoBm%40JmUbDoNb%40yGDsABeEFgDDeOOqXWeJqGqQoNoNsPkLeQyWoo%40mTiZ%7DTgWmU%7BRq_Agn%40k%60A_r%40qhB%7DdBw%7CAyyAsdAy%7D%40qeAs%7D%40yf%40mm%40q%5C%5Cmf%40aR%7DYofAyzAoSw%5DwN%7D%5DgNak%40uOuo%40qv%40ucEei%40yyB_%5E_%7CAam%40%7BnBeh%40gpB%3F_LsBgLyQup%40uYm%60A_JuVwMmTuPaSgaAqw%40eOuP%7DOuVku%40gzAwIiVgIyUsPq%7D%40q%60AcjFmPibA%7DYqxAgIsY_DwK%7BU_e%40c%5Bs%5EifAacAqa%40wb%40sy%40s%7D%40c%5Bqd%40%7B%5Bue%40o%5Eq%5E%7B_%40k%5C%5Cy%5C%5Cs%5Buc%40a%5E_m%40ii%40yMsHiMyBu%40k%40mErC%7DDxCkQj%40oIf%5DgHpUuE%7DDuy%40e_%40gHuCoc%40eSkAnAcAtCmAnZ_C%60f%40oD%7Ee%40GnQ%7DD%7CQyMr%7B%40%7B%40%60RmEfQkf%40ncBsKzPc%60%40%7Cw%40k%60%40zn%40qg%40zp%40qBnGOrG%7B%40nAkB%7EBs%40x%40sAa%40%7D%40c%40oN%60LsUzZoY%60%5Dwa%40vj%40ck%40dlAw%5DndAwD%7E%5DqL%7Eg%40yHtUqQxw%40uE%60%5EkGbj%40aGry%40uEp%5DoIziAcLhgAiMpaAsPfbAuO%60s%40sZbnAc%5C%5CjbAsU%60o%40wbAreCt%40pW%7BKvZ_TzNsP%7Ei%40sKx%60%40yGrXuJj%60%40aS%60%7D%40mT%7EoAiRlcAmOxr%40kVz%7B%40%7DJ%7C%5C%5CcUzl%40aIlTkFj_%40zQaX%7BBvHaLp%5C%5Cl%40%7CD%7BQnl%40uTd%5ByBxJu%40xF%7B%40rHyHtx%40aBhNuEnFqH%7E%40%7B%40%7D%40kBaBc%5B%7D%60%40kz%40yeA%7DY%7D%5C%5C%7DIqJoNiI%7D%40_%40%7BZyJqViKsGmCqL%7DEiSyMeYiXyLuL%7BFqJq%5Dwk%40ob%40im%40kFuJmJmQ_JsVoMen%40%7DJ%7DReAsB_DeGaHkNcAaDgDkKkF%7BLwC%7BE_JsR_IuS_DgIeAqC_CgPOmB%5DoBuEcP%7BAgF%7BA%7BD%7BEqJ_%40q%40eOk%5DyBgF_IqNu%40rAm%5E%7Cr%40kWtYrBdHOvIGvBwHc%40kL%40_%5EKqGo%5EgbAga%40%7Bi%40aLq%5D%7DQ_IvFk%5Br%40us%40_Aif%40sCwDjlAaBt%40sBBqBw%40_I%7BEeKqAsUeAmP%60FjBjLtJjo%40FnGkBrCiMfEaBtDfClp%40cZ%7BBc%5C%5C%7B%40oDIsZ%7EAgDnAaM%60Fux%40%7Cj%40oT%60KoMq%40%7BVrDq%5C%5ChTwr%40jq%40apAbbAwHvF%7DIzGc%5C%5CzPwNvDia%40%7CN%7BA_BwCwF%7DIbA_n%40%7CHse%40vIsP%7CCcu%40jMq%7B%40jHwb%40dAsk%40f%40iRIiRG%7Bd%40%5Eoh%40bCoc%40rEen%40xBwSrIwMdIaCclAgIkoC_n%40hn%40yQbWuEzCsAKsAs%40%7BAq%40k%40YaD%3FiBDsA%60AsArA%7BPlUgNbJo%7BAni%40m%7DAn%7B%40%7DyDvi%40mqFpp%40krGlt%40%7BZ%60CqH%60Vc%5Btg%40cQ%7DpAun%40wtEifAg_I%7Em%40mfK%7BlC%7BXkeD%60I%7BQp%40mx%40n%40_jCcy%40qjA%7DLqiGieA%7D%7BBwd%40qeAs%60%40yMeDcKx%40%7Bk%40dc%40st%40dVsZnQoNf%40%7Dd%40iL%7B%60%40uMy%5BmWsPkQgOgLmO_GiGuEoIaQk%60%40eh%40a%5DwH%7BAoIjAcRfJ_a%40d_%40cs%40d_%40g%7B%40bwBqoEvb%40yfAxa%40ibBpHsc%40lEqWt%40sXl%40wHtOwo%40%7CNiv%40dFiKtOoTvHsLlO_Yuh%40id%40i%7B%40gn%40gc%40eo%40%7D%7E%40gr%40oSgXcViQsZeOwNcKsPsOmPwVqGaOqRwl%40sV%7D%7C%40ajAs%7EBun%40gvAqnBk%7DBwlAyuAgkBweCig%40w%7C%40shAidCmrA%7D%7CDqg%40c%7CAayBgkFyGoHknFcjCmaCkw%40cLoH%7DgA%7BkAwoBoeAesAuc%40%7DrAiYaWkQ%7D%5Ecb%40_JcMmIsLc%5C%5C%7BVa%5C%5CwQ%7BKwHeU%60AyBvAce%40bKq%5C%5CbFwDhEcBxFs%40bQ%7D%40pt%40qBnNqLho%40wYdnAwWtnAmKpb%40eE%7EHe%40bAcV%60e%40uyH%60uFck%40zXyGVmKaKqjE_uEaS%7BNaMaCaRiJa_Beq%40sa%40%7D%5C%5Cke%40sVmn%40%7Dc%40iGmEyB%7DJme%40meAaa%40o%60AgSyb%40eFkGyGoGgh%40eOqLwHmOiMmE_MyBsmAyCcd%40oI%7B%60%40%7D%60BywF%7Bz%40ccCsu%40kmEeJ%7DjBqB_YaCkLiHu%60%40aLy%5D%7D_%40%7BgAqWgjAcLkn%40yV%7DwBgwA%7BnGqiB_pEyQ%7Di%40y%5C%5CseAiGsKom%40ws%40mO%7DIeiAy%60%40qGqDgOoNkKgOyBgFiBkGsLk%7C%40dEs%5BjQwv%40rFyS%7Dc%40in%40ePsYeUgk%40sAoGcAqG%5DmNGoSvDe%7BAxBui%40%60R%7BfCzEyqDiGqdAgXwdAguBsjEeUes%40cWyeBmn%40ksBuwAqrD%7By%40whCe%7DAikAsy%40yUimDymBiu%40g%5B%7BAoOiHce%40_Ied%40yHu%60%40cFqIwIoNaR_QgNw%40uOJcGo%40gSyG_O_Haf%40g%5BeUqJom%40wXePeJec%40ub%40k%5C%5C%7B%5B_b%40ma%40%7BVqVy%7B%40odAuw%40cl%40%7BxBqqAwWaZsk%40gx%40wg%40mx%40iHkMklCoaDeUatAcwBaxG%7DrAarCkj%40%7D%7B%40al%40gy%40_qBa%7EBcnBuoDsuDyrLkt%40_yEwI%7Bj%40se%40iyAouAcaCeZ_y%40ucAmvJuD_z%40uE_lAiC_OgSqKuTsFiw%40%7DLaBUiWqVaNqBaM%60HwH%7EK_InAqHs%40uTcKkk%40%7D%5ByA%7BD%7BG%5C%5Ce%5Eol%40%7Dd%40yiA%7B%40_A%7BAgEWoB%5DsIcAuj%40uO%7Da%40gOmC_%5DdP%7Bu%40uAoC%7Bk%40z%60%40%7Dg%40dEkJpQor%40%7ENaq%40%7CYevBjK%7B%7B%40%60I%7Bz%40jA%7BFlEmPnCkN%7EDyZdE_n%40l%40qR%60CiPlDoPzFoHjKmG%7COc%40EaTm%40uScBwY%7DD_g%40qCwSoDeToHq%5C%5CmJi%5B%7BPwa%40sVwb%40s%60%40me%40ig%40uh%40kd%40ag%40cVk%5C%5CsLf%40wNyFyLcSsK_XcLwOkLcHyjAeVu%7D%40wTy%7DB_dAqtBwg%40qq%40%60K_vFpj%40ko%40n%5C%5Cmi%40jGsu%40dA%7DlAuReoDk%60AqjBag%40atAaMmlByMgn%40wSoCqAcBgAyB%7DDkAuBcA_B%7BAy%40sF%7B%40%7DDsAyRkHkGyD_m%40%7D%60%40ksAa%5D_i%40af%40gNiS_IoJeZoe%40qLgXqCmKkFif%40T%7Bb%40vIaeAcAcLwDkEqBoF%5C%5C%7Dt%40%7BE%7Bc%40_YgqAsGce%40_HuiAoJ_l%40oMmm%40eFgQ%7BU%7Dv%40oNsf%40y%5C%5CkpB%7DSkhAwTmkAm%5EakBeFij%40yFaJgDqFuT%7D%5EsB%7CCmE%7EGeOhPsQlG%7BKz%40mTcE%7Bo%40oPuTs%40%7Bt%40kW_%5EcEab%40qHaM%7BC%7DJiCcQwFuIi%40oIe%40wDoB%7DICcQ%3FwIImOs%40oNgAs%60%40pAoDEcj%40kCeUIiMD_%5DtC%7Dy%40rIqa%40%60AmTgBmd%40%7EFyLlAuYvE%7DECwCB_Et%40tJqn%40nNedBhMknA%60C%7Dn%40%5C%5CaX_Dc%5Bm%40iGGgJvDuP_IqCkAa%40kBq%40q_Bej%40%7BAe%40sAi%40k%40%60DGX%3F%5C%5C%60HrjBFn%40%3FTOD%5DDwbAnWM%40WFk_ArXmDj%40g%40J%5DVkF%60Get%40%7Cz%40eT%7CV_%40%60%40Mv%40e%40jBWr%40%5Df%40yRjU%7DDvC%7BFbCyLlG%7DT%5EcQwEioBquA%7B%40uB%3FwDyBoA_EoCeDrAqWwQsa%40eYa%60Aiq%40_IwFgw%40_q%40O%7BBd%40gDwHqEoIqCWIyk%40%7Db%40aq%40id%40iB_B%7D%40w%40%5DwDkGcEkAIqRuAoNmAe%40hDcAhE%7BPq%40cQpAqR%60EiQrK%7DOhLyRrQke%40dc%40sj%40f_%40cBpBwCP%5C%5CsPcQl%40aHzDcV%60VgIjFqGnCg%7C%40%7EQqM%60AOvBu%40nr%40wC%60qBiH%60hC_Dno%40s%40xRm%40b%5C%5C%3Fvg%40d%40tu%40G%60z%40%7D%40dReD%7EUaCpUsKjrA%7DJn%7B%40m%40fL%5C%5Cvm%40Mth%40vWmQju%40uf%40xRqN%22%2C%22range%22%3Atrue%7D

[kevinkreiser]

I'm wondering if the url encoded polyline is somehow tripping this up. like perhaps undefined behavior can occur when the url decoded polyline gets polyline decoded into bogus values. have you tried POSTing this instead of GETting it? Avoiding url encoding issues is IMHO well worth the trouble of using POST